use borrow::Cow;
use io::{Read, Write};
use ops::{Deref, DerefMut};
use std::{borrow, error, fmt, io, mem, ops, result};
use crc32fast::Hasher as Crc32;
use flate2::write::ZlibEncoder;
use crate::chunk::{self, ChunkType};
use crate::common::{
AnimationControl, BitDepth, BlendOp, BytesPerPixel, ColorType, Compression, DisposeOp,
FrameControl, Info, ParameterError, ParameterErrorKind, PixelDimensions, ScaledFloat,
};
use crate::filter::{filter, AdaptiveFilterType, FilterType};
use crate::text_metadata::{
EncodableTextChunk, ITXtChunk, TEXtChunk, TextEncodingError, ZTXtChunk,
};
use crate::traits::WriteBytesExt;
pub type Result<T> = result::Result<T, EncodingError>;
#[derive(Debug)]
pub enum EncodingError {
IoError(io::Error),
Format(FormatError),
Parameter(ParameterError),
LimitsExceeded,
}
#[derive(Debug)]
pub struct FormatError {
inner: FormatErrorKind,
}
#[derive(Debug)]
enum FormatErrorKind {
ZeroWidth,
ZeroHeight,
InvalidColorCombination(BitDepth, ColorType),
NoPalette,
// TODO: wait, what?
WrittenTooMuch(usize),
NotAnimated,
OutOfBounds,
EndReached,
ZeroFrames,
MissingFrames,
MissingData(usize),
Unrecoverable,
BadTextEncoding(TextEncodingError),
}
impl error::Error for EncodingError {
fn cause(&self) -> Option<&(dyn error::Error + 'static)> {
match self {
EncodingError::IoError(err) => Some(err),
_ => None,
}
}
}
impl fmt::Display for EncodingError {
fn fmt(&self, fmt: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
use self::EncodingError::*;
match self {
IoError(err) => write!(fmt, "{}", err),
Format(desc) => write!(fmt, "{}", desc),
Parameter(desc) => write!(fmt, "{}", desc),
LimitsExceeded => write!(fmt, "Limits are exceeded."),
}
}
}
impl fmt::Display for FormatError {
fn fmt(&self, fmt: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
use FormatErrorKind::*;
match self.inner {
ZeroWidth => write!(fmt, "Zero width not allowed"),
ZeroHeight => write!(fmt, "Zero height not allowed"),
ZeroFrames => write!(fmt, "Zero frames not allowed"),
InvalidColorCombination(depth, color) => write!(
fmt,
"Invalid combination of bit-depth '{:?}' and color-type '{:?}'",
depth, color
),
NoPalette => write!(fmt, "can't write indexed image without palette"),
WrittenTooMuch(index) => write!(fmt, "wrong data size, got {} bytes too many", index),
NotAnimated => write!(fmt, "not an animation"),
OutOfBounds => write!(
fmt,
"the dimension and position go over the frame boundaries"
),
EndReached => write!(fmt, "all the frames have been already written"),
MissingFrames => write!(fmt, "there are still frames to be written"),
MissingData(n) => write!(fmt, "there are still {} bytes to be written", n),
Unrecoverable => write!(
fmt,
"a previous error put the writer into an unrecoverable state"
),
BadTextEncoding(tee) => match tee {
TextEncodingError::Unrepresentable => write!(
fmt,
"The text metadata cannot be encoded into valid ISO 8859-1"
),
TextEncodingError::InvalidKeywordSize => write!(fmt, "Invalid keyword size"),
TextEncodingError::CompressionError => {
write!(fmt, "Unable to compress text metadata")
}
},
}
}
}
impl From<io::Error> for EncodingError {
fn from(err: io::Error) -> EncodingError {
EncodingError::IoError(err)
}
}
impl From<EncodingError> for io::Error {
fn from(err: EncodingError) -> io::Error {
io::Error::new(io::ErrorKind::Other, err.to_string())
}
}
// Private impl.
impl From<FormatErrorKind> for FormatError {
fn from(kind: FormatErrorKind) -> Self {
FormatError { inner: kind }
}
}
impl From<TextEncodingError> for EncodingError {
fn from(tee: TextEncodingError) -> Self {
EncodingError::Format(FormatError {
inner: FormatErrorKind::BadTextEncoding(tee),
})
}
}
/// PNG Encoder.
///
/// This configures the PNG format options such as animation chunks, palette use, color types,
/// auxiliary chunks etc.
///
/// FIXME: Configuring APNG might be easier (less individual errors) if we had an _adapter_ which
/// borrows this mutably but guarantees that `info.frame_control` is not `None`.
pub struct Encoder<'a, W: Write> {
w: W,
info: Info<'a>,
options: Options,
}
/// Decoding options, internal type, forwarded to the Writer.
#[derive(Default)]
struct Options {
filter: FilterType,
adaptive_filter: AdaptiveFilterType,
sep_def_img: bool,
validate_sequence: bool,
}
impl<'a, W: Write> Encoder<'a, W> {
pub fn new(w: W, width: u32, height: u32) -> Encoder<'static, W> {
Encoder {
w,
info: Info::with_size(width, height),
options: Options::default(),
}
}
pub fn with_info(w: W, info: Info<'a>) -> Result<Encoder<'a, W>> {
if info.animation_control.is_some() != info.frame_control.is_some() {
return Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()));
}
if let Some(actl) = info.animation_control {
if actl.num_frames == 0 {
return Err(EncodingError::Format(FormatErrorKind::ZeroFrames.into()));
}
}
Ok(Encoder {
w,
info,
options: Options::default(),
})
}
/// Specify that the image is animated.
///
/// `num_frames` controls how many frames the animation has, while
/// `num_plays` controls how many times the animation should be
/// repeated until it stops, if it's zero then it will repeat
/// infinitely.
///
/// When this method is returns successfully then the images written will be encoded as fdAT
/// chunks, except for the first image that is still encoded as `IDAT`. You can control if the
/// first frame should be treated as an animation frame with [`Encoder::set_sep_def_img()`].
///
/// This method returns an error if `num_frames` is 0.
pub fn set_animated(&mut self, num_frames: u32, num_plays: u32) -> Result<()> {
if num_frames == 0 {
return Err(EncodingError::Format(FormatErrorKind::ZeroFrames.into()));
}
let actl = AnimationControl {
num_frames,
num_plays,
};
let fctl = FrameControl {
sequence_number: 0,
width: self.info.width,
height: self.info.height,
..Default::default()
};
self.info.animation_control = Some(actl);
self.info.frame_control = Some(fctl);
Ok(())
}
/// Mark the first animated frame as a 'separate default image'.
///
/// In APNG each animated frame is preceded by a special control chunk, `fcTL`. It's up to the
/// encoder to decide if the first image, the standard `IDAT` data, should be part of the
/// animation by emitting this chunk or by not doing so. A default image that is _not_ part of
/// the animation is often interpreted as a thumbnail.
///
/// This method will return an error when animation control was not configured
/// (which is done by calling [`Encoder::set_animated`]).
pub fn set_sep_def_img(&mut self, sep_def_img: bool) -> Result<()> {
if self.info.animation_control.is_some() {
self.options.sep_def_img = sep_def_img;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Sets the raw byte contents of the PLTE chunk. This method accepts
/// both borrowed and owned byte data.
pub fn set_palette<T: Into<Cow<'a, [u8]>>>(&mut self, palette: T) {
self.info.palette = Some(palette.into());
}
/// Sets the raw byte contents of the tRNS chunk. This method accepts
/// both borrowed and owned byte data.
pub fn set_trns<T: Into<Cow<'a, [u8]>>>(&mut self, trns: T) {
self.info.trns = Some(trns.into());
}
/// Set the display gamma of the source system on which the image was generated or last edited.
pub fn set_source_gamma(&mut self, source_gamma: ScaledFloat) {
self.info.source_gamma = Some(source_gamma);
}
/// Set the chromaticities for the source system's display channels (red, green, blue) and the whitepoint
/// of the source system on which the image was generated or last edited.
pub fn set_source_chromaticities(
&mut self,
source_chromaticities: super::SourceChromaticities,
) {
self.info.source_chromaticities = Some(source_chromaticities);
}
/// Mark the image data as conforming to the SRGB color space with the specified rendering intent.
///
/// Matching source gamma and chromaticities chunks are added automatically.
/// Any manually specified source gamma or chromaticities will be ignored.
pub fn set_srgb(&mut self, rendering_intent: super::SrgbRenderingIntent) {
self.info.srgb = Some(rendering_intent);
}
/// Start encoding by writing the header data.
///
/// The remaining data can be supplied by methods on the returned [`Writer`].
pub fn write_header(self) -> Result<Writer<W>> {
Writer::new(self.w, PartialInfo::new(&self.info), self.options).init(&self.info)
}
/// Set the color of the encoded image.
///
/// These correspond to the color types in the png IHDR data that will be written. The length
/// of the image data that is later supplied must match the color type, otherwise an error will
/// be emitted.
pub fn set_color(&mut self, color: ColorType) {
self.info.color_type = color;
}
/// Set the indicated depth of the image data.
pub fn set_depth(&mut self, depth: BitDepth) {
self.info.bit_depth = depth;
}
/// Set compression parameters.
///
/// Accepts a `Compression` or any type that can transform into a `Compression`. Notably `deflate::Compression` and
/// `deflate::CompressionOptions` which "just work".
pub fn set_compression(&mut self, compression: Compression) {
self.info.compression = compression;
}
/// Set the used filter type.
///
/// The default filter is [`FilterType::Sub`] which provides a basic prediction algorithm for
/// sample values based on the previous. For a potentially better compression ratio, at the
/// cost of more complex processing, try out [`FilterType::Paeth`].
///
/// [`FilterType::Sub`]: enum.FilterType.html#variant.Sub
/// [`FilterType::Paeth`]: enum.FilterType.html#variant.Paeth
pub fn set_filter(&mut self, filter: FilterType) {
self.options.filter = filter;
}
/// Set the adaptive filter type.
///
/// Adaptive filtering attempts to select the best filter for each line
/// based on heuristics which minimize the file size for compression rather
/// than use a single filter for the entire image. The default method is
/// [`AdaptiveFilterType::NonAdaptive`].
///
/// [`AdaptiveFilterType::NonAdaptive`]: enum.AdaptiveFilterType.html
pub fn set_adaptive_filter(&mut self, adaptive_filter: AdaptiveFilterType) {
self.options.adaptive_filter = adaptive_filter;
}
/// Set the fraction of time every frame is going to be displayed, in seconds.
///
/// *Note that this parameter can be set for each individual frame after
/// [`Encoder::write_header`] is called. (see [`Writer::set_frame_delay`])*
///
/// If the denominator is 0, it is to be treated as if it were 100
/// (that is, the numerator then specifies 1/100ths of a second).
/// If the the value of the numerator is 0 the decoder should render the next frame
/// as quickly as possible, though viewers may impose a reasonable lower bound.
///
/// The default value is 0 for both the numerator and denominator.
///
/// This method will return an error if the image is not animated.
/// (see [`set_animated`])
///
/// [`write_header`]: struct.Encoder.html#method.write_header
/// [`set_animated`]: struct.Encoder.html#method.set_animated
/// [`Writer::set_frame_delay`]: struct.Writer#method.set_frame_delay
pub fn set_frame_delay(&mut self, numerator: u16, denominator: u16) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
fctl.delay_den = denominator;
fctl.delay_num = numerator;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the blend operation for every frame.
///
/// The blend operation specifies whether the frame is to be alpha blended
/// into the current output buffer content, or whether it should completely
/// replace its region in the output buffer.
///
/// *Note that this parameter can be set for each individual frame after
/// [`write_header`] is called. (see [`Writer::set_blend_op`])*
///
/// See the [`BlendOp`] documentation for the possible values and their effects.
///
/// *Note that for the first frame the two blend modes are functionally
/// equivalent due to the clearing of the output buffer at the beginning
/// of each play.*
///
/// The default value is [`BlendOp::Source`].
///
/// This method will return an error if the image is not animated.
/// (see [`set_animated`])
///
/// [`BlendOP`]: enum.BlendOp.html
/// [`BlendOP::Source`]: enum.BlendOp.html#variant.Source
/// [`write_header`]: struct.Encoder.html#method.write_header
/// [`set_animated`]: struct.Encoder.html#method.set_animated
/// [`Writer::set_blend_op`]: struct.Writer#method.set_blend_op
pub fn set_blend_op(&mut self, op: BlendOp) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
fctl.blend_op = op;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the dispose operation for every frame.
///
/// The dispose operation specifies how the output buffer should be changed
/// at the end of the delay (before rendering the next frame)
///
/// *Note that this parameter can be set for each individual frame after
/// [`write_header`] is called (see [`Writer::set_dispose_op`])*
///
/// See the [`DisposeOp`] documentation for the possible values and their effects.
///
/// *Note that if the first frame uses [`DisposeOp::Previous`]
/// it will be treated as [`DisposeOp::Background`].*
///
/// The default value is [`DisposeOp::None`].
///
/// This method will return an error if the image is not animated.
/// (see [`set_animated`])
///
/// [`DisposeOp`]: ../common/enum.BlendOp.html
/// [`DisposeOp::Previous`]: ../common/enum.BlendOp.html#variant.Previous
/// [`DisposeOp::Background`]: ../common/enum.BlendOp.html#variant.Background
/// [`DisposeOp::None`]: ../common/enum.BlendOp.html#variant.None
/// [`write_header`]: struct.Encoder.html#method.write_header
/// [`set_animated`]: struct.Encoder.html#method.set_animated
/// [`Writer::set_dispose_op`]: struct.Writer#method.set_dispose_op
pub fn set_dispose_op(&mut self, op: DisposeOp) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
fctl.dispose_op = op;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
pub fn set_pixel_dims(&mut self, pixel_dims: Option<PixelDimensions>) {
self.info.pixel_dims = pixel_dims
}
/// Convenience function to add tEXt chunks to [`Info`] struct
pub fn add_text_chunk(&mut self, keyword: String, text: String) -> Result<()> {
let text_chunk = TEXtChunk::new(keyword, text);
self.info.uncompressed_latin1_text.push(text_chunk);
Ok(())
}
/// Convenience function to add zTXt chunks to [`Info`] struct
pub fn add_ztxt_chunk(&mut self, keyword: String, text: String) -> Result<()> {
let text_chunk = ZTXtChunk::new(keyword, text);
self.info.compressed_latin1_text.push(text_chunk);
Ok(())
}
/// Convenience function to add iTXt chunks to [`Info`] struct
///
/// This function only sets the `keyword` and `text` field of the iTXt chunk.
/// To set the other fields, create a [`ITXtChunk`] directly, and then encode it to the output stream.
pub fn add_itxt_chunk(&mut self, keyword: String, text: String) -> Result<()> {
let text_chunk = ITXtChunk::new(keyword, text);
self.info.utf8_text.push(text_chunk);
Ok(())
}
/// Validate the written image sequence.
///
/// When validation is turned on (it's turned off by default) then attempts to write more than
/// one `IDAT` image or images beyond the number of frames indicated in the animation control
/// chunk will fail and return an error result instead. Attempts to [finish][finish] the image
/// with missing frames will also return an error.
///
/// [finish]: StreamWriter::finish
///
/// (It's possible to circumvent these checks by writing raw chunks instead.)
pub fn validate_sequence(&mut self, validate: bool) {
self.options.validate_sequence = validate;
}
}
/// PNG writer
///
/// Progresses through the image by writing images, frames, or raw individual chunks. This is
/// constructed through [`Encoder::write_header()`].
///
/// FIXME: Writing of animated chunks might be clearer if we had an _adapter_ that you would call
/// to guarantee the next image to be prefaced with a fcTL-chunk, and all other chunks would be
/// guaranteed to be `IDAT`/not affected by APNG's frame control.
pub struct Writer<W: Write> {
/// The underlying writer.
w: W,
/// The local version of the `Info` struct.
info: PartialInfo,
/// Global encoding options.
options: Options,
/// The total number of image frames, counting all consecutive IDAT and fdAT chunks.
images_written: u64,
/// The total number of animation frames, that is equivalent to counting fcTL chunks.
animation_written: u32,
/// A flag to note when the IEND chunk was already added.
/// This is only set on code paths that drop `Self` to control the destructor.
iend_written: bool,
}
/// Contains the subset of attributes of [Info] needed for [Writer] to function
struct PartialInfo {
width: u32,
height: u32,
bit_depth: BitDepth,
color_type: ColorType,
frame_control: Option<FrameControl>,
animation_control: Option<AnimationControl>,
compression: Compression,
has_palette: bool,
}
impl PartialInfo {
fn new(info: &Info) -> Self {
PartialInfo {
width: info.width,
height: info.height,
bit_depth: info.bit_depth,
color_type: info.color_type,
frame_control: info.frame_control,
animation_control: info.animation_control,
compression: info.compression,
has_palette: info.palette.is_some(),
}
}
fn bpp_in_prediction(&self) -> BytesPerPixel {
// Passthrough
self.to_info().bpp_in_prediction()
}
fn raw_row_length(&self) -> usize {
// Passthrough
self.to_info().raw_row_length()
}
fn raw_row_length_from_width(&self, width: u32) -> usize {
// Passthrough
self.to_info().raw_row_length_from_width(width)
}
/// Converts this partial info to an owned Info struct,
/// setting missing values to their defaults
fn to_info(&self) -> Info<'static> {
Info {
width: self.width,
height: self.height,
bit_depth: self.bit_depth,
color_type: self.color_type,
frame_control: self.frame_control,
animation_control: self.animation_control,
compression: self.compression,
..Default::default()
}
}
}
const DEFAULT_BUFFER_LENGTH: usize = 4 * 1024;
pub(crate) fn write_chunk<W: Write>(mut w: W, name: chunk::ChunkType, data: &[u8]) -> Result<()> {
w.write_be(data.len() as u32)?;
w.write_all(&name.0)?;
w.write_all(data)?;
let mut crc = Crc32::new();
crc.update(&name.0);
crc.update(data);
w.write_be(crc.finalize())?;
Ok(())
}
impl<W: Write> Writer<W> {
fn new(w: W, info: PartialInfo, options: Options) -> Writer<W> {
Writer {
w,
info,
options,
images_written: 0,
animation_written: 0,
iend_written: false,
}
}
fn init(mut self, info: &Info<'_>) -> Result<Self> {
if self.info.width == 0 {
return Err(EncodingError::Format(FormatErrorKind::ZeroWidth.into()));
}
if self.info.height == 0 {
return Err(EncodingError::Format(FormatErrorKind::ZeroHeight.into()));
}
if self
.info
.color_type
.is_combination_invalid(self.info.bit_depth)
{
return Err(EncodingError::Format(
FormatErrorKind::InvalidColorCombination(self.info.bit_depth, self.info.color_type)
.into(),
));
}
self.w.write_all(&[137, 80, 78, 71, 13, 10, 26, 10])?; // PNG signature
info.encode(&mut self.w)?;
Ok(self)
}
/// Write a raw chunk of PNG data.
///
/// The chunk will have its CRC calculated and correctly. The data is not filtered in any way,
/// but the chunk needs to be short enough to have its length encoded correctly.
pub fn write_chunk(&mut self, name: ChunkType, data: &[u8]) -> Result<()> {
use std::convert::TryFrom;
if u32::try_from(data.len()).map_or(true, |length| length > i32::MAX as u32) {
let kind = FormatErrorKind::WrittenTooMuch(data.len() - i32::MAX as usize);
return Err(EncodingError::Format(kind.into()));
}
write_chunk(&mut self.w, name, data)
}
pub fn write_text_chunk<T: EncodableTextChunk>(&mut self, text_chunk: &T) -> Result<()> {
text_chunk.encode(&mut self.w)
}
/// Check if we should allow writing another image.
fn validate_new_image(&self) -> Result<()> {
if !self.options.validate_sequence {
return Ok(());
}
match self.info.animation_control {
None => {
if self.images_written == 0 {
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::EndReached.into()))
}
}
Some(_) => {
if self.info.frame_control.is_some() {
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::EndReached.into()))
}
}
}
}
fn validate_sequence_done(&self) -> Result<()> {
if !self.options.validate_sequence {
return Ok(());
}
if (self.info.animation_control.is_some() && self.info.frame_control.is_some())
|| self.images_written == 0
{
Err(EncodingError::Format(FormatErrorKind::MissingFrames.into()))
} else {
Ok(())
}
}
const MAX_IDAT_CHUNK_LEN: u32 = std::u32::MAX >> 1;
#[allow(non_upper_case_globals)]
const MAX_fdAT_CHUNK_LEN: u32 = (std::u32::MAX >> 1) - 4;
/// Writes the next image data.
pub fn write_image_data(&mut self, data: &[u8]) -> Result<()> {
if self.info.color_type == ColorType::Indexed && !self.info.has_palette {
return Err(EncodingError::Format(FormatErrorKind::NoPalette.into()));
}
self.validate_new_image()?;
let width: usize;
let height: usize;
if let Some(ref mut fctl) = self.info.frame_control {
width = fctl.width as usize;
height = fctl.height as usize;
} else {
width = self.info.width as usize;
height = self.info.height as usize;
}
let in_len = self.info.raw_row_length_from_width(width as u32) - 1;
let data_size = in_len * height;
if data_size != data.len() {
return Err(EncodingError::Parameter(
ParameterErrorKind::ImageBufferSize {
expected: data_size,
actual: data.len(),
}
.into(),
));
}
let prev = vec![0; in_len];
let mut prev = prev.as_slice();
let bpp = self.info.bpp_in_prediction();
let filter_method = self.options.filter;
let adaptive_method = self.options.adaptive_filter;
let zlib_encoded = match self.info.compression {
Compression::Fast => {
let mut compressor = fdeflate::Compressor::new(std::io::Cursor::new(Vec::new()))?;
let mut current = vec![0; in_len + 1];
for line in data.chunks(in_len) {
let filter_type = filter(
filter_method,
adaptive_method,
bpp,
prev,
line,
&mut current[1..],
);
current[0] = filter_type as u8;
compressor.write_data(¤t)?;
prev = line;
}
let compressed = compressor.finish()?.into_inner();
if compressed.len()
> fdeflate::StoredOnlyCompressor::<()>::compressed_size((in_len + 1) * height)
{
// Write uncompressed data since the result from fast compression would take
// more space than that.
//
// We always use FilterType::NoFilter here regardless of the filter method
// requested by the user. Doing filtering again would only add performance
// cost for both encoding and subsequent decoding, without improving the
// compression ratio.
let mut compressor =
fdeflate::StoredOnlyCompressor::new(std::io::Cursor::new(Vec::new()))?;
for line in data.chunks(in_len) {
compressor.write_data(&[0])?;
compressor.write_data(line)?;
}
compressor.finish()?.into_inner()
} else {
compressed
}
}
_ => {
let mut current = vec![0; in_len];
let mut zlib = ZlibEncoder::new(Vec::new(), self.info.compression.to_options());
for line in data.chunks(in_len) {
let filter_type = filter(
filter_method,
adaptive_method,
bpp,
prev,
line,
&mut current,
);
zlib.write_all(&[filter_type as u8])?;
zlib.write_all(¤t)?;
prev = line;
}
zlib.finish()?
}
};
match self.info.frame_control {
None => {
self.write_zlib_encoded_idat(&zlib_encoded)?;
}
Some(_) if self.should_skip_frame_control_on_default_image() => {
self.write_zlib_encoded_idat(&zlib_encoded)?;
}
Some(ref mut fctl) => {
fctl.encode(&mut self.w)?;
fctl.sequence_number = fctl.sequence_number.wrapping_add(1);
self.animation_written += 1;
// If the default image is the first frame of an animation, it's still an IDAT.
if self.images_written == 0 {
self.write_zlib_encoded_idat(&zlib_encoded)?;
} else {
let buff_size = zlib_encoded.len().min(Self::MAX_fdAT_CHUNK_LEN as usize);
let mut alldata = vec![0u8; 4 + buff_size];
for chunk in zlib_encoded.chunks(Self::MAX_fdAT_CHUNK_LEN as usize) {
alldata[..4].copy_from_slice(&fctl.sequence_number.to_be_bytes());
alldata[4..][..chunk.len()].copy_from_slice(chunk);
write_chunk(&mut self.w, chunk::fdAT, &alldata[..4 + chunk.len()])?;
fctl.sequence_number = fctl.sequence_number.wrapping_add(1);
}
}
}
}
self.increment_images_written();
Ok(())
}
fn increment_images_written(&mut self) {
self.images_written = self.images_written.saturating_add(1);
if let Some(actl) = self.info.animation_control {
if actl.num_frames <= self.animation_written {
// If we've written all animation frames, all following will be normal image chunks.
self.info.frame_control = None;
}
}
}
fn write_iend(&mut self) -> Result<()> {
self.iend_written = true;
self.write_chunk(chunk::IEND, &[])
}
fn should_skip_frame_control_on_default_image(&self) -> bool {
self.options.sep_def_img && self.images_written == 0
}
fn write_zlib_encoded_idat(&mut self, zlib_encoded: &[u8]) -> Result<()> {
for chunk in zlib_encoded.chunks(Self::MAX_IDAT_CHUNK_LEN as usize) {
self.write_chunk(chunk::IDAT, chunk)?;
}
Ok(())
}
/// Set the used filter type for the following frames.
///
/// The default filter is [`FilterType::Sub`] which provides a basic prediction algorithm for
/// sample values based on the previous. For a potentially better compression ratio, at the
/// cost of more complex processing, try out [`FilterType::Paeth`].
///
/// [`FilterType::Sub`]: enum.FilterType.html#variant.Sub
/// [`FilterType::Paeth`]: enum.FilterType.html#variant.Paeth
pub fn set_filter(&mut self, filter: FilterType) {
self.options.filter = filter;
}
/// Set the adaptive filter type for the following frames.
///
/// Adaptive filtering attempts to select the best filter for each line
/// based on heuristics which minimize the file size for compression rather
/// than use a single filter for the entire image. The default method is
/// [`AdaptiveFilterType::NonAdaptive`].
///
/// [`AdaptiveFilterType::NonAdaptive`]: enum.AdaptiveFilterType.html
pub fn set_adaptive_filter(&mut self, adaptive_filter: AdaptiveFilterType) {
self.options.adaptive_filter = adaptive_filter;
}
/// Set the fraction of time the following frames are going to be displayed,
/// in seconds
///
/// If the denominator is 0, it is to be treated as if it were 100
/// (that is, the numerator then specifies 1/100ths of a second).
/// If the the value of the numerator is 0 the decoder should render the next frame
/// as quickly as possible, though viewers may impose a reasonable lower bound.
///
/// This method will return an error if the image is not animated.
pub fn set_frame_delay(&mut self, numerator: u16, denominator: u16) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
fctl.delay_den = denominator;
fctl.delay_num = numerator;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the dimension of the following frames.
///
/// This function will return an error when:
/// - The image is not an animated;
///
/// - The selected dimension, considering also the current frame position,
/// goes outside the image boundaries;
///
/// - One or both the width and height are 0;
///
// ??? TODO ???
// - The next frame is the default image
pub fn set_frame_dimension(&mut self, width: u32, height: u32) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
if Some(width) > self.info.width.checked_sub(fctl.x_offset)
|| Some(height) > self.info.height.checked_sub(fctl.y_offset)
{
return Err(EncodingError::Format(FormatErrorKind::OutOfBounds.into()));
} else if width == 0 {
return Err(EncodingError::Format(FormatErrorKind::ZeroWidth.into()));
} else if height == 0 {
return Err(EncodingError::Format(FormatErrorKind::ZeroHeight.into()));
}
fctl.width = width;
fctl.height = height;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the position of the following frames.
///
/// An error will be returned if:
/// - The image is not animated;
///
/// - The selected position, considering also the current frame dimension,
/// goes outside the image boundaries;
///
// ??? TODO ???
// - The next frame is the default image
pub fn set_frame_position(&mut self, x: u32, y: u32) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
if Some(x) > self.info.width.checked_sub(fctl.width)
|| Some(y) > self.info.height.checked_sub(fctl.height)
{
return Err(EncodingError::Format(FormatErrorKind::OutOfBounds.into()));
}
fctl.x_offset = x;
fctl.y_offset = y;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the frame dimension to occupy all the image, starting from
/// the current position.
///
/// To reset the frame to the full image size [`reset_frame_position`]
/// should be called first.
///
/// This method will return an error if the image is not animated.
///
/// [`reset_frame_position`]: struct.Writer.html#method.reset_frame_position
pub fn reset_frame_dimension(&mut self) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
fctl.width = self.info.width - fctl.x_offset;
fctl.height = self.info.height - fctl.y_offset;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the frame position to (0, 0).
///
/// Equivalent to calling [`set_frame_position(0, 0)`].
///
/// This method will return an error if the image is not animated.
///
/// [`set_frame_position(0, 0)`]: struct.Writer.html#method.set_frame_position
pub fn reset_frame_position(&mut self) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
fctl.x_offset = 0;
fctl.y_offset = 0;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the blend operation for the following frames.
///
/// The blend operation specifies whether the frame is to be alpha blended
/// into the current output buffer content, or whether it should completely
/// replace its region in the output buffer.
///
/// See the [`BlendOp`] documentation for the possible values and their effects.
///
/// *Note that for the first frame the two blend modes are functionally
/// equivalent due to the clearing of the output buffer at the beginning
/// of each play.*
///
/// This method will return an error if the image is not animated.
///
/// [`BlendOP`]: enum.BlendOp.html
pub fn set_blend_op(&mut self, op: BlendOp) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
fctl.blend_op = op;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the dispose operation for the following frames.
///
/// The dispose operation specifies how the output buffer should be changed
/// at the end of the delay (before rendering the next frame)
///
/// See the [`DisposeOp`] documentation for the possible values and their effects.
///
/// *Note that if the first frame uses [`DisposeOp::Previous`]
/// it will be treated as [`DisposeOp::Background`].*
///
/// This method will return an error if the image is not animated.
///
/// [`DisposeOp`]: ../common/enum.BlendOp.html
/// [`DisposeOp::Previous`]: ../common/enum.BlendOp.html#variant.Previous
/// [`DisposeOp::Background`]: ../common/enum.BlendOp.html#variant.Background
pub fn set_dispose_op(&mut self, op: DisposeOp) -> Result<()> {
if let Some(ref mut fctl) = self.info.frame_control {
fctl.dispose_op = op;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Create a stream writer.
///
/// This allows you to create images that do not fit in memory. The default
/// chunk size is 4K, use `stream_writer_with_size` to set another chunk
/// size.
///
/// This borrows the writer which allows for manually appending additional
/// chunks after the image data has been written.
pub fn stream_writer(&mut self) -> Result<StreamWriter<W>> {
self.stream_writer_with_size(DEFAULT_BUFFER_LENGTH)
}
/// Create a stream writer with custom buffer size.
///
/// See [`stream_writer`].
///
/// [`stream_writer`]: #fn.stream_writer
pub fn stream_writer_with_size(&mut self, size: usize) -> Result<StreamWriter<W>> {
StreamWriter::new(ChunkOutput::Borrowed(self), size)
}
/// Turn this into a stream writer for image data.
///
/// This allows you to create images that do not fit in memory. The default
/// chunk size is 4K, use `stream_writer_with_size` to set another chunk
/// size.
pub fn into_stream_writer(self) -> Result<StreamWriter<'static, W>> {
self.into_stream_writer_with_size(DEFAULT_BUFFER_LENGTH)
}
/// Turn this into a stream writer with custom buffer size.
///
/// See [`into_stream_writer`].
///
/// [`into_stream_writer`]: #fn.into_stream_writer
pub fn into_stream_writer_with_size(self, size: usize) -> Result<StreamWriter<'static, W>> {
StreamWriter::new(ChunkOutput::Owned(self), size)
}
/// Consume the stream writer with validation.
///
/// Unlike a simple drop this ensures that the final chunk was written correctly. When other
/// validation options (chunk sequencing) had been turned on in the configuration then it will
/// also do a check on their correctness _before_ writing the final chunk.
pub fn finish(mut self) -> Result<()> {
self.validate_sequence_done()?;
self.write_iend()?;
self.w.flush()?;
// Explicitly drop `self` just for clarity.
drop(self);
Ok(())
}
}
impl<W: Write> Drop for Writer<W> {
fn drop(&mut self) {
if !self.iend_written {
let _ = self.write_iend();
}
}
}
enum ChunkOutput<'a, W: Write> {
Borrowed(&'a mut Writer<W>),
Owned(Writer<W>),
}
// opted for deref for practical reasons
impl<'a, W: Write> Deref for ChunkOutput<'a, W> {
type Target = Writer<W>;
fn deref(&self) -> &Self::Target {
match self {
ChunkOutput::Borrowed(writer) => writer,
ChunkOutput::Owned(writer) => writer,
}
}
}
impl<'a, W: Write> DerefMut for ChunkOutput<'a, W> {
fn deref_mut(&mut self) -> &mut Self::Target {
match self {
ChunkOutput::Borrowed(writer) => writer,
ChunkOutput::Owned(writer) => writer,
}
}
}
/// This writer is used between the actual writer and the
/// ZlibEncoder and has the job of packaging the compressed
/// data into a PNG chunk, based on the image metadata
///
/// Currently the way it works is that the specified buffer
/// will hold one chunk at the time and buffer the incoming
/// data until `flush` is called or the maximum chunk size
/// is reached.
///
/// The maximum chunk is the smallest between the selected buffer size
/// and `u32::MAX >> 1` (`0x7fffffff` or `2147483647` dec)
///
/// When a chunk has to be flushed the length (that is now known)
/// and the CRC will be written at the correct locations in the chunk.
struct ChunkWriter<'a, W: Write> {
writer: ChunkOutput<'a, W>,
buffer: Vec<u8>,
/// keeps track of where the last byte was written
index: usize,
curr_chunk: ChunkType,
}
impl<'a, W: Write> ChunkWriter<'a, W> {
fn new(writer: ChunkOutput<'a, W>, buf_len: usize) -> ChunkWriter<'a, W> {
// currently buf_len will determine the size of each chunk
// the len is capped to the maximum size every chunk can hold
// (this wont ever overflow an u32)
//
// TODO (maybe): find a way to hold two chunks at a time if `usize`
// is 64 bits.
const CAP: usize = std::u32::MAX as usize >> 1;
let curr_chunk = if writer.images_written == 0 {
chunk::IDAT
} else {
chunk::fdAT
};
ChunkWriter {
writer,
buffer: vec![0; CAP.min(buf_len)],
index: 0,
curr_chunk,
}
}
/// Returns the size of each scanline for the next frame
/// paired with the size of the whole frame
///
/// This is used by the `StreamWriter` to know when the scanline ends
/// so it can filter compress it and also to know when to start
/// the next one
fn next_frame_info(&self) -> (usize, usize) {
let wrt = self.writer.deref();
let width: usize;
let height: usize;
if let Some(fctl) = wrt.info.frame_control {
width = fctl.width as usize;
height = fctl.height as usize;
} else {
width = wrt.info.width as usize;
height = wrt.info.height as usize;
}
let in_len = wrt.info.raw_row_length_from_width(width as u32) - 1;
let data_size = in_len * height;
(in_len, data_size)
}
/// NOTE: this bypasses the internal buffer so the flush method should be called before this
/// in the case there is some data left in the buffer when this is called, it will panic
fn write_header(&mut self) -> Result<()> {
assert_eq!(self.index, 0, "Called when not flushed");
let wrt = self.writer.deref_mut();
self.curr_chunk = if wrt.images_written == 0 {
chunk::IDAT
} else {
chunk::fdAT
};
match wrt.info.frame_control {
Some(_) if wrt.should_skip_frame_control_on_default_image() => {}
Some(ref mut fctl) => {
fctl.encode(&mut wrt.w)?;
fctl.sequence_number += 1;
}
_ => {}
}
Ok(())
}
/// Set the `FrameControl` for the following frame
///
/// It will ignore the `sequence_number` of the parameter
/// as it is updated internally.
fn set_fctl(&mut self, f: FrameControl) {
if let Some(ref mut fctl) = self.writer.info.frame_control {
// Ignore the sequence number
*fctl = FrameControl {
sequence_number: fctl.sequence_number,
..f
};
} else {
panic!("This function must be called on an animated PNG")
}
}
/// Flushes the current chunk
fn flush_inner(&mut self) -> io::Result<()> {
if self.index > 0 {
// flush the chunk and reset everything
write_chunk(
&mut self.writer.w,
self.curr_chunk,
&self.buffer[..self.index],
)?;
self.index = 0;
}
Ok(())
}
}
impl<'a, W: Write> Write for ChunkWriter<'a, W> {
fn write(&mut self, mut data: &[u8]) -> io::Result<usize> {
if data.is_empty() {
return Ok(0);
}
// index == 0 means a chunk has been flushed out
if self.index == 0 {
let wrt = self.writer.deref_mut();
// Prepare the next animated frame, if any.
let no_fctl = wrt.should_skip_frame_control_on_default_image();
if wrt.info.frame_control.is_some() && !no_fctl {
let fctl = wrt.info.frame_control.as_mut().unwrap();
self.buffer[0..4].copy_from_slice(&fctl.sequence_number.to_be_bytes());
fctl.sequence_number += 1;
self.index = 4;
}
}
// Cap the buffer length to the maximum number of bytes that can't still
// be added to the current chunk
let written = data.len().min(self.buffer.len() - self.index);
data = &data[..written];
self.buffer[self.index..][..written].copy_from_slice(data);
self.index += written;
// if the maximum data for this chunk as been reached it needs to be flushed
if self.index == self.buffer.len() {
self.flush_inner()?;
}
Ok(written)
}
fn flush(&mut self) -> io::Result<()> {
self.flush_inner()
}
}
impl<W: Write> Drop for ChunkWriter<'_, W> {
fn drop(&mut self) {
let _ = self.flush();
}
}
// TODO: find a better name
//
/// This enum is used to be allow the `StreamWriter` to keep
/// its inner `ChunkWriter` without wrapping it inside a
/// `ZlibEncoder`. This is used in the case that between the
/// change of state that happens when the last write of a frame
/// is performed an error occurs, which obviously has to be returned.
/// This creates the problem of where to store the writer before
/// exiting the function, and this is where `Wrapper` comes in.
///
/// Unfortunately the `ZlibWriter` can't be used because on the
/// write following the error, `finish` would be called and that
/// would write some data even if 0 bytes where compressed.
///
/// If the `finish` function fails then there is nothing much to
/// do as the `ChunkWriter` would get lost so the `Unrecoverable`
/// variant is used to signal that.
enum Wrapper<'a, W: Write> {
Chunk(ChunkWriter<'a, W>),
Zlib(ZlibEncoder<ChunkWriter<'a, W>>),
Unrecoverable,
/// This is used in-between, should never be matched
None,
}
impl<'a, W: Write> Wrapper<'a, W> {
/// Like `Option::take` this returns the `Wrapper` contained
/// in `self` and replaces it with `Wrapper::None`
fn take(&mut self) -> Wrapper<'a, W> {
let mut swap = Wrapper::None;
mem::swap(self, &mut swap);
swap
}
}
/// Streaming PNG writer
///
/// This may silently fail in the destructor, so it is a good idea to call
/// [`finish`](#method.finish) or [`flush`] before dropping.
///
/// [`flush`]: https://doc.rust-lang.org/stable/std/io/trait.Write.html#tymethod.flush
pub struct StreamWriter<'a, W: Write> {
/// The option here is needed in order to access the inner `ChunkWriter` in-between
/// each frame, which is needed for writing the fcTL chunks between each frame
writer: Wrapper<'a, W>,
prev_buf: Vec<u8>,
curr_buf: Vec<u8>,
/// Amount of data already written
index: usize,
/// length of the current scanline
line_len: usize,
/// size of the frame (width * height * sample_size)
to_write: usize,
width: u32,
height: u32,
bpp: BytesPerPixel,
filter: FilterType,
adaptive_filter: AdaptiveFilterType,
fctl: Option<FrameControl>,
compression: Compression,
}
impl<'a, W: Write> StreamWriter<'a, W> {
fn new(writer: ChunkOutput<'a, W>, buf_len: usize) -> Result<StreamWriter<'a, W>> {
let PartialInfo {
width,
height,
frame_control: fctl,
compression,
..
} = writer.info;
let bpp = writer.info.bpp_in_prediction();
let in_len = writer.info.raw_row_length() - 1;
let filter = writer.options.filter;
let adaptive_filter = writer.options.adaptive_filter;
let prev_buf = vec![0; in_len];
let curr_buf = vec![0; in_len];
let mut chunk_writer = ChunkWriter::new(writer, buf_len);
let (line_len, to_write) = chunk_writer.next_frame_info();
chunk_writer.write_header()?;
let zlib = ZlibEncoder::new(chunk_writer, compression.to_options());
Ok(StreamWriter {
writer: Wrapper::Zlib(zlib),
index: 0,
prev_buf,
curr_buf,
bpp,
filter,
width,
height,
adaptive_filter,
line_len,
to_write,
fctl,
compression,
})
}
/// Set the used filter type for the next frame.
///
/// The default filter is [`FilterType::Sub`] which provides a basic prediction algorithm for
/// sample values based on the previous. For a potentially better compression ratio, at the
/// cost of more complex processing, try out [`FilterType::Paeth`].
///
/// [`FilterType::Sub`]: enum.FilterType.html#variant.Sub
/// [`FilterType::Paeth`]: enum.FilterType.html#variant.Paeth
pub fn set_filter(&mut self, filter: FilterType) {
self.filter = filter;
}
/// Set the adaptive filter type for the next frame.
///
/// Adaptive filtering attempts to select the best filter for each line
/// based on heuristics which minimize the file size for compression rather
/// than use a single filter for the entire image. The default method is
/// [`AdaptiveFilterType::NonAdaptive`].
///
/// [`AdaptiveFilterType::NonAdaptive`]: enum.AdaptiveFilterType.html
pub fn set_adaptive_filter(&mut self, adaptive_filter: AdaptiveFilterType) {
self.adaptive_filter = adaptive_filter;
}
/// Set the fraction of time the following frames are going to be displayed,
/// in seconds
///
/// If the denominator is 0, it is to be treated as if it were 100
/// (that is, the numerator then specifies 1/100ths of a second).
/// If the the value of the numerator is 0 the decoder should render the next frame
/// as quickly as possible, though viewers may impose a reasonable lower bound.
///
/// This method will return an error if the image is not animated.
pub fn set_frame_delay(&mut self, numerator: u16, denominator: u16) -> Result<()> {
if let Some(ref mut fctl) = self.fctl {
fctl.delay_den = denominator;
fctl.delay_num = numerator;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the dimension of the following frames.
///
/// This function will return an error when:
/// - The image is not an animated;
///
/// - The selected dimension, considering also the current frame position,
/// goes outside the image boundaries;
///
/// - One or both the width and height are 0;
///
pub fn set_frame_dimension(&mut self, width: u32, height: u32) -> Result<()> {
if let Some(ref mut fctl) = self.fctl {
if Some(width) > self.width.checked_sub(fctl.x_offset)
|| Some(height) > self.height.checked_sub(fctl.y_offset)
{
return Err(EncodingError::Format(FormatErrorKind::OutOfBounds.into()));
} else if width == 0 {
return Err(EncodingError::Format(FormatErrorKind::ZeroWidth.into()));
} else if height == 0 {
return Err(EncodingError::Format(FormatErrorKind::ZeroHeight.into()));
}
fctl.width = width;
fctl.height = height;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the position of the following frames.
///
/// An error will be returned if:
/// - The image is not animated;
///
/// - The selected position, considering also the current frame dimension,
/// goes outside the image boundaries;
///
pub fn set_frame_position(&mut self, x: u32, y: u32) -> Result<()> {
if let Some(ref mut fctl) = self.fctl {
if Some(x) > self.width.checked_sub(fctl.width)
|| Some(y) > self.height.checked_sub(fctl.height)
{
return Err(EncodingError::Format(FormatErrorKind::OutOfBounds.into()));
}
fctl.x_offset = x;
fctl.y_offset = y;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the frame dimension to occupy all the image, starting from
/// the current position.
///
/// To reset the frame to the full image size [`reset_frame_position`]
/// should be called first.
///
/// This method will return an error if the image is not animated.
///
/// [`reset_frame_position`]: struct.Writer.html#method.reset_frame_position
pub fn reset_frame_dimension(&mut self) -> Result<()> {
if let Some(ref mut fctl) = self.fctl {
fctl.width = self.width - fctl.x_offset;
fctl.height = self.height - fctl.y_offset;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the frame position to (0, 0).
///
/// Equivalent to calling [`set_frame_position(0, 0)`].
///
/// This method will return an error if the image is not animated.
///
/// [`set_frame_position(0, 0)`]: struct.Writer.html#method.set_frame_position
pub fn reset_frame_position(&mut self) -> Result<()> {
if let Some(ref mut fctl) = self.fctl {
fctl.x_offset = 0;
fctl.y_offset = 0;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the blend operation for the following frames.
///
/// The blend operation specifies whether the frame is to be alpha blended
/// into the current output buffer content, or whether it should completely
/// replace its region in the output buffer.
///
/// See the [`BlendOp`] documentation for the possible values and their effects.
///
/// *Note that for the first frame the two blend modes are functionally
/// equivalent due to the clearing of the output buffer at the beginning
/// of each play.*
///
/// This method will return an error if the image is not animated.
///
/// [`BlendOP`]: enum.BlendOp.html
pub fn set_blend_op(&mut self, op: BlendOp) -> Result<()> {
if let Some(ref mut fctl) = self.fctl {
fctl.blend_op = op;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Set the dispose operation for the following frames.
///
/// The dispose operation specifies how the output buffer should be changed
/// at the end of the delay (before rendering the next frame)
///
/// See the [`DisposeOp`] documentation for the possible values and their effects.
///
/// *Note that if the first frame uses [`DisposeOp::Previous`]
/// it will be treated as [`DisposeOp::Background`].*
///
/// This method will return an error if the image is not animated.
///
/// [`DisposeOp`]: ../common/enum.BlendOp.html
/// [`DisposeOp::Previous`]: ../common/enum.BlendOp.html#variant.Previous
/// [`DisposeOp::Background`]: ../common/enum.BlendOp.html#variant.Background
pub fn set_dispose_op(&mut self, op: DisposeOp) -> Result<()> {
if let Some(ref mut fctl) = self.fctl {
fctl.dispose_op = op;
Ok(())
} else {
Err(EncodingError::Format(FormatErrorKind::NotAnimated.into()))
}
}
/// Consume the stream writer with validation.
///
/// Unlike a simple drop this ensures that the all data was written correctly. When other
/// validation options (chunk sequencing) had been turned on in the configuration of inner
/// [`Writer`], then it will also do a check on their correctness. Differently from
/// [`Writer::finish`], this just `flush`es, returns error if some data is abandoned.
pub fn finish(mut self) -> Result<()> {
if self.to_write > 0 {
let err = FormatErrorKind::MissingData(self.to_write).into();
return Err(EncodingError::Format(err));
}
// TODO: call `writer.finish` somehow?
self.flush()?;
if let Wrapper::Chunk(wrt) = self.writer.take() {
wrt.writer.validate_sequence_done()?;
}
Ok(())
}
/// Flushes the buffered chunk, checks if it was the last frame,
/// writes the next frame header and gets the next frame scanline size
/// and image size.
/// NOTE: This method must only be called when the writer is the variant Chunk(_)
fn new_frame(&mut self) -> Result<()> {
let wrt = match &mut self.writer {
Wrapper::Chunk(wrt) => wrt,
Wrapper::Unrecoverable => {
let err = FormatErrorKind::Unrecoverable.into();
return Err(EncodingError::Format(err));
}
Wrapper::Zlib(_) => unreachable!("never called on a half-finished frame"),
Wrapper::None => unreachable!(),
};
wrt.flush()?;
wrt.writer.validate_new_image()?;
if let Some(fctl) = self.fctl {
wrt.set_fctl(fctl);
}
let (scansize, size) = wrt.next_frame_info();
self.line_len = scansize;
self.to_write = size;
wrt.write_header()?;
wrt.writer.increment_images_written();
// now it can be taken because the next statements cannot cause any errors
match self.writer.take() {
Wrapper::Chunk(wrt) => {
let encoder = ZlibEncoder::new(wrt, self.compression.to_options());
self.writer = Wrapper::Zlib(encoder);
}
_ => unreachable!(),
};
Ok(())
}
}
impl<'a, W: Write> Write for StreamWriter<'a, W> {
fn write(&mut self, mut data: &[u8]) -> io::Result<usize> {
if let Wrapper::Unrecoverable = self.writer {
let err = FormatErrorKind::Unrecoverable.into();
return Err(EncodingError::Format(err).into());
}
if data.is_empty() {
return Ok(0);
}
if self.to_write == 0 {
match self.writer.take() {
Wrapper::Zlib(wrt) => match wrt.finish() {
Ok(chunk) => self.writer = Wrapper::Chunk(chunk),
Err(err) => {
self.writer = Wrapper::Unrecoverable;
return Err(err);
}
},
chunk @ Wrapper::Chunk(_) => self.writer = chunk,
Wrapper::Unrecoverable => unreachable!(),
Wrapper::None => unreachable!(),
};
// Transition Wrapper::Chunk to Wrapper::Zlib.
self.new_frame()?;
}
let written = data.read(&mut self.curr_buf[..self.line_len][self.index..])?;
self.index += written;
self.to_write -= written;
if self.index == self.line_len {
// TODO: reuse this buffer between rows.
let mut filtered = vec![0; self.curr_buf.len()];
let filter_type = filter(
self.filter,
self.adaptive_filter,
self.bpp,
&self.prev_buf,
&self.curr_buf,
&mut filtered,
);
// This can't fail as the other variant is used only to allow the zlib encoder to finish
let wrt = match &mut self.writer {
Wrapper::Zlib(wrt) => wrt,
_ => unreachable!(),
};
wrt.write_all(&[filter_type as u8])?;
wrt.write_all(&filtered)?;
mem::swap(&mut self.prev_buf, &mut self.curr_buf);
self.index = 0;
}
Ok(written)
}
fn flush(&mut self) -> io::Result<()> {
match &mut self.writer {
Wrapper::Zlib(wrt) => wrt.flush()?,
Wrapper::Chunk(wrt) => wrt.flush()?,
// This handles both the case where we entered an unrecoverable state after zlib
// decoding failure and after a panic while we had taken the chunk/zlib reader.
Wrapper::Unrecoverable | Wrapper::None => {
let err = FormatErrorKind::Unrecoverable.into();
return Err(EncodingError::Format(err).into());
}
}
if self.index > 0 {
let err = FormatErrorKind::WrittenTooMuch(self.index).into();
return Err(EncodingError::Format(err).into());
}
Ok(())
}
}
impl<W: Write> Drop for StreamWriter<'_, W> {
fn drop(&mut self) {
let _ = self.flush();
}
}
/// Mod to encapsulate the converters depending on the `deflate` crate.
///
/// Since this only contains trait impls, there is no need to make this public, they are simply
/// available when the mod is compiled as well.
impl Compression {
fn to_options(self) -> flate2::Compression {
#[allow(deprecated)]
match self {
Compression::Default => flate2::Compression::default(),
Compression::Fast => flate2::Compression::fast(),
Compression::Best => flate2::Compression::best(),
#[allow(deprecated)]
Compression::Huffman => flate2::Compression::none(),
#[allow(deprecated)]
Compression::Rle => flate2::Compression::none(),
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::Decoder;
use rand::{thread_rng, Rng};
use std::fs::File;
use std::io::{Cursor, Write};
use std::{cmp, io};
#[test]
fn roundtrip() {
// More loops = more random testing, but also more test wait time
for _ in 0..10 {
for path in glob::glob("tests/pngsuite/*.png")
.unwrap()
.map(|r| r.unwrap())
{
if path.file_name().unwrap().to_str().unwrap().starts_with('x') {
// x* files are expected to fail to decode
continue;
}
eprintln!("{}", path.display());
// Decode image
let decoder = Decoder::new(File::open(path).unwrap());
let mut reader = decoder.read_info().unwrap();
let mut buf = vec![0; reader.output_buffer_size()];
let info = reader.next_frame(&mut buf).unwrap();
// Encode decoded image
let mut out = Vec::new();
{
let mut wrapper = RandomChunkWriter {
rng: thread_rng(),
w: &mut out,
};
let mut encoder = Encoder::new(&mut wrapper, info.width, info.height);
encoder.set_color(info.color_type);
encoder.set_depth(info.bit_depth);
if let Some(palette) = &reader.info().palette {
encoder.set_palette(palette.clone());
}
let mut encoder = encoder.write_header().unwrap();
encoder.write_image_data(&buf).unwrap();
}
// Decode encoded decoded image
let decoder = Decoder::new(&*out);
let mut reader = decoder.read_info().unwrap();
let mut buf2 = vec![0; reader.output_buffer_size()];
reader.next_frame(&mut buf2).unwrap();
// check if the encoded image is ok:
assert_eq!(buf, buf2);
}
}
}
#[test]
fn roundtrip_stream() {
// More loops = more random testing, but also more test wait time
for _ in 0..10 {
for path in glob::glob("tests/pngsuite/*.png")
.unwrap()
.map(|r| r.unwrap())
{
if path.file_name().unwrap().to_str().unwrap().starts_with('x') {
// x* files are expected to fail to decode
continue;
}
// Decode image
let decoder = Decoder::new(File::open(path).unwrap());
let mut reader = decoder.read_info().unwrap();
let mut buf = vec![0; reader.output_buffer_size()];
let info = reader.next_frame(&mut buf).unwrap();
// Encode decoded image
let mut out = Vec::new();
{
let mut wrapper = RandomChunkWriter {
rng: thread_rng(),
w: &mut out,
};
let mut encoder = Encoder::new(&mut wrapper, info.width, info.height);
encoder.set_color(info.color_type);
encoder.set_depth(info.bit_depth);
if let Some(palette) = &reader.info().palette {
encoder.set_palette(palette.clone());
}
let mut encoder = encoder.write_header().unwrap();
let mut stream_writer = encoder.stream_writer().unwrap();
let mut outer_wrapper = RandomChunkWriter {
rng: thread_rng(),
w: &mut stream_writer,
};
outer_wrapper.write_all(&buf).unwrap();
}
// Decode encoded decoded image
let decoder = Decoder::new(&*out);
let mut reader = decoder.read_info().unwrap();
let mut buf2 = vec![0; reader.output_buffer_size()];
reader.next_frame(&mut buf2).unwrap();
// check if the encoded image is ok:
assert_eq!(buf, buf2);
}
}
}
#[test]
fn image_palette() -> Result<()> {
for &bit_depth in &[1u8, 2, 4, 8] {
// Do a reference decoding, choose a fitting palette image from pngsuite
let path = format!("tests/pngsuite/basn3p0{}.png", bit_depth);
let decoder = Decoder::new(File::open(&path).unwrap());
let mut reader = decoder.read_info().unwrap();
let mut decoded_pixels = vec![0; reader.output_buffer_size()];
let info = reader.info();
assert_eq!(
info.width as usize * info.height as usize * usize::from(bit_depth),
decoded_pixels.len() * 8
);
let info = reader.next_frame(&mut decoded_pixels).unwrap();
let indexed_data = decoded_pixels;
let palette = reader.info().palette.as_ref().unwrap();
let mut out = Vec::new();
{
let mut encoder = Encoder::new(&mut out, info.width, info.height);
encoder.set_depth(BitDepth::from_u8(bit_depth).unwrap());
encoder.set_color(ColorType::Indexed);
encoder.set_palette(palette.as_ref());
let mut writer = encoder.write_header().unwrap();
writer.write_image_data(&indexed_data).unwrap();
}
// Decode re-encoded image
let decoder = Decoder::new(&*out);
let mut reader = decoder.read_info().unwrap();
let mut redecoded = vec![0; reader.output_buffer_size()];
reader.next_frame(&mut redecoded).unwrap();
// check if the encoded image is ok:
assert_eq!(indexed_data, redecoded);
}
Ok(())
}
#[test]
fn expect_error_on_wrong_image_len() -> Result<()> {
let width = 10;
let height = 10;
let output = vec![0u8; 1024];
let writer = Cursor::new(output);
let mut encoder = Encoder::new(writer, width as u32, height as u32);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Rgb);
let mut png_writer = encoder.write_header()?;
let correct_image_size = width * height * 3;
let image = vec![0u8; correct_image_size + 1];
let result = png_writer.write_image_data(image.as_ref());
assert!(result.is_err());
Ok(())
}
#[test]
fn expect_error_on_empty_image() -> Result<()> {
let output = vec![0u8; 1024];
let mut writer = Cursor::new(output);
let encoder = Encoder::new(&mut writer, 0, 0);
assert!(encoder.write_header().is_err());
let encoder = Encoder::new(&mut writer, 100, 0);
assert!(encoder.write_header().is_err());
let encoder = Encoder::new(&mut writer, 0, 100);
assert!(encoder.write_header().is_err());
Ok(())
}
#[test]
fn expect_error_on_invalid_bit_depth_color_type_combination() -> Result<()> {
let output = vec![0u8; 1024];
let mut writer = Cursor::new(output);
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::One);
encoder.set_color(ColorType::Rgb);
assert!(encoder.write_header().is_err());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::One);
encoder.set_color(ColorType::GrayscaleAlpha);
assert!(encoder.write_header().is_err());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::One);
encoder.set_color(ColorType::Rgba);
assert!(encoder.write_header().is_err());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Two);
encoder.set_color(ColorType::Rgb);
assert!(encoder.write_header().is_err());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Two);
encoder.set_color(ColorType::GrayscaleAlpha);
assert!(encoder.write_header().is_err());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Two);
encoder.set_color(ColorType::Rgba);
assert!(encoder.write_header().is_err());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Four);
encoder.set_color(ColorType::Rgb);
assert!(encoder.write_header().is_err());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Four);
encoder.set_color(ColorType::GrayscaleAlpha);
assert!(encoder.write_header().is_err());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Four);
encoder.set_color(ColorType::Rgba);
assert!(encoder.write_header().is_err());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Sixteen);
encoder.set_color(ColorType::Indexed);
assert!(encoder.write_header().is_err());
Ok(())
}
#[test]
fn can_write_header_with_valid_bit_depth_color_type_combination() -> Result<()> {
let output = vec![0u8; 1024];
let mut writer = Cursor::new(output);
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::One);
encoder.set_color(ColorType::Grayscale);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::One);
encoder.set_color(ColorType::Indexed);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Two);
encoder.set_color(ColorType::Grayscale);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Two);
encoder.set_color(ColorType::Indexed);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Four);
encoder.set_color(ColorType::Grayscale);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Four);
encoder.set_color(ColorType::Indexed);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Rgb);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Indexed);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::GrayscaleAlpha);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Rgba);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Sixteen);
encoder.set_color(ColorType::Grayscale);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Sixteen);
encoder.set_color(ColorType::Rgb);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Sixteen);
encoder.set_color(ColorType::GrayscaleAlpha);
assert!(encoder.write_header().is_ok());
let mut encoder = Encoder::new(&mut writer, 1, 1);
encoder.set_depth(BitDepth::Sixteen);
encoder.set_color(ColorType::Rgba);
assert!(encoder.write_header().is_ok());
Ok(())
}
#[test]
fn all_filters_roundtrip() -> io::Result<()> {
let pixel: Vec<_> = (0..48).collect();
let roundtrip = |filter: FilterType| -> io::Result<()> {
let mut buffer = vec![];
let mut encoder = Encoder::new(&mut buffer, 4, 4);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Rgb);
encoder.set_filter(filter);
encoder.write_header()?.write_image_data(&pixel)?;
let decoder = crate::Decoder::new(Cursor::new(buffer));
let mut reader = decoder.read_info()?;
let info = reader.info();
assert_eq!(info.width, 4);
assert_eq!(info.height, 4);
let mut dest = vec![0; pixel.len()];
reader.next_frame(&mut dest)?;
assert_eq!(dest, pixel, "Deviation with filter type {:?}", filter);
Ok(())
};
roundtrip(FilterType::NoFilter)?;
roundtrip(FilterType::Sub)?;
roundtrip(FilterType::Up)?;
roundtrip(FilterType::Avg)?;
roundtrip(FilterType::Paeth)?;
Ok(())
}
#[test]
fn some_gamma_roundtrip() -> io::Result<()> {
let pixel: Vec<_> = (0..48).collect();
let roundtrip = |gamma: Option<ScaledFloat>| -> io::Result<()> {
let mut buffer = vec![];
let mut encoder = Encoder::new(&mut buffer, 4, 4);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Rgb);
encoder.set_filter(FilterType::Avg);
if let Some(gamma) = gamma {
encoder.set_source_gamma(gamma);
}
encoder.write_header()?.write_image_data(&pixel)?;
let decoder = crate::Decoder::new(Cursor::new(buffer));
let mut reader = decoder.read_info()?;
assert_eq!(
reader.info().source_gamma,
gamma,
"Deviation with gamma {:?}",
gamma
);
let mut dest = vec![0; pixel.len()];
let info = reader.next_frame(&mut dest)?;
assert_eq!(info.width, 4);
assert_eq!(info.height, 4);
Ok(())
};
roundtrip(None)?;
roundtrip(Some(ScaledFloat::new(0.35)))?;
roundtrip(Some(ScaledFloat::new(0.45)))?;
roundtrip(Some(ScaledFloat::new(0.55)))?;
roundtrip(Some(ScaledFloat::new(0.7)))?;
roundtrip(Some(ScaledFloat::new(1.0)))?;
roundtrip(Some(ScaledFloat::new(2.5)))?;
Ok(())
}
#[test]
fn write_image_chunks_beyond_first() -> Result<()> {
let width = 10;
let height = 10;
let output = vec![0u8; 1024];
let writer = Cursor::new(output);
// Not an animation but we should still be able to write multiple images
// See issue: <https://github.com/image-rs/image-png/issues/301>
// This is technically all valid png so there is no issue with correctness.
let mut encoder = Encoder::new(writer, width, height);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
let mut png_writer = encoder.write_header()?;
for _ in 0..3 {
let correct_image_size = (width * height) as usize;
let image = vec![0u8; correct_image_size];
png_writer.write_image_data(image.as_ref())?;
}
Ok(())
}
#[test]
fn image_validate_sequence_without_animation() -> Result<()> {
let width = 10;
let height = 10;
let output = vec![0u8; 1024];
let writer = Cursor::new(output);
let mut encoder = Encoder::new(writer, width, height);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
encoder.validate_sequence(true);
let mut png_writer = encoder.write_header()?;
let correct_image_size = (width * height) as usize;
let image = vec![0u8; correct_image_size];
png_writer.write_image_data(image.as_ref())?;
assert!(png_writer.write_image_data(image.as_ref()).is_err());
Ok(())
}
#[test]
fn image_validate_animation() -> Result<()> {
let width = 10;
let height = 10;
let output = vec![0u8; 1024];
let writer = Cursor::new(output);
let correct_image_size = (width * height) as usize;
let image = vec![0u8; correct_image_size];
let mut encoder = Encoder::new(writer, width, height);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
encoder.set_animated(1, 0)?;
encoder.validate_sequence(true);
let mut png_writer = encoder.write_header()?;
png_writer.write_image_data(image.as_ref())?;
Ok(())
}
#[test]
fn image_validate_animation2() -> Result<()> {
let width = 10;
let height = 10;
let output = vec![0u8; 1024];
let writer = Cursor::new(output);
let correct_image_size = (width * height) as usize;
let image = vec![0u8; correct_image_size];
let mut encoder = Encoder::new(writer, width, height);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
encoder.set_animated(2, 0)?;
encoder.validate_sequence(true);
let mut png_writer = encoder.write_header()?;
png_writer.write_image_data(image.as_ref())?;
png_writer.write_image_data(image.as_ref())?;
png_writer.finish()?;
Ok(())
}
#[test]
fn image_validate_animation_sep_def_image() -> Result<()> {
let width = 10;
let height = 10;
let output = vec![0u8; 1024];
let writer = Cursor::new(output);
let correct_image_size = (width * height) as usize;
let image = vec![0u8; correct_image_size];
let mut encoder = Encoder::new(writer, width, height);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
encoder.set_animated(1, 0)?;
encoder.set_sep_def_img(true)?;
encoder.validate_sequence(true);
let mut png_writer = encoder.write_header()?;
png_writer.write_image_data(image.as_ref())?;
png_writer.write_image_data(image.as_ref())?;
png_writer.finish()?;
Ok(())
}
#[test]
fn image_validate_missing_image() -> Result<()> {
let width = 10;
let height = 10;
let output = vec![0u8; 1024];
let writer = Cursor::new(output);
let mut encoder = Encoder::new(writer, width, height);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
encoder.validate_sequence(true);
let png_writer = encoder.write_header()?;
assert!(png_writer.finish().is_err());
Ok(())
}
#[test]
fn image_validate_missing_animated_frame() -> Result<()> {
let width = 10;
let height = 10;
let output = vec![0u8; 1024];
let writer = Cursor::new(output);
let correct_image_size = (width * height) as usize;
let image = vec![0u8; correct_image_size];
let mut encoder = Encoder::new(writer, width, height);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
encoder.set_animated(2, 0)?;
encoder.validate_sequence(true);
let mut png_writer = encoder.write_header()?;
png_writer.write_image_data(image.as_ref())?;
assert!(png_writer.finish().is_err());
Ok(())
}
#[test]
fn issue_307_stream_validation() -> Result<()> {
let output = vec![0u8; 1024];
let mut cursor = Cursor::new(output);
let encoder = Encoder::new(&mut cursor, 1, 1); // Create a 1-pixel image
let mut writer = encoder.write_header()?;
let mut stream = writer.stream_writer()?;
let written = stream.write(&[1, 2, 3, 4])?;
assert_eq!(written, 1);
stream.finish()?;
drop(writer);
{
cursor.set_position(0);
let mut decoder = Decoder::new(cursor).read_info().expect("A valid image");
let mut buffer = [0u8; 1];
decoder.next_frame(&mut buffer[..]).expect("Valid read");
assert_eq!(buffer, [1]);
}
Ok(())
}
#[test]
fn stream_filtering() -> Result<()> {
let output = vec![0u8; 1024];
let mut cursor = Cursor::new(output);
let mut encoder = Encoder::new(&mut cursor, 8, 8);
encoder.set_color(ColorType::Rgba);
encoder.set_filter(FilterType::Paeth);
let mut writer = encoder.write_header()?;
let mut stream = writer.stream_writer()?;
for _ in 0..8 {
let written = stream.write(&[1; 32])?;
assert_eq!(written, 32);
}
stream.finish()?;
drop(writer);
{
cursor.set_position(0);
let mut decoder = Decoder::new(cursor).read_info().expect("A valid image");
let mut buffer = [0u8; 256];
decoder.next_frame(&mut buffer[..]).expect("Valid read");
assert_eq!(buffer, [1; 256]);
}
Ok(())
}
#[test]
#[cfg(all(unix, not(target_pointer_width = "32")))]
fn exper_error_on_huge_chunk() -> Result<()> {
// Okay, so we want a proper 4 GB chunk but not actually spend the memory for reserving it.
// Let's rely on overcommit? Otherwise we got the rather dumb option of mmap-ing /dev/zero.
let empty = vec![0; 1usize << 31];
let writer = Cursor::new(vec![0u8; 1024]);
let mut encoder = Encoder::new(writer, 10, 10);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
let mut png_writer = encoder.write_header()?;
assert!(png_writer.write_chunk(chunk::fdAT, &empty).is_err());
Ok(())
}
#[test]
#[cfg(all(unix, not(target_pointer_width = "32")))]
fn exper_error_on_non_u32_chunk() -> Result<()> {
// Okay, so we want a proper 4 GB chunk but not actually spend the memory for reserving it.
// Let's rely on overcommit? Otherwise we got the rather dumb option of mmap-ing /dev/zero.
let empty = vec![0; 1usize << 32];
let writer = Cursor::new(vec![0u8; 1024]);
let mut encoder = Encoder::new(writer, 10, 10);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
let mut png_writer = encoder.write_header()?;
assert!(png_writer.write_chunk(chunk::fdAT, &empty).is_err());
Ok(())
}
#[test]
fn finish_drops_inner_writer() -> Result<()> {
struct NoWriter<'flag>(&'flag mut bool);
impl Write for NoWriter<'_> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl Drop for NoWriter<'_> {
fn drop(&mut self) {
*self.0 = true;
}
}
let mut flag = false;
{
let mut encoder = Encoder::new(NoWriter(&mut flag), 10, 10);
encoder.set_depth(BitDepth::Eight);
encoder.set_color(ColorType::Grayscale);
let mut writer = encoder.write_header()?;
writer.write_image_data(&[0; 100])?;
writer.finish()?;
}
assert!(flag, "PNG finished but writer was not dropped");
Ok(())
}
/// A Writer that only writes a few bytes at a time
struct RandomChunkWriter<R: Rng, W: Write> {
rng: R,
w: W,
}
impl<R: Rng, W: Write> Write for RandomChunkWriter<R, W> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
// choose a random length to write
let len = cmp::min(self.rng.gen_range(1..50), buf.len());
self.w.write(&buf[0..len])
}
fn flush(&mut self) -> io::Result<()> {
self.w.flush()
}
}
}
Codebase Browser
chromium