// Copyright 2023 The MediaPipe Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef MEDIAPIPE_UTIL_FRAME_BUFFER_GRAY_BUFFER_H_
#define MEDIAPIPE_UTIL_FRAME_BUFFER_GRAY_BUFFER_H_
#include <memory>
#include "HalideBuffer.h"
#include "HalideRuntime.h"
namespace mediapipe {
namespace frame_buffer {
// GrayBuffer represents a view over a grayscale (i.e. luminance,
// or Y-only) buffer.
// GrayBuffer may be copied and moved efficiently; their backing buffers are
// shared and never deep copied.
// GrayBuffer requires a minimum image width depending on the natural vector
// size of the platform, e.g., 16px. This is not validated by GrayBuffer.
class GrayBuffer {
public:
// Returns the size (in bytes) of a grayscale image of the given
// dimensions. The given dimensions contain padding.
static int ByteSize(int buffer_width, int buffer_height) {
const int size = buffer_width * buffer_height;
return size;
}
// Builds a grayscale buffer with size as width * height. The buffer should
// be in row-major order with no padding.
//
// Does not take ownership of any backing buffers, which must be large
// enough to fit their contents.
GrayBuffer(uint8_t* buffer, int width, int height);
// Builds a grayscale buffer with size as width * height.
//
// The underlying backing buffer is allocated and owned by this
// GrayBuffer.
GrayBuffer(int width, int height);
// GrayBuffer is copyable. The source retains ownership of its backing
// buffers.
//
// Since the source retains ownership of its backing buffer, the source needs
// to outlive this instance's lifetime when the backing buffer is owned by
// the source. Otherwise, the passing in backing buffer should outlive this
// instance.
GrayBuffer(const GrayBuffer& other);
// GrayBuffer is moveable. The source loses ownership of any backing buffers.
// Specifically, if the source owns its backing buffer, after the move,
// Release() will return nullptr.
GrayBuffer(GrayBuffer&& other);
// GrayBuffer is assignable. The source retains ownership of its backing
// buffers.
//
// Since the source retains ownership of its backing buffer, the source needs
// to outlive this instance's lifetime when the backing buffer is owned by the
// source. Otherwise, the passing in backing buffer should outlive this
// instance.
GrayBuffer& operator=(const GrayBuffer& other);
GrayBuffer& operator=(GrayBuffer&& other);
~GrayBuffer();
// Performs an in-place crop. Modifies this buffer so that the new extent
// matches that of the given crop rectangle -- (x0, y0) becomes (0, 0) and
// the new width and height are x1 - x0 + 1 and y1 - y0 + 1, respectively.
bool Crop(int x0, int y0, int x1, int y1);
// Resizes this image to match the dimensions of the given output GrayBuffer
// and places the result into output's backing buffer.
//
// Note, if the output backing buffer is shared with multiple instances, by
// calling this method, all the instances' backing buffers will change.
bool Resize(GrayBuffer* output);
// Rotates this image into the given buffer by the given angle (90, 180, 270).
//
// Rotation is specified in degrees counter-clockwise such that when rotating
// by 90 degrees, the top-right corner of the source becomes the top-left of
// the output. The output buffer must have its height and width swapped when
// rotating by 90 or 270.
//
// Any angle values other than (90, 180, 270) are invalid.
//
// Note, if the output backing buffer is shared with multiple instances, by
// calling this method, all the instances' backing buffers will change.
bool Rotate(int angle, GrayBuffer* output);
// Flips this image horizontally/vertically into the given buffer. Both buffer
// dimensions must match.
//
// Note, if the output backing buffer is shared with multiple instances, by
// calling this method, all the instances' backing buffers will change.
bool FlipHorizontally(GrayBuffer* output);
bool FlipVertically(GrayBuffer* output);
// Releases ownership of the owned backing buffer.
uint8_t* Release() { return owned_buffer_.release(); }
// Returns the halide_buffer_t* for the image.
halide_buffer_t* buffer() { return buffer_.raw_buffer(); }
// Returns the image width.
const int width() const { return buffer_.dim(0).extent(); }
// Returns the image height.
const int height() const { return buffer_.dim(1).extent(); }
private:
void Initialize(uint8_t* data, int width, int height);
// Non-NULL iff this GrayBuffer owns its buffer.
std::unique_ptr<uint8_t[]> owned_buffer_;
// Backing buffer: layout is always width x height. The backing buffer binds
// to either "owned_buffer_" or an external buffer.
Halide::Runtime::Buffer<uint8_t> buffer_;
};
} // namespace frame_buffer
} // namespace mediapipe
#endif // MEDIAPIPE_UTIL_FRAME_BUFFER_GRAY_BUFFER_H_
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