/**************************************************************************** * * ftimage.h * * FreeType glyph image formats and default raster interface * (specification). * * Copyright (C) 1996-2023 by * David Turner, Robert Wilhelm, and Werner Lemberg. * * This file is part of the FreeType project, and may only be used, * modified, and distributed under the terms of the FreeType project * license, LICENSE.TXT. By continuing to use, modify, or distribute * this file you indicate that you have read the license and * understand and accept it fully. * */ /************************************************************************** * * Note: A 'raster' is simply a scan-line converter, used to render * `FT_Outline`s into `FT_Bitmap`s. * */ #ifndef FTIMAGE_H_ #define FTIMAGE_H_ FT_BEGIN_HEADER /************************************************************************** * * @section: * basic_types * */ /************************************************************************** * * @type: * FT_Pos * * @description: * The type FT_Pos is used to store vectorial coordinates. Depending on * the context, these can represent distances in integer font units, or * 16.16, or 26.6 fixed-point pixel coordinates. */ FT_Pos; /************************************************************************** * * @struct: * FT_Vector * * @description: * A simple structure used to store a 2D vector; coordinates are of the * FT_Pos type. * * @fields: * x :: * The horizontal coordinate. * y :: * The vertical coordinate. */ FT_Vector; /************************************************************************** * * @struct: * FT_BBox * * @description: * A structure used to hold an outline's bounding box, i.e., the * coordinates of its extrema in the horizontal and vertical directions. * * @fields: * xMin :: * The horizontal minimum (left-most). * * yMin :: * The vertical minimum (bottom-most). * * xMax :: * The horizontal maximum (right-most). * * yMax :: * The vertical maximum (top-most). * * @note: * The bounding box is specified with the coordinates of the lower left * and the upper right corner. In PostScript, those values are often * called (llx,lly) and (urx,ury), respectively. * * If `yMin` is negative, this value gives the glyph's descender. * Otherwise, the glyph doesn't descend below the baseline. Similarly, * if `ymax` is positive, this value gives the glyph's ascender. * * `xMin` gives the horizontal distance from the glyph's origin to the * left edge of the glyph's bounding box. If `xMin` is negative, the * glyph extends to the left of the origin. */ FT_BBox; /************************************************************************** * * @enum: * FT_Pixel_Mode * * @description: * An enumeration type used to describe the format of pixels in a given * bitmap. Note that additional formats may be added in the future. * * @values: * FT_PIXEL_MODE_NONE :: * Value~0 is reserved. * * FT_PIXEL_MODE_MONO :: * A monochrome bitmap, using 1~bit per pixel. Note that pixels are * stored in most-significant order (MSB), which means that the * left-most pixel in a byte has value 128. * * FT_PIXEL_MODE_GRAY :: * An 8-bit bitmap, generally used to represent anti-aliased glyph * images. Each pixel is stored in one byte. Note that the number of * 'gray' levels is stored in the `num_grays` field of the @FT_Bitmap * structure (it generally is 256). * * FT_PIXEL_MODE_GRAY2 :: * A 2-bit per pixel bitmap, used to represent embedded anti-aliased * bitmaps in font files according to the OpenType specification. We * haven't found a single font using this format, however. * * FT_PIXEL_MODE_GRAY4 :: * A 4-bit per pixel bitmap, representing embedded anti-aliased bitmaps * in font files according to the OpenType specification. We haven't * found a single font using this format, however. * * FT_PIXEL_MODE_LCD :: * An 8-bit bitmap, representing RGB or BGR decimated glyph images used * for display on LCD displays; the bitmap is three times wider than * the original glyph image. See also @FT_RENDER_MODE_LCD. * * FT_PIXEL_MODE_LCD_V :: * An 8-bit bitmap, representing RGB or BGR decimated glyph images used * for display on rotated LCD displays; the bitmap is three times * taller than the original glyph image. See also * @FT_RENDER_MODE_LCD_V. * * FT_PIXEL_MODE_BGRA :: * [Since 2.5] An image with four 8-bit channels per pixel, * representing a color image (such as emoticons) with alpha channel. * For each pixel, the format is BGRA, which means, the blue channel * comes first in memory. The color channels are pre-multiplied and in * the sRGB colorspace. For example, full red at half-translucent * opacity will be represented as '00,00,80,80', not '00,00,FF,80'. * See also @FT_LOAD_COLOR. */ FT_Pixel_Mode; /* these constants are deprecated; use the corresponding `FT_Pixel_Mode` */ /* values instead. */ #define ft_pixel_mode_none … #define ft_pixel_mode_mono … #define ft_pixel_mode_grays … #define ft_pixel_mode_pal2 … #define ft_pixel_mode_pal4 … /* */ /* For debugging, the @FT_Pixel_Mode enumeration must stay in sync */ /* with the `pixel_modes` array in file `ftobjs.c`. */ /************************************************************************** * * @struct: * FT_Bitmap * * @description: * A structure used to describe a bitmap or pixmap to the raster. Note * that we now manage pixmaps of various depths through the `pixel_mode` * field. * * @fields: * rows :: * The number of bitmap rows. * * width :: * The number of pixels in bitmap row. * * pitch :: * The pitch's absolute value is the number of bytes taken by one * bitmap row, including padding. However, the pitch is positive when * the bitmap has a 'down' flow, and negative when it has an 'up' flow. * In all cases, the pitch is an offset to add to a bitmap pointer in * order to go down one row. * * Note that 'padding' means the alignment of a bitmap to a byte * border, and FreeType functions normally align to the smallest * possible integer value. * * For the B/W rasterizer, `pitch` is always an even number. * * To change the pitch of a bitmap (say, to make it a multiple of 4), * use @FT_Bitmap_Convert. Alternatively, you might use callback * functions to directly render to the application's surface; see the * file `example2.cpp` in the tutorial for a demonstration. * * buffer :: * A typeless pointer to the bitmap buffer. This value should be * aligned on 32-bit boundaries in most cases. * * num_grays :: * This field is only used with @FT_PIXEL_MODE_GRAY; it gives the * number of gray levels used in the bitmap. * * pixel_mode :: * The pixel mode, i.e., how pixel bits are stored. See @FT_Pixel_Mode * for possible values. * * palette_mode :: * This field is intended for paletted pixel modes; it indicates how * the palette is stored. Not used currently. * * palette :: * A typeless pointer to the bitmap palette; this field is intended for * paletted pixel modes. Not used currently. * * @note: * `width` and `rows` refer to the *physical* size of the bitmap, not the * *logical* one. For example, if @FT_Pixel_Mode is set to * `FT_PIXEL_MODE_LCD`, the logical width is a just a third of the * physical one. */ FT_Bitmap; /************************************************************************** * * @section: * outline_processing * */ /************************************************************************** * * @struct: * FT_Outline * * @description: * This structure is used to describe an outline to the scan-line * converter. * * @fields: * n_contours :: * The number of contours in the outline. * * n_points :: * The number of points in the outline. * * points :: * A pointer to an array of `n_points` @FT_Vector elements, giving the * outline's point coordinates. * * tags :: * A pointer to an array of `n_points` chars, giving each outline * point's type. * * If bit~0 is unset, the point is 'off' the curve, i.e., a Bezier * control point, while it is 'on' if set. * * Bit~1 is meaningful for 'off' points only. If set, it indicates a * third-order Bezier arc control point; and a second-order control * point if unset. * * If bit~2 is set, bits 5-7 contain the drop-out mode (as defined in * the OpenType specification; the value is the same as the argument to * the 'SCANMODE' instruction). * * Bits 3 and~4 are reserved for internal purposes. * * contours :: * An array of `n_contours` shorts, giving the end point of each * contour within the outline. For example, the first contour is * defined by the points '0' to `contours[0]`, the second one is * defined by the points `contours[0]+1` to `contours[1]`, etc. * * flags :: * A set of bit flags used to characterize the outline and give hints * to the scan-converter and hinter on how to convert/grid-fit it. See * @FT_OUTLINE_XXX. * * @note: * The B/W rasterizer only checks bit~2 in the `tags` array for the first * point of each contour. The drop-out mode as given with * @FT_OUTLINE_IGNORE_DROPOUTS, @FT_OUTLINE_SMART_DROPOUTS, and * @FT_OUTLINE_INCLUDE_STUBS in `flags` is then overridden. */ FT_Outline; /* */ /* Following limits must be consistent with */ /* FT_Outline.{n_contours,n_points} */ #define FT_OUTLINE_CONTOURS_MAX … #define FT_OUTLINE_POINTS_MAX … /************************************************************************** * * @enum: * FT_OUTLINE_XXX * * @description: * A list of bit-field constants used for the flags in an outline's * `flags` field. * * @values: * FT_OUTLINE_NONE :: * Value~0 is reserved. * * FT_OUTLINE_OWNER :: * If set, this flag indicates that the outline's field arrays (i.e., * `points`, `flags`, and `contours`) are 'owned' by the outline * object, and should thus be freed when it is destroyed. * * FT_OUTLINE_EVEN_ODD_FILL :: * By default, outlines are filled using the non-zero winding rule. If * set to 1, the outline will be filled using the even-odd fill rule * (only works with the smooth rasterizer). * * FT_OUTLINE_REVERSE_FILL :: * By default, outside contours of an outline are oriented in * clock-wise direction, as defined in the TrueType specification. * This flag is set if the outline uses the opposite direction * (typically for Type~1 fonts). This flag is ignored by the scan * converter. * * FT_OUTLINE_IGNORE_DROPOUTS :: * By default, the scan converter will try to detect drop-outs in an * outline and correct the glyph bitmap to ensure consistent shape * continuity. If set, this flag hints the scan-line converter to * ignore such cases. See below for more information. * * FT_OUTLINE_SMART_DROPOUTS :: * Select smart dropout control. If unset, use simple dropout control. * Ignored if @FT_OUTLINE_IGNORE_DROPOUTS is set. See below for more * information. * * FT_OUTLINE_INCLUDE_STUBS :: * If set, turn pixels on for 'stubs', otherwise exclude them. Ignored * if @FT_OUTLINE_IGNORE_DROPOUTS is set. See below for more * information. * * FT_OUTLINE_OVERLAP :: * [Since 2.10.3] This flag indicates that this outline contains * overlapping contours and the anti-aliased renderer should perform * oversampling to mitigate possible artifacts. This flag should _not_ * be set for well designed glyphs without overlaps because it quadruples * the rendering time. * * FT_OUTLINE_HIGH_PRECISION :: * This flag indicates that the scan-line converter should try to * convert this outline to bitmaps with the highest possible quality. * It is typically set for small character sizes. Note that this is * only a hint that might be completely ignored by a given * scan-converter. * * FT_OUTLINE_SINGLE_PASS :: * This flag is set to force a given scan-converter to only use a * single pass over the outline to render a bitmap glyph image. * Normally, it is set for very large character sizes. It is only a * hint that might be completely ignored by a given scan-converter. * * @note: * The flags @FT_OUTLINE_IGNORE_DROPOUTS, @FT_OUTLINE_SMART_DROPOUTS, and * @FT_OUTLINE_INCLUDE_STUBS are ignored by the smooth rasterizer. * * There exists a second mechanism to pass the drop-out mode to the B/W * rasterizer; see the `tags` field in @FT_Outline. * * Please refer to the description of the 'SCANTYPE' instruction in the * OpenType specification (in file `ttinst1.doc`) how simple drop-outs, * smart drop-outs, and stubs are defined. */ #define FT_OUTLINE_NONE … #define FT_OUTLINE_OWNER … #define FT_OUTLINE_EVEN_ODD_FILL … #define FT_OUTLINE_REVERSE_FILL … #define FT_OUTLINE_IGNORE_DROPOUTS … #define FT_OUTLINE_SMART_DROPOUTS … #define FT_OUTLINE_INCLUDE_STUBS … #define FT_OUTLINE_OVERLAP … #define FT_OUTLINE_HIGH_PRECISION … #define FT_OUTLINE_SINGLE_PASS … /* these constants are deprecated; use the corresponding */ /* `FT_OUTLINE_XXX` values instead */ #define ft_outline_none … #define ft_outline_owner … #define ft_outline_even_odd_fill … #define ft_outline_reverse_fill … #define ft_outline_ignore_dropouts … #define ft_outline_high_precision … #define ft_outline_single_pass … /* */ #define FT_CURVE_TAG( flag ) … /* see the `tags` field in `FT_Outline` for a description of the values */ #define FT_CURVE_TAG_ON … #define FT_CURVE_TAG_CONIC … #define FT_CURVE_TAG_CUBIC … #define FT_CURVE_TAG_HAS_SCANMODE … #define FT_CURVE_TAG_TOUCH_X … #define FT_CURVE_TAG_TOUCH_Y … #define FT_CURVE_TAG_TOUCH_BOTH … /* values 0x20, 0x40, and 0x80 are reserved */ /* these constants are deprecated; use the corresponding */ /* `FT_CURVE_TAG_XXX` values instead */ #define FT_Curve_Tag_On … #define FT_Curve_Tag_Conic … #define FT_Curve_Tag_Cubic … #define FT_Curve_Tag_Touch_X … #define FT_Curve_Tag_Touch_Y … /************************************************************************** * * @functype: * FT_Outline_MoveToFunc * * @description: * A function pointer type used to describe the signature of a 'move to' * function during outline walking/decomposition. * * A 'move to' is emitted to start a new contour in an outline. * * @input: * to :: * A pointer to the target point of the 'move to'. * * user :: * A typeless pointer, which is passed from the caller of the * decomposition function. * * @return: * Error code. 0~means success. */ FT_Outline_MoveToFunc; #define FT_Outline_MoveTo_Func … /************************************************************************** * * @functype: * FT_Outline_LineToFunc * * @description: * A function pointer type used to describe the signature of a 'line to' * function during outline walking/decomposition. * * A 'line to' is emitted to indicate a segment in the outline. * * @input: * to :: * A pointer to the target point of the 'line to'. * * user :: * A typeless pointer, which is passed from the caller of the * decomposition function. * * @return: * Error code. 0~means success. */ FT_Outline_LineToFunc; #define FT_Outline_LineTo_Func … /************************************************************************** * * @functype: * FT_Outline_ConicToFunc * * @description: * A function pointer type used to describe the signature of a 'conic to' * function during outline walking or decomposition. * * A 'conic to' is emitted to indicate a second-order Bezier arc in the * outline. * * @input: * control :: * An intermediate control point between the last position and the new * target in `to`. * * to :: * A pointer to the target end point of the conic arc. * * user :: * A typeless pointer, which is passed from the caller of the * decomposition function. * * @return: * Error code. 0~means success. */ FT_Outline_ConicToFunc; #define FT_Outline_ConicTo_Func … /************************************************************************** * * @functype: * FT_Outline_CubicToFunc * * @description: * A function pointer type used to describe the signature of a 'cubic to' * function during outline walking or decomposition. * * A 'cubic to' is emitted to indicate a third-order Bezier arc. * * @input: * control1 :: * A pointer to the first Bezier control point. * * control2 :: * A pointer to the second Bezier control point. * * to :: * A pointer to the target end point. * * user :: * A typeless pointer, which is passed from the caller of the * decomposition function. * * @return: * Error code. 0~means success. */ FT_Outline_CubicToFunc; #define FT_Outline_CubicTo_Func … /************************************************************************** * * @struct: * FT_Outline_Funcs * * @description: * A structure to hold various function pointers used during outline * decomposition in order to emit segments, conic, and cubic Beziers. * * @fields: * move_to :: * The 'move to' emitter. * * line_to :: * The segment emitter. * * conic_to :: * The second-order Bezier arc emitter. * * cubic_to :: * The third-order Bezier arc emitter. * * shift :: * The shift that is applied to coordinates before they are sent to the * emitter. * * delta :: * The delta that is applied to coordinates before they are sent to the * emitter, but after the shift. * * @note: * The point coordinates sent to the emitters are the transformed version * of the original coordinates (this is important for high accuracy * during scan-conversion). The transformation is simple: * * ``` * x' = (x << shift) - delta * y' = (y << shift) - delta * ``` * * Set the values of `shift` and `delta` to~0 to get the original point * coordinates. */ FT_Outline_Funcs; /************************************************************************** * * @section: * basic_types * */ /************************************************************************** * * @macro: * FT_IMAGE_TAG * * @description: * This macro converts four-letter tags to an unsigned long type. * * @note: * Since many 16-bit compilers don't like 32-bit enumerations, you should * redefine this macro in case of problems to something like this: * * ``` * #define FT_IMAGE_TAG( value, _x1, _x2, _x3, _x4 ) value * ``` * * to get a simple enumeration without assigning special numbers. */ #ifndef FT_IMAGE_TAG #define FT_IMAGE_TAG( value, _x1, _x2, _x3, _x4 ) … #endif /* FT_IMAGE_TAG */ /************************************************************************** * * @enum: * FT_Glyph_Format * * @description: * An enumeration type used to describe the format of a given glyph * image. Note that this version of FreeType only supports two image * formats, even though future font drivers will be able to register * their own format. * * @values: * FT_GLYPH_FORMAT_NONE :: * The value~0 is reserved. * * FT_GLYPH_FORMAT_COMPOSITE :: * The glyph image is a composite of several other images. This format * is _only_ used with @FT_LOAD_NO_RECURSE, and is used to report * compound glyphs (like accented characters). * * FT_GLYPH_FORMAT_BITMAP :: * The glyph image is a bitmap, and can be described as an @FT_Bitmap. * You generally need to access the `bitmap` field of the * @FT_GlyphSlotRec structure to read it. * * FT_GLYPH_FORMAT_OUTLINE :: * The glyph image is a vectorial outline made of line segments and * Bezier arcs; it can be described as an @FT_Outline; you generally * want to access the `outline` field of the @FT_GlyphSlotRec structure * to read it. * * FT_GLYPH_FORMAT_PLOTTER :: * The glyph image is a vectorial path with no inside and outside * contours. Some Type~1 fonts, like those in the Hershey family, * contain glyphs in this format. These are described as @FT_Outline, * but FreeType isn't currently capable of rendering them correctly. * * FT_GLYPH_FORMAT_SVG :: * [Since 2.12] The glyph is represented by an SVG document in the * 'SVG~' table. */ FT_Glyph_Format; /* these constants are deprecated; use the corresponding */ /* `FT_Glyph_Format` values instead. */ #define ft_glyph_format_none … #define ft_glyph_format_composite … #define ft_glyph_format_bitmap … #define ft_glyph_format_outline … #define ft_glyph_format_plotter … /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /***** *****/ /***** R A S T E R D E F I N I T I O N S *****/ /***** *****/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /************************************************************************** * * @section: * raster * * @title: * Scanline Converter * * @abstract: * How vectorial outlines are converted into bitmaps and pixmaps. * * @description: * A raster or a rasterizer is a scan converter in charge of producing a * pixel coverage bitmap that can be used as an alpha channel when * compositing a glyph with a background. FreeType comes with two * rasterizers: bilevel `raster1` and anti-aliased `smooth` are two * separate modules. They are usually called from the high-level * @FT_Load_Glyph or @FT_Render_Glyph functions and produce the entire * coverage bitmap at once, while staying largely invisible to users. * * Instead of working with complete coverage bitmaps, it is also possible * to intercept consecutive pixel runs on the same scanline with the same * coverage, called _spans_, and process them individually. Only the * `smooth` rasterizer permits this when calling @FT_Outline_Render with * @FT_Raster_Params as described below. * * Working with either complete bitmaps or spans it is important to think * of them as colorless coverage objects suitable as alpha channels to * blend arbitrary colors with a background. For best results, it is * recommended to use gamma correction, too. * * This section also describes the public API needed to set up alternative * @FT_Renderer modules. * * @order: * FT_Span * FT_SpanFunc * FT_Raster_Params * FT_RASTER_FLAG_XXX * * FT_Raster * FT_Raster_NewFunc * FT_Raster_DoneFunc * FT_Raster_ResetFunc * FT_Raster_SetModeFunc * FT_Raster_RenderFunc * FT_Raster_Funcs * */ /************************************************************************** * * @struct: * FT_Span * * @description: * A structure to model a single span of consecutive pixels when * rendering an anti-aliased bitmap. * * @fields: * x :: * The span's horizontal start position. * * len :: * The span's length in pixels. * * coverage :: * The span color/coverage, ranging from 0 (background) to 255 * (foreground). * * @note: * This structure is used by the span drawing callback type named * @FT_SpanFunc that takes the y~coordinate of the span as a parameter. * * The anti-aliased rasterizer produces coverage values from 0 to 255, * that is, from completely transparent to completely opaque. */ FT_Span; /************************************************************************** * * @functype: * FT_SpanFunc * * @description: * A function used as a call-back by the anti-aliased renderer in order * to let client applications draw themselves the pixel spans on each * scan line. * * @input: * y :: * The scanline's upward y~coordinate. * * count :: * The number of spans to draw on this scanline. * * spans :: * A table of `count` spans to draw on the scanline. * * user :: * User-supplied data that is passed to the callback. * * @note: * This callback allows client applications to directly render the spans * of the anti-aliased bitmap to any kind of surfaces. * * This can be used to write anti-aliased outlines directly to a given * background bitmap using alpha compositing. It can also be used for * oversampling and averaging. */ FT_SpanFunc; #define FT_Raster_Span_Func … /************************************************************************** * * @functype: * FT_Raster_BitTest_Func * * @description: * Deprecated, unimplemented. */ FT_Raster_BitTest_Func; /************************************************************************** * * @functype: * FT_Raster_BitSet_Func * * @description: * Deprecated, unimplemented. */ FT_Raster_BitSet_Func; /************************************************************************** * * @enum: * FT_RASTER_FLAG_XXX * * @description: * A list of bit flag constants as used in the `flags` field of a * @FT_Raster_Params structure. * * @values: * FT_RASTER_FLAG_DEFAULT :: * This value is 0. * * FT_RASTER_FLAG_AA :: * This flag is set to indicate that an anti-aliased glyph image should * be generated. Otherwise, it will be monochrome (1-bit). * * FT_RASTER_FLAG_DIRECT :: * This flag is set to indicate direct rendering. In this mode, client * applications must provide their own span callback. This lets them * directly draw or compose over an existing bitmap. If this bit is * _not_ set, the target pixmap's buffer _must_ be zeroed before * rendering and the output will be clipped to its size. * * Direct rendering is only possible with anti-aliased glyphs. * * FT_RASTER_FLAG_CLIP :: * This flag is only used in direct rendering mode. If set, the output * will be clipped to a box specified in the `clip_box` field of the * @FT_Raster_Params structure. Otherwise, the `clip_box` is * effectively set to the bounding box and all spans are generated. * * FT_RASTER_FLAG_SDF :: * This flag is set to indicate that a signed distance field glyph * image should be generated. This is only used while rendering with * the @FT_RENDER_MODE_SDF render mode. */ #define FT_RASTER_FLAG_DEFAULT … #define FT_RASTER_FLAG_AA … #define FT_RASTER_FLAG_DIRECT … #define FT_RASTER_FLAG_CLIP … #define FT_RASTER_FLAG_SDF … /* these constants are deprecated; use the corresponding */ /* `FT_RASTER_FLAG_XXX` values instead */ #define ft_raster_flag_default … #define ft_raster_flag_aa … #define ft_raster_flag_direct … #define ft_raster_flag_clip … /************************************************************************** * * @struct: * FT_Raster_Params * * @description: * A structure to hold the parameters used by a raster's render function, * passed as an argument to @FT_Outline_Render. * * @fields: * target :: * The target bitmap. * * source :: * A pointer to the source glyph image (e.g., an @FT_Outline). * * flags :: * The rendering flags. * * gray_spans :: * The gray span drawing callback. * * black_spans :: * Unused. * * bit_test :: * Unused. * * bit_set :: * Unused. * * user :: * User-supplied data that is passed to each drawing callback. * * clip_box :: * An optional span clipping box expressed in _integer_ pixels * (not in 26.6 fixed-point units). * * @note: * The @FT_RASTER_FLAG_AA bit flag must be set in the `flags` to * generate an anti-aliased glyph bitmap, otherwise a monochrome bitmap * is generated. The `target` should have appropriate pixel mode and its * dimensions define the clipping region. * * If both @FT_RASTER_FLAG_AA and @FT_RASTER_FLAG_DIRECT bit flags * are set in `flags`, the raster calls an @FT_SpanFunc callback * `gray_spans` with `user` data as an argument ignoring `target`. This * allows direct composition over a pre-existing user surface to perform * the span drawing and composition. To optionally clip the spans, set * the @FT_RASTER_FLAG_CLIP flag and `clip_box`. The monochrome raster * does not support the direct mode. * * The gray-level rasterizer always uses 256 gray levels. If you want * fewer gray levels, you have to use @FT_RASTER_FLAG_DIRECT and reduce * the levels in the callback function. */ FT_Raster_Params; /************************************************************************** * * @type: * FT_Raster * * @description: * An opaque handle (pointer) to a raster object. Each object can be * used independently to convert an outline into a bitmap or pixmap. * * @note: * In FreeType 2, all rasters are now encapsulated within specific * @FT_Renderer modules and only used in their context. * */ FT_Raster; /************************************************************************** * * @functype: * FT_Raster_NewFunc * * @description: * A function used to create a new raster object. * * @input: * memory :: * A handle to the memory allocator. * * @output: * raster :: * A handle to the new raster object. * * @return: * Error code. 0~means success. * * @note: * The `memory` parameter is a typeless pointer in order to avoid * un-wanted dependencies on the rest of the FreeType code. In practice, * it is an @FT_Memory object, i.e., a handle to the standard FreeType * memory allocator. However, this field can be completely ignored by a * given raster implementation. */ FT_Raster_NewFunc; #define FT_Raster_New_Func … /************************************************************************** * * @functype: * FT_Raster_DoneFunc * * @description: * A function used to destroy a given raster object. * * @input: * raster :: * A handle to the raster object. */ FT_Raster_DoneFunc; #define FT_Raster_Done_Func … /************************************************************************** * * @functype: * FT_Raster_ResetFunc * * @description: * FreeType used to provide an area of memory called the 'render pool' * available to all registered rasterizers. This was not thread safe, * however, and now FreeType never allocates this pool. * * This function is called after a new raster object is created. * * @input: * raster :: * A handle to the new raster object. * * pool_base :: * Previously, the address in memory of the render pool. Set this to * `NULL`. * * pool_size :: * Previously, the size in bytes of the render pool. Set this to 0. * * @note: * Rasterizers should rely on dynamic or stack allocation if they want to * (a handle to the memory allocator is passed to the rasterizer * constructor). */ FT_Raster_ResetFunc; #define FT_Raster_Reset_Func … /************************************************************************** * * @functype: * FT_Raster_SetModeFunc * * @description: * This function is a generic facility to change modes or attributes in a * given raster. This can be used for debugging purposes, or simply to * allow implementation-specific 'features' in a given raster module. * * @input: * raster :: * A handle to the new raster object. * * mode :: * A 4-byte tag used to name the mode or property. * * args :: * A pointer to the new mode/property to use. */ FT_Raster_SetModeFunc; #define FT_Raster_Set_Mode_Func … /************************************************************************** * * @functype: * FT_Raster_RenderFunc * * @description: * Invoke a given raster to scan-convert a given glyph image into a * target bitmap. * * @input: * raster :: * A handle to the raster object. * * params :: * A pointer to an @FT_Raster_Params structure used to store the * rendering parameters. * * @return: * Error code. 0~means success. * * @note: * The exact format of the source image depends on the raster's glyph * format defined in its @FT_Raster_Funcs structure. It can be an * @FT_Outline or anything else in order to support a large array of * glyph formats. * * Note also that the render function can fail and return a * `FT_Err_Unimplemented_Feature` error code if the raster used does not * support direct composition. */ FT_Raster_RenderFunc; #define FT_Raster_Render_Func … /************************************************************************** * * @struct: * FT_Raster_Funcs * * @description: * A structure used to describe a given raster class to the library. * * @fields: * glyph_format :: * The supported glyph format for this raster. * * raster_new :: * The raster constructor. * * raster_reset :: * Used to reset the render pool within the raster. * * raster_render :: * A function to render a glyph into a given bitmap. * * raster_done :: * The raster destructor. */ FT_Raster_Funcs; /* */ FT_END_HEADER #endif /* FTIMAGE_H_ */ /* END */ /* Local Variables: */ /* coding: utf-8 */ /* End: */
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