ref: 2c3e895c745fe417e501195310de973867f0d43e
dir: /include/freetype/ftimage.h/
/**************************************************************************** * * ftimage.h * * FreeType glyph image formats and default raster interface * (specification). * * Copyright 1996-2018 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_Outlines into FT_Bitmaps. * */ #ifndef FTIMAGE_H_ #define FTIMAGE_H_ /* STANDALONE_ is from ftgrays.c */ #ifndef STANDALONE_ #include <ft2build.h> #endif 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. */ typedef signed long 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. */ typedef struct FT_Vector_ { FT_Pos x; FT_Pos y; } 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. */ typedef struct FT_BBox_ { FT_Pos xMin, yMin; FT_Pos xMax, yMax; } 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. */ typedef enum FT_Pixel_Mode_ { FT_PIXEL_MODE_NONE = 0, FT_PIXEL_MODE_MONO, FT_PIXEL_MODE_GRAY, FT_PIXEL_MODE_GRAY2, FT_PIXEL_MODE_GRAY4, FT_PIXEL_MODE_LCD, FT_PIXEL_MODE_LCD_V, FT_PIXEL_MODE_BGRA, FT_PIXEL_MODE_MAX /* do not remove */ } FT_Pixel_Mode; /* these constants are deprecated; use the corresponding `FT_Pixel_Mode' */ /* values instead. */ #define ft_pixel_mode_none FT_PIXEL_MODE_NONE #define ft_pixel_mode_mono FT_PIXEL_MODE_MONO #define ft_pixel_mode_grays FT_PIXEL_MODE_GRAY #define ft_pixel_mode_pal2 FT_PIXEL_MODE_GRAY2 #define ft_pixel_mode_pal4 FT_PIXEL_MODE_GRAY4 /************************************************************************** * * @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. */ typedef struct FT_Bitmap_ { unsigned int rows; unsigned int width; int pitch; unsigned char* buffer; unsigned short num_grays; unsigned char pixel_mode; unsigned char palette_mode; void* palette; } 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. */ typedef struct FT_Outline_ { short n_contours; /* number of contours in glyph */ short n_points; /* number of points in the glyph */ FT_Vector* points; /* the outline's points */ char* tags; /* the points flags */ short* contours; /* the contour end points */ int flags; /* outline masks */ } FT_Outline; /* */ /* Following limits must be consistent with */ /* FT_Outline.{n_contours,n_points} */ #define FT_OUTLINE_CONTOURS_MAX SHRT_MAX #define FT_OUTLINE_POINTS_MAX SHRT_MAX /************************************************************************** * * @enum: * FT_OUTLINE_XXX * * @description: * A list of bit-field constants use 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_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 0x0 #define FT_OUTLINE_OWNER 0x1 #define FT_OUTLINE_EVEN_ODD_FILL 0x2 #define FT_OUTLINE_REVERSE_FILL 0x4 #define FT_OUTLINE_IGNORE_DROPOUTS 0x8 #define FT_OUTLINE_SMART_DROPOUTS 0x10 #define FT_OUTLINE_INCLUDE_STUBS 0x20 #define FT_OUTLINE_HIGH_PRECISION 0x100 #define FT_OUTLINE_SINGLE_PASS 0x200 /* these constants are deprecated; use the corresponding */ /* `FT_OUTLINE_XXX' values instead */ #define ft_outline_none FT_OUTLINE_NONE #define ft_outline_owner FT_OUTLINE_OWNER #define ft_outline_even_odd_fill FT_OUTLINE_EVEN_ODD_FILL #define ft_outline_reverse_fill FT_OUTLINE_REVERSE_FILL #define ft_outline_ignore_dropouts FT_OUTLINE_IGNORE_DROPOUTS #define ft_outline_high_precision FT_OUTLINE_HIGH_PRECISION #define ft_outline_single_pass FT_OUTLINE_SINGLE_PASS /* */ #define FT_CURVE_TAG( flag ) ( flag & 3 ) #define FT_CURVE_TAG_ON 1 #define FT_CURVE_TAG_CONIC 0 #define FT_CURVE_TAG_CUBIC 2 #define FT_CURVE_TAG_HAS_SCANMODE 4 #define FT_CURVE_TAG_TOUCH_X 8 /* reserved for the TrueType hinter */ #define FT_CURVE_TAG_TOUCH_Y 16 /* reserved for the TrueType hinter */ #define FT_CURVE_TAG_TOUCH_BOTH ( FT_CURVE_TAG_TOUCH_X | \ FT_CURVE_TAG_TOUCH_Y ) #define FT_Curve_Tag_On FT_CURVE_TAG_ON #define FT_Curve_Tag_Conic FT_CURVE_TAG_CONIC #define FT_Curve_Tag_Cubic FT_CURVE_TAG_CUBIC #define FT_Curve_Tag_Touch_X FT_CURVE_TAG_TOUCH_X #define FT_Curve_Tag_Touch_Y 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. */ typedef int (*FT_Outline_MoveToFunc)( const FT_Vector* to, void* user ); #define FT_Outline_MoveTo_Func FT_Outline_MoveToFunc /************************************************************************** * * @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. */ typedef int (*FT_Outline_LineToFunc)( const FT_Vector* to, void* user ); #define FT_Outline_LineTo_Func FT_Outline_LineToFunc /************************************************************************** * * @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. */ typedef int (*FT_Outline_ConicToFunc)( const FT_Vector* control, const FT_Vector* to, void* user ); #define FT_Outline_ConicTo_Func FT_Outline_ConicToFunc /************************************************************************** * * @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. */ typedef int (*FT_Outline_CubicToFunc)( const FT_Vector* control1, const FT_Vector* control2, const FT_Vector* to, void* user ); #define FT_Outline_CubicTo_Func FT_Outline_CubicToFunc /************************************************************************** * * @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. */ typedef struct FT_Outline_Funcs_ { FT_Outline_MoveToFunc move_to; FT_Outline_LineToFunc line_to; FT_Outline_ConicToFunc conic_to; FT_Outline_CubicToFunc cubic_to; int shift; FT_Pos delta; } 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 ) \ value = ( ( (unsigned long)_x1 << 24 ) | \ ( (unsigned long)_x2 << 16 ) | \ ( (unsigned long)_x3 << 8 ) | \ (unsigned long)_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. */ typedef enum FT_Glyph_Format_ { FT_IMAGE_TAG( FT_GLYPH_FORMAT_NONE, 0, 0, 0, 0 ), FT_IMAGE_TAG( FT_GLYPH_FORMAT_COMPOSITE, 'c', 'o', 'm', 'p' ), FT_IMAGE_TAG( FT_GLYPH_FORMAT_BITMAP, 'b', 'i', 't', 's' ), FT_IMAGE_TAG( FT_GLYPH_FORMAT_OUTLINE, 'o', 'u', 't', 'l' ), FT_IMAGE_TAG( FT_GLYPH_FORMAT_PLOTTER, 'p', 'l', 'o', 't' ) } FT_Glyph_Format; /* these constants are deprecated; use the corresponding */ /* `FT_Glyph_Format' values instead. */ #define ft_glyph_format_none FT_GLYPH_FORMAT_NONE #define ft_glyph_format_composite FT_GLYPH_FORMAT_COMPOSITE #define ft_glyph_format_bitmap FT_GLYPH_FORMAT_BITMAP #define ft_glyph_format_outline FT_GLYPH_FORMAT_OUTLINE #define ft_glyph_format_plotter FT_GLYPH_FORMAT_PLOTTER /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /***** *****/ /***** R A S T E R D E F I N I T I O N S *****/ /***** *****/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /************************************************************************** * * A raster is a scan converter, in charge of rendering an outline into * a bitmap. This section contains the public API for rasters. * * Note that in FreeType 2, all rasters are now encapsulated within * specific modules called `renderers'. See `ftrender.h' for more * details on renderers. * */ /************************************************************************** * * @section: * raster * * @title: * Scanline Converter * * @abstract: * How vectorial outlines are converted into bitmaps and pixmaps. * * @description: * This section contains technical definitions. * * @order: * FT_Raster * FT_Span * FT_SpanFunc * * FT_Raster_Params * FT_RASTER_FLAG_XXX * * FT_Raster_NewFunc * FT_Raster_DoneFunc * FT_Raster_ResetFunc * FT_Raster_SetModeFunc * FT_Raster_RenderFunc * FT_Raster_Funcs * */ /************************************************************************** * * @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. */ typedef struct FT_RasterRec_* FT_Raster; /************************************************************************** * * @struct: * FT_Span * * @description: * A structure used to model a single span of gray 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 coverage value is always between 0 and 255. If you want less * gray values, the callback function has to reduce them. */ typedef struct FT_Span_ { short x; unsigned short len; unsigned char coverage; } 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 gray pixel * spans on each scan line. * * @input: * y :: * The scanline's 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 * gray 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, and even perform translucency. */ typedef void (*FT_SpanFunc)( int y, int count, const FT_Span* spans, void* user ); #define FT_Raster_Span_Func FT_SpanFunc /************************************************************************** * * @functype: * FT_Raster_BitTest_Func * * @description: * Deprecated, unimplemented. */ typedef int (*FT_Raster_BitTest_Func)( int y, int x, void* user ); /************************************************************************** * * @functype: * FT_Raster_BitSet_Func * * @description: * Deprecated, unimplemented. */ typedef void (*FT_Raster_BitSet_Func)( int y, int x, void* user ); /************************************************************************** * * @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. * * 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. * * Note that by default, the glyph bitmap * is clipped to the target pixmap, except * in direct rendering mode where all spans * are generated if no clipping box is set. */ #define FT_RASTER_FLAG_DEFAULT 0x0 #define FT_RASTER_FLAG_AA 0x1 #define FT_RASTER_FLAG_DIRECT 0x2 #define FT_RASTER_FLAG_CLIP 0x4 /* these constants are deprecated; use the corresponding */ /* `FT_RASTER_FLAG_XXX' values instead */ #define ft_raster_flag_default FT_RASTER_FLAG_DEFAULT #define ft_raster_flag_aa FT_RASTER_FLAG_AA #define ft_raster_flag_direct FT_RASTER_FLAG_DIRECT #define ft_raster_flag_clip FT_RASTER_FLAG_CLIP /************************************************************************** * * @struct: * FT_Raster_Params * * @description: * A structure to hold the arguments used by a raster's render * function. * * @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 clipping box. It is only used in * direct rendering mode. Note that coordinates here * should be expressed in _integer_ pixels (and not in * 26.6 fixed-point units). * * @note: * An anti-aliased glyph bitmap is drawn if the @FT_RASTER_FLAG_AA * bit flag is set in the `flags' field, otherwise a monochrome * bitmap is generated. * * If the @FT_RASTER_FLAG_DIRECT bit flag is set in `flags', the * raster will call the `gray_spans' callback to draw gray pixel * spans. This allows direct composition over a pre-existing bitmap * through user-provided callbacks to perform the span drawing and * composition. Not supported by the monochrome rasterizer. */ typedef struct FT_Raster_Params_ { const FT_Bitmap* target; const void* source; int flags; FT_SpanFunc gray_spans; FT_SpanFunc black_spans; /* unused */ FT_Raster_BitTest_Func bit_test; /* unused */ FT_Raster_BitSet_Func bit_set; /* unused */ void* user; FT_BBox clip_box; } FT_Raster_Params; /************************************************************************** * * @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. */ typedef int (*FT_Raster_NewFunc)( void* memory, FT_Raster* raster ); #define FT_Raster_New_Func FT_Raster_NewFunc /************************************************************************** * * @functype: * FT_Raster_DoneFunc * * @description: * A function used to destroy a given raster object. * * @input: * raster :: * A handle to the raster object. */ typedef void (*FT_Raster_DoneFunc)( FT_Raster raster ); #define FT_Raster_Done_Func FT_Raster_DoneFunc /************************************************************************** * * @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). */ typedef void (*FT_Raster_ResetFunc)( FT_Raster raster, unsigned char* pool_base, unsigned long pool_size ); #define FT_Raster_Reset_Func FT_Raster_ResetFunc /************************************************************************** * * @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. */ typedef int (*FT_Raster_SetModeFunc)( FT_Raster raster, unsigned long mode, void* args ); #define FT_Raster_Set_Mode_Func FT_Raster_SetModeFunc /************************************************************************** * * @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. * * XXX: For now, the standard raster doesn't support direct * composition but this should change for the final release (see * the files `demos/src/ftgrays.c' and `demos/src/ftgrays2.c' * for examples of distinct implementations that support direct * composition). */ typedef int (*FT_Raster_RenderFunc)( FT_Raster raster, const FT_Raster_Params* params ); #define FT_Raster_Render_Func FT_Raster_RenderFunc /************************************************************************** * * @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. */ typedef struct FT_Raster_Funcs_ { FT_Glyph_Format glyph_format; FT_Raster_NewFunc raster_new; FT_Raster_ResetFunc raster_reset; FT_Raster_SetModeFunc raster_set_mode; FT_Raster_RenderFunc raster_render; FT_Raster_DoneFunc raster_done; } FT_Raster_Funcs; /* */ FT_END_HEADER #endif /* FTIMAGE_H_ */ /* END */ /* Local Variables: */ /* coding: utf-8 */ /* End: */