diff options
Diffstat (limited to 'src/freetype/ftimage.h')
| -rw-r--r-- | src/freetype/ftimage.h | 973 |
1 files changed, 973 insertions, 0 deletions
diff --git a/src/freetype/ftimage.h b/src/freetype/ftimage.h new file mode 100644 index 0000000..2973a6c --- /dev/null +++ b/src/freetype/ftimage.h @@ -0,0 +1,973 @@ +/***************************************************************************/ +/* */ +/* 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_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_BGRA, + + FT_PIXEL_MODE_MAX /* do not remove */ + + } FT_Pixel_Mode; + + + /*************************************************************************/ + /* */ + /* <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 + + /* */ + +#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. */ + /* */ + 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_Glyph_Format; + + + /*************************************************************************/ + /*************************************************************************/ + /*************************************************************************/ + /***** *****/ + /***** 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 */ + /* */ + /*************************************************************************/ + + + /*************************************************************************/ + /* */ + /* <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 + + + /*************************************************************************/ + /* */ + /* <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 + + + /*************************************************************************/ + /* */ + /* <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. */ + /* */ + /* 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; + void* user; + FT_BBox clip_box; + + } FT_Raster_Params; + + + /*************************************************************************/ + /* */ + /* <FuncType> */ + /* FT_Raster_RenderFunc */ + /* */ + /* <Description> */ + /* Invoke a given raster to scan-convert a given glyph image into a */ + /* target bitmap. */ + /* */ + /* <Input> */ + /* 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)( 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> */ + /* raster_render :: A function to render a glyph into a given bitmap. */ + /* */ + typedef struct FT_Raster_Funcs_ + { + FT_Raster_RenderFunc raster_render; + + } FT_Raster_Funcs; + + /* */ + + +FT_END_HEADER + +#endif /* FTIMAGE_H_ */ + + +/* END */ + + +/* Local Variables: */ +/* coding: utf-8 */ +/* End: */ |