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Diffstat (limited to 'modules/freetype2/include/freetype/ftglyph.h')
| -rw-r--r-- | modules/freetype2/include/freetype/ftglyph.h | 750 |
1 files changed, 750 insertions, 0 deletions
diff --git a/modules/freetype2/include/freetype/ftglyph.h b/modules/freetype2/include/freetype/ftglyph.h new file mode 100644 index 0000000000..4658895f7a --- /dev/null +++ b/modules/freetype2/include/freetype/ftglyph.h @@ -0,0 +1,750 @@ +/**************************************************************************** + * + * ftglyph.h + * + * FreeType convenience functions to handle glyphs (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. + * + */ + + + /************************************************************************** + * + * This file contains the definition of several convenience functions that + * can be used by client applications to easily retrieve glyph bitmaps and + * outlines from a given face. + * + * These functions should be optional if you are writing a font server or + * text layout engine on top of FreeType. However, they are pretty handy + * for many other simple uses of the library. + * + */ + + +#ifndef FTGLYPH_H_ +#define FTGLYPH_H_ + + +#include <freetype/freetype.h> + +#ifdef FREETYPE_H +#error "freetype.h of FreeType 1 has been loaded!" +#error "Please fix the directory search order for header files" +#error "so that freetype.h of FreeType 2 is found first." +#endif + + +FT_BEGIN_HEADER + + + /************************************************************************** + * + * @section: + * glyph_management + * + * @title: + * Glyph Management + * + * @abstract: + * Generic interface to manage individual glyph data. + * + * @description: + * This section contains definitions used to manage glyph data through + * generic @FT_Glyph objects. Each of them can contain a bitmap, + * a vector outline, or even images in other formats. These objects are + * detached from @FT_Face, contrary to @FT_GlyphSlot. + * + */ + + + /* forward declaration to a private type */ + typedef struct FT_Glyph_Class_ FT_Glyph_Class; + + + /************************************************************************** + * + * @type: + * FT_Glyph + * + * @description: + * Handle to an object used to model generic glyph images. It is a + * pointer to the @FT_GlyphRec structure and can contain a glyph bitmap + * or pointer. + * + * @note: + * Glyph objects are not owned by the library. You must thus release + * them manually (through @FT_Done_Glyph) _before_ calling + * @FT_Done_FreeType. + */ + typedef struct FT_GlyphRec_* FT_Glyph; + + + /************************************************************************** + * + * @struct: + * FT_GlyphRec + * + * @description: + * The root glyph structure contains a given glyph image plus its advance + * width in 16.16 fixed-point format. + * + * @fields: + * library :: + * A handle to the FreeType library object. + * + * clazz :: + * A pointer to the glyph's class. Private. + * + * format :: + * The format of the glyph's image. + * + * advance :: + * A 16.16 vector that gives the glyph's advance width. + */ + typedef struct FT_GlyphRec_ + { + FT_Library library; + const FT_Glyph_Class* clazz; + FT_Glyph_Format format; + FT_Vector advance; + + } FT_GlyphRec; + + + /************************************************************************** + * + * @type: + * FT_BitmapGlyph + * + * @description: + * A handle to an object used to model a bitmap glyph image. This is a + * 'sub-class' of @FT_Glyph, and a pointer to @FT_BitmapGlyphRec. + */ + typedef struct FT_BitmapGlyphRec_* FT_BitmapGlyph; + + + /************************************************************************** + * + * @struct: + * FT_BitmapGlyphRec + * + * @description: + * A structure used for bitmap glyph images. This really is a + * 'sub-class' of @FT_GlyphRec. + * + * @fields: + * root :: + * The root fields of @FT_Glyph. + * + * left :: + * The left-side bearing, i.e., the horizontal distance from the + * current pen position to the left border of the glyph bitmap. + * + * top :: + * The top-side bearing, i.e., the vertical distance from the current + * pen position to the top border of the glyph bitmap. This distance + * is positive for upwards~y! + * + * bitmap :: + * A descriptor for the bitmap. + * + * @note: + * You can typecast an @FT_Glyph to @FT_BitmapGlyph if you have + * `glyph->format == FT_GLYPH_FORMAT_BITMAP`. This lets you access the + * bitmap's contents easily. + * + * The corresponding pixel buffer is always owned by @FT_BitmapGlyph and + * is thus created and destroyed with it. + */ + typedef struct FT_BitmapGlyphRec_ + { + FT_GlyphRec root; + FT_Int left; + FT_Int top; + FT_Bitmap bitmap; + + } FT_BitmapGlyphRec; + + + /************************************************************************** + * + * @type: + * FT_OutlineGlyph + * + * @description: + * A handle to an object used to model an outline glyph image. This is a + * 'sub-class' of @FT_Glyph, and a pointer to @FT_OutlineGlyphRec. + */ + typedef struct FT_OutlineGlyphRec_* FT_OutlineGlyph; + + + /************************************************************************** + * + * @struct: + * FT_OutlineGlyphRec + * + * @description: + * A structure used for outline (vectorial) glyph images. This really is + * a 'sub-class' of @FT_GlyphRec. + * + * @fields: + * root :: + * The root @FT_Glyph fields. + * + * outline :: + * A descriptor for the outline. + * + * @note: + * You can typecast an @FT_Glyph to @FT_OutlineGlyph if you have + * `glyph->format == FT_GLYPH_FORMAT_OUTLINE`. This lets you access the + * outline's content easily. + * + * As the outline is extracted from a glyph slot, its coordinates are + * expressed normally in 26.6 pixels, unless the flag @FT_LOAD_NO_SCALE + * was used in @FT_Load_Glyph or @FT_Load_Char. + * + * The outline's tables are always owned by the object and are destroyed + * with it. + */ + typedef struct FT_OutlineGlyphRec_ + { + FT_GlyphRec root; + FT_Outline outline; + + } FT_OutlineGlyphRec; + + + /************************************************************************** + * + * @type: + * FT_SvgGlyph + * + * @description: + * A handle to an object used to model an SVG glyph. This is a + * 'sub-class' of @FT_Glyph, and a pointer to @FT_SvgGlyphRec. + * + * @since: + * 2.12 + */ + typedef struct FT_SvgGlyphRec_* FT_SvgGlyph; + + + /************************************************************************** + * + * @struct: + * FT_SvgGlyphRec + * + * @description: + * A structure used for OT-SVG glyphs. This is a 'sub-class' of + * @FT_GlyphRec. + * + * @fields: + * root :: + * The root @FT_GlyphRec fields. + * + * svg_document :: + * A pointer to the SVG document. + * + * svg_document_length :: + * The length of `svg_document`. + * + * glyph_index :: + * The index of the glyph to be rendered. + * + * metrics :: + * A metrics object storing the size information. + * + * units_per_EM :: + * The size of the EM square. + * + * start_glyph_id :: + * The first glyph ID in the glyph range covered by this document. + * + * end_glyph_id :: + * The last glyph ID in the glyph range covered by this document. + * + * transform :: + * A 2x2 transformation matrix to apply to the glyph while rendering + * it. + * + * delta :: + * Translation to apply to the glyph while rendering. + * + * @note: + * The Glyph Management API requires @FT_Glyph or its 'sub-class' to have + * all the information needed to completely define the glyph's rendering. + * Outline-based glyphs can directly apply transformations to the outline + * but this is not possible for an SVG document that hasn't been parsed. + * Therefore, the transformation is stored along with the document. In + * the absence of a 'ViewBox' or 'Width'/'Height' attribute, the size of + * the ViewPort should be assumed to be 'units_per_EM'. + */ + typedef struct FT_SvgGlyphRec_ + { + FT_GlyphRec root; + + FT_Byte* svg_document; + FT_ULong svg_document_length; + + FT_UInt glyph_index; + + FT_Size_Metrics metrics; + FT_UShort units_per_EM; + + FT_UShort start_glyph_id; + FT_UShort end_glyph_id; + + FT_Matrix transform; + FT_Vector delta; + + } FT_SvgGlyphRec; + + + /************************************************************************** + * + * @function: + * FT_New_Glyph + * + * @description: + * A function used to create a new empty glyph image. Note that the + * created @FT_Glyph object must be released with @FT_Done_Glyph. + * + * @input: + * library :: + * A handle to the FreeType library object. + * + * format :: + * The format of the glyph's image. + * + * @output: + * aglyph :: + * A handle to the glyph object. + * + * @return: + * FreeType error code. 0~means success. + * + * @since: + * 2.10 + */ + FT_EXPORT( FT_Error ) + FT_New_Glyph( FT_Library library, + FT_Glyph_Format format, + FT_Glyph *aglyph ); + + + /************************************************************************** + * + * @function: + * FT_Get_Glyph + * + * @description: + * A function used to extract a glyph image from a slot. Note that the + * created @FT_Glyph object must be released with @FT_Done_Glyph. + * + * @input: + * slot :: + * A handle to the source glyph slot. + * + * @output: + * aglyph :: + * A handle to the glyph object. `NULL` in case of error. + * + * @return: + * FreeType error code. 0~means success. + * + * @note: + * Because `*aglyph->advance.x` and `*aglyph->advance.y` are 16.16 + * fixed-point numbers, `slot->advance.x` and `slot->advance.y` (which + * are in 26.6 fixed-point format) must be in the range ]-32768;32768[. + */ + FT_EXPORT( FT_Error ) + FT_Get_Glyph( FT_GlyphSlot slot, + FT_Glyph *aglyph ); + + + /************************************************************************** + * + * @function: + * FT_Glyph_Copy + * + * @description: + * A function used to copy a glyph image. Note that the created + * @FT_Glyph object must be released with @FT_Done_Glyph. + * + * @input: + * source :: + * A handle to the source glyph object. + * + * @output: + * target :: + * A handle to the target glyph object. `NULL` in case of error. + * + * @return: + * FreeType error code. 0~means success. + */ + FT_EXPORT( FT_Error ) + FT_Glyph_Copy( FT_Glyph source, + FT_Glyph *target ); + + + /************************************************************************** + * + * @function: + * FT_Glyph_Transform + * + * @description: + * Transform a glyph image if its format is scalable. + * + * @inout: + * glyph :: + * A handle to the target glyph object. + * + * @input: + * matrix :: + * A pointer to a 2x2 matrix to apply. + * + * delta :: + * A pointer to a 2d vector to apply. Coordinates are expressed in + * 1/64 of a pixel. + * + * @return: + * FreeType error code (if not 0, the glyph format is not scalable). + * + * @note: + * The 2x2 transformation matrix is also applied to the glyph's advance + * vector. + */ + FT_EXPORT( FT_Error ) + FT_Glyph_Transform( FT_Glyph glyph, + const FT_Matrix* matrix, + const FT_Vector* delta ); + + + /************************************************************************** + * + * @enum: + * FT_Glyph_BBox_Mode + * + * @description: + * The mode how the values of @FT_Glyph_Get_CBox are returned. + * + * @values: + * FT_GLYPH_BBOX_UNSCALED :: + * Return unscaled font units. + * + * FT_GLYPH_BBOX_SUBPIXELS :: + * Return unfitted 26.6 coordinates. + * + * FT_GLYPH_BBOX_GRIDFIT :: + * Return grid-fitted 26.6 coordinates. + * + * FT_GLYPH_BBOX_TRUNCATE :: + * Return coordinates in integer pixels. + * + * FT_GLYPH_BBOX_PIXELS :: + * Return grid-fitted pixel coordinates. + */ + typedef enum FT_Glyph_BBox_Mode_ + { + FT_GLYPH_BBOX_UNSCALED = 0, + FT_GLYPH_BBOX_SUBPIXELS = 0, + FT_GLYPH_BBOX_GRIDFIT = 1, + FT_GLYPH_BBOX_TRUNCATE = 2, + FT_GLYPH_BBOX_PIXELS = 3 + + } FT_Glyph_BBox_Mode; + + + /* these constants are deprecated; use the corresponding */ + /* `FT_Glyph_BBox_Mode` values instead */ +#define ft_glyph_bbox_unscaled FT_GLYPH_BBOX_UNSCALED +#define ft_glyph_bbox_subpixels FT_GLYPH_BBOX_SUBPIXELS +#define ft_glyph_bbox_gridfit FT_GLYPH_BBOX_GRIDFIT +#define ft_glyph_bbox_truncate FT_GLYPH_BBOX_TRUNCATE +#define ft_glyph_bbox_pixels FT_GLYPH_BBOX_PIXELS + + + /************************************************************************** + * + * @function: + * FT_Glyph_Get_CBox + * + * @description: + * Return a glyph's 'control box'. The control box encloses all the + * outline's points, including Bezier control points. Though it + * coincides with the exact bounding box for most glyphs, it can be + * slightly larger in some situations (like when rotating an outline that + * contains Bezier outside arcs). + * + * Computing the control box is very fast, while getting the bounding box + * can take much more time as it needs to walk over all segments and arcs + * in the outline. To get the latter, you can use the 'ftbbox' + * component, which is dedicated to this single task. + * + * @input: + * glyph :: + * A handle to the source glyph object. + * + * mode :: + * The mode that indicates how to interpret the returned bounding box + * values. + * + * @output: + * acbox :: + * The glyph coordinate bounding box. Coordinates are expressed in + * 1/64 of pixels if it is grid-fitted. + * + * @note: + * Coordinates are relative to the glyph origin, using the y~upwards + * convention. + * + * If the glyph has been loaded with @FT_LOAD_NO_SCALE, `bbox_mode` must + * be set to @FT_GLYPH_BBOX_UNSCALED to get unscaled font units in 26.6 + * pixel format. The value @FT_GLYPH_BBOX_SUBPIXELS is another name for + * this constant. + * + * If the font is tricky and the glyph has been loaded with + * @FT_LOAD_NO_SCALE, the resulting CBox is meaningless. To get + * reasonable values for the CBox it is necessary to load the glyph at a + * large ppem value (so that the hinting instructions can properly shift + * and scale the subglyphs), then extracting the CBox, which can be + * eventually converted back to font units. + * + * Note that the maximum coordinates are exclusive, which means that one + * can compute the width and height of the glyph image (be it in integer + * or 26.6 pixels) as: + * + * ``` + * width = bbox.xMax - bbox.xMin; + * height = bbox.yMax - bbox.yMin; + * ``` + * + * Note also that for 26.6 coordinates, if `bbox_mode` is set to + * @FT_GLYPH_BBOX_GRIDFIT, the coordinates will also be grid-fitted, + * which corresponds to: + * + * ``` + * bbox.xMin = FLOOR(bbox.xMin); + * bbox.yMin = FLOOR(bbox.yMin); + * bbox.xMax = CEILING(bbox.xMax); + * bbox.yMax = CEILING(bbox.yMax); + * ``` + * + * To get the bbox in pixel coordinates, set `bbox_mode` to + * @FT_GLYPH_BBOX_TRUNCATE. + * + * To get the bbox in grid-fitted pixel coordinates, set `bbox_mode` to + * @FT_GLYPH_BBOX_PIXELS. + */ + FT_EXPORT( void ) + FT_Glyph_Get_CBox( FT_Glyph glyph, + FT_UInt bbox_mode, + FT_BBox *acbox ); + + + /************************************************************************** + * + * @function: + * FT_Glyph_To_Bitmap + * + * @description: + * Convert a given glyph object to a bitmap glyph object. + * + * @inout: + * the_glyph :: + * A pointer to a handle to the target glyph. + * + * @input: + * render_mode :: + * An enumeration that describes how the data is rendered. + * + * origin :: + * A pointer to a vector used to translate the glyph image before + * rendering. Can be~0 (if no translation). The origin is expressed + * in 26.6 pixels. + * + * destroy :: + * A boolean that indicates that the original glyph image should be + * destroyed by this function. It is never destroyed in case of error. + * + * @return: + * FreeType error code. 0~means success. + * + * @note: + * This function does nothing if the glyph format isn't scalable. + * + * The glyph image is translated with the `origin` vector before + * rendering. + * + * The first parameter is a pointer to an @FT_Glyph handle that will be + * _replaced_ by this function (with newly allocated data). Typically, + * you would do something like the following (omitting error handling). + * + * ``` + * FT_Glyph glyph; + * FT_BitmapGlyph glyph_bitmap; + * + * + * // load glyph + * error = FT_Load_Char( face, glyph_index, FT_LOAD_DEFAULT ); + * + * // extract glyph image + * error = FT_Get_Glyph( face->glyph, &glyph ); + * + * // convert to a bitmap (default render mode + destroying old) + * if ( glyph->format != FT_GLYPH_FORMAT_BITMAP ) + * { + * error = FT_Glyph_To_Bitmap( &glyph, FT_RENDER_MODE_NORMAL, + * 0, 1 ); + * if ( error ) // `glyph' unchanged + * ... + * } + * + * // access bitmap content by typecasting + * glyph_bitmap = (FT_BitmapGlyph)glyph; + * + * // do funny stuff with it, like blitting/drawing + * ... + * + * // discard glyph image (bitmap or not) + * FT_Done_Glyph( glyph ); + * ``` + * + * Here is another example, again without error handling. + * + * ``` + * FT_Glyph glyphs[MAX_GLYPHS] + * + * + * ... + * + * for ( idx = 0; i < MAX_GLYPHS; i++ ) + * error = FT_Load_Glyph( face, idx, FT_LOAD_DEFAULT ) || + * FT_Get_Glyph ( face->glyph, &glyphs[idx] ); + * + * ... + * + * for ( idx = 0; i < MAX_GLYPHS; i++ ) + * { + * FT_Glyph bitmap = glyphs[idx]; + * + * + * ... + * + * // after this call, `bitmap' no longer points into + * // the `glyphs' array (and the old value isn't destroyed) + * FT_Glyph_To_Bitmap( &bitmap, FT_RENDER_MODE_MONO, 0, 0 ); + * + * ... + * + * FT_Done_Glyph( bitmap ); + * } + * + * ... + * + * for ( idx = 0; i < MAX_GLYPHS; i++ ) + * FT_Done_Glyph( glyphs[idx] ); + * ``` + */ + FT_EXPORT( FT_Error ) + FT_Glyph_To_Bitmap( FT_Glyph* the_glyph, + FT_Render_Mode render_mode, + const FT_Vector* origin, + FT_Bool destroy ); + + + /************************************************************************** + * + * @function: + * FT_Done_Glyph + * + * @description: + * Destroy a given glyph. + * + * @input: + * glyph :: + * A handle to the target glyph object. Can be `NULL`. + */ + FT_EXPORT( void ) + FT_Done_Glyph( FT_Glyph glyph ); + + /* */ + + + /* other helpful functions */ + + /************************************************************************** + * + * @section: + * computations + * + */ + + + /************************************************************************** + * + * @function: + * FT_Matrix_Multiply + * + * @description: + * Perform the matrix operation `b = a*b`. + * + * @input: + * a :: + * A pointer to matrix `a`. + * + * @inout: + * b :: + * A pointer to matrix `b`. + * + * @note: + * The result is undefined if either `a` or `b` is zero. + * + * Since the function uses wrap-around arithmetic, results become + * meaningless if the arguments are very large. + */ + FT_EXPORT( void ) + FT_Matrix_Multiply( const FT_Matrix* a, + FT_Matrix* b ); + + + /************************************************************************** + * + * @function: + * FT_Matrix_Invert + * + * @description: + * Invert a 2x2 matrix. Return an error if it can't be inverted. + * + * @inout: + * matrix :: + * A pointer to the target matrix. Remains untouched in case of error. + * + * @return: + * FreeType error code. 0~means success. + */ + FT_EXPORT( FT_Error ) + FT_Matrix_Invert( FT_Matrix* matrix ); + + /* */ + + +FT_END_HEADER + +#endif /* FTGLYPH_H_ */ + + +/* END */ + + +/* Local Variables: */ +/* coding: utf-8 */ +/* End: */ |