minhngoc25a
/
freetype2
mirror of git://git.savannah.gnu.org/freetype/freetype2.git
2
1
Fork 2
Code Issues 4 Releases Wiki Activity
freetype2/include/freetype/ftglyph.h

751 lines
20 KiB
C
Raw Blame History

/****************************************************************************
*
* 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: */
Reference in New Issue View Git Blame Copy Permalink