666 lines
18 KiB
C
666 lines
18 KiB
C
/****************************************************************************
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*
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* ftglyph.h
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*
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* FreeType convenience functions to handle glyphs (specification).
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*
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* Copyright (C) 1996-2020 by
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* David Turner, Robert Wilhelm, and Werner Lemberg.
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*
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* This file is part of the FreeType project, and may only be used,
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* modified, and distributed under the terms of the FreeType project
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* license, LICENSE.TXT. By continuing to use, modify, or distribute
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* this file you indicate that you have read the license and
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* understand and accept it fully.
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*
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*/
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/**************************************************************************
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*
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* This file contains the definition of several convenience functions that
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* can be used by client applications to easily retrieve glyph bitmaps and
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* outlines from a given face.
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*
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* These functions should be optional if you are writing a font server or
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* text layout engine on top of FreeType. However, they are pretty handy
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* for many other simple uses of the library.
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*
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*/
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#ifndef FTGLYPH_H_
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#define FTGLYPH_H_
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#include <ft2build.h>
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#include FT_FREETYPE_H
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#ifdef FREETYPE_H
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#error "freetype.h of FreeType 1 has been loaded!"
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#error "Please fix the directory search order for header files"
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#error "so that freetype.h of FreeType 2 is found first."
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#endif
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FT_BEGIN_HEADER
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/**************************************************************************
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*
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* @section:
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* glyph_management
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*
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* @title:
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* Glyph Management
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*
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* @abstract:
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* Generic interface to manage individual glyph data.
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*
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* @description:
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* This section contains definitions used to manage glyph data through
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* generic @FT_Glyph objects. Each of them can contain a bitmap,
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* a vector outline, or even images in other formats. These objects are
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* detached from @FT_Face, contrary to @FT_GlyphSlot.
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*
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*/
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/* forward declaration to a private type */
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typedef struct FT_Glyph_Class_ FT_Glyph_Class;
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/**************************************************************************
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*
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* @type:
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* FT_Glyph
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*
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* @description:
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* Handle to an object used to model generic glyph images. It is a
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* pointer to the @FT_GlyphRec structure and can contain a glyph bitmap
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* or pointer.
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*
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* @note:
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* Glyph objects are not owned by the library. You must thus release
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* them manually (through @FT_Done_Glyph) _before_ calling
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* @FT_Done_FreeType.
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*/
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typedef struct FT_GlyphRec_* FT_Glyph;
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/**************************************************************************
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*
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* @struct:
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* FT_GlyphRec
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*
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* @description:
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* The root glyph structure contains a given glyph image plus its advance
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* width in 16.16 fixed-point format.
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*
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* @fields:
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* library ::
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* A handle to the FreeType library object.
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*
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* clazz ::
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* A pointer to the glyph's class. Private.
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*
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* format ::
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* The format of the glyph's image.
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*
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* advance ::
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* A 16.16 vector that gives the glyph's advance width.
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*/
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typedef struct FT_GlyphRec_
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{
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FT_Library library;
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const FT_Glyph_Class* clazz;
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FT_Glyph_Format format;
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FT_Vector advance;
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} FT_GlyphRec;
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/**************************************************************************
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*
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* @type:
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* FT_BitmapGlyph
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*
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* @description:
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* A handle to an object used to model a bitmap glyph image. This is a
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* sub-class of @FT_Glyph, and a pointer to @FT_BitmapGlyphRec.
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*/
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typedef struct FT_BitmapGlyphRec_* FT_BitmapGlyph;
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/**************************************************************************
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*
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* @struct:
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* FT_BitmapGlyphRec
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*
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* @description:
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* A structure used for bitmap glyph images. This really is a
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* 'sub-class' of @FT_GlyphRec.
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*
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* @fields:
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* root ::
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* The root @FT_Glyph fields.
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*
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* left ::
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* The left-side bearing, i.e., the horizontal distance from the
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* current pen position to the left border of the glyph bitmap.
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*
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* top ::
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* The top-side bearing, i.e., the vertical distance from the current
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* pen position to the top border of the glyph bitmap. This distance
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* is positive for upwards~y!
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*
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* bitmap ::
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* A descriptor for the bitmap.
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*
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* @note:
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* You can typecast an @FT_Glyph to @FT_BitmapGlyph if you have
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* `glyph->format == FT_GLYPH_FORMAT_BITMAP`. This lets you access the
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* bitmap's contents easily.
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*
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* The corresponding pixel buffer is always owned by @FT_BitmapGlyph and
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* is thus created and destroyed with it.
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*/
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typedef struct FT_BitmapGlyphRec_
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{
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FT_GlyphRec root;
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FT_Int left;
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FT_Int top;
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FT_Bitmap bitmap;
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} FT_BitmapGlyphRec;
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/**************************************************************************
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*
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* @type:
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* FT_OutlineGlyph
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*
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* @description:
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* A handle to an object used to model an outline glyph image. This is a
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* sub-class of @FT_Glyph, and a pointer to @FT_OutlineGlyphRec.
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*/
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typedef struct FT_OutlineGlyphRec_* FT_OutlineGlyph;
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/**************************************************************************
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*
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* @struct:
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* FT_OutlineGlyphRec
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*
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* @description:
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* A structure used for outline (vectorial) glyph images. This really is
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* a 'sub-class' of @FT_GlyphRec.
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*
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* @fields:
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* root ::
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* The root @FT_Glyph fields.
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*
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* outline ::
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* A descriptor for the outline.
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*
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* @note:
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* You can typecast an @FT_Glyph to @FT_OutlineGlyph if you have
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* `glyph->format == FT_GLYPH_FORMAT_OUTLINE`. This lets you access the
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* outline's content easily.
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*
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* As the outline is extracted from a glyph slot, its coordinates are
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* expressed normally in 26.6 pixels, unless the flag @FT_LOAD_NO_SCALE
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* was used in @FT_Load_Glyph or @FT_Load_Char.
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*
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* The outline's tables are always owned by the object and are destroyed
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* with it.
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*/
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typedef struct FT_OutlineGlyphRec_
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{
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FT_GlyphRec root;
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FT_Outline outline;
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} FT_OutlineGlyphRec;
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/**************************************************************************
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*
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* @function:
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* FT_New_Glyph
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*
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* @description:
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* A function used to create a new empty glyph image. Note that the
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* created @FT_Glyph object must be released with @FT_Done_Glyph.
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*
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* @input:
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* library ::
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* A handle to the FreeType library object.
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*
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* format ::
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* The format of the glyph's image.
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*
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* @output:
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* aglyph ::
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* A handle to the glyph object.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @since:
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* 2.10
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*/
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FT_EXPORT( FT_Error )
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FT_New_Glyph( FT_Library library,
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FT_Glyph_Format format,
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FT_Glyph *aglyph );
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/**************************************************************************
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*
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* @function:
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* FT_Get_Glyph
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*
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* @description:
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* A function used to extract a glyph image from a slot. Note that the
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* created @FT_Glyph object must be released with @FT_Done_Glyph.
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*
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* @input:
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* slot ::
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* A handle to the source glyph slot.
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*
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* @output:
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* aglyph ::
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* A handle to the glyph object.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @note:
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* Because `*aglyph->advance.x` and `*aglyph->advance.y` are 16.16
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* fixed-point numbers, `slot->advance.x` and `slot->advance.y` (which
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* are in 26.6 fixed-point format) must be in the range ]-32768;32768[.
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*/
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FT_EXPORT( FT_Error )
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FT_Get_Glyph( FT_GlyphSlot slot,
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FT_Glyph *aglyph );
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/**************************************************************************
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*
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* @function:
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* FT_Glyph_Copy
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*
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* @description:
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* A function used to copy a glyph image. Note that the created
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* @FT_Glyph object must be released with @FT_Done_Glyph.
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*
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* @input:
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* source ::
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* A handle to the source glyph object.
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*
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* @output:
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* target ::
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* A handle to the target glyph object. 0~in case of error.
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*
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* @return:
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* FreeType error code. 0~means success.
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*/
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FT_EXPORT( FT_Error )
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FT_Glyph_Copy( FT_Glyph source,
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FT_Glyph *target );
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/**************************************************************************
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*
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* @function:
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* FT_Glyph_Transform
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*
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* @description:
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* Transform a glyph image if its format is scalable.
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*
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* @inout:
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* glyph ::
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* A handle to the target glyph object.
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*
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* @input:
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* matrix ::
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* A pointer to a 2x2 matrix to apply.
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*
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* delta ::
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* A pointer to a 2d vector to apply. Coordinates are expressed in
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* 1/64th of a pixel.
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*
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* @return:
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* FreeType error code (if not 0, the glyph format is not scalable).
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*
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* @note:
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* The 2x2 transformation matrix is also applied to the glyph's advance
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* vector.
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*/
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FT_EXPORT( FT_Error )
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FT_Glyph_Transform( FT_Glyph glyph,
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FT_Matrix* matrix,
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FT_Vector* delta );
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/**************************************************************************
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*
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* @enum:
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* FT_Glyph_BBox_Mode
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*
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* @description:
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* The mode how the values of @FT_Glyph_Get_CBox are returned.
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*
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* @values:
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* FT_GLYPH_BBOX_UNSCALED ::
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* Return unscaled font units.
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*
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* FT_GLYPH_BBOX_SUBPIXELS ::
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* Return unfitted 26.6 coordinates.
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*
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* FT_GLYPH_BBOX_GRIDFIT ::
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* Return grid-fitted 26.6 coordinates.
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*
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* FT_GLYPH_BBOX_TRUNCATE ::
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* Return coordinates in integer pixels.
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*
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* FT_GLYPH_BBOX_PIXELS ::
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* Return grid-fitted pixel coordinates.
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*/
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typedef enum FT_Glyph_BBox_Mode_
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{
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FT_GLYPH_BBOX_UNSCALED = 0,
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FT_GLYPH_BBOX_SUBPIXELS = 0,
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FT_GLYPH_BBOX_GRIDFIT = 1,
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FT_GLYPH_BBOX_TRUNCATE = 2,
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FT_GLYPH_BBOX_PIXELS = 3
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} FT_Glyph_BBox_Mode;
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/* these constants are deprecated; use the corresponding */
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/* `FT_Glyph_BBox_Mode` values instead */
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#define ft_glyph_bbox_unscaled FT_GLYPH_BBOX_UNSCALED
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#define ft_glyph_bbox_subpixels FT_GLYPH_BBOX_SUBPIXELS
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#define ft_glyph_bbox_gridfit FT_GLYPH_BBOX_GRIDFIT
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#define ft_glyph_bbox_truncate FT_GLYPH_BBOX_TRUNCATE
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#define ft_glyph_bbox_pixels FT_GLYPH_BBOX_PIXELS
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/**************************************************************************
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*
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* @function:
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* FT_Glyph_Get_CBox
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*
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* @description:
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* Return a glyph's 'control box'. The control box encloses all the
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* outline's points, including Bezier control points. Though it
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* coincides with the exact bounding box for most glyphs, it can be
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* slightly larger in some situations (like when rotating an outline that
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* contains Bezier outside arcs).
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*
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* Computing the control box is very fast, while getting the bounding box
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* can take much more time as it needs to walk over all segments and arcs
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* in the outline. To get the latter, you can use the 'ftbbox'
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* component, which is dedicated to this single task.
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*
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* @input:
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* glyph ::
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* A handle to the source glyph object.
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*
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* mode ::
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* The mode that indicates how to interpret the returned bounding box
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* values.
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*
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* @output:
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* acbox ::
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* The glyph coordinate bounding box. Coordinates are expressed in
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* 1/64th of pixels if it is grid-fitted.
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*
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* @note:
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* Coordinates are relative to the glyph origin, using the y~upwards
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* convention.
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*
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* If the glyph has been loaded with @FT_LOAD_NO_SCALE, `bbox_mode` must
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* be set to @FT_GLYPH_BBOX_UNSCALED to get unscaled font units in 26.6
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* pixel format. The value @FT_GLYPH_BBOX_SUBPIXELS is another name for
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* this constant.
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*
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* If the font is tricky and the glyph has been loaded with
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* @FT_LOAD_NO_SCALE, the resulting CBox is meaningless. To get
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* reasonable values for the CBox it is necessary to load the glyph at a
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* large ppem value (so that the hinting instructions can properly shift
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* and scale the subglyphs), then extracting the CBox, which can be
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* eventually converted back to font units.
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*
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* Note that the maximum coordinates are exclusive, which means that one
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* can compute the width and height of the glyph image (be it in integer
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* or 26.6 pixels) as:
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*
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* ```
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* width = bbox.xMax - bbox.xMin;
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* height = bbox.yMax - bbox.yMin;
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* ```
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*
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* Note also that for 26.6 coordinates, if `bbox_mode` is set to
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* @FT_GLYPH_BBOX_GRIDFIT, the coordinates will also be grid-fitted,
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* which corresponds to:
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*
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* ```
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* bbox.xMin = FLOOR(bbox.xMin);
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* bbox.yMin = FLOOR(bbox.yMin);
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* bbox.xMax = CEILING(bbox.xMax);
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* bbox.yMax = CEILING(bbox.yMax);
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* ```
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*
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* To get the bbox in pixel coordinates, set `bbox_mode` to
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* @FT_GLYPH_BBOX_TRUNCATE.
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*
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* To get the bbox in grid-fitted pixel coordinates, set `bbox_mode` to
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* @FT_GLYPH_BBOX_PIXELS.
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*/
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FT_EXPORT( void )
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FT_Glyph_Get_CBox( FT_Glyph glyph,
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FT_UInt bbox_mode,
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FT_BBox *acbox );
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/**************************************************************************
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*
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* @function:
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* FT_Glyph_To_Bitmap
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*
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* @description:
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* Convert a given glyph object to a bitmap glyph object.
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*
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* @inout:
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* the_glyph ::
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* A pointer to a handle to the target glyph.
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*
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* @input:
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* render_mode ::
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* An enumeration that describes how the data is rendered.
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*
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* origin ::
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* A pointer to a vector used to translate the glyph image before
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* rendering. Can be~0 (if no translation). The origin is expressed
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* in 26.6 pixels.
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*
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* destroy ::
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* A boolean that indicates that the original glyph image should be
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* destroyed by this function. It is never destroyed in case of error.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @note:
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* This function does nothing if the glyph format isn't scalable.
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*
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* The glyph image is translated with the `origin` vector before
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* rendering.
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*
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* The first parameter is a pointer to an @FT_Glyph handle, that will be
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* _replaced_ by this function (with newly allocated data). Typically,
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* you would use (omitting error handling):
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*
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* ```
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* FT_Glyph glyph;
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* FT_BitmapGlyph glyph_bitmap;
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*
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*
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* // load glyph
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* error = FT_Load_Char( face, glyph_index, FT_LOAD_DEFAULT );
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*
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* // extract glyph image
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* error = FT_Get_Glyph( face->glyph, &glyph );
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*
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* // convert to a bitmap (default render mode + destroying old)
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* if ( glyph->format != FT_GLYPH_FORMAT_BITMAP )
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* {
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* error = FT_Glyph_To_Bitmap( &glyph, FT_RENDER_MODE_NORMAL,
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* 0, 1 );
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* if ( error ) // `glyph' unchanged
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* ...
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* }
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*
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* // access bitmap content by typecasting
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* glyph_bitmap = (FT_BitmapGlyph)glyph;
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*
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* // do funny stuff with it, like blitting/drawing
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* ...
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*
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* // discard glyph image (bitmap or not)
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* FT_Done_Glyph( glyph );
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* ```
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*
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* Here is another example, again without error handling:
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*
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* ```
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* FT_Glyph glyphs[MAX_GLYPHS]
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*
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*
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* ...
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*
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* for ( idx = 0; i < MAX_GLYPHS; i++ )
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* error = FT_Load_Glyph( face, idx, FT_LOAD_DEFAULT ) ||
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* FT_Get_Glyph ( face->glyph, &glyphs[idx] );
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*
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* ...
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*
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* for ( idx = 0; i < MAX_GLYPHS; i++ )
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* {
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* FT_Glyph bitmap = glyphs[idx];
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*
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*
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* ...
|
|
*
|
|
* // 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,
|
|
FT_Vector* origin,
|
|
FT_Bool destroy );
|
|
|
|
|
|
/**************************************************************************
|
|
*
|
|
* @function:
|
|
* FT_Done_Glyph
|
|
*
|
|
* @description:
|
|
* Destroy a given glyph.
|
|
*
|
|
* @input:
|
|
* glyph ::
|
|
* A handle to the target glyph object.
|
|
*/
|
|
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: */
|