forked from minhngoc25a/freetype2
611 lines
17 KiB
C
611 lines
17 KiB
C
/****************************************************************************
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*
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* ftoutln.h
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*
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* Support for the FT_Outline type used to store glyph shapes of
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* most scalable font formats (specification).
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*
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* Copyright 1996-2018 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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#ifndef FTOUTLN_H_
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#define FTOUTLN_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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* outline_processing
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*
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* @Title:
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* Outline Processing
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*
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* @Abstract:
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* Functions to create, transform, and render vectorial glyph images.
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*
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* @Description:
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* This section contains routines used to create and destroy scalable
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* glyph images known as `outlines'. These can also be measured,
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* transformed, and converted into bitmaps and pixmaps.
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*
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* @Order:
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* FT_Outline
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* FT_Outline_New
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* FT_Outline_Done
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* FT_Outline_Copy
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* FT_Outline_Translate
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* FT_Outline_Transform
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* FT_Outline_Embolden
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* FT_Outline_EmboldenXY
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* FT_Outline_Reverse
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* FT_Outline_Check
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*
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* FT_Outline_Get_CBox
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* FT_Outline_Get_BBox
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*
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* FT_Outline_Get_Bitmap
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* FT_Outline_Render
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* FT_Outline_Decompose
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* FT_Outline_Funcs
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* FT_Outline_MoveToFunc
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* FT_Outline_LineToFunc
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* FT_Outline_ConicToFunc
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* FT_Outline_CubicToFunc
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*
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* FT_Orientation
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* FT_Outline_Get_Orientation
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*
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* FT_OUTLINE_XXX
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*
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*/
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Decompose
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*
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* @Description:
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* Walk over an outline's structure to decompose it into individual
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* segments and Bezier arcs. This function also emits `move to'
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* operations to indicate the start of new contours in the outline.
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*
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* @Input:
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* outline ::
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* A pointer to the source target.
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*
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* func_interface ::
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* A table of `emitters', i.e., function pointers
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* called during decomposition to indicate path
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* operations.
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*
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* @InOut:
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* user ::
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* A typeless pointer that is passed to each
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* emitter during the decomposition. It can be
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* used to store the state during the
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* decomposition.
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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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* A contour that contains a single point only is represented by a
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* `move to' operation followed by `line to' to the same point. In
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* most cases, it is best to filter this out before using the
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* outline for stroking purposes (otherwise it would result in a
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* visible dot when round caps are used).
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*
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* Similarly, the function returns success for an empty outline also
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* (doing nothing, this is, not calling any emitter); if necessary,
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* you should filter this out, too.
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*/
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FT_EXPORT( FT_Error )
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FT_Outline_Decompose( FT_Outline* outline,
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const FT_Outline_Funcs* func_interface,
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void* user );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_New
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*
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* @Description:
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* Create a new outline of a given size.
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*
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* @Input:
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* library ::
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* A handle to the library object from where the
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* outline is allocated. Note however that the new
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* outline will *not* necessarily be *freed*, when
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* destroying the library, by @FT_Done_FreeType.
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*
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* numPoints ::
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* The maximum number of points within the outline.
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* Must be smaller than or equal to 0xFFFF (65535).
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*
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* numContours ::
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* The maximum number of contours within the outline.
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* This value must be in the range 0 to `numPoints'.
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*
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* @Output:
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* anoutline ::
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* A handle to the new outline.
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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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* The reason why this function takes a `library' parameter is simply
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* to use the library's memory allocator.
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*/
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FT_EXPORT( FT_Error )
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FT_Outline_New( FT_Library library,
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FT_UInt numPoints,
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FT_Int numContours,
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FT_Outline *anoutline );
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FT_EXPORT( FT_Error )
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FT_Outline_New_Internal( FT_Memory memory,
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FT_UInt numPoints,
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FT_Int numContours,
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FT_Outline *anoutline );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Done
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*
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* @Description:
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* Destroy an outline created with @FT_Outline_New.
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*
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* @Input:
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* library ::
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* A handle of the library object used to allocate the
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* outline.
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*
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* outline ::
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* A pointer to the outline object to be discarded.
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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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* If the outline's `owner' field is not set, only the outline
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* descriptor will be released.
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*/
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FT_EXPORT( FT_Error )
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FT_Outline_Done( FT_Library library,
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FT_Outline* outline );
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FT_EXPORT( FT_Error )
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FT_Outline_Done_Internal( FT_Memory memory,
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FT_Outline* outline );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Check
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*
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* @Description:
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* Check the contents of an outline descriptor.
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*
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* @Input:
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* outline ::
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* A handle to a source outline.
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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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* An empty outline, or an outline with a single point only is also
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* valid.
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*/
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FT_EXPORT( FT_Error )
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FT_Outline_Check( FT_Outline* outline );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Get_CBox
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*
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* @Description:
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* Return an outline's `control box'. The control box encloses all
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* the 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
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* that contains Bezier outside arcs).
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*
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* Computing the control box is very fast, while getting the bounding
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* box can take much more time as it needs to walk over all segments
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* and arcs in the outline. To get the latter, you can use the
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* `ftbbox' component, which is dedicated to this single task.
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*
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* @Input:
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* outline ::
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* A pointer to the source outline descriptor.
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*
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* @Output:
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* acbox ::
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* The outline's control box.
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*
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* @Note:
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* See @FT_Glyph_Get_CBox for a discussion of tricky fonts.
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*/
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FT_EXPORT( void )
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FT_Outline_Get_CBox( const FT_Outline* outline,
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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_Outline_Translate
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*
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* @Description:
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* Apply a simple translation to the points of an outline.
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*
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* @InOut:
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* outline ::
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* A pointer to the target outline descriptor.
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*
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* @Input:
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* xOffset ::
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* The horizontal offset.
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*
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* yOffset ::
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* The vertical offset.
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*/
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FT_EXPORT( void )
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FT_Outline_Translate( const FT_Outline* outline,
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FT_Pos xOffset,
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FT_Pos yOffset );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Copy
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*
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* @Description:
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* Copy an outline into another one. Both objects must have the
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* same sizes (number of points & number of contours) when this
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* function is called.
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*
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* @Input:
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* source ::
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* A handle to the source outline.
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*
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* @Output:
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* target ::
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* A handle to the target outline.
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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_Outline_Copy( const FT_Outline* source,
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FT_Outline *target );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Transform
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*
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* @Description:
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* Apply a simple 2x2 matrix to all of an outline's points. Useful
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* for applying rotations, slanting, flipping, etc.
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*
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* @InOut:
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* outline ::
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* A pointer to the target outline descriptor.
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*
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* @Input:
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* matrix ::
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* A pointer to the transformation matrix.
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*
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* @Note:
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* You can use @FT_Outline_Translate if you need to translate the
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* outline's points.
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*/
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FT_EXPORT( void )
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FT_Outline_Transform( const FT_Outline* outline,
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const FT_Matrix* matrix );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Embolden
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*
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* @Description:
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* Embolden an outline. The new outline will be at most 4~times
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* `strength' pixels wider and higher. You may think of the left and
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* bottom borders as unchanged.
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*
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* Negative `strength' values to reduce the outline thickness are
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* possible also.
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*
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* @InOut:
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* outline ::
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* A handle to the target outline.
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*
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* @Input:
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* strength ::
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* How strong the glyph is emboldened. Expressed in
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* 26.6 pixel format.
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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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* The used algorithm to increase or decrease the thickness of the
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* glyph doesn't change the number of points; this means that certain
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* situations like acute angles or intersections are sometimes
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* handled incorrectly.
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*
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* If you need `better' metrics values you should call
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* @FT_Outline_Get_CBox or @FT_Outline_Get_BBox.
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*
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* Example call:
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*
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* {
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* FT_Load_Glyph( face, index, FT_LOAD_DEFAULT );
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* if ( face->glyph->format == FT_GLYPH_FORMAT_OUTLINE )
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* FT_Outline_Embolden( &face->glyph->outline, strength );
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* }
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*
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* To get meaningful results, font scaling values must be set with
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* functions like @FT_Set_Char_Size before calling FT_Render_Glyph.
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*/
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FT_EXPORT( FT_Error )
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FT_Outline_Embolden( FT_Outline* outline,
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FT_Pos strength );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_EmboldenXY
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*
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* @Description:
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* Embolden an outline. The new outline will be `xstrength' pixels
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* wider and `ystrength' pixels higher. Otherwise, it is similar to
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* @FT_Outline_Embolden, which uses the same strength in both
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* directions.
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*
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* @Since:
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* 2.4.10
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*/
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FT_EXPORT( FT_Error )
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FT_Outline_EmboldenXY( FT_Outline* outline,
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FT_Pos xstrength,
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FT_Pos ystrength );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Reverse
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*
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* @Description:
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* Reverse the drawing direction of an outline. This is used to
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* ensure consistent fill conventions for mirrored glyphs.
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*
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* @InOut:
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* outline ::
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* A pointer to the target outline descriptor.
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*
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* @Note:
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* This function toggles the bit flag @FT_OUTLINE_REVERSE_FILL in
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* the outline's `flags' field.
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*
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* It shouldn't be used by a normal client application, unless it
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* knows what it is doing.
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*/
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FT_EXPORT( void )
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FT_Outline_Reverse( FT_Outline* outline );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Get_Bitmap
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*
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* @Description:
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* Render an outline within a bitmap. The outline's image is simply
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* OR-ed to the target bitmap.
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*
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* @Input:
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* library ::
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* A handle to a FreeType library object.
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*
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* outline ::
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* A pointer to the source outline descriptor.
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*
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* @InOut:
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* abitmap ::
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* A pointer to the target bitmap descriptor.
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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 NOT CREATE the bitmap, it only renders an
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* outline image within the one you pass to it! Consequently, the
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* various fields in `abitmap' should be set accordingly.
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*
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* It will use the raster corresponding to the default glyph format.
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*
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* The value of the `num_grays' field in `abitmap' is ignored. If
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* you select the gray-level rasterizer, and you want less than 256
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* gray levels, you have to use @FT_Outline_Render directly.
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*/
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FT_EXPORT( FT_Error )
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FT_Outline_Get_Bitmap( FT_Library library,
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FT_Outline* outline,
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const FT_Bitmap *abitmap );
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/**************************************************************************
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*
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* @Function:
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* FT_Outline_Render
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*
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* @Description:
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* Render an outline within a bitmap using the current scan-convert.
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* This function uses an @FT_Raster_Params structure as an argument,
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* allowing advanced features like direct composition, translucency,
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* etc.
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*
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* @Input:
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* library ::
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* A handle to a FreeType library object.
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*
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* outline ::
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* A pointer to the source outline descriptor.
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*
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* @InOut:
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* params ::
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* A pointer to an @FT_Raster_Params structure used to
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* describe the rendering operation.
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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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* You should know what you are doing and how @FT_Raster_Params works
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* to use this function.
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*
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* The field `params.source' will be set to `outline' before the scan
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* converter is called, which means that the value you give to it is
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* actually ignored.
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*
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* The gray-level rasterizer always uses 256 gray levels. If you
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* want less gray levels, you have to provide your own span callback.
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* See the @FT_RASTER_FLAG_DIRECT value of the `flags' field in the
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* @FT_Raster_Params structure for more details.
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*/
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FT_EXPORT( FT_Error )
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FT_Outline_Render( FT_Library library,
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FT_Outline* outline,
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FT_Raster_Params* params );
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/**************************************************************************
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*
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* @enum:
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* FT_Orientation
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*
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* @description:
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* A list of values used to describe an outline's contour orientation.
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*
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* The TrueType and PostScript specifications use different conventions
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* to determine whether outline contours should be filled or unfilled.
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*
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* @values:
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* FT_ORIENTATION_TRUETYPE ::
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* According to the TrueType specification, clockwise contours must
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* be filled, and counter-clockwise ones must be unfilled.
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*
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* FT_ORIENTATION_POSTSCRIPT ::
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* According to the PostScript specification, counter-clockwise contours
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* must be filled, and clockwise ones must be unfilled.
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*
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* FT_ORIENTATION_FILL_RIGHT ::
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* This is identical to @FT_ORIENTATION_TRUETYPE, but is used to
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* remember that in TrueType, everything that is to the right of
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* the drawing direction of a contour must be filled.
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*
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* FT_ORIENTATION_FILL_LEFT ::
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* This is identical to @FT_ORIENTATION_POSTSCRIPT, but is used to
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* remember that in PostScript, everything that is to the left of
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* the drawing direction of a contour must be filled.
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*
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* FT_ORIENTATION_NONE ::
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* The orientation cannot be determined. That is, different parts of
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* the glyph have different orientation.
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*
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*/
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typedef enum FT_Orientation_
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{
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FT_ORIENTATION_TRUETYPE = 0,
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FT_ORIENTATION_POSTSCRIPT = 1,
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FT_ORIENTATION_FILL_RIGHT = FT_ORIENTATION_TRUETYPE,
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FT_ORIENTATION_FILL_LEFT = FT_ORIENTATION_POSTSCRIPT,
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FT_ORIENTATION_NONE
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} FT_Orientation;
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/**************************************************************************
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*
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* @function:
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* FT_Outline_Get_Orientation
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*
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* @description:
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* This function analyzes a glyph outline and tries to compute its
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* fill orientation (see @FT_Orientation). This is done by integrating
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* the total area covered by the outline. The positive integral
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|
* corresponds to the clockwise orientation and @FT_ORIENTATION_POSTSCRIPT
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|
* is returned. The negative integral corresponds to the counter-clockwise
|
|
* orientation and @FT_ORIENTATION_TRUETYPE is returned.
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|
*
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|
* Note that this will return @FT_ORIENTATION_TRUETYPE for empty
|
|
* outlines.
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|
*
|
|
* @input:
|
|
* outline ::
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|
* A handle to the source outline.
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|
*
|
|
* @return:
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|
* The orientation.
|
|
*
|
|
*/
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|
FT_EXPORT( FT_Orientation )
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|
FT_Outline_Get_Orientation( FT_Outline* outline );
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|
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|
/* */
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|
|
|
|
|
FT_END_HEADER
|
|
|
|
#endif /* FTOUTLN_H_ */
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|
|
|
|
|
/* END */
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|
|
|
|
|
/* Local Variables: */
|
|
/* coding: utf-8 */
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|
/* End: */
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