594 lines
17 KiB
C
594 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 (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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#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 called during
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* decomposition to indicate path 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 emitter during the
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* decomposition. It can be 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 'move
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* to' operation followed by 'line to' to the same point. In most cases,
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* it is best to filter this out before using the outline for stroking
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* purposes (otherwise it would result in a visible dot when round caps
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* 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, you
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* 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 outline is allocated.
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* Note however that the new outline will **not** necessarily be
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* **freed**, when 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. Must be smaller
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* 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. This value must
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* 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 to
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* 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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/**************************************************************************
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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 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 descriptor
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* 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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/**************************************************************************
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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 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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* 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 same
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* sizes (number of points & number of contours) when this function is
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* 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 for
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* 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 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 glyph
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* doesn't change the number of points; this means that certain
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* situations like acute angles or intersections are sometimes handled
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* 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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* 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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* @example:
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* ```
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* FT_Load_Glyph( face, index, FT_LOAD_DEFAULT );
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*
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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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*/
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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 wider
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* and `ystrength` pixels higher. Otherwise, it is similar to
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* @FT_Outline_Embolden, which uses the same strength in both 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 ensure
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* 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 the
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* outline's `flags` field.
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*
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* It shouldn't be used by a normal client application, unless it knows
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* 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 you
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* select the gray-level rasterizer, and you want less than 256 gray
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* 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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*
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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 describe the
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* 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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* This advanced function uses @FT_Raster_Params as an argument,
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* allowing FreeType rasterizer to be used for direct composition,
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* translucency, etc. You should know how to set up @FT_Raster_Params
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* for this function to work.
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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 want
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* less gray levels, you have to provide your own span callback. See the
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* @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 be
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* 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
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* contours 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 the
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* 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 the
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* 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 fill
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* orientation (see @FT_Orientation). This is done by integrating the
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* total area covered by the outline. The positive integral corresponds
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* to the clockwise orientation and @FT_ORIENTATION_POSTSCRIPT is
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* returned. The negative integral corresponds to the counter-clockwise
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* 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
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* outlines.
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*
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* @input:
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* outline ::
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* A handle to the source outline.
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*
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* @return:
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|
* The orientation.
|
|
*
|
|
*/
|
|
FT_EXPORT( FT_Orientation )
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|
FT_Outline_Get_Orientation( FT_Outline* outline );
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|
|
|
|
|
/* */
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|
|
|
|
|
FT_END_HEADER
|
|
|
|
#endif /* FTOUTLN_H_ */
|
|
|
|
|
|
/* END */
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|
|
|
|
|
/* Local Variables: */
|
|
/* coding: utf-8 */
|
|
/* End: */
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