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/****************************************************************************
*
* ftsdfrend.h
*
* Signed Distance Field renderer interface (specification).
*
* Copyright (C) 2020-2022 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* Written by Anuj Verma.
*
* This file is part of the FreeType project, and may only be used,
* modified, and distributed under the terms of the FreeType project
* license, LICENSE.TXT. By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
*/
#ifndef FTSDFREND_H_
#define FTSDFREND_H_
#include <freetype/ftrender.h>
#include <freetype/ftmodapi.h>
#include <freetype/internal/ftobjs.h>
FT_BEGIN_HEADER
/**************************************************************************
*
* @struct:
* SDF_Renderer_Module
*
* @description:
* This struct extends the native renderer struct `FT_RendererRec`. It
* is basically used to store various parameters required by the
* renderer and some additional parameters that can be used to tweak the
* output of the renderer.
*
* @fields:
* root ::
* The native rendere struct.
*
* spread ::
* This is an essential parameter/property required by the renderer.
* `spread` defines the maximum unsigned value that is present in the
* final SDF output. For the default value check file
* `ftsdfcommon.h`.
*
* flip_sign ::
* By default positive values indicate positions inside of contours,
* i.e., filled by a contour. If this property is true then that
* output will be the opposite of the default, i.e., negative values
* indicate positions inside of contours.
*
* flip_y ::
* Setting this parameter to true makes the output image flipped
* along the y-axis.
*
* overlaps ::
* Set this to true to generate SDF for glyphs having overlapping
* contours. The overlapping support is limited to glyphs that do not
* have self-intersecting contours. Also, removing overlaps require a
* considerable amount of extra memory; additionally, it will not work
* if generating SDF from bitmap.
*
* @note:
* All properties except `overlaps` are valid for both the 'sdf' and
* 'bsdf' renderers.
*
*/
typedef struct SDF_Renderer_Module_
{
FT_RendererRec root;
FT_UInt spread;
FT_Bool flip_sign;
FT_Bool flip_y;
FT_Bool overlaps;
} SDF_Renderer_Module, *SDF_Renderer;
/**************************************************************************
*
* @renderer:
* ft_sdf_renderer_class
*
* @description:
* Renderer to convert @FT_Outline to signed distance fields.
*
*/
FT_DECLARE_RENDERER( ft_sdf_renderer_class )
/**************************************************************************
*
* @renderer:
* ft_bitmap_sdf_renderer_class
*
* @description:
* This is not exactly a renderer; it is just a converter that
* transforms bitmaps to signed distance fields.
*
* @note:
* This is not a separate module, it is part of the 'sdf' module.
*
*/
FT_DECLARE_RENDERER( ft_bitmap_sdf_renderer_class )
FT_END_HEADER
#endif /* FTSDFREND_H_ */
/* END */
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