ref: a56e4bf7a243f46632e4e2ccf25d2f50ca132b23
dir: /include/freetype/ftoutln.h/
/****************************************************************************
*
* ftoutln.h
*
* Support for the FT_Outline type used to store glyph shapes of
* most scalable font formats (specification).
*
* Copyright 1996-2018 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* This file is part of the FreeType project, and may only be used,
* modified, and distributed under the terms of the FreeType project
* license, LICENSE.TXT. By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
*/
#ifndef FTOUTLN_H_
#define FTOUTLN_H_
#include <ft2build.h>
#include FT_FREETYPE_H
#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif
FT_BEGIN_HEADER
/**************************************************************************
*
* @section:
* outline_processing
*
* @title:
* Outline Processing
*
* @abstract:
* Functions to create, transform, and render vectorial glyph images.
*
* @description:
* This section contains routines used to create and destroy scalable
* glyph images known as `outlines'. These can also be measured,
* transformed, and converted into bitmaps and pixmaps.
*
* @order:
* FT_Outline
* FT_Outline_New
* FT_Outline_Done
* FT_Outline_Copy
* FT_Outline_Translate
* FT_Outline_Transform
* FT_Outline_Embolden
* FT_Outline_EmboldenXY
* FT_Outline_Reverse
* FT_Outline_Check
*
* FT_Outline_Get_CBox
* FT_Outline_Get_BBox
*
* FT_Outline_Get_Bitmap
* FT_Outline_Render
* FT_Outline_Decompose
* FT_Outline_Funcs
* FT_Outline_MoveToFunc
* FT_Outline_LineToFunc
* FT_Outline_ConicToFunc
* FT_Outline_CubicToFunc
*
* FT_Orientation
* FT_Outline_Get_Orientation
*
* FT_OUTLINE_XXX
*
*/
/**************************************************************************
*
* @function:
* FT_Outline_Decompose
*
* @description:
* Walk over an outline's structure to decompose it into individual
* segments and Bezier arcs. This function also emits `move to'
* operations to indicate the start of new contours in the outline.
*
* @input:
* outline ::
* A pointer to the source target.
*
* func_interface ::
* A table of `emitters', i.e., function pointers
* called during decomposition to indicate path
* operations.
*
* @inout:
* user ::
* A typeless pointer that is passed to each
* emitter during the decomposition. It can be
* used to store the state during the
* decomposition.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* A contour that contains a single point only is represented by a
* `move to' operation followed by `line to' to the same point. In
* most cases, it is best to filter this out before using the
* outline for stroking purposes (otherwise it would result in a
* visible dot when round caps are used).
*
* Similarly, the function returns success for an empty outline also
* (doing nothing, this is, not calling any emitter); if necessary,
* you should filter this out, too.
*/
FT_EXPORT( FT_Error )
FT_Outline_Decompose( FT_Outline* outline,
const FT_Outline_Funcs* func_interface,
void* user );
/**************************************************************************
*
* @function:
* FT_Outline_New
*
* @description:
* Create a new outline of a given size.
*
* @input:
* library ::
* A handle to the library object from where the
* outline is allocated. Note however that the new
* outline will *not* necessarily be *freed*, when
* destroying the library, by @FT_Done_FreeType.
*
* numPoints ::
* The maximum number of points within the outline.
* Must be smaller than or equal to 0xFFFF (65535).
*
* numContours ::
* The maximum number of contours within the outline.
* This value must be in the range 0 to `numPoints'.
*
* @output:
* anoutline ::
* A handle to the new outline.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* The reason why this function takes a `library' parameter is simply
* to use the library's memory allocator.
*/
FT_EXPORT( FT_Error )
FT_Outline_New( FT_Library library,
FT_UInt numPoints,
FT_Int numContours,
FT_Outline *anoutline );
FT_EXPORT( FT_Error )
FT_Outline_New_Internal( FT_Memory memory,
FT_UInt numPoints,
FT_Int numContours,
FT_Outline *anoutline );
/**************************************************************************
*
* @function:
* FT_Outline_Done
*
* @description:
* Destroy an outline created with @FT_Outline_New.
*
* @input:
* library ::
* A handle of the library object used to allocate the
* outline.
*
* outline ::
* A pointer to the outline object to be discarded.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* If the outline's `owner' field is not set, only the outline
* descriptor will be released.
*/
FT_EXPORT( FT_Error )
FT_Outline_Done( FT_Library library,
FT_Outline* outline );
FT_EXPORT( FT_Error )
FT_Outline_Done_Internal( FT_Memory memory,
FT_Outline* outline );
/**************************************************************************
*
* @function:
* FT_Outline_Check
*
* @description:
* Check the contents of an outline descriptor.
*
* @input:
* outline ::
* A handle to a source outline.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* An empty outline, or an outline with a single point only is also
* valid.
*/
FT_EXPORT( FT_Error )
FT_Outline_Check( FT_Outline* outline );
/**************************************************************************
*
* @function:
* FT_Outline_Get_CBox
*
* @description:
* Return an outline's `control box'. The control box encloses all
* the outline's points, including Bezier control points. Though it
* coincides with the exact bounding box for most glyphs, it can be
* slightly larger in some situations (like when rotating an outline
* that contains Bezier outside arcs).
*
* Computing the control box is very fast, while getting the bounding
* box can take much more time as it needs to walk over all segments
* and arcs in the outline. To get the latter, you can use the
* `ftbbox' component, which is dedicated to this single task.
*
* @input:
* outline ::
* A pointer to the source outline descriptor.
*
* @output:
* acbox ::
* The outline's control box.
*
* @note:
* See @FT_Glyph_Get_CBox for a discussion of tricky fonts.
*/
FT_EXPORT( void )
FT_Outline_Get_CBox( const FT_Outline* outline,
FT_BBox *acbox );
/**************************************************************************
*
* @function:
* FT_Outline_Translate
*
* @description:
* Apply a simple translation to the points of an outline.
*
* @inout:
* outline ::
* A pointer to the target outline descriptor.
*
* @input:
* xOffset ::
* The horizontal offset.
*
* yOffset ::
* The vertical offset.
*/
FT_EXPORT( void )
FT_Outline_Translate( const FT_Outline* outline,
FT_Pos xOffset,
FT_Pos yOffset );
/**************************************************************************
*
* @function:
* FT_Outline_Copy
*
* @description:
* Copy an outline into another one. Both objects must have the
* same sizes (number of points & number of contours) when this
* function is called.
*
* @input:
* source ::
* A handle to the source outline.
*
* @output:
* target ::
* A handle to the target outline.
*
* @return:
* FreeType error code. 0~means success.
*/
FT_EXPORT( FT_Error )
FT_Outline_Copy( const FT_Outline* source,
FT_Outline *target );
/**************************************************************************
*
* @function:
* FT_Outline_Transform
*
* @description:
* Apply a simple 2x2 matrix to all of an outline's points. Useful
* for applying rotations, slanting, flipping, etc.
*
* @inout:
* outline ::
* A pointer to the target outline descriptor.
*
* @input:
* matrix ::
* A pointer to the transformation matrix.
*
* @note:
* You can use @FT_Outline_Translate if you need to translate the
* outline's points.
*/
FT_EXPORT( void )
FT_Outline_Transform( const FT_Outline* outline,
const FT_Matrix* matrix );
/**************************************************************************
*
* @function:
* FT_Outline_Embolden
*
* @description:
* Embolden an outline. The new outline will be at most 4~times
* `strength' pixels wider and higher. You may think of the left and
* bottom borders as unchanged.
*
* Negative `strength' values to reduce the outline thickness are
* possible also.
*
* @inout:
* outline ::
* A handle to the target outline.
*
* @input:
* strength ::
* How strong the glyph is emboldened. Expressed in
* 26.6 pixel format.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* The used algorithm to increase or decrease the thickness of the
* glyph doesn't change the number of points; this means that certain
* situations like acute angles or intersections are sometimes
* handled incorrectly.
*
* If you need `better' metrics values you should call
* @FT_Outline_Get_CBox or @FT_Outline_Get_BBox.
*
* To get meaningful results, font scaling values must be set with
* functions like @FT_Set_Char_Size before calling FT_Render_Glyph.
*
* @example:
* {
* FT_Load_Glyph( face, index, FT_LOAD_DEFAULT );
*
* if ( face->glyph->format == FT_GLYPH_FORMAT_OUTLINE )
* FT_Outline_Embolden( &face->glyph->outline, strength );
* }
*
*/
FT_EXPORT( FT_Error )
FT_Outline_Embolden( FT_Outline* outline,
FT_Pos strength );
/**************************************************************************
*
* @function:
* FT_Outline_EmboldenXY
*
* @description:
* Embolden an outline. The new outline will be `xstrength' pixels
* wider and `ystrength' pixels higher. Otherwise, it is similar to
* @FT_Outline_Embolden, which uses the same strength in both
* directions.
*
* @since:
* 2.4.10
*/
FT_EXPORT( FT_Error )
FT_Outline_EmboldenXY( FT_Outline* outline,
FT_Pos xstrength,
FT_Pos ystrength );
/**************************************************************************
*
* @function:
* FT_Outline_Reverse
*
* @description:
* Reverse the drawing direction of an outline. This is used to
* ensure consistent fill conventions for mirrored glyphs.
*
* @inout:
* outline ::
* A pointer to the target outline descriptor.
*
* @note:
* This function toggles the bit flag @FT_OUTLINE_REVERSE_FILL in
* the outline's `flags' field.
*
* It shouldn't be used by a normal client application, unless it
* knows what it is doing.
*/
FT_EXPORT( void )
FT_Outline_Reverse( FT_Outline* outline );
/**************************************************************************
*
* @function:
* FT_Outline_Get_Bitmap
*
* @description:
* Render an outline within a bitmap. The outline's image is simply
* OR-ed to the target bitmap.
*
* @input:
* library ::
* A handle to a FreeType library object.
*
* outline ::
* A pointer to the source outline descriptor.
*
* @inout:
* abitmap ::
* A pointer to the target bitmap descriptor.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* This function does NOT CREATE the bitmap, it only renders an
* outline image within the one you pass to it! Consequently, the
* various fields in `abitmap' should be set accordingly.
*
* It will use the raster corresponding to the default glyph format.
*
* The value of the `num_grays' field in `abitmap' is ignored. If
* you select the gray-level rasterizer, and you want less than 256
* gray levels, you have to use @FT_Outline_Render directly.
*/
FT_EXPORT( FT_Error )
FT_Outline_Get_Bitmap( FT_Library library,
FT_Outline* outline,
const FT_Bitmap *abitmap );
/**************************************************************************
*
* @function:
* FT_Outline_Render
*
* @description:
* Render an outline within a bitmap using the current scan-convert.
* This function uses an @FT_Raster_Params structure as an argument,
* allowing advanced features like direct composition, translucency,
* etc.
*
* @input:
* library ::
* A handle to a FreeType library object.
*
* outline ::
* A pointer to the source outline descriptor.
*
* @inout:
* params ::
* A pointer to an @FT_Raster_Params structure used to
* describe the rendering operation.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* You should know what you are doing and how @FT_Raster_Params works
* to use this function.
*
* The field `params.source' will be set to `outline' before the scan
* converter is called, which means that the value you give to it is
* actually ignored.
*
* The gray-level rasterizer always uses 256 gray levels. If you
* want less gray levels, you have to provide your own span callback.
* See the @FT_RASTER_FLAG_DIRECT value of the `flags' field in the
* @FT_Raster_Params structure for more details.
*/
FT_EXPORT( FT_Error )
FT_Outline_Render( FT_Library library,
FT_Outline* outline,
FT_Raster_Params* params );
/**************************************************************************
*
* @enum:
* FT_Orientation
*
* @description:
* A list of values used to describe an outline's contour orientation.
*
* The TrueType and PostScript specifications use different conventions
* to determine whether outline contours should be filled or unfilled.
*
* @values:
* FT_ORIENTATION_TRUETYPE ::
* According to the TrueType specification, clockwise contours must
* be filled, and counter-clockwise ones must be unfilled.
*
* FT_ORIENTATION_POSTSCRIPT ::
* According to the PostScript specification, counter-clockwise contours
* must be filled, and clockwise ones must be unfilled.
*
* FT_ORIENTATION_FILL_RIGHT ::
* This is identical to @FT_ORIENTATION_TRUETYPE, but is used to
* remember that in TrueType, everything that is to the right of
* the drawing direction of a contour must be filled.
*
* FT_ORIENTATION_FILL_LEFT ::
* This is identical to @FT_ORIENTATION_POSTSCRIPT, but is used to
* remember that in PostScript, everything that is to the left of
* the drawing direction of a contour must be filled.
*
* FT_ORIENTATION_NONE ::
* The orientation cannot be determined. That is, different parts of
* the glyph have different orientation.
*
*/
typedef enum FT_Orientation_
{
FT_ORIENTATION_TRUETYPE = 0,
FT_ORIENTATION_POSTSCRIPT = 1,
FT_ORIENTATION_FILL_RIGHT = FT_ORIENTATION_TRUETYPE,
FT_ORIENTATION_FILL_LEFT = FT_ORIENTATION_POSTSCRIPT,
FT_ORIENTATION_NONE
} FT_Orientation;
/**************************************************************************
*
* @function:
* FT_Outline_Get_Orientation
*
* @description:
* This function analyzes a glyph outline and tries to compute its
* fill orientation (see @FT_Orientation). This is done by integrating
* the total area covered by the outline. The positive integral
* corresponds to the clockwise orientation and @FT_ORIENTATION_POSTSCRIPT
* is returned. The negative integral corresponds to the counter-clockwise
* orientation and @FT_ORIENTATION_TRUETYPE is returned.
*
* Note that this will return @FT_ORIENTATION_TRUETYPE for empty
* outlines.
*
* @input:
* outline ::
* A handle to the source outline.
*
* @return:
* The orientation.
*
*/
FT_EXPORT( FT_Orientation )
FT_Outline_Get_Orientation( FT_Outline* outline );
/* */
FT_END_HEADER
#endif /* FTOUTLN_H_ */
/* END */
/* Local Variables: */
/* coding: utf-8 */
/* End: */