minhngoc25a
/
freetype2
mirror of git://git.savannah.gnu.org/freetype/freetype2.git
2
1
Fork 2
Code Issues 9 Releases Wiki Activity
freetype2/include/freetype/ftoutln.h

589 lines
17 KiB
C
Raw Blame History

/****************************************************************************
*
* ftoutln.h
*
* Support for the FT_Outline type used to store glyph shapes of
* most scalable font formats (specification).
*
* Copyright (C) 1996-2022 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 <freetype/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:
* Degenerate contours, segments, and Bezier arcs may be reported. In
* most cases, it is best to filter these out before using the outline
* for stroking or other path modification purposes (which may cause
* degenerate segments to become non-degenrate and visible, like when
* stroke caps are used or the path is otherwise outset). Some glyph
* outlines may contain deliberate degenerate single points for mark
* attachement.
*
* 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 );
/**************************************************************************
*
* @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 );
/**************************************************************************
*
* @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.
*
* @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:
* This advanced function uses @FT_Raster_Params as an argument.
* 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. Either `params.target` must point to preallocated
* bitmap, or @FT_RASTER_FLAG_DIRECT must be set in `params.flags`
* allowing FreeType rasterizer to be used for direct composition,
* translucency, etc. See @FT_Raster_Params 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: */
Reference in New Issue View Git Blame Copy Permalink