scanline handling.

Data Structures
struct	hpgs_scanline_point_st
	An intersection point of a path with a scanline. More...
struct	hpgs_paint_scanline_st
	A scanline of the pixel renderer. More...
struct	hpgs_paint_clipper_st
	A collection of scanlines for mapping paths onto images. More...
Functions
HPGS_INTERNAL_API hpgs_paint_clipper *	hpgs_new_paint_clipper (const hpgs_bbox *bb, int height, int scanline_msize, int overscan)
HPGS_INTERNAL_API hpgs_paint_clipper *	hpgs_paint_clipper_clip (const hpgs_paint_clipper *orig, const hpgs_paint_clipper *clip, hpgs_bool winding)
HPGS_INTERNAL_API int	hpgs_paint_clipper_cut (hpgs_paint_clipper *c, hpgs_paint_path *path)
HPGS_INTERNAL_API int	hpgs_paint_clipper_thin_cut (hpgs_paint_clipper *c, hpgs_paint_path *path, const hpgs_gstate *gstate)
HPGS_INTERNAL_API int	hpgs_paint_clipper_emit (hpgs_image *image, const hpgs_paint_clipper *img, const hpgs_paint_clipper *clip, const hpgs_paint_color *c, hpgs_bool winding, hpgs_bool stroke)
HPGS_INTERNAL_API int	hpgs_paint_clipper_reset (hpgs_paint_clipper *c, double llx, double urx)
HPGS_INTERNAL_API void	hpgs_paint_clipper_clear (hpgs_paint_clipper *c)
HPGS_INTERNAL_API void	hpgs_paint_clipper_destroy (hpgs_paint_clipper *c)

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Detailed Description

This module contains the documentation of the internals of the vector graphics renderer hpgs_paint_device.

The dcomumentation of hpgs_paint_clipper_st explains the concepts used throughout the implementation of the objects in this module.

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Function Documentation

HPGS_INTERNAL_API hpgs_paint_clipper* hpgs_new_paint_clipper	(	const hpgs_bbox *	bb,
		int	height,
		int	scanline_msize,
		int	overscan
	)

Returns a new clipper on the heap, which covers the given bounding box an applies to an image with height rows.

scanline_msize determines the number of intersection points, for which memory is preallocated in each scanline.

The value of overscan determines the type of antialiasing applied as described under hpgs_paint_device_st::overscan.

Use hpgs_paint_clipper_destroy in order to destroy the returned hpgs_paint_clipper from the heap.

Returns a null pointer, if the system is out of memory.

References hpgs_paint_clipper_st::height, hpgs_paint_clipper_st::iscan0, hpgs_paint_clipper_st::iscan1, hpgs_paint_clipper_st::overscan, hpgs_paint_clipper_st::scanlines, and hpgs_paint_clipper_st::yfac.

Referenced by hpgs_new_paint_device(), and hpgs_paint_clipper_clip().

HPGS_INTERNAL_API void hpgs_paint_clipper_clear

(

hpgs_paint_clipper *

c

)

Resets a clipper to be completely empty .

• 0 Sucess.
• -1 The system is out of memory.

References hpgs_paint_clipper_st::iscan0, hpgs_paint_clipper_st::iscan1, and hpgs_paint_clipper_st::scanlines.

Referenced by hpgs_paint_device_clip(), and hpgs_paint_device_fill().

HPGS_INTERNAL_API hpgs_paint_clipper* hpgs_paint_clipper_clip	(	const hpgs_paint_clipper *	orig,
		const hpgs_paint_clipper *	clip,
		hpgs_bool	winding
	)

Returna a new clipper on the heap, which holds the intersection of the given path clipper with the current clip clipper.

If winding is HPGS_TRUE, the non-zero winding rule is used for the path intersection, otherwise the exclusive-or rule applies.

Use hpgs_paint_clipper_destroy in order to destroy the returned hpgs_paint_clipper from the heap.

Returns a null pointer, if the system is out of memory.

References hpgs_paint_clipper_st::height, hpgs_log(), hpgs_new_paint_clipper(), hpgs_paint_clipper_destroy(), hpgs_paint_clipper_st::iscan0, hpgs_paint_clipper_st::iscan1, hpgs_paint_clipper_st::overscan, and hpgs_paint_clipper_st::scanlines.

Referenced by hpgs_paint_device_clip().

HPGS_INTERNAL_API int hpgs_paint_clipper_cut	(	hpgs_paint_clipper *	c,
		hpgs_paint_path *	path
	)

Cuts te given path with the scanlines of the given clipper c. If you emit the clipper afterwards, the interior of the given path is drawn to the image.

If you want to stroke the path use either hpgs_paint_clipper_thin_cut for thin lines or contruct the outline of a thick line using the line style of a graphics state with hpgs_paint_path_stroke_path.

Return value:

• 0 Success.
• -1 The system is out of memory.

References hpgs_paint_clipper_st::overscan.

Referenced by hpgs_paint_device_clip(), and hpgs_paint_device_fill().

HPGS_INTERNAL_API void hpgs_paint_clipper_destroy

(

hpgs_paint_clipper *

c

)

Destroys a clipper from the heap.

References hpgs_paint_clipper_st::scanlines.

Referenced by hpgs_new_paint_device(), hpgs_paint_clipper_clip(), and hpgs_paint_device_clip().

HPGS_INTERNAL_API int hpgs_paint_clipper_emit	(	hpgs_image *	image,
		const hpgs_paint_clipper *	img,
		const hpgs_paint_clipper *	clip,
		const hpgs_paint_color *	c,
		hpgs_bool	winding,
		hpgs_bool	stroke
	)

Emits the intersection of the visible segments of the given clippers img and clip to the given image img using the given color c.

If stroke is HPGS_TRUE, zero-width segments are also emitted, which is feasible for clippers retrieved through hpgs_paint_clipper_thin_cut.

If winding is HPGS_TRUE, the non-zero winding rule is used for the segment intersection, otherwise the exclusive-or rule applies.

Return values:

• 0 Sucess.
• -1 The system is out of memory or an error from the image has occurred.

References hpgs_paint_clipper_st::height, hpgs_image_st::height, hpgs_log(), hpgs_paint_clipper_st::iscan0, hpgs_paint_clipper_st::iscan1, hpgs_paint_clipper_st::overscan, and hpgs_paint_clipper_st::scanlines.

Referenced by hpgs_paint_device_fill().

HPGS_INTERNAL_API int hpgs_paint_clipper_reset	(	hpgs_paint_clipper *	c,
		double	llx,
		double	urx
	)

Resets a clipper to be empty and to cover the whole rectanlge of an image covering the x coordinates in the range from llx to urx.

• 0 Sucess.
• -1 The system is out of memory.

References hpgs_paint_clipper_st::iscan0, hpgs_paint_clipper_st::iscan1, hpgs_paint_clipper_st::overscan, and hpgs_paint_clipper_st::scanlines.

Referenced by hpgs_new_paint_device().

HPGS_INTERNAL_API int hpgs_paint_clipper_thin_cut	(	hpgs_paint_clipper *	c,
		hpgs_paint_path *	path,
		const hpgs_gstate *	gstate
	)

Cuts the border of the given path with the scanlines of the given clipper c. The linewidth of the given gstate is ignored and an optimized algorithm is used in order to retrieve the cut of the border of the path as if the linewidth has been exactly one pixel of the underlying image.

Return value:

• 0 Success.
• -1 The system is out of memory.

References hpgs_log(), hpgs_paint_clipper_st::iscan0, hpgs_scanline_point_st::order, hpgs_paint_scanline_st::points, hpgs_paint_clipper_st::scanlines, and hpgs_scanline_point_st::x.