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/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
/* cairo - a vector graphics library with display and print output
*
* Copyright (c) 2008 M Joonas Pihlaja
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef CAIRO_SPANS_PRIVATE_H
#define CAIRO_SPANS_PRIVATE_H
#include "cairo-types-private.h"
#include "cairo-compiler-private.h"
/* Number of bits of precision used for alpha. */
#define CAIRO_SPANS_UNIT_COVERAGE_BITS 8
#define CAIRO_SPANS_UNIT_COVERAGE ((1 << CAIRO_SPANS_UNIT_COVERAGE_BITS)-1)
/* A structure representing an open-ended horizontal span of constant
* pixel coverage. */
typedef struct _cairo_half_open_span {
/* The inclusive x-coordinate of the start of the span. */
int x;
/* The pixel coverage for the pixels to the right. */
int coverage;
} cairo_half_open_span_t;
/* Span renderer interface. Instances of renderers are provided by
* surfaces if they want to composite spans instead of trapezoids. */
typedef struct _cairo_span_renderer cairo_span_renderer_t;
struct _cairo_span_renderer {
/* Called to destroy the renderer. */
cairo_destroy_func_t destroy;
/* Render the spans on row y of the source by whatever compositing
* method is required. The function should ignore spans outside
* the bounding box set by the init() function. */
cairo_status_t (*render_row)(
void *abstract_renderer,
int y,
const cairo_half_open_span_t *coverages,
unsigned num_coverages);
/* Called after all rows have been rendered to perform whatever
* final rendering step is required. This function is called just
* once before the renderer is destroyed. */
cairo_status_t (*finish)(
void *abstract_renderer);
/* Private status variable. */
cairo_status_t status;
};
/* Scan converter interface. */
typedef struct _cairo_scan_converter cairo_scan_converter_t;
struct _cairo_scan_converter {
/* Destroy this scan converter. */
cairo_destroy_func_t destroy;
/* Add an edge to the converter. */
cairo_status_t
(*add_edge)(
void *abstract_converter,
cairo_fixed_t x1,
cairo_fixed_t y1,
cairo_fixed_t x2,
cairo_fixed_t y2);
/* Generates coverage spans for rows for the added edges and calls
* the renderer function for each row. After generating spans the
* only valid thing to do with the converter is to destroy it. */
cairo_status_t
(*generate)(
void *abstract_converter,
cairo_span_renderer_t *renderer);
/* Private status. Read with _cairo_scan_converter_status(). */
cairo_status_t status;
};
/* cairo-spans.c: */
cairo_private cairo_scan_converter_t *
_cairo_scan_converter_create_in_error (cairo_status_t error);
cairo_private cairo_status_t
_cairo_scan_converter_status (void *abstract_converter);
cairo_private cairo_status_t
_cairo_scan_converter_set_error (void *abstract_converter,
cairo_status_t error);
cairo_private cairo_span_renderer_t *
_cairo_span_renderer_create_in_error (cairo_status_t error);
cairo_private cairo_status_t
_cairo_span_renderer_status (void *abstract_renderer);
/* Set the renderer into an error state. This sets all the method
* pointers except ->destroy() of the renderer to no-op
* implementations that just return the error status. */
cairo_private cairo_status_t
_cairo_span_renderer_set_error (void *abstract_renderer,
cairo_status_t error);
#endif /* CAIRO_SPANS_PRIVATE_H */
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