Clip invariance issue

/*
 * Copyright © 2006 M Joonas Pihlaja
 * Copyright © 2011 Chris Wilson
 * Copyright © 2012 Soren Sandmann
 *
 * 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.
 *
 * Authors:
 *   M Joonas Pihlaja <[email protected]>
 *   Chris Wilson <[email protected]>
 *   Soren Sandmann <[email protected]>
 */
#include <cairo.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#define SIZE 512
#define STEP (512+2)
#define NUM_SEGMENTS 128
#define NUM_RECTANGLES 25

#define TRUE 1
#define FALSE 0

static uint32_t state;

static double
uniform_random (double minval, double maxval)
{
    static uint32_t const poly = 0x9a795537U;
    uint32_t n = 32;
    while (n-->0)
	state = 2*state < state ? (2*state ^ poly) : 2*state;
    return minval + state * (maxval - minval) / 4294967296.0;
}

static uint32_t *
copy_image_data (cairo_surface_t *image)
{
    uint32_t *result;
    int height, stride;

    height = cairo_image_surface_get_height (image);
    stride = cairo_image_surface_get_stride (image);

    result = malloc (height * stride);

    memcpy (result, cairo_image_surface_get_data (image), height * stride);

    return result;
}

static cairo_bool_t
compare_image_to_data (cairo_surface_t *image, uint32_t *data)
{
    int w = cairo_image_surface_get_width (image);
    int h = cairo_image_surface_get_height (image);
    int stride = cairo_image_surface_get_stride (image);
    uint32_t *data2 = (uint32_t *)cairo_image_surface_get_data (image);
    int i, j;
    int maxdiff = 0;
    int max_x, max_y;
    int error = 0;
    uint32_t max1, max2;

    for (i = 0; i < h; ++i)
    {
	for (j = 0; j < w; ++j)
	{
	    uint32_t pixel1 = data[i * stride/4 + j];
	    uint32_t pixel2 = data2[i * stride/4 + j];
	    int a1, r1, g1, b1;
	    int a2, r2, g2, b2;

	    if (pixel1 != pixel2)
	    {
		a1 = (pixel1 >> 24) & 0xff;
		r1 = (pixel1 >> 16) & 0xff;
		g1 = (pixel1 >>  8) & 0xff;
		b1 = (pixel1 >>  0) & 0xff;

		a2 = (pixel2 >> 24) & 0xff;
		r2 = (pixel2 >> 16) & 0xff;
		g2 = (pixel2 >>  8) & 0xff;
		b2 = (pixel2 >>  0) & 0xff;

#define CHECK(c1, c2)							\
		do {							\
		    if (abs (c1 - c2) > maxdiff)			\
		    {							\
			maxdiff = abs (c1 - c2);			\
			max_x = j;					\
			max_y = i;					\
			max1 = pixel1;					\
			max2 = pixel2;					\
		    }							\
		} while (0)

		CHECK (a1, a2);
		CHECK (r1, r2);
		CHECK (g1, g2);
		CHECK (b1, b2);

		if (!error)
		{
		    printf ("== Error detected: %x != %x, at (%d, %d)\n",
			    pixel1, pixel2, j, i);

		    error = 1;
		}
	    }
	}
    }

    if (maxdiff)
    {
	printf ("== Maximum difference: %d, at (%d, %d). Pixels: %x %x\n", maxdiff, max_x, max_y, max1, max2);
	return FALSE;
    }

    return TRUE;
}

static cairo_region_t *
random_region (int size, uint32_t s)
{
    int i;
    cairo_region_t *region = cairo_region_create ();

    state = s;

    for (i = 0; i < NUM_RECTANGLES; ++i)
    {
	cairo_rectangle_int_t rect;

	rect.x = uniform_random (0, size);
	rect.y = uniform_random (0, size);
	rect.width = uniform_random (1, 100);
	rect.height = uniform_random (1, 100);

	cairo_region_union_rectangle (region, &rect);
    }

    return region;
}

static cairo_region_t *
region_invert (cairo_region_t *region, int size)
{
    cairo_rectangle_int_t rect = { 0, 0, size, size };
    cairo_region_t *inverted = cairo_region_create_rectangle (&rect);
    cairo_region_subtract (inverted, region);
    return inverted;
}

static void
clip_to_region (cairo_t *cr, cairo_region_t *region)
{
    int n;

    n = cairo_region_num_rectangles (region);
    while (n--)
    {
	cairo_rectangle_int_t rect;

	cairo_region_get_rectangle (region, n, &rect);

	cairo_rectangle (cr, rect.x, rect.y, rect.width, rect.height);
    }

    cairo_clip (cr);
}

static void
nz_path (cairo_t *cr, uint32_t s)
{
    int i;

    state = s;
    cairo_move_to (cr, 0, 0);
    for (i = 0; i < NUM_SEGMENTS; i++) {
	double x = uniform_random (0, SIZE);
	double y = uniform_random (0, SIZE);
	cairo_line_to (cr, x, y);
    }
    cairo_close_path (cr);
}

static void
nz_fill_stroke (cairo_t *cr, uint32_t state)
{
    nz_path (cr, state);

    cairo_set_source_rgb (cr, 1, 0, 0);
    cairo_fill_preserve (cr);
    cairo_set_source_rgb (cr, 0, 1, 0);
    cairo_set_line_width (cr, 1.0);
    cairo_stroke (cr);
}

#define NUM_TESTS 2000

static void
paint_region (cairo_t *cr, cairo_region_t *region)
{
    int n = cairo_region_num_rectangles (region);
    while (n--)
    {
	cairo_rectangle_int_t rect;

	cairo_region_get_rectangle (region, n, &rect);

	cairo_rectangle (cr, rect.x, rect.y, rect.width, rect.height);

	cairo_set_source_rgba (cr, 0, 0, 0.4, 0.2);
	cairo_fill (cr);
    }
}

static void
run_test (cairo_t *cr, int width, int height)
{
    cairo_surface_t *surface;
    int i;

    cairo_set_fill_rule (cr, CAIRO_FILL_RULE_EVEN_ODD);

    surface = cairo_get_target (cr);

    for (i = 0; i < NUM_TESTS; ++i)
    {
	double x, y;
	cairo_region_t *region, *inverted;
	uint32_t *data;

	printf ("Test %d\n", i);
	cairo_set_source_rgb (cr, 0, 0, 0.2);
	cairo_paint (cr);

	cairo_reset_clip (cr);
	region = random_region (width, i + 1);
	clip_to_region (cr, region);
	nz_fill_stroke (cr, i + 1);

	cairo_reset_clip (cr);
	inverted = region_invert (region, width);
	clip_to_region (cr, inverted);
	nz_fill_stroke (cr, i + 1);

	paint_region (cr, region);

	cairo_surface_write_to_png (surface, "image1.png");

	data = copy_image_data (surface);

	cairo_reset_clip (cr);
	cairo_set_source_rgb (cr, 0, 0, 0.2);
	cairo_paint (cr);

	nz_fill_stroke (cr, i + 1);

	cairo_surface_write_to_png (surface, "image2.png");

	if (!compare_image_to_data (surface, data))
	{
#if 0
	    printf ("Error detected. Images in \"image1.png\" and \"image2.png\"\n");

	    exit (-1);
#endif
	}

	cairo_region_destroy (inverted);
	cairo_region_destroy (region);
	free (data);
    }
}

int
main ()
{
    cairo_surface_t *surface =
	cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 512, 512);
    cairo_t *cr = cairo_create (surface);

    run_test (cr, SIZE, SIZE);
}