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+/* imagediff - Compare two images
+ *
+ * Copyright © 2004 Richard D. Worth
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without
+ * fee, provided that the above copyright notice appear in all copies
+ * and that both that copyright notice and this permission notice
+ * appear in supporting documentation, and that the name of Richard Worth
+ * not be used in advertising or publicity pertaining to distribution
+ * of the software without specific, written prior permission.
+ * Richard Worth makes no representations about the suitability of this
+ * software for any purpose. It is provided "as is" without express
+ * or implied warranty.
+ *
+ * RICHARD WORTH DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
+ * NO EVENT SHALL RICHARD WORTH BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+ * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+ * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Author: Richard D. Worth <richard@theworths.org> */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#include <errno.h>
+
+#include "buffer-diff.h"
+
+static void
+_xunlink (const char *pathname)
+{
+ if (unlink (pathname) < 0 && errno != ENOENT) {
+ fprintf (stderr, " Error: Cannot remove %s: %s\n",
+ pathname, strerror (errno));
+ exit (1);
+ }
+}
+
+void
+cairo_test_logv (const cairo_test_context_t *ctx,
+ const char *fmt, va_list va)
+{
+ vfprintf (stderr, fmt, va);
+}
+
+void
+cairo_test_log (const cairo_test_context_t *ctx, const char *fmt, ...)
+{
+ va_list va;
+
+ va_start (va, fmt);
+ vfprintf (stderr, fmt, va);
+ va_end (va);
+}
+
+/* Flatten an ARGB surface by blending it over white. The resulting
+ * surface, (still in ARGB32 format, but with only alpha==1.0
+ * everywhere) is returned in the same surface pointer.
+ *
+ * The original surface will be destroyed.
+ *
+ * The (x,y) value specify an origin of interest for the original
+ * image. The flattened image will be generated only from the box
+ * extending from (x,y) to (width,height).
+ */
+static void
+flatten_surface (cairo_surface_t **surface, int x, int y)
+{
+ cairo_surface_t *flat;
+ cairo_t *cr;
+
+ flat = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
+ cairo_image_surface_get_width (*surface) - x,
+ cairo_image_surface_get_height (*surface) - y);
+ cairo_surface_set_device_offset (flat, -x, -y);
+
+ cr = cairo_create (flat);
+ cairo_surface_destroy (flat);
+
+ cairo_set_source_rgb (cr, 1, 1, 1);
+ cairo_paint (cr);
+
+ cairo_set_source_surface (cr, *surface, 0, 0);
+ cairo_surface_destroy (*surface);
+ cairo_paint (cr);
+
+ *surface = cairo_surface_reference (cairo_get_target (cr));
+ cairo_destroy (cr);
+}
+
+/* Given an image surface, create a new surface that has the same
+ * contents as the sub-surface with its origin at x,y.
+ *
+ * The original surface will be destroyed.
+ */
+static void
+extract_sub_surface (cairo_surface_t **surface, int x, int y)
+{
+ cairo_surface_t *sub;
+ cairo_t *cr;
+
+ sub = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
+ cairo_image_surface_get_width (*surface) - x,
+ cairo_image_surface_get_height (*surface) - y);
+
+ /* We don't use a device offset like flatten_surface. That's not
+ * for any important reason, (the results should be
+ * identical). This style just seemed more natural to me this
+ * time, so I'm leaving both here so I can look at both to see
+ * which I like better. */
+ cr = cairo_create (sub);
+ cairo_surface_destroy (sub);
+
+ cairo_set_source_surface (cr, *surface, -x, -y);
+ cairo_surface_destroy (*surface);
+ cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
+ cairo_paint (cr);
+
+ *surface = cairo_surface_reference (cairo_get_target (cr));
+ cairo_destroy (cr);
+}
+
+static cairo_status_t
+stdio_write_func (void *closure, const unsigned char *data, unsigned int length)
+{
+ FILE *file = closure;
+
+ if (fwrite (data, 1, length, file) != length)
+ return CAIRO_STATUS_WRITE_ERROR;
+
+ return CAIRO_STATUS_SUCCESS;
+}
+
+static cairo_status_t
+write_png (cairo_surface_t *surface, const char *filename)
+{
+ cairo_status_t status;
+ FILE *png_file;
+
+ if (filename != NULL) {
+ png_file = fopen (filename, "wb");
+ if (png_file == NULL) {
+ switch (errno) {
+ case ENOMEM:
+ return CAIRO_STATUS_NO_MEMORY;
+ default:
+ return CAIRO_STATUS_WRITE_ERROR;
+ }
+ }
+ } else
+ png_file = stdout;
+
+ status = cairo_surface_write_to_png_stream (surface,
+ stdio_write_func,
+ png_file);
+
+ if (png_file != stdout)
+ fclose (png_file);
+
+ return status;
+}
+
+static cairo_status_t
+png_diff (const char *filename_a,
+ const char *filename_b,
+ const char *filename_diff,
+ int ax,
+ int ay,
+ int bx,
+ int by,
+ buffer_diff_result_t *result)
+{
+ cairo_surface_t *surface_a;
+ cairo_surface_t *surface_b;
+ cairo_surface_t *surface_diff;
+ cairo_status_t status;
+
+ surface_a = cairo_image_surface_create_from_png (filename_a);
+ status = cairo_surface_status (surface_a);
+ if (status) {
+ fprintf (stderr, "Error: Failed to create surface from %s: %s\n",
+ filename_a, cairo_status_to_string (status));
+ return status;
+ }
+
+ surface_b = cairo_image_surface_create_from_png (filename_b);
+ status = cairo_surface_status (surface_b);
+ if (status) {
+ fprintf (stderr, "Error: Failed to create surface from %s: %s\n",
+ filename_b, cairo_status_to_string (status));
+ cairo_surface_destroy (surface_a);
+ return status;
+ }
+
+ if (ax || ay) {
+ extract_sub_surface (&surface_a, ax, ay);
+ ax = ay = 0;
+ }
+
+ if (bx || by) {
+ extract_sub_surface (&surface_b, bx, by);
+ bx = by = 0;
+ }
+
+ status = cairo_surface_status (surface_a);
+ if (status) {
+ fprintf (stderr, "Error: Failed to extract surface from %s: %s\n",
+ filename_a, cairo_status_to_string (status));
+ cairo_surface_destroy (surface_a);
+ cairo_surface_destroy (surface_b);
+ return status;
+ }
+ status = cairo_surface_status (surface_b);
+ if (status) {
+ fprintf (stderr, "Error: Failed to extract surface from %s: %s\n",
+ filename_b, cairo_status_to_string (status));
+ cairo_surface_destroy (surface_a);
+ cairo_surface_destroy (surface_b);
+ return status;
+ }
+
+ surface_diff = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
+ cairo_image_surface_get_width (surface_a),
+ cairo_image_surface_get_height (surface_a));
+ status = cairo_surface_status (surface_diff);
+ if (status) {
+ fprintf (stderr,
+ "Error: Failed to allocate surface to hold differences\n");
+ cairo_surface_destroy (surface_a);
+ cairo_surface_destroy (surface_b);
+ return CAIRO_STATUS_NO_MEMORY;
+ }
+
+ status = image_diff (NULL,
+ surface_a, surface_b, surface_diff,
+ result);
+
+ if (filename_diff)
+ _xunlink (filename_diff);
+
+ if (status == CAIRO_STATUS_SUCCESS &&
+ result->pixels_changed)
+ {
+ status = write_png (surface_diff, filename_diff);
+ }
+
+ cairo_surface_destroy (surface_a);
+ cairo_surface_destroy (surface_b);
+ cairo_surface_destroy (surface_diff);
+
+ return status;
+}
+
+int
+main (int argc, char *argv[])
+{
+ buffer_diff_result_t result;
+ cairo_status_t status;
+
+ unsigned int ax, ay, bx, by;
+
+ if (argc != 3 && argc != 7) {
+ fprintf (stderr, "Usage: %s image1.png image2.png [ax ay bx by]\n", argv[0]);
+ fprintf (stderr, "Computes an output image designed to present a \"visual diff\" such that even\n");
+ fprintf (stderr, "small errors in single pixels are readily apparent in the output.\n");
+ fprintf (stderr, "The output image is written on stdout.\n");
+ exit (1);
+ }
+
+ if (argc == 7) {
+ ax = strtoul (argv[3], NULL, 0);
+ ay = strtoul (argv[4], NULL, 0);
+ bx = strtoul (argv[5], NULL, 0);
+ by = strtoul (argv[6], NULL, 0);
+ } else {
+ ax = ay = bx = by = 0;
+ }
+
+ status = png_diff (argv[1], argv[2], NULL, ax, ay, bx, by, &result);
+
+ if (status) {
+ fprintf (stderr, "Error comparing images: %s\n",
+ cairo_status_to_string (status));
+ return 1;
+ }
+
+ if (result.pixels_changed)
+ fprintf (stderr, "Total pixels changed: %d with a maximum channel difference of %d.\n",
+ result.pixels_changed,
+ result.max_diff);
+
+ return (result.pixels_changed != 0);
+}