[test] Add a regression test for bug 10921

This bug first was fixed in 40558cb15e,
but then reintroduced in 9cfd82e87b, which
became part of the 1.6.2 quick release.

As penance to make sure I never repeat this same bug again, I offer this
test case which exercises the XSetClipMask(NULL) path and hopefully
simulates some 'typical' usage of cairo by GUI toolkits.

test/.gitignore

@@ -200,6 +200,7 @@ truetype-tables
 unantialiased-shapes
 unbounded-operator
 user-data
+xlib-expose-event
 xlib-surface
 xlib-surface-source
 zero-alpha

test/Makefile.am

@@ -239,6 +239,7 @@ TESTS += svg-surface-source$(EXEEXT)
 endif
 
 if CAIRO_HAS_XLIB_SURFACE
+TESTS += xlib-expose-event$(EXEEXT)
 TESTS += xlib-surface$(EXEEXT)
 TESTS += xlib-surface-source$(EXEEXT)
 endif
@@ -686,6 +687,7 @@ REFERENCE_IMAGES = \
 	unbounded-operator-rgb24-ref.png	\
 	unbounded-operator-quartz-ref.png	\
 	unbounded-operator-quartz-rgb24-ref.png	\
+	xlib-expose-event-ref.png \
 	xlib-surface-source-ref.png \
 	zero-alpha-ref.png
 

test/xlib-expose-event.c

@@ -0,0 +1,275 @@
+/*
+ * Copyright © 2008 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+/* This test tries to emulate the behaviour of most toolkits; it tries
+ * to simulate typical usage of a single surface with multiple exposures.
+ *
+ * The first goal of the test is to reproduce the XSetClipMask(NULL) bug
+ * reintroduced in 1.6.2 (but was originally fixed in 40558cb15). As I've
+ * made the same mistake again, it is worth adding a regression test...
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "cairo.h"
+#include "cairo-xlib.h"
+#include "cairo-test.h"
+
+#include "cairo-boilerplate-xlib.h"
+
+#include "buffer-diff.h"
+
+#define SIZE 160
+#define NLOOPS 10
+
+static const char	png_filename[]	= "romedalen.png";
+
+static cairo_bool_t
+check_visual (Display *dpy)
+{
+    Visual *visual = DefaultVisual (dpy, DefaultScreen (dpy));
+
+    if ((visual->red_mask   == 0xff0000 &&
+	 visual->green_mask == 0x00ff00 &&
+	 visual->blue_mask  == 0x0000ff) ||
+	(visual->red_mask   == 0x0000ff &&
+	 visual->green_mask == 0x00ff00 &&
+	 visual->blue_mask  == 0xff0000))
+	return 1;
+    else
+	return 0;
+}
+
+static void
+clear (cairo_surface_t *surface)
+{
+    cairo_t *cr = cairo_create (surface);
+    cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
+    cairo_paint (cr);
+    cairo_destroy (cr);
+}
+
+static void
+draw_mask (cairo_t *cr)
+{
+    cairo_surface_t *surface;
+    cairo_t *cr2;
+
+    surface = cairo_surface_create_similar (cairo_get_group_target (cr),
+	                                    CAIRO_CONTENT_ALPHA,
+					    50, 50);
+    cairo_boilerplate_xlib_surface_disable_render (surface);
+
+    cr2 = cairo_create (surface);
+
+    /* This complex clip and forcing of fallbacks is to reproduce bug
+     * http://bugs.freedesktop.org/show_bug.cgi?id=10921
+     */
+    cairo_rectangle (cr2,
+	             0, 0,
+	             40, 40);
+    cairo_rectangle (cr2,
+	             10, 10,
+	             40, 40);
+    cairo_clip (cr2);
+
+    cairo_move_to (cr2, 0, 25);
+    cairo_line_to (cr2, 50, 25);
+    cairo_move_to (cr2, 25, 0);
+    cairo_line_to (cr2, 25, 50);
+    cairo_set_source_rgb (cr2, 1, 1, 1);
+    cairo_stroke (cr2);
+    cairo_destroy (cr2);
+
+    cairo_set_source_rgb (cr, 1, 0, 0);
+    cairo_mask_surface (cr, surface, 50, 50);
+    cairo_surface_destroy (surface);
+}
+
+static cairo_surface_t *
+clone_similar_surface (cairo_surface_t * target, cairo_surface_t *surface)
+{
+    cairo_t *cr;
+    cairo_surface_t *similar;
+
+    similar = cairo_surface_create_similar (target,
+	                              cairo_surface_get_content (surface),
+				      cairo_image_surface_get_width (surface),
+				      cairo_image_surface_get_height (surface));
+
+    cr = cairo_create (similar);
+    cairo_set_source_surface (cr, surface, 0, 0);
+    cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
+    cairo_paint (cr);
+    cairo_destroy (cr);
+
+    return similar;
+}
+
+static void
+draw_image (cairo_t *cr)
+{
+    cairo_surface_t *surface, *similar;
+
+    surface = cairo_test_create_surface_from_png (png_filename);
+    similar = clone_similar_surface (cairo_get_group_target (cr), surface);
+    cairo_surface_destroy (surface);
+
+    cairo_set_source_surface (cr, similar, 0, 0);
+    cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
+    cairo_paint (cr);
+    cairo_surface_destroy (similar);
+}
+
+static void
+draw (cairo_surface_t *surface, cairo_rectangle_t *region, int n_regions)
+{
+    cairo_t *cr = cairo_create (surface);
+    if (region != NULL) {
+	int i;
+	for (i = 0; i < n_regions; i++) {
+	    cairo_rectangle (cr,
+			     region[i].x, region[i].y,
+			     region[i].width, region[i].height);
+	}
+	cairo_clip (cr);
+    }
+    cairo_push_group (cr);
+    draw_image (cr);
+    draw_mask (cr);
+    cairo_pop_group_to_source (cr);
+    cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
+    cairo_paint (cr);
+    cairo_destroy (cr);
+}
+
+static cairo_test_status_t
+compare (cairo_surface_t *surface)
+{
+    cairo_t *cr;
+    cairo_surface_t *image, *reference, *diff;
+    buffer_diff_result_t result;
+
+    diff = cairo_image_surface_create (CAIRO_FORMAT_RGB24, SIZE, SIZE);
+
+    /* copy the pixmap to an image buffer */
+    image = cairo_image_surface_create (CAIRO_FORMAT_RGB24, SIZE, SIZE);
+    cr = cairo_create (image);
+    cairo_set_source_surface (cr, surface, 0, 0);
+    cairo_paint (cr);
+    cairo_destroy (cr);
+
+    reference = cairo_test_create_surface_from_png ("xlib-expose-event-ref.png");
+    if (cairo_image_surface_get_width (image) != cairo_image_surface_get_width (reference) ||
+        cairo_image_surface_get_height (image) != cairo_image_surface_get_height (reference))
+	return CAIRO_TEST_FAILURE;
+
+    compare_surfaces (reference, image, diff, &result);
+
+    cairo_surface_destroy (reference);
+    cairo_surface_destroy (image);
+    cairo_surface_destroy (diff);
+
+    return result.pixels_changed ? CAIRO_TEST_FAILURE : CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    Display *dpy;
+    Drawable drawable;
+    int screen;
+    cairo_surface_t *surface;
+    cairo_rectangle_t region[4];
+    int i, j;
+    cairo_test_status_t result = CAIRO_TEST_SUCCESS;
+
+    cairo_test_init ("xlib-expose-event");
+
+    dpy = XOpenDisplay (NULL);
+    if (dpy == NULL) {
+	cairo_test_log ("xlib-expose-event: Cannot open display, skipping\n");
+	goto CLEANUP_TEST;
+    }
+
+    if (! check_visual (dpy)) {
+	cairo_test_log ("xlib-expose-event: default visual is not RGB24 or BGR24, skipping\n");
+	goto CLEANUP_DISPLAY;
+    }
+
+    screen = DefaultScreen (dpy);
+    drawable = XCreatePixmap (dpy, DefaultRootWindow (dpy),
+			      SIZE, SIZE, DefaultDepth (dpy, screen));
+    surface = cairo_xlib_surface_create (dpy,
+					 drawable,
+					 DefaultVisual (dpy, screen),
+					 SIZE, SIZE);
+    clear (surface);
+    draw (surface, NULL, 0);
+    for (i = 0; i < NLOOPS; i++) {
+	for (j = 0; j < NLOOPS; j++) {
+	    region[0].x = i * SIZE / NLOOPS;
+	    region[0].y = i * SIZE / NLOOPS;
+	    region[0].width = SIZE / 4;
+	    region[0].height = SIZE / 4;
+
+	    region[1].x = j * SIZE / NLOOPS;
+	    region[1].y = j * SIZE / NLOOPS;
+	    region[1].width = SIZE / 4;
+	    region[1].height = SIZE / 4;
+
+	    region[2].x = i * SIZE / NLOOPS;
+	    region[2].y = j * SIZE / NLOOPS;
+	    region[2].width = SIZE / 4;
+	    region[2].height = SIZE / 4;
+
+	    region[3].x = j * SIZE / NLOOPS;
+	    region[3].y = i * SIZE / NLOOPS;
+	    region[3].width = SIZE / 4;
+	    region[3].height = SIZE / 4;
+
+	    draw (surface, region, 4);
+	}
+    }
+
+    result = compare (surface);
+
+    cairo_surface_destroy (surface);
+
+    XFreePixmap (dpy, drawable);
+
+  CLEANUP_DISPLAY:
+    XCloseDisplay (dpy);
+
+  CLEANUP_TEST:
+    cairo_debug_reset_static_data ();
+
+    cairo_test_fini ();
+
+    return result;
+}
+