[test] Add new test checking is_clear is handled properly

This test does various operations with a clear source surface with
various content types.
The idea is to make sure optimizations done when surface->is_clear ==
TRUE only happen in the proper cases.

test/Makefile.sources

@@ -13,6 +13,7 @@ test_sources = \
 	caps-joins-curve.c				\
 	caps-sub-paths.c				\
 	clear.c						\
+	clear-source.c					\
 	clip-all.c					\
 	clip-disjoint.c					\
 	clip-device-offset.c				\

test/clear-source.c

@@ -0,0 +1,163 @@
+/*
+ * Copyright 2009 Benjamin Otte
+ *
+ * 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
+ * Benjamin Otte not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Benjamin Otte makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * BENJAMIN OTTE DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL BENJAMIN OTTE 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: Benjamin Otte <otte@gnome.org>
+ */
+
+#include "cairo-test.h"
+
+#define ARRAY_LENGTH(x) (sizeof(x) / sizeof(x[0]))
+typedef enum {
+  CLEAR,
+  CLEARED,
+  PAINTED
+} surface_type_t;
+
+#define SIZE 10
+#define SPACE 5
+
+static cairo_surface_t *
+create_surface (cairo_t *target, cairo_content_t content, surface_type_t type)
+{
+    cairo_surface_t *surface;
+    cairo_t *cr;
+
+    surface = cairo_surface_create_similar (cairo_get_target (target),
+                                            content,
+                                            SIZE, SIZE);
+
+    if (type == CLEAR)
+        return surface;
+
+    cr = cairo_create (surface);
+    cairo_set_source_rgb (cr, 0.75, 0, 0);
+    cairo_paint (cr);
+    cairo_destroy (cr);
+
+    if (type == PAINTED)
+        return surface;
+
+    cr = cairo_create (surface);
+    cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
+    cairo_paint (cr);
+    cairo_destroy (cr);
+
+    return surface;
+}
+
+static void
+paint (cairo_t *cr, cairo_surface_t *surface)
+{
+    cairo_set_source_surface (cr, surface, 0, 0);
+    cairo_paint (cr);
+}
+
+static void
+fill (cairo_t *cr, cairo_surface_t *surface)
+{
+    cairo_set_source_surface (cr, surface, 0, 0);
+    cairo_rectangle (cr, -SPACE, -SPACE, SIZE + 2 * SPACE, SIZE + 2 * SPACE);
+    cairo_fill (cr);
+}
+
+static void
+stroke (cairo_t *cr, cairo_surface_t *surface)
+{
+    cairo_set_source_surface (cr, surface, 0, 0);
+    cairo_set_line_width (cr, 2.0);
+    cairo_rectangle (cr, 1, 1, SIZE - 2, SIZE - 2);
+    cairo_stroke (cr);
+}
+
+static void
+mask (cairo_t *cr, cairo_surface_t *surface)
+{
+    cairo_set_source_rgb (cr, 0, 0, 0.75);
+    cairo_mask_surface (cr, surface, 0, 0);
+}
+
+static void
+mask_self (cairo_t *cr, cairo_surface_t *surface)
+{
+    cairo_set_source_surface (cr, surface, 0, 0);
+    cairo_mask_surface (cr, surface, 0, 0);
+}
+
+static void
+glyphs (cairo_t *cr, cairo_surface_t *surface)
+{
+    cairo_set_source_surface (cr, surface, 0, 0);
+    cairo_select_font_face (cr,
+			    "@cairo:",
+			    CAIRO_FONT_SLANT_NORMAL,
+			    CAIRO_FONT_WEIGHT_NORMAL);
+    cairo_set_font_size (cr, 16);
+    cairo_translate (cr, 0, SIZE);
+    cairo_show_text (cr, "C");
+}
+
+typedef void (* operation_t) (cairo_t *cr, cairo_surface_t *surface);
+static operation_t operations[] = {
+  paint,
+  fill,
+  stroke,
+  mask,
+  mask_self,
+  glyphs
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_content_t contents[] = { CAIRO_CONTENT_COLOR_ALPHA, CAIRO_CONTENT_COLOR, CAIRO_CONTENT_ALPHA };
+    unsigned int content, type, ops;
+    cairo_surface_t *surface;
+
+    cairo_set_source_rgb (cr, 0.5, 0.5, 0.5);
+    cairo_paint (cr);
+    cairo_translate (cr, SPACE, SPACE);
+
+    for (type = 0; type <= PAINTED; type++) {
+        for (content = 0; content < ARRAY_LENGTH (contents); content++) {
+            surface = create_surface (cr, contents[content], type);
+
+            cairo_save (cr);
+            for (ops = 0; ops < ARRAY_LENGTH (operations); ops++) {
+                cairo_save (cr);
+                operations[ops] (cr, surface);
+                cairo_restore (cr);
+                cairo_translate (cr, 0, SIZE + SPACE);
+            }
+            cairo_restore (cr);
+            cairo_translate (cr, SIZE + SPACE, 0);
+        }
+    }
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (clear_source,
+	    "Check painting with cleared surfaces works as expected",
+	    NULL, /* keywords */
+	    NULL, /* requirements */
+	    (SIZE + SPACE) * 9 + SPACE, ARRAY_LENGTH (operations) * (SIZE + SPACE) + SPACE,
+	    NULL, draw)