Add a conformance test for atlas migration

This adds a conformance test which creates a lot of textures with
increasing size and destroys them again a number of times in order to
cause a few atlas migrations. The last time the textures are created
they are all read back and the data is verified to confirm that the
atlas migration successfully preserved the data.

tests/conform/Makefile.am

@@ -48,6 +48,7 @@ units_sources += \
 	test-cogl-texture-mipmaps.c     	\
 	test-cogl-texture-pixmap-x11.c  	\
 	test-cogl-texture-rectangle.c   	\
+	test-cogl-atlas-migration.c		\
 	test-cogl-vertex-buffer-contiguous.c 	\
 	test-cogl-vertex-buffer-interleved.c 	\
 	test-cogl-vertex-buffer-mutability.c 	\

tests/conform/test-cogl-atlas-migration.c

@@ -0,0 +1,133 @@
+#include <clutter/clutter.h>
+
+#include "test-conform-common.h"
+
+#define N_TEXTURES 128
+
+#define OPACITY_FOR_ROW(y) \
+  (0xff - ((y) & 0xf) * 0x10)
+
+#define COLOR_FOR_SIZE(size) \
+  (colors + (size) % 3)
+
+static const ClutterColor colors[] =
+  { { 0xff, 0x00, 0x00, 0xff },
+    { 0x00, 0xff, 0x00, 0xff },
+    { 0x00, 0x00, 0xff, 0xff } };
+
+static CoglHandle
+create_texture (int size)
+{
+  CoglHandle texture;
+  const ClutterColor *color;
+  guint8 *data, *p;
+  int x, y;
+
+  /* Create a red, green or blue texture depending on the size */
+  color = COLOR_FOR_SIZE (size);
+
+  p = data = g_malloc (size * size * 4);
+
+  /* Fill the data with the color but fade the opacity out with
+     increasing y coordinates so that we can see the blending it the
+     atlas migration accidentally blends with garbage in the
+     texture */
+  for (y = 0; y < size; y++)
+    {
+      int opacity = OPACITY_FOR_ROW (y);
+
+      for (x = 0; x < size; x++)
+        {
+          /* Store the colors premultiplied */
+          p[0] = color->red * opacity / 255;
+          p[1] = color->green * opacity / 255;
+          p[2] = color->blue * opacity / 255;
+          p[3] = opacity;
+
+          p += 4;
+        }
+    }
+
+  texture = cogl_texture_new_from_data (size, /* width */
+                                        size, /* height */
+                                        COGL_TEXTURE_NONE, /* flags */
+                                        /* format */
+                                        COGL_PIXEL_FORMAT_RGBA_8888,
+                                        /* internal format */
+                                        COGL_PIXEL_FORMAT_RGBA_8888,
+                                        /* rowstride */
+                                        size * 4,
+                                        data);
+
+  g_free (data);
+
+  return texture;
+}
+
+static void
+verify_texture (CoglHandle texture, int size)
+{
+  guint8 *data, *p;
+  int x, y;
+  const ClutterColor *color;
+
+  color = COLOR_FOR_SIZE (size);
+
+  p = data = g_malloc (size * size * 4);
+
+  cogl_texture_get_data (texture,
+                         COGL_PIXEL_FORMAT_RGBA_8888,
+                         size * 4,
+                         data);
+
+  for (y = 0; y < size; y++)
+    {
+      int opacity = OPACITY_FOR_ROW (y);
+
+      for (x = 0; x < size; x++)
+        {
+          g_assert_cmpint (p[0], ==, color->red * opacity / 255);
+          g_assert_cmpint (p[1], ==, color->green * opacity / 255);
+          g_assert_cmpint (p[2], ==, color->blue * opacity / 255);
+          g_assert_cmpint (p[3], ==, opacity);
+
+          p += 4;
+        }
+    }
+
+  g_free (data);
+}
+
+void
+test_cogl_atlas_migration (TestConformSimpleFixture *fixture,
+                           gconstpointer data)
+{
+  CoglHandle textures[N_TEXTURES];
+  int i, tex_num;
+
+  /* Create and destroy all of the textures a few times to increase
+     the chances that we'll end up reusing the buffers for previously
+     discarded atlases */
+  for (i = 0; i < 5; i++)
+    {
+      for (tex_num = 0; tex_num < N_TEXTURES; tex_num++)
+        textures[tex_num] = create_texture (tex_num + 1);
+      for (tex_num = 0; tex_num < N_TEXTURES; tex_num++)
+        cogl_object_unref (textures[tex_num]);
+    }
+
+  /* Create all the textures again */
+  for (tex_num = 0; tex_num < N_TEXTURES; tex_num++)
+    textures[tex_num] = create_texture (tex_num + 1);
+
+  /* Verify that they all still have the right data */
+  for (tex_num = 0; tex_num < N_TEXTURES; tex_num++)
+    verify_texture (textures[tex_num], tex_num + 1);
+
+  /* Destroy them all */
+  for (tex_num = 0; tex_num < N_TEXTURES; tex_num++)
+    cogl_object_unref (textures[tex_num]);
+
+  if (g_test_verbose ())
+    g_print ("OK\n");
+}

tests/conform/test-conform-main.c

@@ -230,6 +230,7 @@ main (int argc, char **argv)
   TEST_CONFORM_SIMPLE ("/cogl/texture", test_cogl_wrap_modes);
   TEST_CONFORM_SIMPLE ("/cogl/texture", test_cogl_texture_pixmap_x11);
   TEST_CONFORM_SIMPLE ("/cogl/texture", test_cogl_texture_get_set_data);
+  TEST_CONFORM_SIMPLE ("/cogl/texture", test_cogl_atlas_migration);
 
   TEST_CONFORM_SIMPLE ("/cogl/vertex-buffer", test_cogl_vertex_buffer_contiguous);
   TEST_CONFORM_SIMPLE ("/cogl/vertex-buffer", test_cogl_vertex_buffer_interleved);