cogl: add support for quartz imagebackend

Bug #930 - add support for quartz imagebackend

	* clutter/cogl/common/cogl-bitmap-pixbuf.c
	(_cogl_bitmap_from_file): When USE_QUARTZ is defined implement
	using Core Graphics.
	* configure.ac: support --with-imagebackend=quartz and print
	which imagebackend is selected. Make quartz default on OSX

common/cogl-bitmap-pixbuf.c

@@ -33,7 +33,9 @@
 
 #include <string.h>
 
-#ifdef USE_GDKPIXBUF
+#ifdef USE_QUARTZ
+#include <ApplicationServices/ApplicationServices.h>
+#elif defined(USE_GDKPIXBUF)
 #include <gdk-pixbuf/gdk-pixbuf.h>
 #endif
 
@@ -64,7 +66,115 @@ _cogl_bitmap_unpremult (const CoglBitmap *bmp,
   return FALSE;
 }
 
-#ifdef USE_GDKPIXBUF
+#ifdef USE_QUARTZ
+
+/* lacking GdkPixbuf and other useful GError domains, define one of our own */
+
+#define COGL_BITMAP_ERROR cogl_bitmap_error_quark ()
+
+typedef enum {
+  COGL_BITMAP_ERROR_FAILED,
+  COGL_BITMAP_ERROR_UNKNOWN_TYPE,
+  COGL_BITMAP_ERROR_CORRUPT_IMAGE
+} CoglBitmapError;
+
+GQuark
+cogl_bitmap_error_quark (void)
+{
+  return g_quark_from_static_string ("cogl-bitmap-error-quark");
+}
+
+/* the error does not contain the filename as the caller already has it */
+gboolean
+_cogl_bitmap_from_file (CoglBitmap  *bmp,
+			const gchar *filename,
+			GError     **error)
+{
+  g_assert (bmp != NULL);
+  g_assert (filename != NULL);
+  g_assert (error == NULL || *error == NULL);
+
+  CFURLRef url = CFURLCreateFromFileSystemRepresentation (NULL, (guchar*)filename, strlen(filename), false);
+  CGImageSourceRef image_source = CGImageSourceCreateWithURL (url, NULL);
+  int save_errno = errno;
+  CFRelease (url);
+  if (image_source == NULL)
+    {
+      /* doesn't exist, not readable, etc. */
+      g_set_error (error, COGL_BITMAP_ERROR, COGL_BITMAP_ERROR_FAILED,
+                   "%s", g_strerror (save_errno));
+      return FALSE;
+    }
+
+  /* Unknown images would be cleanly caught as zero width/height below, but try
+   * to provide better error message
+   */
+  CFStringRef type = CGImageSourceGetType (image_source);
+  if (type == NULL)
+    {
+      CFRelease (image_source);
+      g_set_error (error, COGL_BITMAP_ERROR, COGL_BITMAP_ERROR_UNKNOWN_TYPE,
+                   "Unknown image type");
+      return FALSE;
+    }
+  CFRelease (type);
+
+  CGImageRef image = CGImageSourceCreateImageAtIndex (image_source, 0, NULL);
+  CFRelease (image_source);
+
+  size_t width = CGImageGetWidth (image);
+  size_t height = CGImageGetHeight (image);
+  if (width == 0 || height == 0)
+    {
+      /* incomplete or corrupt */
+      CFRelease (image);
+      g_set_error (error, COGL_BITMAP_ERROR, COGL_BITMAP_ERROR_CORRUPT_IMAGE,
+                   "Image has zero width or height");
+      return FALSE;
+    }
+
+  /* allocate buffer big enough to hold pixel data */
+  size_t rowstride;
+  CGBitmapInfo bitmap_info = CGImageGetBitmapInfo (image);
+  if ((bitmap_info & kCGBitmapAlphaInfoMask) == kCGImageAlphaNone)
+    {
+      bitmap_info = kCGImageAlphaNone;
+      rowstride = 3 * width;
+    }
+  else
+    {
+      bitmap_info = kCGImageAlphaPremultipliedFirst;
+      rowstride = 4 * width;
+    }
+  guint8 *out_data = g_malloc0 (height * rowstride);
+
+  /* render to buffer */
+  CGColorSpaceRef color_space = CGColorSpaceCreateWithName (kCGColorSpaceGenericRGB);
+  CGContextRef bitmap_context = CGBitmapContextCreate (out_data,
+                                                       width, height, 8,
+                                                       rowstride, color_space,
+                                                       bitmap_info);
+  CGColorSpaceRelease (color_space);
+
+  const CGRect rect = {{0, 0}, {width, height}};
+  CGContextDrawImage (bitmap_context, rect, image);
+
+  CGImageRelease (image);
+  CGContextRelease (bitmap_context);
+
+  /* store bitmap info */
+  bmp->data = out_data;
+  bmp->format = bitmap_info == kCGImageAlphaPremultipliedFirst
+                ? COGL_PIXEL_FORMAT_ARGB_8888
+                : COGL_PIXEL_FORMAT_RGB_888;
+  bmp->width = width;
+  bmp->height = height;
+  bmp->rowstride = rowstride;
+
+  return TRUE;
+}
+
+#elif defined(USE_GDKPIXBUF)
 
 gboolean
 _cogl_bitmap_from_file (CoglBitmap  *bmp,