Add a public cogl_bitmap_new_for_data

This creates a CoglBitmap which points into an existing buffer in
system memory. That way it can be used to create a texture or to read
pixel data into. The function replaces the existing internal function
_cogl_bitmap_new_from_data but removes the destroy notify call back.
If the application wants notification of destruction it can just use
the cogl_object_set_user_data function as normal. Internally there is
now a convenience function to create a bitmap for system memory and
automatically free the buffer using that mechanism.

The name of the function is inspired by
cairo_image_surface_create_for_data which has similar semantics.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

cogl/cogl-bitmap.h

@@ -129,6 +129,34 @@ cogl_bitmap_new_with_size (CoglContext *context,
                            unsigned int height,
                            CoglPixelFormat format);
 
+/**
+ * cogl_bitmap_new_for_data:
+ * @context: A #CoglContext
+ * @width: The width of the bitmap.
+ * @height: The height of the bitmap.
+ * @format: The format of the pixel data.
+ * @rowstride: The rowstride of the bitmap (the number of bytes from
+ *   the start of one row of the bitmap to the next).
+ * @data: A pointer to the data. The bitmap will take ownership of this data.
+ *
+ * Creates a bitmap using some existing data. The data is not copied
+ * so the application must keep the buffer alive for the lifetime of
+ * the #CoglBitmap. This can be used for example with
+ * cogl_framebuffer_read_pixels_into_bitmap() to read data directly
+ * into an application buffer with the specified rowstride.
+ *
+ * Return value: A new #CoglBitmap.
+ * Since: 1.10
+ * Stability: unstable
+ */
+CoglBitmap *
+cogl_bitmap_new_for_data (CoglContext *context,
+                          int width,
+                          int height,
+                          CoglPixelFormat format,
+                          int rowstride,
+                          guint8 *data);
+
 /**
  * cogl_bitmap_get_format:
  * @bitmap: A #CoglBitmap