From 91c16023066b3d71ed569e0dcb97bdd0fe8b4667 Mon Sep 17 00:00:00 2001
From: Neil Roberts <neil@linux.intel.com>
Date: Fri, 17 Dec 2010 14:52:25 +0000
Subject: [PATCH] cogl-texture: Don't use the source rowstride if we have to
 copy bitmap

If we have to copy the bitmap to do the premultiplication then we were
previously using the rowstride of the source image as the rowstride
for the new image. This is wasteful if the source image is a subregion
of a larger image which would make it use a large rowstride. If we
have to copy the data anyway we might as well compact it to the
smallest rowstride. This also prevents the copy from reading past the
end of the last row of pixels.

An internal function called _cogl_bitmap_copy has been added to do the
copy. It creates a new bitmap with the smallest possible rowstride
rounded up the nearest multiple of 4 bytes. There may be other places
in Cogl that are currently assuming we can read height*rowstride of
the source buffer so they may want to take advantage of this function
too.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2491
---
 clutter/cogl/cogl/cogl-bitmap-private.h |  4 ++++
 clutter/cogl/cogl/cogl-bitmap.c         | 29 +++++++++++++++++++++++++
 clutter/cogl/cogl/cogl-texture.c        | 22 +------------------
 3 files changed, 34 insertions(+), 21 deletions(-)

diff --git a/clutter/cogl/cogl/cogl-bitmap-private.h b/clutter/cogl/cogl/cogl-bitmap-private.h
index d14293fad..bf21a5732 100644
--- a/clutter/cogl/cogl/cogl-bitmap-private.h
+++ b/clutter/cogl/cogl/cogl-bitmap-private.h
@@ -155,6 +155,10 @@ _cogl_bitmap_copy_subregion (CoglBitmap *src,
 			     int         width,
 			     int         height);
 
+/* Creates a deep copy of the source bitmap */
+CoglBitmap *
+_cogl_bitmap_copy (CoglBitmap *src_bmp);
+
 gboolean
 _cogl_bitmap_get_size_from_file (const char *filename,
                                  int        *width,
diff --git a/clutter/cogl/cogl/cogl-bitmap.c b/clutter/cogl/cogl/cogl-bitmap.c
index 355a2a253..cc83dda72 100644
--- a/clutter/cogl/cogl/cogl-bitmap.c
+++ b/clutter/cogl/cogl/cogl-bitmap.c
@@ -181,6 +181,35 @@ _cogl_bitmap_convert_format_and_premult (CoglBitmap *bmp,
   return dst_bmp;
 }
 
+CoglBitmap *
+_cogl_bitmap_copy (CoglBitmap *src_bmp)
+{
+  CoglBitmap *dst_bmp;
+  CoglPixelFormat src_format = _cogl_bitmap_get_format (src_bmp);
+  int bpp = _cogl_get_format_bpp (src_format);
+  int width = _cogl_bitmap_get_width (src_bmp);
+  int height = _cogl_bitmap_get_height (src_bmp);
+  int dst_rowstride = width * bpp;
+
+  /* Round the rowstride up to the next nearest multiple of 4 bytes */
+  dst_rowstride = (dst_rowstride + 3) & ~3;
+
+  dst_bmp = _cogl_bitmap_new_from_data (g_malloc (dst_rowstride * height),
+                                        src_format,
+                                        width, height,
+                                        dst_rowstride,
+                                        (CoglBitmapDestroyNotify) g_free,
+                                        NULL);
+
+  _cogl_bitmap_copy_subregion (src_bmp,
+                               dst_bmp,
+                               0, 0, /* src_x/y */
+                               0, 0, /* dst_x/y */
+                               width, height);
+
+  return dst_bmp;
+}
+
 void
 _cogl_bitmap_copy_subregion (CoglBitmap *src,
 			     CoglBitmap *dst,
diff --git a/clutter/cogl/cogl/cogl-texture.c b/clutter/cogl/cogl/cogl-texture.c
index 15835aba7..bedde9091 100644
--- a/clutter/cogl/cogl/cogl-texture.c
+++ b/clutter/cogl/cogl/cogl-texture.c
@@ -184,27 +184,7 @@ _cogl_texture_prepare_for_upload (CoglBitmap      *src_bmp,
   if (_cogl_texture_needs_premult_conversion (src_format,
                                               dst_format))
     {
-      guint8 *src_data;
-      guint8 *dst_data;
-
-      if ((src_data = _cogl_bitmap_map (src_bmp,
-                                        COGL_BUFFER_ACCESS_READ, 0)) == NULL)
-        return NULL;
-
-      dst_data = g_memdup (src_data,
-                           _cogl_bitmap_get_height (src_bmp) *
-                           _cogl_bitmap_get_rowstride (src_bmp));
-
-      _cogl_bitmap_unmap (src_bmp);
-
-      dst_bmp =
-        _cogl_bitmap_new_from_data (dst_data,
-                                    src_format,
-                                    _cogl_bitmap_get_width (src_bmp),
-                                    _cogl_bitmap_get_height (src_bmp),
-                                    _cogl_bitmap_get_rowstride (src_bmp),
-                                    (CoglBitmapDestroyNotify) g_free,
-                                    NULL);
+      dst_bmp = _cogl_bitmap_copy (src_bmp);
 
       if (!_cogl_bitmap_convert_premult_status (dst_bmp,
                                                 src_format ^