cogl-bitmap: Encapsulate the CoglBitmap even internally

The CoglBitmap struct is now only defined within cogl-bitmap.c so that
all of its members can now only be accessed with accessor
functions. To get to the data pointer for the bitmap image you must
first call _cogl_bitmap_map and later call _cogl_bitmap_unmap. The map
function takes the same arguments as cogl_pixel_array_map so that
eventually we can make a bitmap optionally internally divert to a
pixel array.

There is a _cogl_bitmap_new_from_data function which constructs a new
bitmap object and takes ownership of the data pointer. The function
gets passed a destroy callback which gets called when the bitmap is
freed. This is similar to how gdk_pixbuf_new_from_data
works. Alternatively NULL can be passed for the destroy function which
means that the caller will manage the life of the pointer (but must
guarantee that it stays alive at least until the bitmap is
freed). This mechanism is used instead of the old approach of creating
a CoglBitmap struct on the stack and manually filling in the
members. It could also later be used to create a CoglBitmap that owns
a GdkPixbuf ref so that we don't necessarily have to copy the
GdkPixbuf data when converting to a bitmap.

There is also _cogl_bitmap_new_shared. This creates a bitmap using a
reference to another CoglBitmap for the data. This is a bit of a hack
but it is needed by the atlas texture backend which wants to divert
the set_region virtual to another texture but it needs to override the
format of the bitmap to ignore the premult flag.

1 files changed, 193 insertions, 35 deletions

diff --git a/cogl/cogl-bitmap.c b/cogl/cogl-bitmap.c
index 55140928..31317778 100644
--- a/cogl/cogl-bitmap.c
+++ b/cogl/cogl-bitmap.c
@@ -31,6 +31,25 @@
 
 #include <string.h>
 
+struct _CoglBitmap
+{
+  CoglHandleObject         _parent;
+  CoglPixelFormat          format;
+  int                      width;
+  int                      height;
+  int                      rowstride;
+
+  guint8                  *data;
+  CoglBitmapDestroyNotify  destroy_fn;
+  void                    *destroy_fn_data;
+
+  gboolean                 mapped;
+
+  /* If this is non-null then 'data' is ignored and instead it is
+     fetched from this shared bitmap. */
+  CoglBitmap              *shared_bmp;
+};
+
 static void _cogl_bitmap_free (CoglBitmap *bmp);
 
 COGL_OBJECT_DEFINE (Bitmap, bitmap);
@@ -38,8 +57,15 @@ COGL_OBJECT_DEFINE (Bitmap, bitmap);
 static void
 _cogl_bitmap_free (CoglBitmap *bmp)
 {
-  g_free (bmp->data);
-  g_free (bmp);
+  g_assert (!bmp->mapped);
+
+  if (bmp->destroy_fn)
+    bmp->destroy_fn (bmp->data, bmp->destroy_fn_data);
+
+  if (bmp->shared_bmp)
+    cogl_object_unref (bmp->shared_bmp);
+
+  g_slice_free (CoglBitmap, bmp);
 }
 
 int
@@ -83,45 +109,65 @@ _cogl_bitmap_convert_premult_status (CoglBitmap      *bmp,
   return TRUE;
 }
 
-gboolean
-_cogl_bitmap_convert_format_and_premult (const CoglBitmap *bmp,
-                                         CoglBitmap       *dst_bmp,
+CoglBitmap *
+_cogl_bitmap_convert_format_and_premult (CoglBitmap *bmp,
                                          CoglPixelFormat   dst_format)
 {
+  CoglPixelFormat src_format = _cogl_bitmap_get_format (bmp);
+  CoglBitmap *dst_bmp;
+
   /* Is base format different (not considering premult status)? */
-  if ((bmp->format & COGL_UNPREMULT_MASK) !=
+  if ((src_format & COGL_UNPREMULT_MASK) !=
       (dst_format & COGL_UNPREMULT_MASK))
     {
       /* Try converting using imaging library */
-      if (!_cogl_bitmap_convert (bmp, dst_bmp, dst_format))
+      if ((dst_bmp = _cogl_bitmap_convert (bmp, dst_format)) == NULL)
         {
           /* ... or try fallback */
-          if (!_cogl_bitmap_fallback_convert (bmp, dst_bmp, dst_format))
-            return FALSE;
+          if ((dst_bmp = _cogl_bitmap_fallback_convert (bmp,
+                                                        dst_format)) == NULL)
+            return NULL;
         }
     }
   else
     {
+      int rowstride = _cogl_bitmap_get_rowstride (bmp);
+      int height = _cogl_bitmap_get_height (bmp);
+      guint8 *data;
+
       /* Copy the bitmap so that we can premultiply in-place */
-      *dst_bmp = *bmp;
-      dst_bmp->data = g_memdup (bmp->data, bmp->rowstride * bmp->height);
+
+      if ((data = _cogl_bitmap_map (bmp, COGL_BUFFER_ACCESS_READ, 0)) == NULL)
+        return NULL;
+
+      dst_bmp = _cogl_bitmap_new_from_data (g_memdup (data, height * rowstride),
+                                            src_format,
+                                            _cogl_bitmap_get_width (bmp),
+                                            height,
+                                            rowstride,
+                                            (CoglBitmapDestroyNotify) g_free,
+                                            NULL);
+
+      _cogl_bitmap_unmap (bmp);
     }
 
+  src_format = _cogl_bitmap_get_format (dst_bmp);
+
   /* We only need to do a premult conversion if both formats have an
      alpha channel. If we're converting from RGB to RGBA then the
      alpha will have been filled with 255 so the premult won't do
      anything or if we are converting from RGBA to RGB we're losing
      information so either converting or not will be wrong for
      transparent pixels */
-  if ((dst_bmp->format & COGL_A_BIT) == COGL_A_BIT &&
+  if ((src_format & COGL_A_BIT) == COGL_A_BIT &&
       (dst_format & COGL_A_BIT) == COGL_A_BIT &&
       !_cogl_bitmap_convert_premult_status (dst_bmp, dst_format))
     {
-      g_free (dst_bmp->data);
-      return FALSE;
+      cogl_object_unref (dst_bmp);
+      return NULL;
     }
 
-  return TRUE;
+  return dst_bmp;
 }
 
 void
@@ -143,14 +189,24 @@ _cogl_bitmap_copy_subregion (CoglBitmap *src,
   g_assert (src->format == dst->format);
   bpp = _cogl_get_format_bpp (src->format);
 
-  srcdata = src->data + src_y * src->rowstride + src_x * bpp;
-  dstdata = dst->data + dst_y * dst->rowstride + dst_x * bpp;
-
-  for (line=0; line<height; ++line)
+  if ((srcdata = _cogl_bitmap_map (src, COGL_BUFFER_ACCESS_READ, 0)))
     {
-      memcpy (dstdata, srcdata, width * bpp);
-      srcdata += src->rowstride;
-      dstdata += dst->rowstride;
+      if ((dstdata = _cogl_bitmap_map (dst, COGL_BUFFER_ACCESS_WRITE, 0)))
+        {
+          srcdata += src_y * src->rowstride + src_x * bpp;
+          dstdata += dst_y * dst->rowstride + dst_x * bpp;
+
+          for (line=0; line<height; ++line)
+            {
+              memcpy (dstdata, srcdata, width * bpp);
+              srcdata += src->rowstride;
+              dstdata += dst->rowstride;
+            }
+
+          _cogl_bitmap_unmap (dst);
+        }
+
+      _cogl_bitmap_unmap (src);
     }
 }
 
@@ -163,29 +219,88 @@ cogl_bitmap_get_size_from_file (const char *filename,
 }
 
 CoglBitmap *
+_cogl_bitmap_new_from_data (guint8                  *data,
+                            CoglPixelFormat          format,
+                            int                      width,
+                            int                      height,
+                            int                      rowstride,
+                            CoglBitmapDestroyNotify  destroy_fn,
+                            void                    *destroy_fn_data)
+{
+  CoglBitmap *bmp = g_slice_new (CoglBitmap);
+
+  bmp->format = format;
+  bmp->width = width;
+  bmp->height = height;
+  bmp->rowstride = rowstride;
+  bmp->data = data;
+  bmp->destroy_fn = destroy_fn;
+  bmp->destroy_fn_data = destroy_fn_data;
+  bmp->mapped = FALSE;
+  bmp->shared_bmp = NULL;
+
+  return _cogl_bitmap_object_new (bmp);
+}
+
+CoglBitmap *
+_cogl_bitmap_new_shared (CoglBitmap              *shared_bmp,
+                         CoglPixelFormat          format,
+                         int                      width,
+                         int                      height,
+                         int                      rowstride)
+{
+  CoglBitmap *bmp = _cogl_bitmap_new_from_data (NULL, /* data */
+                                                format,
+                                                width,
+                                                height,
+                                                rowstride,
+                                                NULL, /* destroy_fn */
+                                                NULL /* destroy_fn_data */);
+
+  bmp->shared_bmp = cogl_object_ref (shared_bmp);
+
+  return bmp;
+}
+
+CoglBitmap *
 cogl_bitmap_new_from_file (const char  *filename,
                            GError     **error)
 {
-  CoglBitmap   bmp;
-  CoglBitmap  *ret;
+  CoglBitmap *bmp;
 
   g_return_val_if_fail (error == NULL || *error == NULL, COGL_INVALID_HANDLE);
 
-  /* Try loading with imaging backend */
-  if (!_cogl_bitmap_from_file (&bmp, filename, error))
+  if ((bmp = _cogl_bitmap_from_file (filename, error)) == NULL)
     {
       /* Try fallback */
-      if (!_cogl_bitmap_fallback_from_file (&bmp, filename))
-	return NULL;
-      else if (error && *error)
-	{
-	  g_error_free (*error);
-	  *error = NULL;
-	}
+      if ((bmp = _cogl_bitmap_fallback_from_file (filename))
+          && error && *error)
+        {
+          g_error_free (*error);
+          *error = NULL;
+        }
     }
 
-  ret = g_memdup (&bmp, sizeof (CoglBitmap));
-  return _cogl_bitmap_object_new (ret);
+  return bmp;
+}
+
+CoglPixelFormat
+_cogl_bitmap_get_format (CoglBitmap *bitmap)
+{
+  return bitmap->format;
+}
+
+void
+_cogl_bitmap_set_format (CoglBitmap *bitmap,
+                         CoglPixelFormat format)
+{
+  bitmap->format = format;
+}
+
+int
+_cogl_bitmap_get_width (CoglBitmap *bitmap)
+{
+  return bitmap->width;
 }
 
 GQuark
@@ -193,3 +308,46 @@ cogl_bitmap_error_quark (void)
 {
   return g_quark_from_static_string ("cogl-bitmap-error-quark");
 }
+
+int
+_cogl_bitmap_get_height (CoglBitmap *bitmap)
+{
+  return bitmap->height;
+}
+
+int
+_cogl_bitmap_get_rowstride (CoglBitmap *bitmap)
+{
+  return bitmap->rowstride;
+}
+
+guint8 *
+_cogl_bitmap_map (CoglBitmap *bitmap,
+                  CoglBufferAccess access,
+                  CoglBufferMapHint hints)
+{
+  /* Divert to another bitmap if this data is shared */
+  if (bitmap->shared_bmp)
+    return _cogl_bitmap_map (bitmap->shared_bmp, access, hints);
+
+  g_assert (!bitmap->mapped);
+  bitmap->mapped = TRUE;
+
+  /* Currently the bitmap is always in regular memory so we can just
+     directly return the pointer */
+  return bitmap->data;
+}
+
+void
+_cogl_bitmap_unmap (CoglBitmap *bitmap)
+{
+  /* Divert to another bitmap if this data is shared */
+  if (bitmap->shared_bmp)
+    return _cogl_bitmap_unmap (bitmap->shared_bmp);
+
+  g_assert (bitmap->mapped);
+  bitmap->mapped = FALSE;
+
+  /* Currently the bitmap is always in regular memory so we don't need
+     to do anything */
+}