cogl-texture: Share the common code in the get_data virtual

Previously cogl_texture_get_data would pretty much directly pass on to
the get_data texture virtual function. This ended up with a lot of
common code that was copied to all of the backends. For example, the
method is expected to return the required data size if the data
pointer is NULL and to calculate its own rowstride if the rowstride is
0. Also it needs to convert the downloaded data if GL can't support
that format directly.

This patch moves the common code to cogl-texture.c so the virtual is
always called with a format that can be downloaded directly by GL and
with a valid rowstride. If the download fails then the virtual can
return FALSE in which case cogl-texture will use the draw and read
fallback.

cogl/cogl-atlas-texture.c

@@ -595,7 +595,7 @@ _cogl_atlas_texture_set_region (CoglTexture    *tex,
                                     data);
 }
 
-static int
+static gboolean
 _cogl_atlas_texture_get_data (CoglTexture     *tex,
                               CoglPixelFormat  format,
                               unsigned int     rowstride,

cogl/cogl-sub-texture.c

@@ -448,7 +448,7 @@ _cogl_sub_texture_copy_region (guint8 *dst,
     }
 }
 
-static int
+static gboolean
 _cogl_sub_texture_get_data (CoglTexture     *tex,
                             CoglPixelFormat  format,
                             unsigned int     rowstride,
@@ -457,7 +457,7 @@ _cogl_sub_texture_get_data (CoglTexture     *tex,
   CoglSubTexture *sub_tex = COGL_SUB_TEXTURE (tex);
   unsigned int full_rowstride;
   guint8 *full_data;
-  int byte_size, full_size;
+  gboolean ret = TRUE;
   int bpp;
   int full_tex_width, full_tex_height;
 
@@ -466,30 +466,16 @@ _cogl_sub_texture_get_data (CoglTexture     *tex,
      texture_get_sub_data virtual and it can just munge the texture
      coordinates */
 
-  /* Default to internal format if none specified */
-  if (format == COGL_PIXEL_FORMAT_ANY)
-    format = cogl_texture_get_format (sub_tex->full_texture);
-
   full_tex_width = cogl_texture_get_width (sub_tex->full_texture);
   full_tex_height = cogl_texture_get_height (sub_tex->full_texture);
 
-  /* Rowstride from texture width if none specified */
   bpp = _cogl_get_format_bpp (format);
-  if (rowstride == 0)
-    rowstride = sub_tex->sub_width * bpp;
-
-  /* Return byte size if only that requested */
-  byte_size = sub_tex->sub_height * rowstride;
-  if (data == NULL)
-    return byte_size;
 
   full_rowstride = _cogl_get_format_bpp (format) * full_tex_width;
   full_data = g_malloc (full_rowstride * full_tex_height);
 
-  full_size = cogl_texture_get_data (sub_tex->full_texture, format,
+  if (cogl_texture_get_data (sub_tex->full_texture, format,
-                                     full_rowstride, full_data);
+                             full_rowstride, full_data))
-
-  if (full_size)
     _cogl_sub_texture_copy_region (data, full_data,
                                    0, 0,
                                    sub_tex->sub_x,
@@ -500,11 +486,11 @@ _cogl_sub_texture_get_data (CoglTexture     *tex,
                                    full_rowstride,
                                    bpp);
   else
-    byte_size = 0;
+    ret = FALSE;
 
   g_free (full_data);
 
-  return byte_size;
+  return ret;
 }
 
 static CoglPixelFormat

cogl/cogl-texture-2d-sliced.c

@@ -1633,96 +1633,27 @@ _cogl_texture_2d_sliced_get_data (CoglTexture     *tex,
 {
   CoglTexture2DSliced *tex_2ds = COGL_TEXTURE_2D_SLICED (tex);
   int             bpp;
-  int             byte_size;
+  GLenum          gl_format;
-  CoglPixelFormat closest_format;
+  GLenum          gl_type;
-  int             closest_bpp;
-  GLenum          closest_gl_format;
-  GLenum          closest_gl_type;
   CoglBitmap      target_bmp;
-  CoglBitmap      new_bmp;
-  gboolean        success;
-  guint8         *src;
-  guint8         *dst;
-  int             y;
 
-  /* Default to internal format if none specified */
-  if (format == COGL_PIXEL_FORMAT_ANY)
-    format = tex_2ds->format;
-
-  /* Rowstride from texture width if none specified */
   bpp = _cogl_get_format_bpp (format);
-  if (rowstride == 0)
-    rowstride = tex_2ds->width * bpp;
 
-  /* Return byte size if only that requested */
+  _cogl_pixel_format_to_gl (format,
-  byte_size =  tex_2ds->height * rowstride;
+                            NULL, /* internal format */
-  if (data == NULL)
+                            &gl_format,
-    return byte_size;
+                            &gl_type);
-
-  closest_format =
-    _cogl_texture_driver_find_best_gl_get_data_format (format,
-                                                       &closest_gl_format,
-                                                       &closest_gl_type);
-  closest_bpp = _cogl_get_format_bpp (closest_format);
 
   target_bmp.width = tex_2ds->width;
   target_bmp.height = tex_2ds->height;
-
-  /* Is the requested format supported? */
-  if (closest_format == format)
-    {
-      /* Target user data directly */
   target_bmp.format = format;
   target_bmp.rowstride = rowstride;
   target_bmp.data = data;
-    }
-  else
-    {
-      /* Target intermediate buffer */
-      target_bmp.format = closest_format;
-      target_bmp.rowstride = target_bmp.width * closest_bpp;
-      target_bmp.data = g_malloc (target_bmp.height * target_bmp.rowstride);
-    }
 
   /* Retrieve data from slices */
-  if (!_cogl_texture_2d_sliced_download_from_gl (tex_2ds, &target_bmp,
+  return _cogl_texture_2d_sliced_download_from_gl (tex_2ds, &target_bmp,
-                                                 closest_gl_format,
+                                                   gl_format,
-                                                 closest_gl_type))
+                                                   gl_type);
-    {
-      /* XXX: In some cases _cogl_texture_2d_sliced_download_from_gl may
-       * fail to read back the texture data; such as for GLES which doesn't
-       * support glGetTexImage, so here we fallback to drawing the texture
-       * and reading the pixels from the framebuffer. */
-      _cogl_texture_draw_and_read (tex, &target_bmp,
-                                   closest_gl_format,
-                                   closest_gl_type);
-    }
-
-  /* Was intermediate used? */
-  if (closest_format != format)
-    {
-      /* Convert to requested format */
-      success = _cogl_bitmap_convert_format_and_premult (&target_bmp,
-                                                         &new_bmp,
-                                                         format);
-
-      /* Free intermediate data and return if failed */
-      g_free (target_bmp.data);
-      if (!success) return 0;
-
-      /* Copy to user buffer */
-      for (y = 0; y < new_bmp.height; ++y)
-        {
-          src = new_bmp.data + y * new_bmp.rowstride;
-          dst = data + y * rowstride;
-          memcpy (dst, src, new_bmp.rowstride);
-        }
-
-      /* Free converted data */
-      g_free (new_bmp.data);
-    }
-
-  return byte_size;
 }
 
 static CoglPixelFormat

cogl/cogl-texture-2d.c

@@ -513,7 +513,7 @@ _cogl_texture_2d_set_region (CoglTexture    *tex,
   return TRUE;
 }
 
-static int
+static gboolean
 _cogl_texture_2d_get_data (CoglTexture     *tex,
                            CoglPixelFormat  format,
                            unsigned int     rowstride,
@@ -521,103 +521,25 @@ _cogl_texture_2d_get_data (CoglTexture     *tex,
 {
   CoglTexture2D   *tex_2d = COGL_TEXTURE_2D (tex);
   int              bpp;
-  int              byte_size;
+  GLenum           gl_format;
-  CoglPixelFormat  closest_format;
+  GLenum           gl_type;
-  int              closest_bpp;
-  GLenum           closest_gl_format;
-  GLenum           closest_gl_type;
-  CoglBitmap       target_bmp;
-  CoglBitmap       new_bmp;
-  gboolean         success;
-  guint8          *src;
-  guint8          *dst;
-  int              y;
 
-  /* Default to internal format if none specified */
-  if (format == COGL_PIXEL_FORMAT_ANY)
-    format = tex_2d->format;
-
-  /* Rowstride from texture width if none specified */
   bpp = _cogl_get_format_bpp (format);
-  if (rowstride == 0)
-    rowstride = tex_2d->width * bpp;
 
-  /* Return byte size if only that requested */
+  _cogl_pixel_format_to_gl (format,
-  byte_size =  tex_2d->height * rowstride;
+                            NULL, /* internal format */
-  if (data == NULL)
+                            &gl_format,
-    return byte_size;
+                            &gl_type);
 
-  closest_format =
+  _cogl_texture_driver_prep_gl_for_pixels_download (rowstride, bpp);
-    _cogl_texture_driver_find_best_gl_get_data_format (format,
-                                                       &closest_gl_format,
-                                                       &closest_gl_type);
-  closest_bpp = _cogl_get_format_bpp (closest_format);
-
-  target_bmp.width = tex_2d->width;
-  target_bmp.height = tex_2d->height;
-
-  /* Is the requested format supported? */
-  if (closest_format == format)
-    {
-      /* Target user data directly */
-      target_bmp.format = format;
-      target_bmp.rowstride = rowstride;
-      target_bmp.data = data;
-    }
-  else
-    {
-      /* Target intermediate buffer */
-      target_bmp.format = closest_format;
-      target_bmp.rowstride = target_bmp.width * closest_bpp;
-      target_bmp.data = g_malloc (target_bmp.height * target_bmp.rowstride);
-    }
-
-  _cogl_texture_driver_prep_gl_for_pixels_download (target_bmp.rowstride,
-                                                    closest_bpp);
 
   _cogl_bind_gl_texture_transient (GL_TEXTURE_2D,
                                    tex_2d->gl_texture,
                                    FALSE);
-  if (!_cogl_texture_driver_gl_get_tex_image (GL_TEXTURE_2D,
+  return _cogl_texture_driver_gl_get_tex_image (GL_TEXTURE_2D,
-                                              closest_gl_format,
+                                                gl_format,
-                                              closest_gl_type,
+                                                gl_type,
-                                              target_bmp.data))
+                                                data);
-    {
-      /* XXX: In some cases _cogl_texture_2d_download_from_gl may
-       * fail to read back the texture data; such as for GLES which doesn't
-       * support glGetTexImage, so here we fallback to drawing the texture
-       * and reading the pixels from the framebuffer. */
-      _cogl_texture_draw_and_read (tex, &target_bmp,
-                                   closest_gl_format,
-                                   closest_gl_type);
-    }
-
-  /* Was intermediate used? */
-  if (closest_format != format)
-    {
-      /* Convert to requested format */
-      success = _cogl_bitmap_convert_format_and_premult (&target_bmp,
-                                                         &new_bmp,
-                                                         format);
-
-      /* Free intermediate data and return if failed */
-      g_free (target_bmp.data);
-      if (!success)
-        return 0;
-
-      /* Copy to user buffer */
-      for (y = 0; y < new_bmp.height; ++y)
-        {
-          src = new_bmp.data + y * new_bmp.rowstride;
-          dst = data + y * rowstride;
-          memcpy (dst, src, new_bmp.width);
-        }
-
-      /* Free converted data */
-      g_free (new_bmp.data);
-    }
-
-  return byte_size;
 }
 
 static CoglPixelFormat

cogl/cogl-texture-private.h

@@ -81,7 +81,12 @@ struct _CoglTextureVtable
                            unsigned int    rowstride,
                            const guint8   *data);
 
-  int (* get_data) (CoglTexture     *tex,
+  /* This should copy the image data of the texture into @data. The
+     requested format will have been first passed through
+     _cogl_texture_driver_find_best_gl_get_data_format so it should
+     always be a format that is valid for GL (ie, no conversion should
+     be necessary). */
+  gboolean (* get_data) (CoglTexture     *tex,
                          CoglPixelFormat  format,
                          unsigned int     rowstride,
                          guint8          *data);

cogl/cogl-texture-rectangle.c

@@ -507,7 +507,7 @@ _cogl_texture_rectangle_set_region (CoglTexture    *tex,
   return TRUE;
 }
 
-static int
+static gboolean
 _cogl_texture_rectangle_get_data (CoglTexture     *tex,
                                   CoglPixelFormat  format,
                                   unsigned int     rowstride,
@@ -515,103 +515,25 @@ _cogl_texture_rectangle_get_data (CoglTexture     *tex,
 {
   CoglTextureRectangle *tex_rect = COGL_TEXTURE_RECTANGLE (tex);
   int                   bpp;
-  int              byte_size;
+  GLenum                gl_format;
-  CoglPixelFormat  closest_format;
+  GLenum                gl_type;
-  int              closest_bpp;
-  GLenum           closest_gl_format;
-  GLenum           closest_gl_type;
-  CoglBitmap       target_bmp;
-  CoglBitmap       new_bmp;
-  gboolean         success;
-  guint8          *src;
-  guint8          *dst;
-  int              y;
 
-  /* Default to internal format if none specified */
-  if (format == COGL_PIXEL_FORMAT_ANY)
-    format = tex_rect->format;
-
-  /* Rowstride from texture width if none specified */
   bpp = _cogl_get_format_bpp (format);
-  if (rowstride == 0)
-    rowstride = tex_rect->width * bpp;
 
-  /* Return byte size if only that requested */
+  _cogl_pixel_format_to_gl (format,
-  byte_size =  tex_rect->height * rowstride;
+                            NULL, /* internal format */
-  if (data == NULL)
+                            &gl_format,
-    return byte_size;
+                            &gl_type);
 
-  closest_format =
+  _cogl_texture_driver_prep_gl_for_pixels_download (rowstride, bpp);
-    _cogl_texture_driver_find_best_gl_get_data_format (format,
-                                                       &closest_gl_format,
-                                                       &closest_gl_type);
-  closest_bpp = _cogl_get_format_bpp (closest_format);
-
-  target_bmp.width = tex_rect->width;
-  target_bmp.height = tex_rect->height;
-
-  /* Is the requested format supported? */
-  if (closest_format == format)
-    {
-      /* Target user data directly */
-      target_bmp.format = format;
-      target_bmp.rowstride = rowstride;
-      target_bmp.data = data;
-    }
-  else
-    {
-      /* Target intermediate buffer */
-      target_bmp.format = closest_format;
-      target_bmp.rowstride = target_bmp.width * closest_bpp;
-      target_bmp.data = g_malloc (target_bmp.height * target_bmp.rowstride);
-    }
-
-  _cogl_texture_driver_prep_gl_for_pixels_download (target_bmp.rowstride,
-                                                    closest_bpp);
 
   GE( _cogl_bind_gl_texture_transient (GL_TEXTURE_RECTANGLE_ARB,
                                        tex_rect->gl_texture,
                                        FALSE) );
-  if (!_cogl_texture_driver_gl_get_tex_image (GL_TEXTURE_RECTANGLE_ARB,
+  return _cogl_texture_driver_gl_get_tex_image (GL_TEXTURE_RECTANGLE_ARB,
-                                              closest_gl_format,
+                                                gl_format,
-                                              closest_gl_type,
+                                                gl_type,
-                                              target_bmp.data))
+                                                data);
-    {
-      /* XXX: In some cases _cogl_texture_rectangle_download_from_gl may
-       * fail to read back the texture data; such as for GLES which doesn't
-       * support glGetTexImage, so here we fallback to drawing the texture
-       * and reading the pixels from the framebuffer. */
-      _cogl_texture_draw_and_read (tex, &target_bmp,
-                                   closest_gl_format,
-                                   closest_gl_type);
-    }
-
-  /* Was intermediate used? */
-  if (closest_format != format)
-    {
-      /* Convert to requested format */
-      success = _cogl_bitmap_convert_format_and_premult (&target_bmp,
-                                                         &new_bmp,
-                                                         format);
-
-      /* Free intermediate data and return if failed */
-      g_free (target_bmp.data);
-      if (!success)
-        return 0;
-
-      /* Copy to user buffer */
-      for (y = 0; y < new_bmp.height; ++y)
-        {
-          src = new_bmp.data + y * new_bmp.rowstride;
-          dst = data + y * rowstride;
-          memcpy (dst, src, new_bmp.width);
-        }
-
-      /* Free converted data */
-      g_free (new_bmp.data);
-    }
-
-  return byte_size;
 }
 
 static CoglPixelFormat

cogl/cogl-texture.c

@@ -1085,12 +1085,104 @@ cogl_texture_get_data (CoglHandle       handle,
 		       guint8          *data)
 {
   CoglTexture     *tex;
+  int              bpp;
+  int              byte_size;
+  CoglPixelFormat  closest_format;
+  int              closest_bpp;
+  GLenum           closest_gl_format;
+  GLenum           closest_gl_type;
+  CoglBitmap       target_bmp;
+  CoglBitmap       new_bmp;
+  gboolean         success;
+  guint8          *src;
+  guint8          *dst;
+  int              y;
+  int              tex_width;
+  int              tex_height;
 
   if (!cogl_is_texture (handle))
     return FALSE;
 
   tex = COGL_TEXTURE (handle);
 
-  return tex->vtable->get_data (handle, format, rowstride, data);
+  /* Default to internal format if none specified */
+  if (format == COGL_PIXEL_FORMAT_ANY)
+    format = cogl_texture_get_format (handle);
+
+  tex_width = cogl_texture_get_width (handle);
+  tex_height = cogl_texture_get_height (handle);
+
+  /* Rowstride from texture width if none specified */
+  bpp = _cogl_get_format_bpp (format);
+  if (rowstride == 0)
+    rowstride = tex_width * bpp;
+
+  /* Return byte size if only that requested */
+  byte_size = tex_height * rowstride;
+  if (data == NULL)
+    return byte_size;
+
+  closest_format =
+    _cogl_texture_driver_find_best_gl_get_data_format (format,
+                                                       &closest_gl_format,
+                                                       &closest_gl_type);
+  closest_bpp = _cogl_get_format_bpp (closest_format);
+
+  target_bmp.width = tex_width;
+  target_bmp.height = tex_height;
+
+  /* Is the requested format supported? */
+  if (closest_format == format)
+    {
+      /* Target user data directly */
+      target_bmp.format = format;
+      target_bmp.rowstride = rowstride;
+      target_bmp.data = data;
+    }
+  else
+    {
+      /* Target intermediate buffer */
+      target_bmp.format = closest_format;
+      target_bmp.rowstride = target_bmp.width * closest_bpp;
+      target_bmp.data = g_malloc (target_bmp.height * target_bmp.rowstride);
     }
 
+  if (!tex->vtable->get_data (tex,
+                              target_bmp.format,
+                              target_bmp.rowstride,
+                              target_bmp.data))
+    /* XXX: In some cases _cogl_texture_2d_download_from_gl may fail
+     * to read back the texture data; such as for GLES which doesn't
+     * support glGetTexImage, so here we fallback to drawing the
+     * texture and reading the pixels from the framebuffer. */
+    _cogl_texture_draw_and_read (tex, &target_bmp,
+                                 closest_gl_format,
+                                 closest_gl_type);
+
+  /* Was intermediate used? */
+  if (closest_format != format)
+    {
+      /* Convert to requested format */
+      success = _cogl_bitmap_convert_format_and_premult (&target_bmp,
+                                                         &new_bmp,
+                                                         format);
+
+      /* Free intermediate data and return if failed */
+      g_free (target_bmp.data);
+      if (!success)
+        return 0;
+
+      /* Copy to user buffer */
+      for (y = 0; y < new_bmp.height; ++y)
+        {
+          src = new_bmp.data + y * new_bmp.rowstride;
+          dst = data + y * rowstride;
+          memcpy (dst, src, new_bmp.width);
+        }
+
+      /* Free converted data */
+      g_free (new_bmp.data);
+    }
+
+  return byte_size;
+}

cogl/winsys/cogl-texture-pixmap-x11.c

@@ -1129,7 +1129,7 @@ _cogl_texture_pixmap_x11_set_region (CoglTexture     *tex,
   return FALSE;
 }
 
-static int
+static gboolean
 _cogl_texture_pixmap_x11_get_data (CoglTexture     *tex,
                                    CoglPixelFormat  format,
                                    unsigned int     rowstride,