video-blend: fix clipping of overlay images on the left

Fix clipping of images that are partially left of the video
surface, they would get clipped on the right side instead of
the left side, because the video unpack functions currently
ignore the x offset parameter. Work around that until that
is implemented.

https://bugzilla.gnome.org/show_bug.cgi?id=739281

diff --git a/gst-libs/gst/video/video-blend.c b/gst-libs/gst/video/video-blend.c
index 3c916edfc9a21ae0213bcaf37acd16c145941522..2632de970edeed1261d9f611fe092b984d6ea716 100644 (file)
--- a/gst-libs/gst/video/video-blend.c
+++ b/gst-libs/gst/video/video-blend.c
@@ -292,6 +292,9 @@ gst_video_blend (GstVideoFrame * dest,
 
   ensure_debug_category ();
 
+  GST_LOG ("blend src %dx%d onto dest %dx%d @ %d,%d", src_width, src_height,
+      dest_width, dest_height, x, y);
+
   /* In case overlay is completely outside the video, dont render */
   if (x + src_width <= 0 || y + src_height <= 0
       || x >= dest_width || y >= dest_height) {
@@ -334,6 +337,7 @@ gst_video_blend (GstVideoFrame * dest,
 
   /* If we're here we know that the overlay image fully or
    * partially overlaps with the video frame */
+
   /* adjust src image for negative offsets */
   if (x < 0) {
     src_xoff = -x;
@@ -347,7 +351,8 @@ gst_video_blend (GstVideoFrame * dest,
     y = 0;
   }
 
-  /* adjust width/height if the src is bigger than dest */
+  /* adjust width/height to render (i.e. clip source image) if the source
+   * image extends beyond the right or bottom border of the video surface */
   if (x + src_width > dest_width)
     src_width = dest_width - x;
 
@@ -360,11 +365,13 @@ gst_video_blend (GstVideoFrame * dest,
     dinfo->unpack_func (dinfo, 0, tmpdestline, dest->data, dest->info.stride,
         0, i, dest_width);
     sinfo->unpack_func (sinfo, 0, tmpsrcline, src->data, src->info.stride,
-        src_xoff, src_yoff, src_width);
+        0, src_yoff, src_width + src_xoff);
 
     matrix (tmpsrcline, src_width);
 
+    /* FIXME: use the x parameter of the unpack func once implemented */
     tmpdestline += 4 * x;
+    tmpsrcline += 4 * src_xoff;
 
     /* Here dest and src are both either in AYUV or ARGB
      * TODO: Make the orc version working properly*/
@@ -405,7 +412,9 @@ gst_video_blend (GstVideoFrame * dest,
 
 #undef BLENDLOOP
 
+    /* undo previous pointer adjustments to pass right pointer to g_free */
     tmpdestline -= 4 * x;
+    tmpsrcline -= 4 * src_xoff;
 
     /* FIXME
      * #if G_BYTE_ORDER == LITTLE_ENDIAN