gdkpixbufoverlay: Allow negative offsets to specify offset from bottom/right

https://bugzilla.gnome.org/show_bug.cgi?id=702826

1 files changed, 17 insertions, 14 deletions

diff --git a/ext/gdk_pixbuf/gstgdkpixbufoverlay.c b/ext/gdk_pixbuf/gstgdkpixbufoverlay.c
index b011b850d..46adfb65a 100644
--- a/ext/gdk_pixbuf/gstgdkpixbufoverlay.c
+++ b/ext/gdk_pixbuf/gstgdkpixbufoverlay.c
@@ -138,14 +138,16 @@ gst_gdk_pixbuf_overlay_class_init (GstGdkPixbufOverlayClass * klass)
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
   g_object_class_install_property (gobject_class, PROP_OFFSET_X,
       g_param_spec_int ("offset-x", "X Offset",
-          "Horizontal offset of overlay image in pixels from top-left corner "
-          "of video image", G_MININT, G_MAXINT, 0,
+          "For positive value, horizontal offset of overlay image in pixels from"
+          " left of video image. For negative value, horizontal offset of overlay"
+          " image in pixels from right of video image", G_MININT, G_MAXINT, 0,
           GST_PARAM_CONTROLLABLE | GST_PARAM_MUTABLE_PLAYING | G_PARAM_READWRITE
           | G_PARAM_STATIC_STRINGS));
   g_object_class_install_property (gobject_class, PROP_OFFSET_Y,
       g_param_spec_int ("offset-y", "Y Offset",
-          "Vertical offset of overlay image in pixels from top-left corner "
-          "of video image", G_MININT, G_MAXINT, 0,
+          "For positive value, vertical offset of overlay image in pixels from"
+          " top of video image. For negative value, vertical offset of overlay"
+          " image in pixels from bottom of video image", G_MININT, G_MAXINT, 0,
           GST_PARAM_CONTROLLABLE | GST_PARAM_MUTABLE_PLAYING | G_PARAM_READWRITE
           | G_PARAM_STATIC_STRINGS));
   g_object_class_install_property (gobject_class, PROP_RELATIVE_X,
@@ -436,6 +438,8 @@ gst_gdk_pixbuf_overlay_update_composition (GstGdkPixbufOverlay * overlay)
   GstVideoOverlayRectangle *rect;
   GstVideoMeta *overlay_meta;
   gint x, y, width, height;
+  gint video_width = GST_VIDEO_INFO_WIDTH (&GST_VIDEO_FILTER (overlay)->in_info);
+  gint video_height = GST_VIDEO_INFO_HEIGHT (&GST_VIDEO_FILTER (overlay)->in_info);
 
   if (overlay->comp) {
     gst_video_overlay_composition_unref (overlay->comp);
@@ -447,14 +451,14 @@ gst_gdk_pixbuf_overlay_update_composition (GstGdkPixbufOverlay * overlay)
 
   overlay_meta = gst_buffer_get_video_meta (overlay->pixels);
 
-  x = overlay->offset_x + (overlay->relative_x * overlay_meta->width);
-  y = overlay->offset_y + (overlay->relative_y * overlay_meta->height);
-
-  /* FIXME: this should work, but seems to crash */
-  if (x < 0)
-    x = 0;
-  if (y < 0)
-    y = 0;
+  x = overlay->offset_x < 0 ?
+    video_width + overlay->offset_x - overlay_meta->width +
+    (overlay->relative_x * overlay_meta->width) :
+    overlay->offset_x + (overlay->relative_x * overlay_meta->width);
+  y = overlay->offset_y < 0 ?
+    video_height + overlay->offset_y - overlay_meta->height +
+    (overlay->relative_y * overlay_meta->height) :
+    overlay->offset_y + (overlay->relative_y * overlay_meta->height);
 
   width = overlay->overlay_width;
   if (width == 0)
@@ -472,8 +476,7 @@ gst_gdk_pixbuf_overlay_update_composition (GstGdkPixbufOverlay * overlay)
       overlay->overlay_height, overlay->overlay_width);
   GST_DEBUG_OBJECT (overlay, "overlay rendered: %d x %d @ %d,%d (onto %d x %d)",
       width, height, x, y,
-      GST_VIDEO_INFO_WIDTH (&GST_VIDEO_FILTER (overlay)->in_info),
-      GST_VIDEO_INFO_HEIGHT (&GST_VIDEO_FILTER (overlay)->in_info));
+      video_width, video_height);
 
   rect = gst_video_overlay_rectangle_new_raw (overlay->pixels,
       x, y, width, height, GST_VIDEO_OVERLAY_FORMAT_FLAG_NONE);