textoverlay: fix comparison is always false due to limited range of data type

Perform calculation in a temp var with enough room as there's guarantee that
ret will be able to hold the result for example in _blit_AYUV.

diff --git a/ext/pango/gsttextoverlay.c b/ext/pango/gsttextoverlay.c
index 21ac013..914c216 100644 (file)
--- a/ext/pango/gsttextoverlay.c
+++ b/ext/pango/gsttextoverlay.c
@@ -145,8 +145,9 @@ GST_DEBUG_CATEGORY (pango_debug);
 
 #define OVER(ret, alphaA, Ca, alphaB, Cb, alphaNew)    \
 { \
-    ret = (Ca * alphaA + Cb * alphaB * (255 - alphaA) / 255) / alphaNew; \
-    ret = CLAMP (ret, 0, 255); \
+    gint _tmp; \
+    _tmp = (Ca * alphaA + Cb * alphaB * (255 - alphaA) / 255) / alphaNew; \
+    ret = CLAMP (_tmp, 0, 255); \
 }
 
 #if G_BYTE_ORDER == G_LITTLE_ENDIAN