From 4f9ded77422bc4a8721c0a9305aab81717486fb1 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wim.taymans@collabora.co.uk>
Date: Thu, 24 Dec 2009 22:59:09 +0100
Subject: [PATCH] videomixer: scale and clamp

Scale and clamp to the max alpha values.
---
 gst/videomixer/blend_ayuv.c | 8 ++++----
 gst/videomixer/blend_bgra.c | 6 +++---
 gst/videomixer/blend_i420.c | 2 +-
 gst/videomixer/blend_rgb.c  | 2 +-
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/gst/videomixer/blend_ayuv.c b/gst/videomixer/blend_ayuv.c
index e86b3be442..af5f174301 100644
--- a/gst/videomixer/blend_ayuv.c
+++ b/gst/videomixer/blend_ayuv.c
@@ -185,7 +185,7 @@ gst_videomixer_blend_ayuv_ayuv (guint8 * src, gint xpos, gint ypos,
     gint src_width, gint src_height, gdouble src_alpha,
     guint8 * dest, gint dest_width, gint dest_height)
 {
-  gint alpha, b_alpha;
+  gint alpha, s_alpha;
   gint i, j;
   gint src_stride, dest_stride;
   gint src_add, dest_add;
@@ -194,7 +194,7 @@ gst_videomixer_blend_ayuv_ayuv (guint8 * src, gint xpos, gint ypos,
   src_stride = src_width * 4;
   dest_stride = dest_width * 4;
 
-  b_alpha = (gint) (src_alpha * 255);
+  s_alpha = CLAMP ((gint) (src_alpha * 256), 0, 256);
 
   /* adjust src pointers for negative sizes */
   if (xpos < 0) {
@@ -222,7 +222,7 @@ gst_videomixer_blend_ayuv_ayuv (guint8 * src, gint xpos, gint ypos,
 
   for (i = 0; i < src_height; i++) {
     for (j = 0; j < src_width; j++) {
-      alpha = (src[0] * b_alpha) >> 8;
+      alpha = (src[0] * s_alpha) >> 8;
       BLEND_MODE (dest[1], dest[2], dest[3], src[1], src[2], src[3],
           alpha, Y, U, V);
       dest[0] = 0xff;
@@ -254,7 +254,7 @@ gst_videomixer_blend_ayuv_ayuv_mmx (guint8 * src, gint xpos, gint ypos,
   src_stride = src_width * 4;
   dest_stride = dest_width * 4;
 
-  b_alpha = (gint) (src_alpha * 255);
+  b_alpha = CLAMP ((gint) (src_alpha * 255), 0, 255);
 
   /* adjust src pointers for negative sizes */
   if (xpos < 0) {
diff --git a/gst/videomixer/blend_bgra.c b/gst/videomixer/blend_bgra.c
index 279a179839..8636e0a33b 100644
--- a/gst/videomixer/blend_bgra.c
+++ b/gst/videomixer/blend_bgra.c
@@ -32,7 +32,7 @@ gst_videomixer_blend_##name##_##name (guint8 * src, gint xpos, gint ypos, \
     gint src_width, gint src_height, gdouble src_alpha, \
     guint8 * dest, gint dest_width, gint dest_height) \
 { \
-  gint alpha, b_alpha; \
+  gint alpha, s_alpha; \
   gint i, j; \
   gint src_stride, dest_stride; \
   gint src_add, dest_add; \
@@ -41,7 +41,7 @@ gst_videomixer_blend_##name##_##name (guint8 * src, gint xpos, gint ypos, \
   src_stride = src_width * 4; \
   dest_stride = dest_width * 4; \
   \
-  b_alpha = (gint) (src_alpha * 255); \
+  s_alpha = CLAMP ((gint) (src_alpha * 256), 0, 256); \
   \
   /* adjust src pointers for negative sizes */ \
   if (xpos < 0) { \
@@ -69,7 +69,7 @@ gst_videomixer_blend_##name##_##name (guint8 * src, gint xpos, gint ypos, \
   \
   for (i = 0; i < src_height; i++) { \
     for (j = 0; j < src_width; j++) { \
-      alpha = (src[a] * b_alpha) >> 8; \
+      alpha = (src[a] * s_alpha) >> 8; \
       BLEND_MODE (dest[b], dest[g], dest[r], src[b], src[g], src[r], \
           B, G, R, alpha); \
       dest[b] = B; \
diff --git a/gst/videomixer/blend_i420.c b/gst/videomixer/blend_i420.c
index d9412a0503..dcf55f3eef 100644
--- a/gst/videomixer/blend_i420.c
+++ b/gst/videomixer/blend_i420.c
@@ -209,7 +209,7 @@ gst_i420_do_blend (guint8 * src, guint8 * dest,
     return;
   }
 
-  b_alpha = (gint) (src_alpha * 255);
+  b_alpha = CLAMP ((gint) (src_alpha * 255), 0, 255);
 
   for (i = 0; i < src_height; i++) {
     for (j = 0; j < src_width; j++) {
diff --git a/gst/videomixer/blend_rgb.c b/gst/videomixer/blend_rgb.c
index 9a7a39c2e7..d6a2451b26 100644
--- a/gst/videomixer/blend_rgb.c
+++ b/gst/videomixer/blend_rgb.c
@@ -45,7 +45,7 @@ gst_videomixer_blend_##name##_##name (guint8 * src, gint xpos, gint ypos, \
   src_stride = GST_ROUND_UP_4 (src_width * bpp); \
   dest_stride = GST_ROUND_UP_4 (dest_width * bpp); \
   \
-  b_alpha = (gint) (src_alpha * 255); \
+  b_alpha = CLAMP ((gint) (src_alpha * 255), 0, 255); \
   \
   /* adjust src pointers for negative sizes */ \
   if (xpos < 0) { \