From d93ad296e5d96c59961db873fe9531406ce6e1b3 Mon Sep 17 00:00:00 2001
From: niksedk <nikse.dk@gmail.com>
Date: Tue, 13 Sep 2011 18:19:57 +0000
Subject: [PATCH] VobSub - Added reading of transparency settings + fixed bug
 where background color was not changed (sometimes background color is used
 for... not background)

git-svn-id: https://subtitleedit.googlecode.com/svn/trunk@636 99eadd0c-20b8-1223-b5c4-2a2b2df33de2
---
 src/Logic/VobSub/SubPicture.cs | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/Logic/VobSub/SubPicture.cs b/src/Logic/VobSub/SubPicture.cs
index a09525c04..ece370850 100644
--- a/src/Logic/VobSub/SubPicture.cs
+++ b/src/Logic/VobSub/SubPicture.cs
@@ -108,7 +108,17 @@ namespace Nikse.SubtitleEdit.Logic.VobSub
                             commandIndex += 3;
                             break;
                         case (int)DisplayControlCommand.SetContrast: // 4
-                            imageContrast = new[] { _data[commandIndex + 1], _data[commandIndex + 2] };
+                            if (colorLookUpTable != null && fourColors.Count == 4)
+                            {
+                                imageContrast = new[] { _data[commandIndex + 1], _data[commandIndex + 2] };
+                                //if (imageContrast[0] + imageContrast[1] > 0)
+                                //{
+                                    SetTransparency(fourColors, 3, (imageContrast[0] & 0xF0) >> 4);
+                                    SetTransparency(fourColors, 2, imageContrast[0] & Helper.B00001111);
+                                    SetTransparency(fourColors, 1, (imageContrast[1] & 0xF0) >> 4);
+                                    SetTransparency(fourColors, 0, imageContrast[1] & Helper.B00001111);
+                                //}
+                            }
                             commandIndex += 3;
                             break;
                         case (int)DisplayControlCommand.SetDisplayArea: // 5
@@ -157,10 +167,18 @@ namespace Nikse.SubtitleEdit.Logic.VobSub
 
         private static void SetColor(List<Color> fourColors, int fourColorIndex, int clutIndex, List<Color> colorLookUpTable)
         {
-            if (clutIndex >= 0 && clutIndex < colorLookUpTable.Count && fourColorIndex > 0)
+            if (clutIndex >= 0 && clutIndex < colorLookUpTable.Count && fourColorIndex >= 0)
                 fourColors[fourColorIndex] = colorLookUpTable[clutIndex];
         }
 
+        private static void SetTransparency(List<Color> fourColors, int fourColorIndex, int alpha)
+        {
+            // alpha: 0x0 = transparent, 0xF = opaque (in C# 0 is fully transparent, and 255 is fully opaque so we have to multiply by 17)
+
+            if (fourColorIndex >= 0)
+                fourColors[fourColorIndex] = Color.FromArgb(alpha * 17, fourColors[fourColorIndex].R, fourColors[fourColorIndex].G, fourColors[fourColorIndex].B);
+        }
+
         private Bitmap GenerateBitmap(Rectangle imageDisplayArea, int imageTopFieldDataAddress, int imageBottomFieldDataAddress, List<Color> fourColors)
         {
             var bmp = new Bitmap(imageDisplayArea.Width + 1, imageDisplayArea.Height + 1);