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Fixed alpha blending.

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git-svn-id: http://svn.code.sf.net/p/greenshot/code/trunk@1759 7dccd23d-a4a3-4e1f-8c07-b4c1b4018ab4
This commit is contained in:
RKrom 2012-04-06 13:55:07 +00:00
parent 1beb0656f4
commit bfd6cc902e
1 changed files with 8 additions and 16 deletions
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24
GreenshotPlugin/Core/BitmapBuffer.cs
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@ -33,23 +33,16 @@ namespace GreenshotPlugin.Core {
private static log4net.ILog LOG = log4net.LogManager.GetLogger(typeof(BitmapBuffer));
private bool clone;
private Bitmap bitmap;
private static int[] factors = new int[256];
private static int[] remainings = new int[256];
static BitmapBuffer() {
// Pre calculate for alpha blending
for (int i = 0; i < 256; i++) {
int factor = 0x10000 * i / 255;
factors[i] = factor;
remainings[i] = (0x10000 * 255) - factor;
}
}
public static Color BackgroundBlendColor {
get;
set;
}
static BitmapBuffer() {
BackgroundBlendColor = Color.White;
}
/// <summary>
/// Get the bitmap, you will always need to dispose the returned bitmap!!
/// Only works, and makes sense, if cloned and not locked!
@ -340,11 +333,10 @@ namespace GreenshotPlugin.Core {
int blue = pointer[bIndex + offset];
if (a < 255) {
int aMult = factors[a];
int rem = remainings[a];
red = (red * rem + BackgroundBlendColor.R * aMult) >> 16;
green = (green * rem + BackgroundBlendColor.G * aMult) >> 16;
blue = (blue * rem + BackgroundBlendColor.B * aMult) >> 16;
int rem = 255 - a;
red = (red * a + BackgroundBlendColor.R * rem) / 255;
green = (green * a + BackgroundBlendColor.G * rem) / 255;
blue = (blue * a + BackgroundBlendColor.B * rem) / 255;
}
return Color.FromArgb(255, red, green, blue);
} else {