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Added an option in Image::Copy to take into account the source transparency

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git-svn-id: https://sfml.svn.sourceforge.net/svnroot/sfml/trunk@1012 4e206d99-4929-0410-ac5d-dfc041789085
This commit is contained in:
laurentgom 2009-02-10 18:27:42 +00:00
parent 6c98d270b9
commit 73c041cbcf
1 changed files with 31 additions and 5 deletions
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36
src/SFML/Graphics/Image.cpp
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@ -267,7 +267,7 @@ void Image::CreateMaskFromColor(Color ColorKey, Uint8 Alpha)
/// This function does a slow pixel copy and should only
/// be used at initialization time
////////////////////////////////////////////////////////////
void Image::Copy(const Image& Source, unsigned int DestX, unsigned int DestY, const IntRect& SourceRect)
void Image::Copy(const Image& Source, unsigned int DestX, unsigned int DestY, const IntRect& SourceRect, bool ApplyAlpha)
{
// Make sure both images are valid
if ((Source.myWidth == 0) || (Source.myHeight == 0) || (myWidth == 0) || (myHeight == 0))
@ -313,11 +313,37 @@ void Image::Copy(const Image& Source, unsigned int DestX, unsigned int DestY, co
Uint8* DstPixels = reinterpret_cast<Uint8*>(&myPixels[0]) + (DestX + DestY * myWidth) * 4;
// Copy the pixels
for (int i = 0; i < Rows; ++i)
if (ApplyAlpha)
{
memcpy(DstPixels, SrcPixels, Pitch);
SrcPixels += SrcStride;
DstPixels += DstStride;
// Interpolation using alpha values, pixel by pixel (slower)
for (int i = 0; i < Rows; ++i)
{
for (int j = 0; j < Width; ++j)
{
// Get a direct pointer to the components of the current pixel
const Uint8* Src = SrcPixels + j * 4;
Uint8* Dst = DstPixels + j * 4;
// Interpolate RGB components using the alpha value of the source pixel
Uint8 Alpha = Src[3];
Dst[0] = (Src[0] * Alpha + Dst[0] * (255 - Alpha)) / 255;
Dst[1] = (Src[1] * Alpha + Dst[1] * (255 - Alpha)) / 255;
Dst[2] = (Src[2] * Alpha + Dst[2] * (255 - Alpha)) / 255;
}
SrcPixels += SrcStride;
DstPixels += DstStride;
}
}
else
{
// Optimized copy ignoring alpha values, row by row (faster)
for (int i = 0; i < Rows; ++i)
{
memcpy(DstPixels, SrcPixels, Pitch);
SrcPixels += SrcStride;
DstPixels += DstStride;
}
}
// The texture will need an update