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Only use stairstepping for resampling when absolutely necessary (when the downscaling factor is a power of 2). Somewhat fixes #176

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Simon Robertshaw 2012-09-05 18:27:16 +01:00
parent d61690bc09
commit 98725dea26
1 changed files with 25 additions and 1 deletions
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26
src/graphics/Graphics.cpp
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@ -334,6 +334,30 @@ pixel *Graphics::resample_img(pixel *src, int sw, int sh, int rw, int rh)
#ifdef DEBUG
std::cout << "Resampling " << sw << "x" << sh << " to " << rw << "x" << rh << std::endl;
#endif
bool stairstep = false;
if(rw < sw || rh < sh)
{
float fx = (float)(((float)sw)/((float)rw));
float fy = (float)(((float)sh)/((float)rh));
int fxint, fyint;
double fxintp_t, fyintp_t;
float fxf = modf(fx, &fxintp_t), fyf = modf(fy, &fyintp_t);
fxint = fxintp_t;
fyint = fyintp_t;
if(((fxint & (fxint-1)) == 0 && fxf < 0.1f) || ((fyint & (fyint-1)) == 0 && fyf < 0.1f))
stairstep = true;
#ifdef DEBUG
if(stairstep)
std::cout << "Downsampling by " << fx << "x" << fy << " using stairstepping" << std::endl;
else
std::cout << "Downsampling by " << fx << "x" << fy << " without stairstepping" << std::endl;
#endif
}
int y, x, fxceil, fyceil;
//int i,j,x,y,w,h,r,g,b,c;
pixel *q = NULL;
@ -341,7 +365,7 @@ pixel *Graphics::resample_img(pixel *src, int sw, int sh, int rw, int rh)
//Don't resample
q = (pixel *)malloc(rw*rh*PIXELSIZE);
memcpy(q, src, rw*rh*PIXELSIZE);
} else if(rw >= sw && rh >= sh){
} else if(!stairstep) {
float fx, fy, fyc, fxc;
double intp;
pixel tr, tl, br, bl;