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73 lines
1.8 KiB
C++
73 lines
1.8 KiB
C++
#include "Draw.h"
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namespace Upp {
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double BicubicKernel(double x)
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{
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double r = 0;
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double xp2 = x + 2;
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double xp1 = x + 1;
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double xm1 = x - 1;
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if(xp2 > 0)
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r += xp2 * xp2 * xp2;
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if(xp1 > 0)
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r -= 4 * xp1 * xp1 * xp1;
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if(x > 0)
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r += 6 * x * x * x;
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if(xm1 > 0)
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r -= 4 * xm1 * xm1 * xm1;
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return 0.16666666666666666 * r;
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}
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Image RescaleBicubic(const Image& img, Size sz, const Rect& sr, Gate<int, int> progress)
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{
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ASSERT(sr.top >= 0 && sr.left >= 0 && sr.right <= img.GetWidth() && sr.bottom <= img.GetHeight());
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Size isz = sr.GetSize();
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ImageBuffer ib(sz);
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RGBA *t = ~ib;
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double inv_cx = 1.0 / sz.cx;
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for(int y = 0; y < sz.cy; y++) {
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if(progress(y, sz.cy))
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return ib;
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int sy = y * isz.cy / sz.cy;
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double dy = y * isz.cy / (double)sz.cy - sy;
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for(int x = 0; x < sz.cx; x++) {
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int sx = x * isz.cx / sz.cx;
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double dx = x * isz.cx * inv_cx - sx;
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double red = 0;
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double green = 0;
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double blue = 0;
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double alpha = 0;
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for(int yy = -1; yy <= 2; yy++) {
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double ky = BicubicKernel(yy - dy);
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const RGBA *l = img[minmax(sy + yy + sr.top, sr.top, sr.bottom - 1)];
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for(int xx = -1; xx <= 2; xx++) {
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const RGBA& s = l[minmax(sx + xx + sr.left, sr.left, sr.right - 1)];
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double weight = ky * BicubicKernel(xx - dx);
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red += weight * s.r;
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green += weight * s.g;
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blue += weight * s.b;
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alpha += weight * s.a;
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}
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}
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t->r = (int)fround(red);
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t->g = (int)fround(green);
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t->b = (int)fround(blue);
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t->a = (int)fround(alpha);
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t++;
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}
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}
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return ib;
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}
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Image RescaleBicubic(const Image& img, int cx, int cy, Gate<int, int> progress)
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{
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return RescaleBicubic(img, Size(cx, cy), img.GetSize(), progress);
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}
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Image RescaleBicubic(const Image& img, Size sz, Gate<int, int> progress)
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{
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return RescaleBicubic(img, sz, img.GetSize(), progress);
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}
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}
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