148 lines
4.0 KiB
C++
148 lines
4.0 KiB
C++
#ifndef BLUR_CPP
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#define BLUR_CPP
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/*
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* Copyright 2007 Jani Huhtanen <jani.huhtanen@tut.fi>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Library General Public License version 2 as
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* published by the Free Software Foundation
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include <cmath>
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// Exponential blur, Jani Huhtanen, 2006
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//
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template<int aprec, int zprec>
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static inline void blurinner(unsigned char *bptr, int &zR, int &zG, int &zB, int &zA, int alpha);
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template<int aprec,int zprec>
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static inline void blurrow(QImage &im, int line, int alpha);
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template<int aprec, int zprec>
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static inline void blurcol(QImage &im, int col, int alpha);
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/*
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* expblur(QImage &img, int radius)
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*
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* In-place blur of image 'img' with kernel
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* of approximate radius 'radius'.
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*
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* Blurs with two sided exponential impulse
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* response.
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*
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* aprec = precision of alpha parameter
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* in fixed-point format 0.aprec
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*
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* zprec = precision of state parameters
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* zR,zG,zB and zA in fp format 8.zprec
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*/
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template<int aprec,int zprec>
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void expblur(QImage &img, int radius)
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{
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if(radius < 1) {
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return;
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}
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/* Calculate the alpha such that 90% of
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the kernel is within the radius.
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(Kernel extends to infinity)
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*/
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int alpha = (int)((1 << aprec) * (1.0f - std::exp(-2.3f / (radius + 1.f))));
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for (int row=0; row<img.height(); row++) {
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blurrow<aprec,zprec>(img, row, alpha);
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}
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for (int col=0; col<img.width(); col++) {
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blurcol<aprec,zprec>(img, col, alpha);
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}
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return;
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}
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template<int aprec, int zprec>
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static inline void blurinner(unsigned char *bptr, int &zR, int &zG, int &zB, int &zA, int alpha)
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{
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int R, G, B, A;
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R = *bptr;
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G = *(bptr + 1);
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B = *(bptr + 2);
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A = *(bptr + 3);
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zR += (alpha * ((R << zprec) - zR)) >> aprec;
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zG += (alpha * ((G << zprec) - zG)) >> aprec;
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zB += (alpha * ((B << zprec) - zB)) >> aprec;
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zA += (alpha * ((A << zprec) - zA)) >> aprec;
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*bptr = zR >> zprec;
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*(bptr+1) = zG >> zprec;
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*(bptr+2) = zB >> zprec;
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*(bptr+3) = zA >> zprec;
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}
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template<int aprec,int zprec>
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static inline void blurrow(QImage &im, int line, int alpha)
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{
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int zR, zG, zB, zA;
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QRgb *ptr = (QRgb *)im.scanLine(line);
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zR = *((unsigned char *)ptr ) << zprec;
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zG = *((unsigned char *)ptr + 1) << zprec;
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zB = *((unsigned char *)ptr + 2) << zprec;
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zA = *((unsigned char *)ptr + 3) << zprec;
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for (int index=1; index<im.width(); index++) {
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blurinner<aprec,zprec>((unsigned char *)&ptr[index],zR,zG,zB,zA,alpha);
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}
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for (int index=im.width()-2; index>=0; index--) {
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blurinner<aprec,zprec>((unsigned char *)&ptr[index],zR,zG,zB,zA,alpha);
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}
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}
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template<int aprec, int zprec>
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static inline void blurcol(QImage &im, int col, int alpha)
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{
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int zR, zG, zB, zA;
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QRgb *ptr = (QRgb *)im.bits();
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ptr += col;
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zR = *((unsigned char *)ptr ) << zprec;
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zG = *((unsigned char *)ptr + 1) << zprec;
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zB = *((unsigned char *)ptr + 2) << zprec;
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zA = *((unsigned char *)ptr + 3) << zprec;
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for (int index=im.width(); index<(im.height()-1)*im.width(); index+=im.width()) {
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blurinner<aprec,zprec>((unsigned char *)&ptr[index], zR, zG, zB, zA, alpha);
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}
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for (int index=(im.height()-2)*im.width(); index>=0; index-=im.width()) {
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blurinner<aprec,zprec>((unsigned char *)&ptr[index], zR, zG, zB, zA, alpha);
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}
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}
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template<class T>
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inline const T &qClamp(const T &x, const T &low, const T &high)
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{
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if (x < low) {
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return low;
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} else if (x > high) {
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return high;
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} else {
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return x;
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}
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}
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#endif
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