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126 lines
3.7 KiB
C++
126 lines
3.7 KiB
C++
/* Copyright (C) 2006 TightVNC Team. All Rights Reserved.
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*
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* This is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This software 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 General Public License
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* along with this software; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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* USA.
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*/
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#include <string.h>
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#include <assert.h>
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#include <math.h>
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#include <rfb/Rect.h>
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#include <rfb/ScaleFilters.h>
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using namespace rfb;
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//
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// -=- 1-D filters functions
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//
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// Nearest neighbor filter function
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double nearest_neighbor(double x) {
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if (x < -0.5) return 0.0;
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if (x < 0.5) return 1.0;
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return 0.0;
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}
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// Linear filter function
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double linear(double x) {
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if (x < -1.0) return 0.0;
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if (x < 0.0) return 1.0+x;
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if (x < 1.0) return 1.0-x;
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return 0.0;
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}
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// Cubic filter functions
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double cubic(double x) {
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double t;
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if (x < -2.0) return 0.0;
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if (x < -1.0) {t = 2.0+x; return t*t*t/6.0;}
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if (x < 0.0) return (4.0+x*x*(-6.0+x*-3.0))/6.0;
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if (x < 1.0) return (4.0+x*x*(-6.0+x*3.0))/6.0;
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if (x < 2.0) {t = 2.0-x; return t*t*t/6.0;}
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return 0.0;
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}
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//
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// -=- ScaleFilters class
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//
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SFilter &ScaleFilters::operator[](unsigned int filter_id) {
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assert(filter_id <= scaleFilterMaxNumber);
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return filters[filter_id];
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}
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int ScaleFilters::getFilterIdByName(char *filterName) {
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for (unsigned int i = 0; i <= scaleFilterMaxNumber; i++) {
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if (strcasecmp(filters[i].name, filterName) == 0) return i;
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}
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return -1;
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}
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void ScaleFilters::initFilters() {
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filters[scaleFilterNearestNeighbor] = create("Nearest neighbor", 0.5, nearest_neighbor);
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filters[scaleFilterBilinear] = create("Bilinear", 1, linear);
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filters[scaleFilterBicubic] = create("Bicubic", 2, cubic);
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}
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SFilter ScaleFilters::create(const char *name_, double radius_, filter_func func_) {
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SFilter filter;
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strncpy(filter.name, name_, sizeof(filter.name)-1);
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filter.name[sizeof(filter.name)-1] = '\0';
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filter.radius = radius_;
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filter.func = func_;
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return filter;
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}
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void ScaleFilters::makeWeightTabs(int filter_id, int src_x, int dst_x, SFilterWeightTab **pWeightTabs) {
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double sxc;
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double offset = 0.5;
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double ratio = (double)dst_x / src_x;
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double sourceScale = __rfbmax(1.0, 1.0/ratio);
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double sourceRadius = __rfbmax(0.5, sourceScale * filters[filter_id].radius);
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double sum, nc;
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int i, ci;
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SFilter sFilter = filters[filter_id];
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*pWeightTabs = new SFilterWeightTab[dst_x];
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SFilterWeightTab *weightTabs = *pWeightTabs;
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// Make the weight tab for the each dest x position
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for (int x = 0; x < dst_x; x++) {
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sxc = (double(x)+offset) / ratio;
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// Calculate the scale filter interval, [i0, i1)
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int i0 = int(__rfbmax(sxc-sourceRadius+0.5, 0));
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int i1 = int(__rfbmin(sxc+sourceRadius+0.5, src_x));
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weightTabs[x].i0 = i0; weightTabs[x].i1 = i1;
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weightTabs[x].weight = new short[i1-i0];
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// Calculate coeff to normalize the filter weights
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for (sum = 0, i = i0; i < i1; i++) sum += sFilter.func((double(i)-sxc+0.5)/sourceScale);
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if (sum == 0.) nc = (double)(WEIGHT_OF_ONE); else nc = (double)(WEIGHT_OF_ONE)/sum;
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// Calculate the weight coeffs on the scale filter interval
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for (ci = 0, i = i0; i < i1; i++) {
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weightTabs[x].weight[ci++] = (short)floor((sFilter.func((double(i)-sxc+0.5)/sourceScale) * nc) + 0.5);
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}
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}
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}
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