Initial commit

common/rfb/ScaleFilters.cxx

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+/* Copyright (C) 2006 TightVNC Team.  All Rights Reserved.
+ *    
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+#include <string.h>
+#include <assert.h>
+#include <math.h>
+
+#include <rfb/Rect.h>
+#include <rfb/ScaleFilters.h>
+
+using namespace rfb;
+
+//
+// -=- 1-D filters functions
+//
+
+// Nearest neighbor filter function
+double nearest_neighbor(double x) {
+  if (x < -0.5) return 0.0;
+  if (x < 0.5) return 1.0;
+  return 0.0;
+}
+
+// Linear filter function
+double linear(double x) {
+  if (x < -1.0) return 0.0;
+  if (x < 0.0) return 1.0+x;
+  if (x < 1.0) return 1.0-x;
+  return 0.0;
+}
+
+// Cubic filter functions
+double cubic(double x) {
+  double t;
+  if (x < -2.0) return 0.0;
+  if (x < -1.0) {t = 2.0+x; return t*t*t/6.0;}
+  if (x < 0.0) return (4.0+x*x*(-6.0+x*-3.0))/6.0;
+  if (x < 1.0) return (4.0+x*x*(-6.0+x*3.0))/6.0;
+  if (x < 2.0) {t = 2.0-x; return t*t*t/6.0;}
+  return 0.0;
+}
+
+
+//
+// -=- ScaleFilters class
+//
+
+SFilter &ScaleFilters::operator[](unsigned int filter_id) {
+  assert(filter_id <= scaleFilterMaxNumber);
+  return filters[filter_id];
+}
+
+int ScaleFilters::getFilterIdByName(char *filterName) {
+  for (unsigned int i = 0; i <= scaleFilterMaxNumber; i++) {
+    if (strcasecmp(filters[i].name, filterName) == 0) return i;
+  }
+  return -1;
+}
+
+void ScaleFilters::initFilters() {
+  filters[scaleFilterNearestNeighbor] = create("Nearest neighbor", 0.5, nearest_neighbor);
+  filters[scaleFilterBilinear] = create("Bilinear", 1, linear);
+  filters[scaleFilterBicubic] = create("Bicubic", 2, cubic);
+}
+
+SFilter ScaleFilters::create(const char *name_, double radius_, filter_func func_) {
+  SFilter filter;
+  strncpy(filter.name, name_, sizeof(filter.name)-1); 
+  filter.name[sizeof(filter.name)-1] = '\0';
+  filter.radius = radius_;
+  filter.func = func_;
+  return filter;
+}
+
+void ScaleFilters::makeWeightTabs(int filter_id, int src_x, int dst_x, SFilterWeightTab **pWeightTabs) {
+  double sxc;
+  double offset = 0.5;
+  double ratio = (double)dst_x / src_x;
+  double sourceScale  = __rfbmax(1.0, 1.0/ratio);
+  double sourceRadius = __rfbmax(0.5, sourceScale * filters[filter_id].radius);
+  double sum, nc;
+  int i, ci;
+
+  SFilter sFilter = filters[filter_id];
+  
+  *pWeightTabs = new SFilterWeightTab[dst_x];
+  SFilterWeightTab *weightTabs = *pWeightTabs;
+
+  // Make the weight tab for the each dest x position
+  for (int x = 0; x < dst_x; x++) {
+    sxc = (double(x)+offset) / ratio;
+
+    // Calculate the scale filter interval, [i0, i1)
+    int i0 = int(__rfbmax(sxc-sourceRadius+0.5, 0));
+    int i1 = int(__rfbmin(sxc+sourceRadius+0.5, src_x));
+
+    weightTabs[x].i0 = i0; weightTabs[x].i1 = i1;
+    weightTabs[x].weight = new short[i1-i0];
+
+    // Calculate coeff to normalize the filter weights
+    for (sum = 0, i = i0; i < i1; i++) sum += sFilter.func((double(i)-sxc+0.5)/sourceScale);
+    if (sum == 0.) nc = (double)(WEIGHT_OF_ONE); else nc = (double)(WEIGHT_OF_ONE)/sum;
+
+
+    // Calculate the weight coeffs on the scale filter interval
+    for (ci = 0, i = i0; i < i1; i++) {
+      weightTabs[x].weight[ci++] = (short)floor((sFilter.func((double(i)-sxc+0.5)/sourceScale) * nc) + 0.5);
+    }
+  }
+}