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common/rfb/ScaleFilters.h

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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.
+ */
+
+// -=- ScaleFilters.h
+//
+// Definitions of the 1-D filters and routines using for the image scaling.
+//  
+// 
+
+namespace rfb {
+
+  #define SCALE_ERROR (1e-7)
+  #define BITS_OF_CHANEL 8
+  #define BITS_OF_WEIGHT 14
+  #define FINALSHIFT (2 * BITS_OF_WEIGHT - BITS_OF_CHANEL)
+  #define WEIGHT_OF_ONE (1 << BITS_OF_WEIGHT)
+
+  typedef double (*filter_func)(double x);
+
+  const double pi = 3.14159265358979;
+
+  const unsigned int scaleFilterNearestNeighbor = 0;
+  const unsigned int scaleFilterBilinear = 1;
+  const unsigned int scaleFilterBicubic = 2;
+
+  const unsigned int scaleFilterMaxNumber = 2;
+  const unsigned int defaultScaleFilter = scaleFilterBilinear;
+
+  //
+  // -=- Scale filters structures and routines
+  //
+
+  // Scale filter stuct
+  typedef struct {
+    char name[30];     // Filter name
+    double radius;     // Radius where filter function is nonzero
+    filter_func func;  // Pointer to filter function
+  } SFilter;
+
+  // Scale filter weight table
+  typedef struct {
+    short i0, i1;  // Filter function interval, [i0..i1)
+    short *weight;    // Weight coefficients on the filter function interval
+  } SFilterWeightTab;
+
+
+  // ScaleFilters class helps us using a set of 1-d scale filters.
+  class ScaleFilters {
+  public:
+    ScaleFilters() { initFilters(); };
+
+    SFilter &operator[](unsigned int filter_id);
+
+    int getFilterIdByName(char *filterName);
+
+    void makeWeightTabs(int filter, int src_x, int dst_x, SFilterWeightTab **weightTabs);
+
+  protected:
+    void initFilters();
+
+    SFilter create(const char *name_, double radius_, filter_func func_);
+
+    SFilter filters[scaleFilterMaxNumber+1];
+  };
+
+};