lib/ext/expblur.cpp

   1 #include <QImage>
   2 #include <cmath>
   3 #include <QPainter>
   4
   5 #include "extensions.h"
   6
   7 /*
   8 struct ruby_object {
   9     bool allocated;
  10     Smoke* smoke;
  11     int classId;
  12     void* ptr;
  13 };*/
  14
  15 template<int aprec, int zprec>
  16 static inline void blurinner(unsigned char *bptr, int &zR,
  17                              int &zG, int &zB, int &zA, int alpha);
  18
  19 template<int aprec,int zprec>
  20 static inline void blurrow(QImage & im, int line, int alpha);
  21
  22 template<int aprec, int zprec>
  23 static inline void blurcol(QImage & im, int col, int alpha);
  24
  25 /*
  26  *  expblur(QImage &img, int radius)
  27  *
  28  *  In-place blur of image 'img' with kernel
  29  *  of approximate radius 'radius'.
  30  *
  31  *  Blurs with two sided exponential impulse
  32  *  response.
  33  *
  34  *  aprec = precision of alpha parameter
  35  *  in fixed-point format 0.aprec
  36  *
  37  *  zprec = precision of state parameters
  38  *  zR,zG,zB and zA in fp format 8.zprec
  39  */
  40 template<int aprec,int zprec>
  41 static void expblur(QImage &img, int radius )
  42 {
  43     if (radius < 1)
  44         return;
  45
  46     /* Calculate the alpha such that 90% of
  47        the kernel is within the radius.
  48        (Kernel extends to infinity)
  49     */
  50     int alpha = (int)((1<<aprec)*(1.0f-expf(-2.3f/(radius+1.f))));
  51
  52     for(int row=0;row<img.height();row++) {
  53         blurrow<aprec,zprec>(img,row,alpha);
  54     }
  55
  56     for(int col=0;col<img.width();col++) {
  57         blurcol<aprec,zprec>(img,col,alpha);
  58     }
  59     return;
  60 }
  61
  62 template<int aprec, int zprec>
  63 static inline void blurinner(unsigned char *bptr,
  64                              int &zR, int &zG, int &zB, int &zA, int alpha)
  65 {
  66     int R,G,B,A;
  67     R = *bptr;
  68     G = *(bptr+1);
  69     B = *(bptr+2);
  70     A = *(bptr+3);
  71
  72     zR += (alpha * ((R<<zprec)-zR))>>aprec;
  73     zG += (alpha * ((G<<zprec)-zG))>>aprec;
  74     zB += (alpha * ((B<<zprec)-zB))>>aprec;
  75     zA += (alpha * ((A<<zprec)-zA))>>aprec;
  76
  77     *bptr =     zR>>zprec;
  78     *(bptr+1) = zG>>zprec;
  79     *(bptr+2) = zB>>zprec;
  80     *(bptr+3) = zA>>zprec;
  81 }
  82
  83 template<int aprec,int zprec>
  84 static inline void blurrow( QImage & im, int line, int alpha)
  85 {
  86     int zR,zG,zB,zA;
  87
  88     QRgb *ptr = (QRgb *)im.scanLine(line);
  89
  90     zR = *((unsigned char *)ptr    )<<zprec;
  91     zG = *((unsigned char *)ptr + 1)<<zprec;
  92     zB = *((unsigned char *)ptr + 2)<<zprec;
  93     zA = *((unsigned char *)ptr + 3)<<zprec;
  94
  95     for(int index=1; index<im.width(); index++) {
  96         blurinner<aprec,zprec>((unsigned char *)&ptr[index],
  97                                zR, zG, zB, zA, alpha);
  98     }
  99     for(int index=im.width()-2; index>=0; index--) {
 100         blurinner<aprec,zprec>((unsigned char *)&ptr[index],
 101                                zR, zG, zB, zA, alpha);
 102     }
 103
 104
 105 }
 106
 107 template<int aprec, int zprec>
 108 static inline void blurcol(QImage & im, int col, int alpha)
 109 {
 110     int zR,zG,zB,zA;
 111
 112     QRgb *ptr = (QRgb *)im.bits();
 113     ptr+=col;
 114
 115     zR = *((unsigned char *)ptr    )<<zprec;
 116     zG = *((unsigned char *)ptr + 1)<<zprec;
 117     zB = *((unsigned char *)ptr + 2)<<zprec;
 118     zA = *((unsigned char *)ptr + 3)<<zprec;
 119
 120     for(int index=im.width(); index<(im.height()-1)*im.width();
 121         index+=im.width()) {
 122         blurinner<aprec,zprec>((unsigned char *)&ptr[index],
 123                                zR, zG, zB, zA, alpha);
 124     }
 125
 126     for(int index=(im.height()-2)*im.width(); index>=0;
 127         index-=im.width()) {
 128         blurinner<aprec,zprec>((unsigned char *)&ptr[index],
 129                                zR, zG, zB, zA, alpha);
 130     }
 131
 132 }
 133
 134 void Extensions::exp_blur(QImage* img, int radius) const {
 135   return expblur<15,7>(*img, radius);
 136 }
 137
 138
 139 /*
 140 static ruby_object* get_object(VALUE val) {
 141   if (TYPE(val) != T_DATA) {
 142     return 0;
 143   }
 144
 145   ruby_object* o = 0;
 146   Data_Get_Struct(val, ruby_object, o);
 147   return o;
 148 }
 149
 150 extern "C" VALUE test_expblur(VALUE self, VALUE val, VALUE radius) {
 151   ruby_object* o = get_object(val);
 152   if (o) {
 153     QImage* img = (QImage*)o->smoke->cast(o->ptr, o->classId, o->smoke->idClass("QImage"));
 154     expblur<15,7>(*img, NUM2INT(radius));
 155   }
 156
 157   return Qnil;
 158 }
 159
 160 extern "C" void Init_expblur() {
 161   rb_define_method(Qnil, "expblur", (VALUE (*)(...))test_expblur, 2);
 162 }*/