use bilinear interpolation for the rotozoom

Originally committed as revision 1759 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/rotozoom.c b/tests/rotozoom.c
index 71d369f9e5..f7c3b0c956 100644
--- a/tests/rotozoom.c
+++ b/tests/rotozoom.c
@@ -163,6 +163,21 @@ int teta = 0;
 int h_cos [360];
 int h_sin [360];
 
+static int ipol(uint8_t *src, int x, int y){
+    int int_x= x>>16;
+    int int_y= y>>16;
+    int frac_x= x&0xFFFF;
+    int frac_y= y&0xFFFF;
+    int s00= src[ ( int_x   &255) + 256*( int_y   &255) ];
+    int s01= src[ ((int_x+1)&255) + 256*( int_y   &255) ];
+    int s10= src[ ( int_x   &255) + 256*((int_y+1)&255) ];
+    int s11= src[ ((int_x+1)&255) + 256*((int_y+1)&255) ];
+    int s0= (((1<<16) - frac_x)*s00 + frac_x*s01)>>8;
+    int s1= (((1<<16) - frac_x)*s10 + frac_x*s11)>>8;
+    
+    return (((1<<16) - frac_y)*s0 + frac_y*s1)>>24;
+}
+
 void gen_image(int num, int w, int h)
 {
   const int c = h_cos [teta];
@@ -193,8 +208,12 @@ void gen_image(int num, int w, int h)
     for ( i=0 ; i<w ; i++ ) {
       x += c;
       y -= s;
+#if 1
+      put_pixel(i, j, ipol(tab_r, x, y), ipol(tab_g, x, y), ipol(tab_b, x, y));
+#else
       dep = ((x>>16)&255) + (((y>>16)&255)<<8);
       put_pixel(i, j, tab_r[dep], tab_g[dep], tab_b[dep]);
+#endif
     }
   }
   teta = (teta+1) % 360;