chiark / gitweb /
Faster, by cacheing last colour
authorIan Jackson <ian@liberator.relativity.greenend.org.uk>
Sun, 28 Jun 2009 17:17:28 +0000 (18:17 +0100)
committerIan Jackson <ian@liberator.relativity.greenend.org.uk>
Sun, 28 Jun 2009 17:17:28 +0000 (18:17 +0100)
pctb/structure.h

index 0ad92a6..ec399a2 100644 (file)
@@ -42,38 +42,45 @@ extern const CanonColourInfo canoncolourinfos[];
 
 CanonImage *alloc_canon_image(int w, int h);
 
-#define CANONICALISE_IMAGE(im,w,h, COMPUTE_RGB) do{            \
-    /* compute_rgb should be a number of statements, or                \
-     * a block, which assigns to                               \
-     *   unsigned long rgb;                                    \
-     * given the values of                                     \
-     *   int x,y;                                              \
-     * all of which are anamorphic.  Result is stored in im.   \
-     * The COMPUTE_RGB is executed exactly once for            \
-     * each pixel in reading order.                            \
-     */                                                                \
-    (im)= alloc_canon_image((w), (h));                         \
-                                                               \
-    int x,y;                                                   \
-    for (y=0; y<(h); y++) {                                    \
-      for (x=0; x<(w); x++) {                                  \
-        const CanonColourInfo *cci;                            \
-        unsigned long rgb;                                     \
-       COMPUTE_RGB;                                            \
-       for (cci=canoncolourinfos; cci->c; cci++) {             \
-         if (cci->rgb == rgb) {                                \
-           (im)->d[y*(w) + x]= cci->c;                         \
-           break;                                              \
-         }                                                     \
-       }                                                       \
-      }                                                                \
-      if (DEBUGP(rect)) {                                      \
-       fprintf(debug, "%4d ",y);                               \
-       fwrite(im->d + y*w, 1,w, debug);                        \
-       fputc('\n',debug);                                      \
-      }                                                                \
-    }                                                          \
-    debug_flush();                                             \
+#define CANONICALISE_IMAGE(im,w,h, COMPUTE_RGB) do{                    \
+    /* compute_rgb should be a number of statements, or                        \
+     * a block, which assigns to                                       \
+     *   unsigned long rgb;                                            \
+     * given the values of                                             \
+     *   int x,y;                                                      \
+     * all of which are anamorphic.  Result is stored in im.           \
+     * The COMPUTE_RGB is executed exactly once for                    \
+     * each pixel in reading order.                                    \
+     */                                                                        \
+    (im)= alloc_canon_image((w), (h));                                 \
+                                                                       \
+    int x,y;                                                           \
+    unsigned long last_rgb= ~0UL;                                      \
+    int last_c= -1;                                                    \
+    for (y=0; y<(h); y++) {                                            \
+      for (x=0; x<(w); x++) {                                          \
+        const CanonColourInfo *cci;                                    \
+        unsigned long rgb;                                             \
+       COMPUTE_RGB;                                                    \
+       if (rgb == last_rgb) {                                          \
+         (im)->d[y*(w) + x]= last_c;                                   \
+       } else {                                                        \
+         for (cci=canoncolourinfos; cci->c; cci++) {                   \
+           if (cci->rgb == rgb) {                                      \
+             last_rgb= rgb;                                            \
+             (im)->d[y*(w) + x]= last_c= cci->c;                       \
+             break;                                                    \
+           }                                                           \
+         }                                                             \
+       }                                                               \
+      }                                                                        \
+      if (DEBUGP(rect)) {                                              \
+       fprintf(debug, "%4d ",y);                                       \
+       fwrite(im->d + y*w, 1,w, debug);                                \
+       fputc('\n',debug);                                              \
+      }                                                                        \
+    }                                                                  \
+    debug_flush();                                                     \
   }while(0)