premultiply alpha

[swftools.git] / src / png2swf.c

diff --git a/src/png2swf.c b/src/png2swf.c
index abb654f..0d7e1a6 100644 (file)
--- a/src/png2swf.c
+++ b/src/png2swf.c
@@ -478,6 +478,8 @@ TAG *MovieAddFrame(SWF * swf, TAG * t, char *sname, int id)
     int alphapalettelen = 0;
     struct png_header header;
     int bypp;
+    U8 alphacolor[3];
+    int hasalphacolor=0;
 
     FILE *fi;
     U8 *scanline;
@@ -511,7 +513,7 @@ TAG *MovieAddFrame(SWF * swf, TAG * t, char *sname, int id)
        }
        if(!strncmp(tagid, "PLTE", 4)) {
            palette = data;
-           palettelen = len/3;
+           palettelen = len/bypp;
            data = 0; //don't free data
            if(VERBOSE(2))
                printf("%d colors in palette\n", palettelen);
@@ -523,6 +525,21 @@ TAG *MovieAddFrame(SWF * swf, TAG * t, char *sname, int id)
                data = 0; //don't free data
                if(VERBOSE(2))
                    printf("found %d alpha colors\n", alphapalettelen);
+           } else if(header.mode == 0) {
+               int t;
+               if(header.mode == 3) { // palette or grayscale?
+                   alphacolor[0] = data[1];
+                   alphacolor[1] = data[3];
+                   alphacolor[2] = data[5];
+               } else {
+                   alphacolor[0] = alphacolor[1] = alphacolor[2] = data[1];
+               }
+               if(VERBOSE(2))
+                   printf("found alpha color: %02x%02x%02x\n", alphacolor[0], alphacolor[1], alphacolor[2]);
+               hasalphacolor = 1;
+           } else {
+               if(VERBOSE(2))
+                   printf("ignoring tRNS %d entry (%d bytes)\n", header.mode, len);
            }
        }
        if(!strncmp(tagid, "IDAT", 4)) {
@@ -548,7 +565,7 @@ TAG *MovieAddFrame(SWF * swf, TAG * t, char *sname, int id)
     }
     free(zimagedata);
 
-    if(alphapalette)
+    if(alphapalette || hasalphacolor)
        t = swf_InsertTag(t, ST_DEFINEBITSLOSSLESS2);
     else
        t = swf_InsertTag(t, ST_DEFINEBITSLOSSLESS);
@@ -647,6 +664,16 @@ TAG *MovieAddFrame(SWF * swf, TAG * t, char *sname, int id)
                } else {
                    rgba[i].a = 255;
                }
+               if(hasalphacolor) {
+                   if(rgba[i].r == alphacolor[0] &&
+                      rgba[i].g == alphacolor[1] &&
+                      rgba[i].b == alphacolor[2]) {
+                       rgba[i].r = 0;
+                       rgba[i].g = 0;
+                       rgba[i].b = 0;
+                       rgba[i].a = 0;
+                   }
+               }
            }
        } else {
             int mult = (0x1ff>>header.bpp);
@@ -656,6 +683,15 @@ TAG *MovieAddFrame(SWF * swf, TAG * t, char *sname, int id)
                rgba[i].r = i*mult;
                rgba[i].g = i*mult;
                rgba[i].b = i*mult;
+               rgba[i].a = 255;
+               if(hasalphacolor) {
+                   if(rgba[i].r == alphacolor[0]) {
+                       rgba[i].r = 0;
+                       rgba[i].g = 0;
+                       rgba[i].b = 0;
+                       rgba[i].a = 0;
+                   }
+               }
            }
        }