fixed bug with y-direction predictors in the first scanline

diff --git a/lib/png.c b/lib/png.c
index fac4f77..739b895 100644 (file)
--- a/lib/png.c
+++ b/lib/png.c
@@ -619,6 +619,9 @@ EXPORT int getPNG(const char*sname, int*destwidth, int*destheight, unsigned char
        int x,y;
        int pos=0;
        *destdata = data2;
+       
+       unsigned char* firstline = malloc(header.width*4);
+       memset(firstline,0,header.width*4);
        for(y=0;y<header.height;y++) {
            int mode = imagedata[pos++]; //filter mode
            unsigned char*src;
@@ -639,8 +642,7 @@ EXPORT int getPNG(const char*sname, int*destwidth, int*destheight, unsigned char
            }
 
            if(!y) {
-               memset(data2,0,header.width*4);
-               old = &data2[y*header.width*4];
+               old = firstline;
            } else {
                old = &data2[(y-1)*header.width*4];
            }
@@ -661,6 +663,7 @@ EXPORT int getPNG(const char*sname, int*destwidth, int*destheight, unsigned char
                }
            }
        }
+       free(firstline);
         free(imagedata);
     } else if(header.mode == 0 || header.mode == 3) {
        COL*rgba = 0;