* stock.c: generate images with random noise.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2697 92316355-f0b4-4df1-b90c-862c8a59935f

pipi/stock.c

@@ -65,6 +65,41 @@ pipi_image_t *pipi_load_stock(char const *name)
         return ret;
     }
 
+    /* Generate a completely random image. */
+    if(!strncmp(name, "random", 6))
+    {
+        unsigned int ctx = 1;
+        int x, y, w, h;
+
+        w = atoi(name + 6);
+        name = strchr(name + 6, 'x');
+        if(!name)
+            return NULL;
+        h = atoi(name + 1);
+        if(w <= 0 || h <= 0)
+            return NULL;
+
+        ret = pipi_new(w, h);
+        pix = pipi_getpixels(ret, PIPI_PIXELS_Y_F);
+        data = (float *)pix->pixels;
+
+        for(y = 0; y < h; y++)
+            for(x = 0; x < w; x++)
+            {
+                long hi, lo;
+
+                hi = ctx / 12773L;
+                lo = ctx % 12773L;
+                ctx = 16807L * lo - 2836L * hi;
+                if(ctx <= 0)
+                    ctx += 0x7fffffffL;
+
+                data[y * w + x] = (double)((ctx % 65536) / 65535.);
+            }
+
+        return ret;
+    }
+
     return NULL;
 }