avoid a possible sign-extension for offsets/sizes in SGI

[imager.git] / render.im

diff --git a/render.im b/render.im
index 4f9bbd3841f9cbbfef91571d1f2047bf57ad6db5..46211d0816c35815070b816e4e7adb029a35a3d4 100644 (file)
--- a/render.im
+++ b/render.im
@@ -485,6 +485,7 @@ IM_SUFFIX(render_color_13)(i_render *r, i_img_dim x, i_img_dim y,
   IM_COLOR *linep = r->IM_SUFFIX(line);
   int ch, channels = im->channels;
   i_img_dim fetch_offset;
+  int color_alpha = color->channel[im->channels];
 #undef STORE_COLOR
 #ifdef IM_EIGHT_BIT
 #define STORE_COLOR (*color)
@@ -498,17 +499,19 @@ IM_SUFFIX(render_color_13)(i_render *r, i_img_dim x, i_img_dim y,
 #endif
  
   fetch_offset = 0;
-  while (fetch_offset < width && *src == 0xFF) {
-    *linep++ = STORE_COLOR;
-    ++src;
-    ++fetch_offset;
+  if (color_alpha == 0xFF) {
+    while (fetch_offset < width && *src == 0xFF) {
+      *linep++ = STORE_COLOR;
+      ++src;
+      ++fetch_offset;
+    }
   }
   IM_GLIN(im, x+fetch_offset, x+width, y, linep);
   while (fetch_offset < width) {
 #ifdef IM_EIGHT_BIT
-    IM_WORK_T alpha = *src++;
+    IM_WORK_T alpha = *src++ * color_alpha / 255;
 #else
-    IM_WORK_T alpha = *src++ / 255.0;
+    IM_WORK_T alpha = *src++ * color_alpha / (255.0 * 255.0);
 #endif
     if (alpha == IM_SAMPLE_MAX)
       *linep = STORE_COLOR;
@@ -533,6 +536,7 @@ IM_SUFFIX(render_color_alpha)(i_render *r, i_img_dim x, i_img_dim y,
   int ch;
   int alpha_channel = r->im->channels - 1;
   i_img_dim fetch_offset;
+  int color_alpha = color->channel[alpha_channel];
 #undef STORE_COLOR
 #ifdef IM_EIGHT_BIT
 #define STORE_COLOR (*color)
@@ -546,17 +550,19 @@ IM_SUFFIX(render_color_alpha)(i_render *r, i_img_dim x, i_img_dim y,
 #endif
 
   fetch_offset = 0;
-  while (fetch_offset < width && *src == 0xFF) {
-    *linep++ = STORE_COLOR;
-    ++src;
-    ++fetch_offset;
+  if (color->channel[alpha_channel] == 0xFF) {
+    while (fetch_offset < width && *src == 0xFF) {
+      *linep++ = STORE_COLOR;
+      ++src;
+      ++fetch_offset;
+    }
   }
   IM_GLIN(r->im, x+fetch_offset, x+width, y, linep);
   while (fetch_offset < width) {
 #ifdef IM_EIGHT_BIT
-    IM_WORK_T src_alpha = *src++;
+    IM_WORK_T src_alpha = *src++ * color_alpha / 255;
 #else
-    IM_WORK_T src_alpha = *src++ / 255.0;
+    IM_WORK_T src_alpha = *src++ * color_alpha / (255.0 * 255.0);
 #endif
     if (src_alpha == IM_SAMPLE_MAX)
       *linep = STORE_COLOR;
@@ -742,7 +748,7 @@ static const IM_FILL_COMBINE_F IM_SUFFIX(combines)[] =
 
 void i_get_combine(int combine, i_fill_combine_f *color_func, 
                    i_fill_combinef_f *fcolor_func) {
-  if (combine < 0 || combine > sizeof(combines_8) / sizeof(*combines_8))
+  if (combine < 0 || combine >= sizeof(combines_8) / sizeof(*combines_8))
     combine = 0;
 
   *color_func = combines_8[combine];