Fix pixel calculation for TrueVisuals.

src/ChangeLog

@@ -1,3 +1,13 @@
+2003-08-30  Jan Dj,Ad(Brv  <jan.h.d@swipnet.se>
+
+	* xterm.c (x_term_init): Initialize new fields in x_display_info.
+
+	* xterm.h (struct x_display_info): Add red/green/blue_bits and
+	*_offset.
+
+	* xfns.c (lookup_rgb_color): Use new fields in x_display_info to
+	calculate pixel value.
+
 2003-08-29  Gerd Moellmann  <gerd.moellmann@t-online.de>
 
 	* xdisp.c (redisplay_internal): Fix change of 2003-04-30.  Don't

src/xfns.c

@@ -6755,16 +6755,15 @@ lookup_rgb_color (f, r, g, b)
   unsigned hash = CT_HASH_RGB (r, g, b);
   int i = hash % CT_SIZE;
   struct ct_color *p;
-  Visual *visual;
+  struct x_display_info *dpyinfo;
 
   /* Handle TrueColor visuals specially, which improves performance by
      two orders of magnitude.  Freeing colors on TrueColor visuals is
      a nop, and pixel colors specify RGB values directly.  See also
      the Xlib spec, chapter 3.1.  */
-  visual = FRAME_X_DISPLAY_INFO (f)->visual;
-  if (visual->class == TrueColor)
+  dpyinfo = FRAME_X_DISPLAY_INFO (f);
+  if (dpyinfo->red_bits > 0)
     {
-      int bits = visual->bits_per_rgb;
       unsigned long pr, pg, pb;
 
       /* Apply gamma-correction like normal color allocation does.  */
@@ -6779,14 +6778,9 @@ lookup_rgb_color (f, r, g, b)
       /* Scale down RGB values to the visual's bits per RGB, and shift
 	 them to the right position in the pixel color.  Note that the
 	 original RGB values are 16-bit values, as usual in X.  */
-      pr = (r >> (16 - bits)) << 2 * bits;
-      pg = (g >> (16 - bits)) << 1 * bits;
-      pb = (b >> (16 - bits)) << 0 * bits;
-
-      /* Apply RGB masks of the visual.  */
-      pr &= visual->red_mask;
-      pg &= visual->green_mask;
-      pb &= visual->blue_mask;
+      pr = (r >> (16 - dpyinfo->red_bits))   << dpyinfo->red_offset;
+      pg = (g >> (16 - dpyinfo->green_bits)) << dpyinfo->green_offset;
+      pb = (b >> (16 - dpyinfo->blue_bits))  << dpyinfo->blue_offset;
 
       /* Assemble the pixel color.  */
       return pr | pg | pb;

src/xterm.c

@@ -10120,6 +10120,34 @@ same_x_server (name1, name2)
 }
 #endif
 
+/* Count number of set bits in mask and number of bits to shift to
+   get to the first bit.  With MASK 0x7e0, *BITS is set to 6, and *OFFSET
+   to 5.  */
+static void
+get_bits_and_offset (mask, bits, offset)
+     unsigned long mask;
+     int *bits;
+     int *offset;
+{
+  int nr = 0;
+  int off = 0;
+
+  while (!(mask & 1))
+    {
+      off++;
+      mask >>= 1;
+    }
+
+  while (mask & 1)
+    {
+      nr++;
+      mask >>= 1;
+    }
+
+  *offset = off;
+  *bits = nr;
+}
+
 struct x_display_info *
 x_term_init (display_name, xrm_option, resource_name)
      Lisp_Object display_name;
@@ -10367,6 +10395,20 @@ x_term_init (display_name, xrm_option, resource_name)
   dpyinfo->x_highlight_frame = 0;
   dpyinfo->image_cache = make_image_cache ();
 
+  /* See if we can construct pixel values from RGB values.  */
+  dpyinfo->red_bits = dpyinfo->blue_bits = dpyinfo->green_bits = 0;
+  dpyinfo->red_offset = dpyinfo->blue_offset = dpyinfo->green_offset = 0;
+
+  if (dpyinfo->visual->class == TrueColor)
+    {
+      get_bits_and_offset (dpyinfo->visual->red_mask,
+                           &dpyinfo->red_bits, &dpyinfo->red_offset);
+      get_bits_and_offset (dpyinfo->visual->blue_mask,
+                           &dpyinfo->blue_bits, &dpyinfo->blue_offset);
+      get_bits_and_offset (dpyinfo->visual->green_mask,
+                           &dpyinfo->green_bits, &dpyinfo->green_offset);
+    }
+      
   /* See if a private colormap is requested.  */
   if (dpyinfo->visual == DefaultVisualOfScreen (dpyinfo->screen))
     {

src/xterm.h

@@ -360,6 +360,11 @@ struct x_display_info
      use this directly, call x_color_cells instead.  */
   XColor *color_cells;
   int ncolor_cells;
+
+  /* Bits and shifts to use to compose pixel values on Direct and TrueColor
+     visuals.  */
+  int red_bits, blue_bits, green_bits;
+  int red_offset, blue_offset, green_offset;
 };
 
 #ifdef HAVE_X_I18N