Simplify building of color names in image.c

* src/image.c (make_color_name): New function.
(image_background, image_build_heuristic_mask, png_load_body): Use it.

1 files changed, 18 insertions, 23 deletions

diff --git a/src/image.c b/src/image.c
index 4350c415d9c..901063c9bde 100644
--- a/src/image.c
+++ b/src/image.c
@@ -1971,6 +1971,12 @@ four_corners_best (Emacs_Pix_Context pimg, int *corners,
   return best;
 }
 
+static Lisp_Object
+make_color_name (unsigned int red, unsigned int green, unsigned int blue)
+{
+  return make_formatted_string ("#%04x%04x%04x", red, green, blue);
+}
+
 /* Return the `background' field of IMG.  If IMG doesn't have one yet,
    it is guessed heuristically.  If non-zero, XIMG is an existing
    Emacs_Pix_Context object (device context with the image selected on
@@ -1993,14 +1999,10 @@ image_background (struct image *img, struct frame *f, Emacs_Pix_Context pimg)
       RGB_PIXEL_COLOR bg
         = four_corners_best (pimg, img->corners, img->width, img->height);
 #ifdef USE_CAIRO
-      {
-        char color_name[30];
-        snprintf (color_name, sizeof color_name, "#%04x%04x%04x",
-                  (unsigned int) RED16_FROM_ULONG (bg),
-                  (unsigned int) GREEN16_FROM_ULONG (bg),
-                  (unsigned int) BLUE16_FROM_ULONG (bg));
-        bg = image_alloc_image_color (f, img, build_string (color_name), 0);
-      }
+      Lisp_Object color_name = make_color_name (RED16_FROM_ULONG (bg),
+                                                GREEN16_FROM_ULONG (bg),
+                                                BLUE16_FROM_ULONG (bg));
+      bg = image_alloc_image_color (f, img, color_name, 0);
 #endif
       img->background = bg;
 
@@ -7383,15 +7385,11 @@ image_build_heuristic_mask (struct frame *f, struct image *img,
       if (i == 3 && NILP (how))
         {
 #ifndef USE_CAIRO
-          char color_name[30];
-          int len = snprintf (color_name, sizeof color_name, "#%04x%04x%04x",
-                              rgb[0] + 0u, rgb[1] + 0u, rgb[2] + 0u);
-          eassert (len < sizeof color_name);
-          bg = (
-#ifdef HAVE_NTGUI
-                0x00ffffff & /* Filter out palette info.  */
-#endif /* HAVE_NTGUI */
-                image_alloc_image_color (f, img, build_string (color_name), 0));
+          Lisp_Object color_name = make_color_name (rgb[0], rgb[1], rgb[2]);
+          bg = image_alloc_image_color (f, img, color_name, 0);
+# ifdef HAVE_NTGUI
+          bg &= 0x00ffffff; /* Filter out palette info.  */
+# endif
 #else  /* USE_CAIRO */
           bg = lookup_rgb_color (f, rgb[0], rgb[1], rgb[2]);
 #endif  /* USE_CAIRO */
@@ -8535,12 +8533,9 @@ png_load_body (struct frame *f, struct image *img, struct png_load_context *c)
 #ifndef USE_CAIRO
           img->background = lookup_rgb_color (f, bg->red, bg->green, bg->blue);
 #else  /* USE_CAIRO */
-          char color_name[30];
-          int len = snprintf (color_name, sizeof color_name, "#%04x%04x%04x",
-                              bg->red, bg->green, bg->blue);
-          eassert (len < sizeof color_name);
-          img->background
-            = image_alloc_image_color (f, img, build_string (color_name), 0);
+          Lisp_Object color_name
+            = make_color_name (bg->red, bg->green, bg->blue);
+          img->background = image_alloc_image_color (f, img, color_name, 0);
 #endif /* USE_CAIRO */
           img->background_valid = 1;
         }