diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/fl_color.cxx | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/src/fl_color.cxx b/src/fl_color.cxx index d1a9dfa63..d2dcefb1c 100644 --- a/src/fl_color.cxx +++ b/src/fl_color.cxx @@ -362,20 +362,26 @@ Fl_Color fl_inactive(Fl_Color c) { } Fl_Color fl_contrast(Fl_Color fg, Fl_Color bg) { - unsigned c1, c2; + unsigned c1, c2; // RGB colors + int l1, l2; // Luminosities + + // Get the RGB values for each color... if (fg & 0xffffff00) c1 = (unsigned)fg; else c1 = fl_cmap[fg]; if (bg & 0xffffff00) c2 = (unsigned)bg; else c2 = fl_cmap[bg]; - if ((c1^c2)&0x80800000) - return fg; - else if (c2&0x80800000) - return FL_BLACK; - else - return FL_WHITE; + // Compute the luminosity... + l1 = ((c1 >> 24) * 31 + ((c1 >> 16) & 255) * 61 + ((c1 >> 8) & 255) * 8) / 100; + l2 = ((c2 >> 24) * 31 + ((c2 >> 16) & 255) * 61 + ((c2 >> 8) & 255) * 8) / 100; + + // Compare and return the contrasting color... + if ((l1 - l2) > 127) return fg; + else if ((l2 - l1) > 127) return fg; + else if (l2 > 127) return FL_BLACK; + else return FL_WHITE; } // |