Add ability to constrain dominant color selection to a HSL range.

ui/gfx/color_utils.cc

Index: ui/gfx/color_utils.cc
diff --git a/ui/gfx/color_utils.cc b/ui/gfx/color_utils.cc
index de429495990ae13bcfaaac696953599f87c788ce..39e8e351869a59a1fa4791ba291911327b2aca2e 100644
--- a/ui/gfx/color_utils.cc
+++ b/ui/gfx/color_utils.cc
@@ -151,6 +151,31 @@ SkColor HSLToSkColor(const HSL& hsl, SkAlpha alpha) {
       calcHue(temp1, temp2, hue - 1.0 / 3.0));
 }
 
+bool IsWithinHSLRange(const HSL& hsl,
+                      const HSL& lower_bound,
+                      const HSL& upper_bound) {
+  DCHECK(hsl.h >= 0 && hsl.h <= 1);

[Alexei Svitkine (slow), 2014/05/30 14:56:39]

Nit: DCHECK(hsl.h >= 0 && hsl.h <= 1) << hsl.h;

So that it prints the hsl.h value if the check fails. Same for the two below.

[calamity, 2014/06/02 03:53:17]

Done.

+  DCHECK(hsl.s >= 0 && hsl.s <= 1);
+  DCHECK(hsl.l >= 0 && hsl.l <= 1);
+  DCHECK(lower_bound.h <= 1);

[Alexei Svitkine (slow), 2014/05/30 14:56:39]

Nit: DCHECK_LE

[calamity, 2014/06/02 03:53:17]

Removed.

+  DCHECK(lower_bound.s <= 1);
+  DCHECK(lower_bound.l <= 1);
+  DCHECK(lower_bound.h < 0 ||
+         (upper_bound.h >= 0 && upper_bound.h <= lower_bound.h + 1));

[Alexei Svitkine (slow), 2014/05/30 14:56:39]

Don't these three checks not match what's documented by this comment:

// If a component is negative in either |lower_bound| or |upper_bound|, that
// component will be ignored.

i.e. the above comment seems to imply you can set e.g. upper_bound.h to a
negative value to ignore that component, but these checks are only checking the
lower_bound.h for negative value.

Either fix the checks or make the comment match the checks.

[calamity, 2014/06/02 03:53:17]

They were a subset. Changed to exactly match comment.

+  DCHECK(lower_bound.s < 0 || (upper_bound.s >= 0 && upper_bound.s <= 1));
+  DCHECK(lower_bound.l < 0 || (upper_bound.l >= 0 && upper_bound.l <= 1));
+
+  // If the upper hue is >1, the given hue bounds wrap around at 1.
+  bool matches_hue = upper_bound.h > 1
+                         ? hsl.h >= lower_bound.h || hsl.h <= upper_bound.h - 1
+                         : hsl.h >= lower_bound.h && hsl.h <= upper_bound.h;
+  return (upper_bound.h < 0 || lower_bound.h < 0 || matches_hue) &&
+         (upper_bound.s < 0 || lower_bound.s < 0 ||
+          (hsl.s >= lower_bound.s && hsl.s <= upper_bound.s)) &&
+         (upper_bound.l < 0 || lower_bound.l < 0 ||
+          (hsl.l >= lower_bound.l && hsl.l <= upper_bound.l));
+}
+
 SkColor HSLShift(SkColor color, const HSL& shift) {
   HSL hsl;
   int alpha = SkColorGetA(color);