added built in functions: alpha, fade, mix, percentage

leafo · leafo · commit 2cee7ab241a3 · 2012-01-08T18:07:16.000-08:00
diff --git a/lessc.inc.php b/lessc.inc.php
@@ -1310,6 +1310,64 @@ function lib_lightness($color) {
 		return round($hsl[3]);
 	}
 
+	// get the alpha of a color
+	// defaults to 1 for non-colors or colors without an alpha
+	function lib_alpha($color) {
+		if ($color[0] != 'color') return 1;
+		return isset($color[4]) ? $color[4] : 1;
+	}
+
+	// set the alpha of the color
+	function lib_fade($args) {
+		list($color, $alpha) = $this->colorArgs($args);
+		$color[4] = $this->clamp($alpha / 100.0);
+		return $color;
+	}
+
+	function lib_percentage($number) {
+		return array('%', $number[1]*100);
+	}
+
+	// mixes two colors by weight
+	// mix(@color1, @color2, @weight);
+	// http://sass-lang.com/docs/yardoc/Sass/Script/Functions.html#mix-instance_method
+	function lib_mix($args) {
+		if ($args[0] != "list")
+			throw new exception("mix expects (color1, color2, weight)");
+
+		list($first, $second, $weight) = $args[2];
+		$first = $this->assertColor($first);
+		$second = $this->assertColor($second);
+
+		$first_a = $this->lib_alpha($first);
+		$second_a = $this->lib_alpha($second);
+		$weight = $weight[1] / 100.0;
+
+		$w = $weight * 2 - 1;
+		$a = $first_a - $second_a;
+
+		$w1 = (($w * $a == -1 ? $w : ($w + $a)/(1 + $w * $a)) + 1) / 2.0;
+		$w2 = 1.0 - $w1;
+
+		$new = array('color',
+			$w1 * $first[1] + $w2 * $second[1],
+			$w1 * $first[2] + $w2 * $second[2],
+			$w1 * $first[3] + $w2 * $second[3],
+		);
+
+		if ($first_a != 1.0 || $second_a != 1.0) {
+			$new[] = $first_a * $p + $second_a * ($p - 1);
+		}
+
+		return $new;
+	}
+
+	function assertColor($value, $error = "expected color value") {
+		if ($value[0] != "color")
+			throw new exception($error);
+		return $value;
+	}
+
 	function toHSL($color) {
 		if ($color[0] == 'hsl') return $color;
 
diff --git a/tests/inputs/colors.less b/tests/inputs/colors.less
@@ -63,3 +63,29 @@ body {
 	zero: spin(#000000, 100);
 	zero: spin(#ffffff, 100);
 }
+
+
+alpha {
+	// g: alpha(red);
+	g: alpha(rgba(0,0,0,0));
+	g: alpha(rgb(155,55,0));
+}
+
+fade {
+	f: fade(red, 50%);
+	f: fade(#fff, 20%);
+	f: fade(rgba(34,23,64,0.4), 50%);
+}
+
+@a: rgb(255,255,255);
+@b: rgb(0,0,0);
+
+.mix {
+	color: mix(@a, @b, 50%);
+}
+
+.percent {
+	per: percentage(0.5);
+}
+
+
diff --git a/tests/outputs/colors.css b/tests/outputs/colors.css
@@ -43,4 +43,15 @@ body {
   zero:#56124b;
   zero:#000000;
   zero:#ffffff;
-}
+}
+alpha {
+  g:0;
+  g:1;
+}
+fade {
+  f:rgba(0,0,0,0.5);
+  f:rgba(255,255,255,0.2);
+  f:rgba(34,23,64,0.5);
+}
+.mix { color:#7f7f7f; }
+.percent { per:50%; }
