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// Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// @dart = 2.7
/// Utility library for creating web colors.
library sourcemaps.colors;
/// A web color.
abstract class Color {
/// The css code for the color.
String get toCss;
}
/// A web color defined as RGB.
class RGB implements Color {
final double r;
final double g;
final double b;
/// Creates a color defined by the amount of red [r], green [g], and blue [b]
/// all in range 0..1.
const RGB(this.r, this.g, this.b);
@override
String get toCss {
StringBuffer sb = new StringBuffer();
sb.write('#');
void writeHex(double value) {
int i = (value * 255.0).round();
if (i < 16) {
sb.write('0');
}
sb.write(i.toRadixString(16));
}
writeHex(r);
writeHex(g);
writeHex(b);
return sb.toString();
}
@override
String toString() => 'rgb($r,$g,$b)';
}
class RGBA extends RGB {
final double a;
const RGBA(double r, double g, double b, this.a) : super(r, g, b);
@override
String get toCss {
StringBuffer sb = new StringBuffer();
void writeInt(double value) {
int i = (value * 255.0).round();
if (i < 16) {
sb.write('0');
}
sb.write(i);
}
sb.write('rgba(');
writeInt(r);
sb.write(', ');
writeInt(g);
sb.write(', ');
writeInt(b);
sb.write(', ');
sb.write(a);
sb.write(')');
return sb.toString();
}
}
/// A web color defined as HSV.
class HSV implements Color {
final double h;
final double s;
final double v;
/// Creates a color defined by the hue [h] in range 0..360 (360 excluded),
/// saturation [s] in range 0..1, and value [v] in range 0..1.
const HSV(this.h, this.s, this.v);
@override
String get toCss => toRGB(this).toCss;
static RGB toRGB(HSV hsv) {
double h = hsv.h;
double s = hsv.s;
double v = hsv.v;
if (s == 0.0) {
// Grey.
return new RGB(v, v, v);
}
h /= 60.0; // Sector 0 to 5.
int i = h.floor();
double f = h - i; // Factorial part of [h].
double p = v * (1.0 - s);
double q = v * (1.0 - s * f);
double t = v * (1.0 - s * (1.0 - f));
switch (i) {
case 0:
return new RGB(v, t, p);
case 1:
return new RGB(q, v, p);
case 2:
return new RGB(p, v, t);
case 3:
return new RGB(p, q, v);
case 4:
return new RGB(t, p, v);
default: // case 5:
return new RGB(v, p, q);
}
}
@override
String toString() => 'hsv($h,$s,$v)';
}