Color class

Represents a color in the RGBA color space. This representation is designed for simplicity of conversion to/from color representations in various languages over compactness; for example, the fields of this representation can be trivially provided to the constructor of "java.awt.Color" in Java; it can also be trivially provided to UIColor's "+colorWithRed:green:blue:alpha" method in iOS; and, with just a little work, it can be easily formatted into a CSS "rgba()" string in JavaScript, as well.

Note: this proto does not carry information about the absolute color space that should be used to interpret the RGB value (e.g. sRGB, Adobe RGB, DCI-P3, BT.2020, etc.). By default, applications SHOULD assume the sRGB color space.

Example (Java):

  import com.google.type.Color;

  // ...
  public static java.awt.Color fromProto(Color protocolor) {
    float alpha = protocolor.hasAlpha()
        ? protocolor.getAlpha().getValue()
        : 1.0;

    return new java.awt.Color(
        protocolor.getRed(),
        protocolor.getGreen(),
        protocolor.getBlue(),
        alpha);
  }

  public static Color toProto(java.awt.Color color) {
    float red = (float) color.getRed();
    float green = (float) color.getGreen();
    float blue = (float) color.getBlue();
    float denominator = 255.0;
    Color.Builder resultBuilder =
        Color
            .newBuilder()
            .setRed(red / denominator)
            .setGreen(green / denominator)
            .setBlue(blue / denominator);
    int alpha = color.getAlpha();
    if (alpha != 255) {
      result.setAlpha(
          FloatValue
              .newBuilder()
              .setValue(((float) alpha) / denominator)
              .build());
    }
    return resultBuilder.build();
  }
  // ...

Example (iOS / Obj-C):

  // ...
  static UIColor* fromProto(Color* protocolor) {
     float red = [protocolor red];
     float green = [protocolor green];
     float blue = [protocolor blue];
     FloatValue* alpha_wrapper = [protocolor alpha];
     float alpha = 1.0;
     if (alpha_wrapper != nil) {
       alpha = [alpha_wrapper value];
     }
     return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
  }

  static Color* toProto(UIColor* color) {
      CGFloat red, green, blue, alpha;
      if (![color getRed:&red green:&green blue:&blue alpha:&alpha]) {
        return nil;
      }
      Color* result = [[Color alloc] init];
      [result setRed:red];
      [result setGreen:green];
      [result setBlue:blue];
      if (alpha <= 0.9999) {
        [result setAlpha:floatWrapperWithValue(alpha)];
      }
      [result autorelease];
      return result;
 }
 // ...

Example (JavaScript):

 // ...

 var protoToCssColor = function(rgb_color) {
    var redFrac = rgb_color.red || 0.0;
    var greenFrac = rgb_color.green || 0.0;
    var blueFrac = rgb_color.blue || 0.0;
    var red = Math.floor(redFrac * 255);
    var green = Math.floor(greenFrac * 255);
    var blue = Math.floor(blueFrac * 255);

    if (!('alpha' in rgb_color)) {
       return rgbToCssColor_(red, green, blue);
    }

    var alphaFrac = rgb_color.alpha.value || 0.0;
    var rgbParams = [red, green, blue].join(',');
    return ['rgba(', rgbParams, ',', alphaFrac, ')'].join('');
 };

 var rgbToCssColor_ = function(red, green, blue) {
   var rgbNumber = new Number((red << 16) | (green << 8) | blue);
   var hexString = rgbNumber.toString(16);
   var missingZeros = 6 - hexString.length;
   var resultBuilder = ['#'];
   for (var i = 0; i < missingZeros; i++) {
      resultBuilder.push('0');
   }
   resultBuilder.push(hexString);
   return resultBuilder.join('');
 };

 // ...