toColorShort method

Color toColorShort(bool enableShortRGB)

Convert a HEX value encoded (A)RGB string to a Dart Color.

• The string may include the '#' char, but does not have to.
• String may also include '0x' Dart Hex indicator, but does not have to.
• Any '#' '0x' patterns are trimmed out and String is assumed to be Hex.
• The String may start with alpha channel hex value, but does not have to, if alpha value is missing "FF" is used for alpha.
• String may be longer than 8 chars, after trimming out # and 0x, it will be RIGHT truncated to max 8 chars before parsing.
• If enableShortRGB is true a CSS style 3 char RGB value is interpreted as RRGGBB, if false it used it as a partial color value.

IF the resulting string cannot be parsed to a Color, is empty or null THEN fully opaque black color is returned ELSE the Color is returned.

To give caller a chance to handle parsing errors, use the same extension on nullable Color toColorMaybeNull. It returns null when there is a string that cannot be parsed to color value. You can then decide what to do with the error instead of just receiving fully opaque black color.

Implementation

Color toColorShort(bool enableShortRGB) {
  // If String was zero length, then we return transparent, cannot parse.
  if (this == '') return const Color(0xFF000000);
  // If String length is > 200 we as a safety precaution will not try to
  // parse it to a color, for shorter lengths the last 8 chars will be used.
  if (this.length > 200) return const Color(0xFF000000);
  // Remove all num signs, we allow them, but disregard them all.
  String hexColor = replaceAll('#', '');
  if (hexColor == '') return const Color(0xFF000000);
  // Remove all spaces, we allow them, but disregard them all.
  hexColor = hexColor.replaceAll(' ', '');
  if (hexColor == '') return const Color(0xFF000000);
  // Remove all '0x' Hex code marks, we allow them, but disregard them all.
  hexColor = hexColor.replaceAll('0x', '');
  if (hexColor == '') return const Color(0xFF000000);
  // If the input is exactly 3 chars long, we may have a short Web hex code,
  // let's make the potential 'RGB' code to a 'RRGGBB' code.
  if (hexColor.length == 3 && enableShortRGB) {
    hexColor = hexColor[0] +
        hexColor[0] +
        hexColor[1] +
        hexColor[1] +
        hexColor[2] +
        hexColor[2];
  }
  // Pad anything shorter than 7 with left 0 -> fill non spec channels with 0.
  hexColor = hexColor.padLeft(6, '0');
  // Pad anything shorter than 9 with left F -> fill with opaque alpha.
  hexColor = hexColor.padLeft(8, 'F');

  // We only try to parse the last 8 chars in the remaining string, rest can
  // still be whatever.
  final int length = hexColor.length;
  return Color(int.tryParse('0x${hexColor.substring(length - 8, length)}') ??
      0xFF000000);
}