How to Get a Color from Hexadecimal Color String

Create a hexadecimal colour based on a string with JavaScript

Just porting over the Java from Compute hex color code for an arbitrary string to Javascript:

function hashCode(str) { // java String#hashCode
    var hash = 0;
    for (var i = 0; i < str.length; i++) {
       hash = str.charCodeAt(i) + ((hash << 5) - hash);
    }
    return hash;
} 

function intToRGB(i){
    var c = (i & 0x00FFFFFF)
        .toString(16)
        .toUpperCase();

    return "00000".substring(0, 6 - c.length) + c;
}

To convert you would do:

intToRGB(hashCode(your_string))

How to get a Color from hexadecimal Color String

Try Color class method:

public static int parseColor (String colorString)

From Android documentation:

Supported formats are: #RRGGBB #AARRGGBB 'red', 'blue', 'green', 'black', 'white', 'gray', 'cyan', 'magenta', 'yellow', 'lightgray', 'darkgray'

AndroidX: String.toColorInt()

How do I use hexadecimal color strings in Flutter?

In Flutter, the Color class only accepts integers as parameters, or there is the possibility to use the named constructors fromARGB and fromRGBO.

So we only need to convert the string #b74093 to an integer value. Also we need to respect that opacity always needs to be specified.

255 (full) opacity is represented by the hexadecimal value FF. This already leaves us with 0xFF. Now, we just need to append our color string like this:

const color = const Color(0xffb74093); // Second `const` is optional in assignments.

The letters can by choice be capitalized or not:

const color = const Color(0xFFB74093);

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If you want to use percentage opacity values, you can replace the first FF with the values from this table (also works for the other color channels).

Extension class

Starting with Dart 2.6.0, you can create an extension for the Color class that lets you use hexadecimal color strings to create a Color object:

extension HexColor on Color {
  /// String is in the format "aabbcc" or "ffaabbcc" with an optional leading "#".
  static Color fromHex(String hexString) {
    final buffer = StringBuffer();
    if (hexString.length == 6 || hexString.length == 7) buffer.write('ff');
    buffer.write(hexString.replaceFirst('#', ''));
    return Color(int.parse(buffer.toString(), radix: 16));
  }

  /// Prefixes a hash sign if [leadingHashSign] is set to `true` (default is `true`).
  String toHex({bool leadingHashSign = true}) => '${leadingHashSign ? '#' : ''}'
      '${alpha.toRadixString(16).padLeft(2, '0')}'
      '${red.toRadixString(16).padLeft(2, '0')}'
      '${green.toRadixString(16).padLeft(2, '0')}'
      '${blue.toRadixString(16).padLeft(2, '0')}';
}

The fromHex method could also be declared in a mixin or class because the HexColor name needs to be explicitly specified in order to use it, but the extension is useful for the toHex method, which can be used implicitly. Here is an example:

void main() {
  final Color color = HexColor.fromHex('#aabbcc');

  print(color.toHex());
  print(const Color(0xffaabbcc).toHex());
}

Disadvantage of using hex strings

Many of the other answers here show how you can dynamically create a Color from a hex string, like I did above. However, doing this means that the color cannot be a const.

Ideally, you would assign your colors the way I explained in the first part of this answer, which is more efficient when instantiating colors a lot, which is usually the case for Flutter widgets.

How do I get the color from a hexadecimal color code using .NET?

I'm assuming that's an ARGB code... Are you referring to System.Drawing.Color or System.Windows.Media.Color? The latter is used in WPF for example. I haven't seen anyone mention it yet, so just in case you were looking for it:

using System.Windows.Media;

Color color = (Color)ColorConverter.ConvertFromString("#FFDFD991");

Flutter/Dart: Convert HEX color string to Color?

/// Construct a color from a hex code string, of the format #RRGGBB.
Color hexToColor(String code) {
  return new Color(int.parse(code.substring(1, 7), radix: 16) + 0xFF000000);
}

How do I get the color from a hexadecimal color code using .NET?

I'm assuming that's an ARGB code... Are you referring to System.Drawing.Color or System.Windows.Media.Color? The latter is used in WPF for example. I haven't seen anyone mention it yet, so just in case you were looking for it:

using System.Windows.Media;

Color color = (Color)ColorConverter.ConvertFromString("#FFDFD991");

processing hex string to color

What I did was simply recreated the color like this:

int c = Integer.parseInt(obj.getString("color"), 16);
c = color(red(c), green(c), blue(c));

Color from hex string in jetpack compose

You can use this object class with a getColor method.

object HexToJetpackColor {
    fun getColor(colorString: String): Color {
            return Color(android.graphics.Color.parseColor("#" + colorString))
    }
}

Or we can use an extension function

fun Color.fromHex(color: String) = Color(android.graphics.Color.parseColor("#" + colorString))

Jetpack Color class i.e androidx.ui.graphics.Color only takes RGB, ARGB, ColorSpace and colorInt in constructor. See: Color.kt

so, here we are directly accessing parseColor() method from android.graphics.Color which returns colorInt.

Hence parseColor() method can be used to get colorInt and then providing it to Jetpack Color class to get androidx.ui.graphics.Color object.

How to use hex color values

#ffffff are actually 3 color components in hexadecimal notation - red ff, green ff and blue ff. You can write hexadecimal notation in Swift using 0x prefix, e.g 0xFF

To simplify the conversion, let's create an initializer that takes integer (0 - 255) values:

extension UIColor {
   convenience init(red: Int, green: Int, blue: Int) {
       assert(red >= 0 && red <= 255, "Invalid red component")
       assert(green >= 0 && green <= 255, "Invalid green component")
       assert(blue >= 0 && blue <= 255, "Invalid blue component")

       self.init(red: CGFloat(red) / 255.0, green: CGFloat(green) / 255.0, blue: CGFloat(blue) / 255.0, alpha: 1.0)
   }

   convenience init(rgb: Int) {
       self.init(
           red: (rgb >> 16) & 0xFF,
           green: (rgb >> 8) & 0xFF,
           blue: rgb & 0xFF
       )
   }
}

Usage:

let color = UIColor(red: 0xFF, green: 0xFF, blue: 0xFF)
let color2 = UIColor(rgb: 0xFFFFFF)

How to get alpha?

Depending on your use case, you can simply use the native UIColor.withAlphaComponent method, e.g.

let semitransparentBlack = UIColor(rgb: 0x000000).withAlphaComponent(0.5)

Or you can add an additional (optional) parameter to the above methods:

convenience init(red: Int, green: Int, blue: Int, a: CGFloat = 1.0) {
    self.init(
        red: CGFloat(red) / 255.0,
        green: CGFloat(green) / 255.0,
        blue: CGFloat(blue) / 255.0,
        alpha: a
    )
}

convenience init(rgb: Int, a: CGFloat = 1.0) {
    self.init(
        red: (rgb >> 16) & 0xFF,
        green: (rgb >> 8) & 0xFF,
        blue: rgb & 0xFF,
        a: a
    )
}

(we cannot name the parameter alpha because of a name collision with the existing initializer).

Called as:

let color = UIColor(red: 0xFF, green: 0xFF, blue: 0xFF, a: 0.5)
let color2 = UIColor(rgb: 0xFFFFFF, a: 0.5)

To get the alpha as an integer 0-255, we can

convenience init(red: Int, green: Int, blue: Int, a: Int = 0xFF) {
    self.init(
        red: CGFloat(red) / 255.0,
        green: CGFloat(green) / 255.0,
        blue: CGFloat(blue) / 255.0,
        alpha: CGFloat(a) / 255.0
    )
}

// let's suppose alpha is the first component (ARGB)
convenience init(argb: Int) {
    self.init(
        red: (argb >> 16) & 0xFF,
        green: (argb >> 8) & 0xFF,
        blue: argb & 0xFF,
        a: (argb >> 24) & 0xFF
    )
}

Called as

let color = UIColor(red: 0xFF, green: 0xFF, blue: 0xFF, a: 0xFF)
let color2 = UIColor(argb: 0xFFFFFFFF)

Or a combination of the previous methods. There is absolutely no need to use strings.

Convert hex color value ( #ffffff ) to integer value

The real answer is to use:

Color.parseColor(myPassedColor) in Android, myPassedColor being the hex value like #000 or #000000 or #00000000.

However, this function does not support shorthand hex values such as #000.

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