2019-11-29-win10-uwp- color conversion

Original: 2019-11-29 uwp- color-conversion-win10

title	author	date	CreateTime	categories
win10 uwp color conversion	lindexi	2019-11-29 10:18:27 +0800	2018-2-13 17:23:3 +0800	Win10 UWP

This article tells you how to turn color from a string, the string transferred from the color

String turn color

You can use the following code in the WPF hexadecimal color string rotation Color

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

string hex = "#FFFFFF";  
Color color = System.Drawing.ColorTranslator.FromHtml(hex); 

UWP but this method did not, so we need a way to write their own

        public SolidColorBrush GetSolidColorBrush(string hex)
        {
            hex = hex.Replace("#", string.Empty);
            byte a = (byte) (Convert.ToUInt32(hex.Substring(0, 2), 16));
            byte r = (byte) (Convert.ToUInt32(hex.Substring(2, 2), 16));
            byte g = (byte) (Convert.ToUInt32(hex.Substring(4, 2), 16));
            byte b = (byte) (Convert.ToUInt32(hex.Substring(6, 2), 16));
            return new SolidColorBrush(Windows.UI.Color.FromArgb(a, r, g, b));
        }

If there is an incoming junior partner without a transparent, then the above code will appear abnormal, because without a transparent color only six characters, so you can not use the code above, I modified the following code can be converted color

       public SolidColorBrush GetSolidColorBrush(string hex)
        {
            hex = hex.Replace("#", string.Empty);

            bool existAlpha = hex.Length == 8;

            if (!existAlpha && hex.Length != 6)
            {
                the throw  new new  ArgumentException The ( " hex entered is not a valid color " );
            }

            int n = 0;
            byte a;
            if (existAlpha)
            {
                n = 2;
                a = (byte) ConvertHexToByte(hex, 0);
            }
            else
            {
                the  =  0xFF ;
            }

            var r = (byte) ConvertHexToByte(hex, n);
            var g = (byte) ConvertHexToByte(hex, n + 2);
            var b = (byte) ConvertHexToByte(hex, n + 4);
            return new SolidColorBrush(Windows.UI.Color.FromArgb(a, r, g, b));
        }

        private static uint ConvertHexToByte(string hex, int n)
        {
            return Convert.ToUInt32(hex.Substring(n, 2), 16);
        }

We can see from the above code ConvertHexToByte this is the hexadecimal int transfer method, see C # 16 hexadecimal strings turn int

But there is written color #FD92 #DACcolor, so it needs to continue to modify the algorithm

       public SolidColorBrush GetSolidColorBrush(string hex)
        {
            hex = hex.Replace("#", string.Empty);

            // # FFDFD991 
            // # DFD991 
            // # FD92 
            // #DAC

            bool existAlpha = hex.Length == 8 || hex.Length == 4;
            bool isDoubleHex = hex.Length == 8 || hex.Length == 6;

            if (!existAlpha && hex.Length != 6 && hex.Length != 3)
            {
                the throw  new new  ArgumentException The ( " hex entered is not a valid color " );
            }

            int n = 0;
            byte a;
            int hexCount = isDoubleHex ? 2 : 1;
            if (existAlpha)
            {
                n = hexCount;
                a = (byte) ConvertHexToByte(hex, 0, hexCount);
                if (!isDoubleHex)
                {
                    a = (byte) (a * 16 + a);
                }
            }
            else
            {
                the  =  0xFF ;
            }

            var r = (byte) ConvertHexToByte(hex, n, hexCount);
            var g = (byte) ConvertHexToByte(hex, n + hexCount, hexCount);
            var b = (byte) ConvertHexToByte(hex, n + 2 * hexCount, hexCount);
            if (!isDoubleHex)
            {
                // # = # FD92 FFDD9922

                r = (byte) (r * 16 + r);
                g = (byte) (g * 16 + g);
                b = (byte) (b * 16 + b);
            }

            return new SolidColorBrush(Windows.UI.Color.FromArgb(a, r, g, b));
        }

        private static uint ConvertHexToByte(string hex, int n, int count = 2)
        {
            return Convert.ToUInt32(hex.Substring(n, count), 16);
        }

If you want to see Microsoft's conversion, see https://referencesource.microsoft.com/#PresentationCore/Core/CSharp/System/Windows/Media/Parsers.cs

You can copy the source code:

<script src=" https://gist.github.com/lindexi/36c5e223ff77cfb8adc4909dec1576b5.js"></script>

If you do not see the code above, please click < https://gist.github.com/lindexi/36c5e223ff77cfb8adc4909dec1576b5 >

Color to String

If you need to switch from color string is very simple

Color.ToString()

The above codes can be output string