WPF C# TextBlock. How to format textblock text programatically to format foreground color of certain-CodePudding

Problem:
I have WPF TextBlock with dynamically changed text. This text contains words that are color names.
For example:

MyTextBlock.Text = "This is some dynamic text that contains red, green and yellow words inside it.";

Result should be rendered so all "red", "green" and "yellow" words are formatted with their color.

Note: Text is dynamically changed so static formatting is not an option.)

CodePudding user response：

You can take benefit from Inline collection property inside TextBlock to customize the content and set it dynamically..

<TextBlock
    x:Name="MyTextBlock"
    Height="100"
    Padding="8"
    FontSize="18"
    TextWrapping="Wrap" />

You would do something like this in code behind..

{
    InitializeComponent();
    var input = "This is some dynamic text that contains Red and green and yellow words inside it.";
    UpdateTextBoxWithColoredText(MyTextBlock, input, _colors);
}

Where UpdateTextBoxWithColoredText is

private void UpdateTextBoxWithColoredText(TextBlock textBlock,
    string input, List<string> colors)
{
    var list = input
        .Split(' ')
        .ToList();
    var stringBuilder = new StringBuilder();
    foreach (var currentString in list)
    {
        if (colors.Contains(currentString.ToLower()))
        {
            textBlock.Inlines.Add($"{stringBuilder} ");
            stringBuilder.Clear();
            var run = new Run(currentString)
            {
                Foreground = ColorName2Brush(currentString.ToLower())
            };
            textBlock.Inlines.Add(run);
            textBlock.Inlines.Add(" ");
        }
        else
            stringBuilder.Append($"{currentString} ");
    }

    textBlock.Inlines.Add($"{stringBuilder} ");
}

private readonly List<string> _colors = new() { "red", "green", "yellow" };

private Brush ColorName2Brush(string colorName) =>
    colorName switch
    {
        "green" => ToSolidColorBrush("#00FF00"),
        "yellow" => ToSolidColorBrush("#FFFF00"),
        "red" => ToSolidColorBrush("#FF0000"),
        _ => ToSolidColorBrush("#000000")
    };

private SolidColorBrush ToSolidColorBrush(string hex)
{
    try
    {
        return (SolidColorBrush)new BrushConverter().ConvertFrom(hex);
    }
    catch (Exception)
    {
        return (SolidColorBrush)new BrushConverter().ConvertFrom("#000000");
    }
}

Sample output

Note: punctuations are not handled in the solution above, also linebreaks (you can do textblock.Inlines.Add(new LineBreak()); or stringBuilder.AppendLine();), this is sort of string processing that you can do it in your behalf :)

CodePudding user response：

The very first answer contains a great solution but there is a lack of dynamic update, so try to add TargetUpdated event to the TextBlock you are using:

<TextBlock x:Name="MyTextBlock"
           Text="{Binding YourTextProperty, NotifyOnTargetUpdated=True}" 
           TargetUpdated="OnTargetUpdated"/>

Then exploit the TextBoxWithColoredText method from the same answer:

private void OnTargetUpdated(object sender, DataTransferEventArgs e)
{
    if (sender is TextBlock textBlock)
    {
        TextBoxWithColoredText(textBlock, textBlock.Text, _color);
    }
}