How to control the color of the text in a TreeView, if it is possible?

[Andras-Csanyi]

Hi all,

This is an amazing project!

I'd like to build a TreeView and changing the text color depending on a property of the node. I could achieve defining the foreground and background color of field, but I am curious if the text color can be changed. I assume it is not as the content of the node "field" is text (toString() method of the node).

[tznind]

The ColorGetter delegate allows you to provide a function that returns a ColorScheme for each node. Below is an example that renders directories in green, executables in red and everything else in white.

Note that you return a ColorScheme not an Attribute or a Color

• ColorScheme: A collection of Attribute to be used depending on state (normal, focused, disabled etc)
• Attribute : A foreground and background color
• Color : A color

For the example I have used delegate for tree building, you can read more about that approach in Tree View Deep Dive. It is not a requirement though, ColorGetter delegate works just fine on regular TreeView too.

I assume it is not as the content of the node "field" is text (toString() method of the node).

This is indeed the default implementation, however you can tailor the text that appears by using AspectGetter e.g.

tv.AspectGetter = (fsi) => fsi.Name;

using Terminal.Gui;
using Terminal.Gui.Trees;

namespace Test
{
    public class Program
    {
        static void Main()
        {
            Application.Init();
            var w = new Window() { Title = "My Window" };

            var treeBuilder = new DelegateTreeBuilder<FileSystemInfo>(
                    (fsi) => {
                            try
                            {
                                return fsi is DirectoryInfo d ? d.GetFileSystemInfos() : Enumerable.Empty<FileSystemInfo>();
                            }
                            catch {
                                // Exception e.g. caused by file access permissions
                                return Enumerable.Empty<FileSystemInfo>();
                            }
                        }
                    );

            var tv = new TreeView<FileSystemInfo>(treeBuilder)
            {
                Width = Dim.Fill(),
                Height = Dim.Fill(),
            };

            tv.AddObjects(DriveInfo.GetDrives().Select(d=>d.RootDirectory));

            tv.AspectGetter = (fsi) => fsi.Name;

            var green = CreateScheme(Color.BrightGreen);
            var white = CreateScheme(Color.White);
            var red = CreateScheme(Color.Red);

            tv.ColorGetter = (fsi) =>
            {
                if(fsi is FileSystemInfo fi && fi.Extension == ".exe")
                {
                    return red;
                }
                return fsi is DirectoryInfo ? green : white;
            };

            w.Add(tv);
            Application.Run(w);
            Application.Shutdown();
            
            return;
        }

        private static ColorScheme CreateScheme(Color foreground)
        {
            return new ColorScheme
            {
                Normal = new Terminal.Gui.Attribute(foreground, Color.Blue),

                // flip color for selected nodes
                Focus = new Terminal.Gui.Attribute(Color.Blue, foreground),
                HotNormal = new Terminal.Gui.Attribute(foreground, Color.Blue),
                HotFocus = new Terminal.Gui.Attribute(Color.Blue, foreground),
                Disabled = new Terminal.Gui.Attribute(foreground, Color.Blue),

            };
        }
    }
}

[BDisp]

I recommend call w.Dispose() before calling Application.Shutdown(); to avoid throwing an exception during debug time.