Addresses #4058. Basic support for non-color text styles.

[Error-String-Expected-Got-Nil]

Changes:

• Adds TextStyle enum
• Adds EscSeqUtils.CSI_AppendTextStyleChange() method, which emits the ANSI escape codes for a text style
• Adds TextStyle property to Attribute
• Adds handling for TextStyles to OutputBuffer, NetOutput, and WindowsOutput, allowing styled text to be displayed with the NetOutput and WindowsOutput drivers

Example:

Title says "addresses" and not "fixes" #4058 because this definitely doesn't completely resolve that issue, only fully completing the first proposed change, and partially completing the second. I think it's still worthwhile as a good stepping-off point for more comprehensive updates.

This pull request isn't necessarily final at time of creation, and there are a couple notable improvements I haven't made yet, but am willing to make after feedback:

• Attribute.TextStyle is only settable as an init property, there are no new constructors including it yet. I didn't add any due to it already having quite a few constructors, I wasn't sure if I should double them by adding variants with an extra TextStyle field.
• Only the V2 NetOutput and WindowsOutput drivers were updated to handle text styles. In order for them to have any effect, you'll have to explicitly create a V2 application and use either one of those drivers.
• No unit tests. The changes in this are surprisingly simple, and I'm not sure what there is that can be tested. The only thing that comes to mind is making sure EscSeqUtils.CSI_AppendTextStyleChange() produces correct escape sequences, but I'm not sure what a good set of test cases for that is.

Pull Request checklist:

• I've named my PR in the form of "Fixes #issue. Terse description."
• My code follows the style guidelines of Terminal.Gui - if you use Visual Studio, hit CTRL-K-D to automatically reformat your files before committing.
• My code follows the Terminal.Gui library design guidelines
• I ran dotnet test before commit
• I have made corresponding changes to the API documentation (using /// style comments)
• My changes generate no new warnings
• I have checked my code and corrected any poor grammar or misspellings
• I conducted basic QA to assure all features are working

[Error-String-Expected-Got-Nil]

Problem I just realized but I'm not exactly sure how to handle: While my code comments say that bold and faint text are mutually exclusive, this is not exactly true. They are exclusive if your terminal is set to display bold text as simply a brighter color, but if you have it use a heavier font weight instead, it will work just fine.

However, they do still share the same disable code ^[[22m. This could be handled be re-enabling one when only disabling the other, though.

Should simultaneously bold-faint styles be permitted, or should I leave it as-is?

Edit: Slept on it, and ended up deciding to add it. Included some remarks in TextStyle noting that the two styles might be incompatible.

[Error-String-Expected-Got-Nil]

As of the last commit, also added support for rendering TextStyle to WindowsOuptut. Surprisingly easy- probably would also be easy for other outputs? Haven't checked yet, might later.

[tig]

Excellent work! Thank you.

[Copilot]

Pull Request Overview

This PR introduces basic support for non-color text styles by adding a new TextStyle enum and updating related classes to emit ANSI escape codes for styled text output.

• Added TextStyle enum and integrated support in drivers (NetOutput and WindowsOutput)
• Updated the Attribute class with a TextStyle property and corresponding TODOs for future improvements
• Enhanced the escape sequence utility (EscSeqUtils) to manage text style changes

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Terminal.Gui/Drawing/TextStyle.cs	Introduces the new TextStyle enum with flag values for various text styles
Terminal.Gui/Drawing/Attribute.cs	Adds a TextStyle property with TODOs for extending constructors and updating ToString
Terminal.Gui/ConsoleDrivers/V2/WindowsOutput.cs	Updates text output to include text style changes using the new escape sequence method
Terminal.Gui/ConsoleDrivers/V2/NetOutput.cs	Similar update to handle text styles with V2 NetOutput driver
Terminal.Gui/ConsoleDrivers/V2/OutputBuffer.cs	Updates attribute assignment to include TextStyle
Terminal.Gui/ConsoleDrivers/EscSeqUtils/EscSeqUtils.cs	Adds a new method to generate ANSI escape sequences for changing text styles

Comments suppressed due to low confidence (2)

Terminal.Gui/Drawing/Attribute.cs:107

• The TextStyle property is not incorporated into GetHashCode, which may lead to inconsistencies if two Attributes differ only in TextStyle. Consider updating GetHashCode (and related equality members) to include TextStyle if it is meant to be part of the attribute identity.

public override int GetHashCode () { return HashCode.Combine (PlatformColor, Foreground, Background); }

Terminal.Gui/ConsoleDrivers/EscSeqUtils/EscSeqUtils.cs:1868

• Although the changes are straightforward, consider adding unit tests for CSI_AppendTextStyleChange to ensure it produces the correct ANSI escape sequences, especially given the nuanced handling of mutually exclusive styles such as Bold and Faint.

internal static void CSI_AppendTextStyleChange (StringBuilder output, TextStyle prev, TextStyle next)

[BDisp]

Thanks. That greats.

[tig]

@Error-String-Expected-Got-Nil - PR incoming to this PR with a simple Scenario to illustrate.

[tig]

@tznind - Now, how would we add gradient support to Attribute in the same vein? Would that even be possible?

[tznind]

@tznind - Now, how would we add gradient support to Attribute in the same vein? Would that even be possible?

Hmn... Gradients are composed of color transitions (spectrum) with helper methods that let you sample the spectrum across an area (vertical, diagonal, radial etc).

You could potentially use IFill which has a gradient implementation somehow.

Maybe if an attribute has a referenced IFill? Then that overrides it's existing color?

It's more a question though of flow of control. Does the attribute 'reach up' or is Attribute lowest level data class and gradient is imposed implicitly as runes/attributes are created.

[tig]

Note on all this: I discovered that WT has a setting that impacts Bold:

In my case, this was set to "Bright colors" which meant in my testing I couldn't distinguish TextStyle.Bold.

I had to set it to Bold Font or Bold font with bright colors for Bold to actually be bold.

Super annoying thing to discover.

[Error-String-Expected-Got-Nil]

Yes, that was quite annoying, I had to discover it during testing- at first it seemed like bold did nothing, but it was just that the default text color was pure white, so couldn't be any brighter.

I didn't think to mention it in any documentation remarks or anything because it's technically a user-side issue, though now I wonder if it deserves at least a mention? Would probably save some headache.

[tig]

Yes, that was quite annoying, I had to discover it during testing- at first it seemed like bold did nothing, but it was just that the default text color was pure white, so couldn't be any brighter.

I didn't think to mention it in any documentation remarks or anything because it's technically a user-side issue, though now I wonder if it deserves at least a mention? Would probably save some headache.

Really bums me out because I was hoping to be able to use Bold for Border Title to show Focus.

[tig]

See

microsoft/terminal#18284

[tig]

I went ahead and merged this without you integrating my PR.

Instead that's here:

• More on #4058 - Adds TextStyle Scenario #4079

[Error-String-Expected-Got-Nil]

I went ahead and merged this without you integrating my PR.

Instead that's here:

• More on #4058 - Adds TextStyle Scenario #4079

Ah, sorry! First time submitting a PR like this, didn't realize there was something I needed to do.

[ChristopheI]

Hi,
I have some remarks / questions about TextStyle:

1. Is-it possible to use a style in a label (for example) using ColorScheme property with correct Attribute ? (I can't do it) Or it's necessary to use SetAttribute / AddStr ?

I tried this without success:

static public Attribute AtributeBlackOnGrayBlink = new Attribute(Color.Black, LightGray)  { TextStyle = TextStyle.Blink };
static public ColorScheme ColorSchemeBlackOnGrayBlink = new(AtributeBlackOnGrayBlink);

        lblOrganizers = new()
        {
            X = 0,
            Y = 0,
            Text = LBL_ORGANIZERS,
            Height = 1,
            ColorScheme = Tools.ColorSchemeBlackOnGrayBlink
        };

2. It would be create to dissociate ColorScheme and TextStyle.
   For example for a Label, we have Text and TextAlignment I expected TextStyle on the same level
   And not to set it it using ColorScheme

Thanks

[Error-String-Expected-Got-Nil]

In my testing, I used the following code to apply a style to a label:

public class StyledLabel : Label
{
    public TextStyle Style = TextStyle.None;
    
    public override ColorScheme? ColorScheme
    {
        get
        {
            var baseScheme = base.ColorScheme;
            if (baseScheme is null) return null;
            return baseScheme with
            {
                Normal = baseScheme.Normal with { TextStyle = Style },
                Focus = baseScheme.Focus with { TextStyle = Style },
                HotNormal = baseScheme.HotNormal with { TextStyle = Style },
                HotFocus = baseScheme.HotFocus with { TextStyle = Style }
            };
        }
        set => base.ColorScheme = value;
    }
}

I'm not certain why your method isn't working though, since it should as far as I can tell. Are you using the V2 net/windows driver? If not, you'll have to do that to make it work.

As for setting it through a method other than ColorScheme... I don't think that's possible just based on how it's implemented. TextStyle is tied to Attribute, which can be set in a couple ways, but the only simple one is to just change it in the ColorScheme (eventually to be renamed just Scheme).

[ChristopheI]

1. Yes I'm using v2net. I played with TextStyle.Blink (which I want the most to display warning info). but it's not working. If I use TextStyle.Strikethrough instead it's working ...
   Thanks to share this code. It's very useful ! I will use it

2. Looking in the code I see effectively that Attribute and TextStyle are highly related ... And it's why It's a property of ColorScheme.

[ChristopheI]

Using your StyledLabel (and running using v2net driver) some TextStyle are not working (Bold, Faint, Blink) in my project
But strangely when running UICatalog (also with v2net driver) all TextStyle are working ....

Could it be related to Color used ? What could be the reason ?

[ChristopheI]

I confirm. Setting nearly all my ColorScheme to null (so using the default one) TextStyle .Blink is working in my project ....

[Error-String-Expected-Got-Nil]

I'm not sure what the issue could be, unfortunately. If you can figure out exactly what you need to change in order to make it work or stop working though, do submit an issue about it.

[tig]

1. Is-it possible to use a style in a label (for example) using ColorScheme property with correct Attribute ? (I can't do it) Or it's necessary to use SetAttribute / AddStr ?

I tried this without success:

static public Attribute AtributeBlackOnGrayBlink = new Attribute(Color.Black, LightGray)  { TextStyle = TextStyle.Blink };
static public ColorScheme ColorSchemeBlackOnGrayBlink = new(AtributeBlackOnGrayBlink);

        lblOrganizers = new()
        {
            X = 0,
            Y = 0,
            Text = LBL_ORGANIZERS,
            Height = 1,
            ColorScheme = Tools.ColorSchemeBlackOnGrayBlink
        };

2. It would be create to dissociate ColorScheme and TextStyle.
   For example for a Label, we have Text and TextAlignment I expected TextStyle on the same level
   And not to set it it using ColorScheme

Thanks

You'll need to wait for

• Fixes #4057 - MASSIVE! Fully implements ColorScheme->Scheme + VisualRole + Colors.->SchemeManager.  #4062

Before TextStyle is broadly supported. I just got most of it working yesterday....

[ChristopheI]

If it helps, a mini example which reproduce the pb about Blink when a ColorSheme is set
Result output:

using Terminal.Gui;
using RuntimeEnvironment = Microsoft.DotNet.PlatformAbstractions.RuntimeEnvironment;

public class StyledLabel : Label
{
    public TextStyle Style = TextStyle.None;

    public override ColorScheme? ColorScheme
    {
        get
        {
            var baseScheme = base.ColorScheme;
            if (baseScheme is null) return null;
            return baseScheme with
            {
                Normal = baseScheme.Normal with { TextStyle = Style },
                Focus = baseScheme.Focus with { TextStyle = Style },
                HotNormal = baseScheme.HotNormal with { TextStyle = Style },
                HotFocus = baseScheme.HotFocus with { TextStyle = Style }
            };
        }
        set => base.ColorScheme = value;
    }
}

public class TestWindow: Window
{
    static public Terminal.Gui.Attribute AttributeTest = new Terminal.Gui.Attribute(Color.Blue, Color.White);
    static public ColorScheme ColorSchemeTest = new(AttributeTest);

    private Shortcut ShVersion;

    public TestWindow()
    {
        BorderStyle = LineStyle.None;

        TextStyle[] allStyles = Enum.GetValues(typeof(TextStyle))
                                         .Cast<TextStyle>()
                                         .ToArray();

        View? previousView = null;
        foreach (var style in allStyles)
        {
            string styleName = Enum.GetName(typeof(TextStyle), style)!;

            var styleLabelWithColorScheme = new StyledLabel()
            {
                X = previousView is null ? 0 : Pos.Right(previousView) + 1,
                Y = 1,
                Width = Dim.Auto(DimAutoStyle.Text),
                Height = 1,
                Text = styleName + "+ColorScheme",
                Style = style,
                ColorScheme = ColorSchemeTest
            };

            var styleLabel = new StyledLabel()
            {
                X = previousView is null ? 0 : Pos.Right(previousView) + 1,
                Y = 0,
                Width = Dim.Auto(DimAutoStyle.Text),
                Height = 1,
                Text = styleName,
                Style = style
            };

            Add(styleLabel, styleLabelWithColorScheme);
            previousView = styleLabelWithColorScheme;
        }

        // Create StatusBar
        StatusBar statusBar = new()
        {
            Visible = true,
            AlignmentModes = AlignmentModes.IgnoreFirstOrLast,
            CanFocus = false
        };

        ShVersion = new()
        {
            Title = "Version Info",
            CanFocus = false
        };
        statusBar.Add(ShVersion); // always add it as the last one
        Add(statusBar);

        Height = Dim.Fill();
        Width = Dim.Fill();

        // Need to manage Loaded event
        Loaded += LoadedHandler;
    }

    private void LoadedHandler(object? sender, EventArgs? args)
    {
        if (ShVersion is { })
        {
            ShVersion.Title = $"{RuntimeEnvironment.OperatingSystem} {RuntimeEnvironment.OperatingSystemVersion}, {Driver.GetVersionInfo()}";
        }
    }
}

[tig]

I took your sample and tweaked it to use the new API in #4062 :

public class TestWindow : Window
{
    private Shortcut ShVersion;

    public TestWindow ()
    {
        BorderStyle = LineStyle.None;

        TextStyle [] allStyles = Enum.GetValues (typeof (TextStyle))
                                         .Cast<TextStyle> ()
                                         .ToArray ();

        View? previousView = null;
        foreach (var style in allStyles)
        {
            string styleName = Enum.GetName (typeof (TextStyle), style)!;

            var styleLabelWithScheme = new Label ()
            {
                X = previousView is null ? 0 : Pos.Right (previousView) + 1,
                Y = 1,
                Width = Dim.Auto (DimAutoStyle.Text),
                Height = 1,
                SchemeName = "Dialog",
                Text = styleName + "+SchemeName",
            };
            styleLabelWithScheme.SetScheme (styleLabelWithScheme.GetScheme () with { Normal = styleLabelWithScheme.GetScheme ().Normal with { Foreground = Color.Yellow, Style = style } });

            var styleLabel = new Label ()
            {
                X = previousView is null ? 0 : Pos.Right (previousView) + 1,
                Y = 0,
                Width = Dim.Auto (DimAutoStyle.Text),
                Height = 1,
                Text = styleName,
            };
            styleLabel.SetScheme (styleLabel.GetScheme () with { Normal = styleLabel.GetScheme ().Normal with { Style = style } });

            Add (styleLabel, styleLabelWithScheme);
            previousView = styleLabelWithScheme;
        }

        // Create StatusBar
        StatusBar statusBar = new ()
        {
            Visible = true,
            AlignmentModes = AlignmentModes.IgnoreFirstOrLast,
            CanFocus = false
        };

        ShVersion = new ()
        {
            Title = "Version Info",
            CanFocus = false
        };
        ShVersion.SetScheme (ShVersion.GetScheme () with { Normal = ShVersion.GetScheme ().Normal with { Style = TextStyle.Italic } });
        statusBar.Add (ShVersion); // always add it as the last one
        Add (statusBar);

        Height = Dim.Fill ();
        Width = Dim.Fill ();

        // Need to manage Loaded event
        Loaded += LoadedHandler;
    }

    private void LoadedHandler (object? sender, EventArgs? args)
    {
        if (ShVersion is { })
        {
            ShVersion.Title = $"{RuntimeEnvironment.OperatingSystem} {RuntimeEnvironment.OperatingSystemVersion}, {Application.Driver.GetVersionInfo ()}";
        }
    }
}

[ChristopheI]

Hi,
I migrate to the last version (branch v2_develop - commit: 38c1182 [38c1182]
I still have the pb about the blink style.
I tried with v2win et v2net.

The label "With color - With Blink" is not blinking ...

Here is the code used;

using Terminal.Gui.Drawing;
using Terminal.Gui.ViewBase;
using Terminal.Gui.Views;
using RuntimeEnvironment = Microsoft.DotNet.PlatformAbstractions.RuntimeEnvironment;
using Attribute = Terminal.Gui.Drawing.Attribute;

public class TestWindow: Window
{
    static public Attribute AttributeTest = new (Color.Blue, Color.White);
    static public Scheme SchemeTest = new(AttributeTest);

    private Shortcut ShVersion;

    public TestWindow()
    {
        BorderStyle = LineStyle.None;

        TextStyle[] allStyles = Enum.GetValues(typeof(TextStyle))
                                         .Cast<TextStyle>()
                                         .ToArray();

        View? previousView = null;
        foreach (var style in allStyles)
        {
            string styleName = Enum.GetName(typeof(TextStyle), style)!;

            Attribute attributeWithoutColorWithStyle = new Attribute()
            {
                Style = style
            };
            var labelWithoutColorWithStyle = new Label()
            {
                X = previousView is null ? 0 : Pos.Right(previousView) + 1,
                Y = 0,
                Width = Dim.Auto(DimAutoStyle.Text),
                Height = 1,
                Text = $"Without Color - With {styleName}"
            };
            labelWithoutColorWithStyle.SetScheme(new Scheme(attributeWithoutColorWithStyle));
            Add(labelWithoutColorWithStyle);
            
            Attribute attributeWithColorWithoutStyle = new Attribute()
            {
                Foreground = Color.Blue,
                Background = Color.White,
                Style = TextStyle.None
            };
            var labelWithColorWithoutStyle = new Label()
            {
                X = previousView is null ? 0 : Pos.Right(previousView) + 1,
                Y = 1,
                Width = Dim.Auto(DimAutoStyle.Text),
                Height = 1,
                Text = $"With Color - Without {styleName}"
            };
            labelWithColorWithoutStyle.SetScheme(new Scheme(attributeWithColorWithoutStyle));
            Add(labelWithColorWithoutStyle);

            Attribute attributeWithColorWithStyle = new Attribute()
            {
                Foreground = Color.Blue,
                Background = Color.White,
                Style = style
            };
            var labelWithColorWithStyle = new Label()
            {
                X = previousView is null ? 0 : Pos.Right(previousView) + 1,
                Y = 2,
                Width = Dim.Auto(DimAutoStyle.Text),
                Height = 1,
                Text = $"With Color - With {styleName}"
            };
            labelWithColorWithStyle.SetScheme(new Scheme(attributeWithColorWithStyle));
            Add(labelWithColorWithStyle);

            previousView = labelWithoutColorWithStyle;
        }

        // Create StatusBar
        StatusBar statusBar = new()
        {
            Visible = true,
            AlignmentModes = AlignmentModes.IgnoreFirstOrLast,
            CanFocus = false
        };

        ShVersion = new()
        {
            Title = "Version Info",
            CanFocus = false
        };
        statusBar.Add(ShVersion); // always add it as the last one
        Add(statusBar);

        Height = Dim.Fill();
        Width = Dim.Fill();

        // Need to manage Loaded event
        Loaded += LoadedHandler;
    }

    private void LoadedHandler(object? sender, EventArgs? args)
    {
        if (ShVersion is { })
        {
            ShVersion.Title = $"{RuntimeEnvironment.OperatingSystem} {RuntimeEnvironment.OperatingSystemVersion}, {Terminal.Gui.App.Application.Driver.GetVersionInfo()}";
        }
    }
}

[BDisp]

I'm using the latest v2_develop and it's blinking. Are you sure that the terminal is focused? If you have another window focused, even your app is visible, you won't see blinking in the terminal.

[Error-String-Expected-Got-Nil]

The code looks fine to me at a glance, however, not all terminals support all text stylings. It's possible the terminal you're using (default Windows cmd, I think?) simply doesn't support blinking text. Perhaps it might work if you tried it in Powershell? Assuming Powershell supports it, I haven't checked that though.

[ChristopheI]

My bad ... Very very sorry.
Yes it's blinking but since the "faint color" and the "nor mal color" are very similar I didn't see it well ...
I need a coffee break ! ☕