Cleartype not working

[Joe-Fernico]

Describe the bug

Using FluentWindow stops cleartype from working
Here is an example image, on the left is non-cleartype using greyscale and cleartype is on the right of the image

Even setting the WindowBackdropType to None does not fix this, however you can do the following to fix it:

public class ClearTypeFluentWindow : FluentWindow
{
    protected override void SetWindowChrome()
    {
        try
        {
            WindowChrome.SetWindowChrome(
                this,
                new WindowChrome
                {
                    CaptionHeight = 0,
                    CornerRadius = default,
                    GlassFrameThickness = new Thickness(0),
                    ResizeBorderThickness = this.ResizeMode == ResizeMode.NoResize ? default : new Thickness(4),
                    UseAeroCaptionButtons = false,
                });
        }
        catch (COMException)
        {
            // Ignored, matching WPF-UI's own SetWindowChrome.
        }
    }
}

If you look at

wpfui/src/Wpf.Ui/Controls/FluentWindow/FluentWindow.cs

Line 294 in ffebacd

protected virtual void SetWindowChrome()

you can see the comment "// 0.00001 so there's no glass frame drawn around the window, but the border is still drawn." Anything other than 0 will still call DwmExtendFrameIntoClientArea, which breaks ClearType.
At least on my version of windows the comment is out of date and actually has no effect anyway. I would imagine that it may be there to fix windows 10, maybe a call to Utilities.IsOSWindows11OrNewer could be used?

To Reproduce

Use a FluentWindow

Expected behavior

Cleartype should work if Window set to None.
It is understandable that Mica cannot render cleartype as explained in #177 (comment)

Screenshots

No response

OS version

Windows 11 25H2 26200.8875
I am using tfm net10.0-windows10.0.19041.0

.NET version

Net 10

WPF-UI NuGet version

4.3.0

Additional context

No response

[Nuklon]

No, > 0 is still needed on W11. If you use backdrop None, there's no border drawn around the window. I think 0.0001 workaround was needed for W10 and lower. I'll investigate this.

[Joe-Fernico]

Maybe I am misunderstanding what the "border" is referring to, but I have the GlassThickness set to zero using my ClearTypeFluentWindow code above and I do get a grey border with some shadowing behind it

[Nuklon]

Specify WindowBackdropType as None, it won't render a border then.

With > 0:

I just tried Windows 7 and 11 and with GlassFrameThickness = 1 it works fine, but I think the issue was with W10 needing 0.00001, I'm creating a new W10 image now for testing, so it'll take some time.

[Nuklon]

OK, W10 works as well with 1. I'll create a PR.

[Joe-Fernico]

A thickness of 1 still doesn't give Cleartype
With 1:

With 0:

[Nuklon]

Hmm, I see, same issue occurs with -1 for that matter.

[Nuklon]

Seems non-fixable as when GlassFrameThickness is non-zero, it makes DWM have an alpha channel, which blocks ClearType from working. Probably also why WinUI doesn't support ClearType. ModernWpf has the same issue, as well as WPF official Fluent theme. You're either losing your border or ClearType.

[chucker]

it makes DWM have an alpha channel, which blocks ClearType from working. Probably also why WinUI doesn't support ClearType

I think so. As soon as you have an alpha channel (which is materialized on the GPU), the CPU cannot predict the background against which you're rendering, so subpixel rendering (ClearType) would need to occur on the GPU as well, which Microsoft hasn't implemented.

Between "it's harder to do" and "it's less useful" (due to increased dpi these days), it has fallen out of favor.

[Nuklon]

I have a workaround for Windows 11 24H2 and newer when using WindowBackdropType.None. It's not possible with Mica and Acrylic given how they're rendered.

[Joe-Fernico]

Hey @Nuklon, all the information is in my original post to get Cleartype working:

• GlassFrameThickness = new Thickness(0), with WindowBackdropType.None in Windows 11 gives a border and ClearType working.
• Currently if WindowBackdropType is set to None, 0.00001 is set as the GlassFrameThickness. Anything other than 0 means a call to DwmExtendFrameIntoClientArea and then ClearType doesn't work.
• I suggested a call to Utilities.IsOSWindows11OrNewer, but I have not tested on Windows 7 and I assumed that the 0.00001 was a fix for W10. I am also not sure if this would cover someone on less than Windows 11 24H2

[Nuklon]

GlassFrameThickness = new Thickness(0), with WindowBackdropType.None in Windows 11 gives a border and ClearType working.

No, it doesn't give a border (see screenshots above). It only gives a border when you set WindowCornerPreference to Rounded or RoundedSmall but not with Default and DoNotRound.

Check my PR with a fix for latest Windows 11 versions. It's not fixable for Mica and Acrylic as these surfaces are always rendered with an alpha channel.