Blurry icon in application switcher

[ialokim]

trafficstars

When setting the window icon using the Windows API, the icon looks blurry / pixelated in the XFCE application switcher (when pressing ALT+TAB). I think it has to do with how the icon is rasterized and set in Window.desktop.kt:

// In fact, this size doesn't affect anything on Windows/Linux, and isn't used by macOs (macOs
// doesn't have separate Window icons). We specify it to support Painter's with
// Unspecified intrinsicSize
private val iconSize = Size(32f, 32f)

internal fun Window.setIcon(painter: Painter?) {
    setIconImage(painter?.toAwtImage(density, layoutDirection, iconSize))
}

Java Swing/AWT has support for setting multiple versions of the window icon by setIconImages() from which the OS / Window Manager should be able to choose the right one depending on the resolution.

[ialokim]

Since you've added the windows label: I'm actually experiencing this on a XFCE desktop, so I don't know if the same problems occurs on Windows too, but it's definitely not something Windows-specific.

[ptitjes]

Yep, I observe the same on Fedora/Linux with Wayland and Gnome.

Here is my workaround:

Window(
    // ...
) {
    // TODO this is a workaround for https://github.com/JetBrains/compose-jb/issues/1838
    val icon = painterResource("/assets/icon.svg")
    val density = LocalDensity.current
    SideEffect {
        window.iconImage = icon.toAwtImage(density, LayoutDirection.Ltr, Size(128f, 128f))
    }
    
    // ...
}

[sebkur]

I think the problem is in this file, currently line 174: https://github.com/JetBrains/compose-multiplatform-core/blob/jb-main/compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/util/Windows.desktop.kt

// In fact, this size doesn't affect anything on Windows/Linux, and isn't used by macOS (macOS
// doesn't have separate Window icons). We specify it to support Painter's with
// Unspecified intrinsicSize
private val iconSize = Size(32f, 32f)

internal fun Window.setIcon(painter: Painter?) {
    setIconImage(painter?.toAwtImage(density, layoutDirectionFor(this), iconSize))
}

looks like that assumption is not right, the size does seem to affect things on Windows and Linux.