Size SwingPanel according to its content

[m-sasha]

Size SwingPanel according to its min/pref/max sizes.

Fixes https://youtrack.jetbrains.com/issue/CMP-3206

Screen.Recording.2025-08-15.at.15.12.41.mp4

Testing

Added a unit test and tested manually with

fun main() {
    var text = "I'm a Swing JLabel"
    val label = JLabel(text)

    singleWindowApplication {
        Box(
            contentAlignment = Alignment.Center,
            modifier = Modifier
                .fillMaxSize()
                .background(Color.Red)
        ) {
            SwingPanel(
                factory = { label },
                modifier = Modifier
//                    .size(200.dp, 200.dp)
            )
        }

        LaunchedEffect(Unit) {
            delay(1000)
            while (true) {
                repeat(20) {
                    delay(200)
                    text = "#${text}#"
                    label.text = text
                }
                repeat(20) {
                    delay(200)
                    text = text.substring(1, text.length - 1)
                    label.text = text
                }
            }
        }
    }
}

Release Notes

Fixes - Desktop

• SwingPanel no longer requires to be manually sized to a fixed value; it will size according to its content's min/pref/max sizes.

[MatkovIvan]

Please move it into SwingInteropViewHolder or separate file

[m-sasha]

What is the advantage of doing that?

Under the same reasoning you would move SwingInteropViewGroup into SwingInteropViewHolder.

[MatkovIvan]

Why not component directly?

[m-sasha]

Did you mean to ask this in the next conversation down below?

I could ask the component directly, but it seems a bit more correct to follow the hierarchy. Maybe tomorrow we'll want SwingPanels to have a border for debugging purposes or something.

[MatkovIvan]

It's basically the same consern as with assigning the size directly - it's not supposed to be the same, and I'm wonder if this might break it in some cases

[MatkovIvan]

Did you mean to ask this in the next conversation down below?

Yep, sorry

[MatkovIvan]

Under the same reasoning you would move SwingInteropViewGroup into SwingInteropViewHolder.

As far as I remember @igordmn wanded to keep them file-private, but it's no longer the case

[m-sasha]

It delegates directly to the child, so I don't see how it can break.

Also, it's not actually possible to ask the component directly. When SwingInteropViewHolder calls its super constructor, it needs to pass it measurePolicy, but at this point the component (typedInteropView) doesn't exist yet.

[m-sasha]

So it's not possible to create AwtContentMeasurePolicy unless it would be an inner class of SwingInteropViewHolder, or it would need to take a getter () -> Component rather than the Component itself. Seems too much...

[MatkovIvan]

Why do we need to override getPreferredSize/getMinimumSize/getMaximumSize if we control sizing manually now? Does it really related to the fix of the issue?

[m-sasha]

AwtContentMeasurePolicy queries SwingInteropViewGroup for its min/pref/max size.

[MatkovIvan]

The main blocker from previous iteration was resolved - not blocking anymore.

The main review should still on @igordmn