Canvas

A composable that hands you the raw Graphics2D of a blank Swing surface so you can draw whatever you like.

Repaint is snapshot-observed. Any snapshot state you read directly inside onDraw is tracked; when such state changes the surface repaints and re-invokes onDraw automatically. Read your state where you use it, at paint time:

var radius by remember { mutableStateOf(10) }
Canvas(modifier = SwingModifier.preferredSize(Dimension(200, 200))) { g, width, height ->
    g.fillOval(width / 2 - radius, height / 2 - radius, radius * 2, radius * 2)
}

The surface is non-opaque and paints no background of its own: only what onDraw renders appears. Size it with the preferred-size modifier (see org.jetbrains.compose.swing.modifier.layout.preferredSize).

Parameters

See also