Eraser malfunction after System Drag & Drop

[NiazSagor]

After initiating a system drag-and-drop session via view.startDragAndDrop (triggered by a long-press on the DrawingSurface), subsequent touch interactions for the Eraser tool fail to function.
Although the lines are erased from the underlying canvas, the screen still displays them. The strokes_data column for that particular note contains an empty array.

Steps to Reproduce

1. Open a Note in Cahier and draw several lines using any brush.
2. Toggle the Eraser mode off (ensure you are in drawing mode).
3. Long-press on the drawing to initiate the System Drag (the ghost image appears).
4. Release the drag (the ghost image disappears).
5. Toggle Eraser mode ON.
6. Attempt to erase the existing lines.

Actual Result: The lines remain visible on the canvas. The eraser appears "dead" or desynced.

Expected Result: The eraser should function immediately and accurately after the drag session ends.

Screen_recording_20260127_214724.mp4

[NiazSagor]

What I have found working is to invalidate the current view that contains the DrawingSurface after the DragEvent.ACTION_DRAG_ENDED event.

I added this to the DrawingSurface composable, and it resolves the issue.

val view = LocalView.current
DisposableEffect(view) {
    val listener = View.OnDragListener { v, event ->
        when (event.action) {
            DragEvent.ACTION_DRAG_STARTED -> true
            DragEvent.ACTION_DRAG_ENDED -> {
                v.invalidate()
                true
            }
            else -> false
        }
    }
    view.setOnDragListener(listener)
    onDispose { view.setOnDragListener(null) }
}

[cka-dev]

Hi @NiazSagor,

Thanks for catching this , and finding a solution.
I will test it on my end and create a PR to fix it.