Feature Request: Add Drag-and-Drop Swapping for MPR Planes in Weasis

[shivaramakrishna009]

Description:
I'd like to propose adding a drag-and-drop feature to the Multi-Planar Reconstruction (MPR) views in Weasis. This would allow users to swap the planes (e.g., axial with coronal) by dragging one view panel onto another, making it easier to rearrange the layout during analysis without manual reconfiguration.

Current Behavior:
In the current MPR tool (as of v4.6.1+), the three orthogonal planes (axial, coronal, sagittal) are fixed in their positions based on the layout model (e.g., 1x2 or 2x1). Users can rotate or adjust slices, but swapping planes requires closing and reopening the MPR or changing layouts, which disrupts workflow.

Proposed Feature:

• Gesture: Left-mouse drag from one MPR view (source) and drop onto another (target). Only initiates if drag distance > 10 pixels (to avoid accidental swaps) and not over the crosshair (to prevent conflicts with crosshair dragging).
• Behavior: On drop, swap the planes, images, slice indices, thickness extensions, and view actions (e.g., WL, zoom, LUT) between the source and target views. Recompute crosslines and recenter for seamless continuity.
• Toggle: Enable/disable via a context menu checkbox ("Enable Drag Swap (All Views)") or toolbar button, stored in actionsInView under ActionW.DRAG_SWAP.
• Implementation Notes:
  • Uses Swing TransferHandler for DnD, with custom Transferable carrying the source MprView and Plane.
  • Integrated with MprController for swap logic (e.g., swapMprViews(MprView a, MprView b)).
  • Handles oblique/MIP modes; tested on 3D CT/MRI series.
  • No conflicts with existing mouse handlers (e.g., crosshair via CrosshairListener).

Why Add This?
This would improve usability for radiologists, especially in dynamic reviews where quick plane rearrangement (e.g., sagittal to axial for better comparison) is common. It's intuitive, reduces clicks, and aligns with modern medical imaging tools like OsiriX or Horos.

Prototype Code Snippet (in MprView.java):

// Inner Transferable and TransferHandler for DnD
private static class MprPlaneTransferable implements Transferable {
    // [Implementation as before]
}

private static class MprTransferHandler extends TransferHandler {
    // [Implementation as before, with importData calling controller.swapMprViews]
}

// In constructor
getJComponent().setTransferHandler(new MprTransferHandler(mprController));

// Paint highlight
@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    if (isDragOver) {
        // Yellow overlay
    }
}

Questions for Community:

• Is this feature already planned or in a branch?
• Any suggestions for improvements (e.g., handling custom layouts in MprContainer)?
• Willing to contribute a PR if interested—I've prototyped it locally.

Thanks for the great tool! Looking forward to feedback.

[nroduit]

A couple of notes from the current code/UX:

Drag-and-drop is already used by the views for different actions and for dropping files/folders or series thumbnails, so adding a new global DnD semantic to swap MPR planes would risk conflicts with existing DnD behaviour (and with existing mouse handlers like crosshair dragging).
For the use-case you describe (automatic/repeatable placement of planes/layouts), the intended/cleaner solution in Weasis is hanging protocols: define the preferred layout for a modality and have Weasis arrange MPR/2D views accordingly. That keeps the UI DnD semantics intact and makes the behaviour reproducible across studies.