Dynamic refresh of a composite

Question

I have a tree viewer next to a specialized viewer. When something is selected in the tree viewer, details about this object are shown in the specialized viewer. TreeViewer tree, Composite control, and MySpecializedViewer viewer are instance variables.

public TheEverythingViewer(Composite parent) {
    control = new Composite(parent, SWT.NONE);
    control.setLayout(new GridLayout(2, false));

    tree = new TreeViewer(control);
    tree.setContentProvider(new MyContentProvider());
    tree.setLabelProvider(new MyLabelProvider());
    tree.setUseHashlookup(true);
    tree.getControl().setLayoutData(new GridData(GridData.BEGINNING, GridData.FILL, false, true, 1, 1));

    tree.addSelectionChangedListener(new ISelectionChangedListener() {
        @Override public void selectionChanged(SelectionChangedEvent event) {
            try {
                IStructuredSelection sel = (IStructuredSelection) event.getSelection();
                MyClass myInput = (MyClass) sel.getFirstElement();

                if (viewer != null)
                    if (!viewer.getControl().isDisposed())
                        viewer.getControl().dispose();
                viewer = new MySpecializedViewer(control, table);

                control.getShell().layout();
            } catch (Exception e) {
                if (viewer != null)
                    if (!viewer.getControl().isDisposed())
                        viewer.getControl().dispose();
                viewer = null;
            }
        }
    });
}

Am I doing something wrong? I just want:

+--------------+--------------------------------------------+
| + Node       |                                            |
|   - Node     |                                            |
|   + Node     |                       My                   |
|     - Node   |                                            |
|   - Node     |      Specialized                           |
|              |                              Viewer        |
|              |                                            |
|              |                                            |
|              |                                            |
|              |                                            |
|              |                                            |
|              |                                            |
|              |                +--------+                  |
|              |                |        |                  |
|              |                |        |                  |
|              |                |        |                  |
|              |                +--------+                  |
|              |                                            |
|              |                                            |
|              |                                            |
|              |                                            |
+--------------+--------------------------------------------+

The specialized viewer has tables that need to consume more or less space depending on the selected node. And currently, creating a new instance of the specialized viewer is much, much simpler than changing it's input (that wouldn't work ATM).

score 2 · Accepted Answer · answered Jul 07 '12 at 06:21

2

Yes, you shouldn't be recreating the viewer every time selection changes in your tree, you should just be sending the tree's selection to the existing viewer as its input, at which point it can do whatever you want it to do with the new input. You're also never setting the layout data on your specialized viewer's control, and then forcing the entire shell to re-layout is wasteful.

answered Jul 07 '12 at 06:21

nitind

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1

Not recreating the viewer involves changing the structure of the table. If I don't force the shell to re-layout, what method do I call (on what object) to get the stupid thing to actually update the UI? I've never seen `someControl.redraw()` actually work in this case. – Ethan Reesor Jul 07 '12 at 14:12
1

What table? There was no mention of a table. How would *not* recreating the viewer require changing the structure? pack() and layout() the parent Composite, not the entire Shell. – nitind Jul 07 '12 at 17:39
1

I mentioned at the end, "The specialized viewer has tables that need to consume more or less space depending on the selected node." The pack() and layout() methods seem to be doing the trick. Now I'm dealing with a funny error where, each `pack(); layout();`, the table eats up more width, progressing father and farther past the edge of the composite. – Ethan Reesor Jul 08 '12 at 03:38
1

SWT is a mite obtuse. There should really be refresh(int flags) with flags for redraw, pack, layout, refresh, etc. Not four different functions. – Ethan Reesor Jul 08 '12 at 03:39
1

Don't use `pack()`. If you set layout on a container, all you need is to call `layout()` when its children changed. – dragn Jul 11 '12 at 11:22

Dynamic refresh of a composite

1 Answers1