Description Cliff Collins 2010-02-25 14:06:53 EST

Build Identifier: I20090611-1540

Complex property sheets spend more time doing layout of the controls than they need to. Some of the code generates events to re-layout which does rebuild of the values in the sheet 2 times on a tab property switch. 

The SelectionChangedListener is called multiple times for the same object and should filter the second calls to so it doesn't re-layout the tab a second time. The second call comes from listeners on itself.

Changing the code in TabbedPropertySheetPage: to be this improves the layout issues:

	class SelectionChangedListener
		implements ISelectionChangedListener {

	    IStructuredSelection current = null;
	    Object               previousInput = null;
	    
		/**
		 * Shows the tab associated with the selection.
		 */
		public void selectionChanged(SelectionChangedEvent event) {
			IStructuredSelection selection = (IStructuredSelection) event
				.getSelection();
			if ((current != null) && current.equals(selection) &&
			    (previousInput != null) && previousInput.equals(tabbedPropertyViewer.getInput()) ) {
			    return;
			}
			current = selection;
			previousInput = tabbedPropertyViewer.getInput();
			
			TabContents tab = null;
			ITabDescriptor descriptor = (ITabDescriptor) selection
					.getFirstElement();

			if (descriptor == null) {
				// pretend the tab is empty.
				hideTab(currentTab);
			} else {
				// create tab if necessary
				// can not cache based on the id - tabs may have the same id,
				// but different section depending on the selection
				tab = (TabContents) descriptorToTab.get(descriptor);

				if (tab != currentTab) {
					hideTab(currentTab);
				}

				Composite tabComposite = (Composite) tabToComposite.get(tab);
				if (tabComposite == null) {
					tabComposite = createTabComposite();
					tab.createControls(tabComposite,
						TabbedPropertySheetPage.this);
					// tabAreaComposite.layout(true);
					tabToComposite.put(tab, tabComposite);
				}
				// force widgets to be resized
				tab.setInput(tabbedPropertyViewer.getWorkbenchPart(),
					(ISelection) tabbedPropertyViewer.getInput());

				// store tab selection
				storeCurrentTabSelection(descriptor.getLabel());

				if (tab != currentTab) {
					showTab(tab);
				}

				tab.refresh();
			}
			if (tab != currentTab) {
			    tabbedPropertyComposite.getScrolledComposite().setLayoutDeferred(true);
			    tabbedPropertyComposite.getTabComposite().layout(true);
			    currentTab = tab;
	            resizeScrolledComposite();
                tabbedPropertyComposite.getScrolledComposite().setLayoutDeferred(false);
			}

			if (descriptor != null) {
				handleTabSelection(descriptor);
			}
		}



NOTE: the code below is not as critical but the resizeScrolledComposite cause a "layout" as does the tabbedPropertyComposite.getTabComposite().layout(true); but these could be handled in one layout by doing the deferred. 

			if (tab != currentTab) {
			    tabbedPropertyComposite.getScrolledComposite().setLayoutDeferred(true);
			    tabbedPropertyComposite.getTabComposite().layout(true);
			    currentTab = tab;
	            resizeScrolledComposite();
                tabbedPropertyComposite.getScrolledComposite().setLayoutDeferred(false);
			}

NOTE: it seems like if we are switch inputs with the same tab, we shouldn't need to "layout" so that is why it does the if (tab != currentTab). This also improved some performance.


This change is the most useful change:

if ((current != null) && current.equals(selection) &&
	(previousInput != null) && previousInput.equals(tabbedPropertyViewer.getInput()) ) {
	 return;
}

since the method will be call 2 times for each tab selection change. This prevents the second loop over.


NOTE, this can't be patched by a "coder" (workaround) since all these methods/classes etc are private in the package.




Reproducible: Always

Steps to Reproduce:
1.have an editor with tab properties that have many controls on the sheet (complex controls etc)
2.Switch between edit parts that cause tabs to be switched.
3.THe SelectionChangedListener is called multiple times for the same object and should filter the second calls to it doesn't re-layout the tab a second time.