org.eclipse.swt.widgets.Composite#requestLayout ( )源码实例Demo

private void addDropListener(Composite parent) {
	LocalSelectionTransfer transfer = LocalSelectionTransfer.getTransfer();

	DropTargetAdapter dragAdapter = new DropTargetAdapter() {
		@Override
		public void drop(DropTargetEvent event) {
			Control droppedObj = (Control) ((StructuredSelection) transfer.getSelection()).getFirstElement();

			// Get the existing parent of the dragged control
			Composite oldParent = droppedObj.getParent();

			if (oldParent == parent) {
				return;
			}

			if  (droppedObj instanceof Label) {
				System.out.println("Dropped");
			}
			// handle the drop
			if (droppedObj instanceof Label) {
				Label droppedLabel = (Label) droppedObj;
				droppedLabel.setParent(parent); // Change parent
			}

			if (droppedObj instanceof Button) {
				Button droppedButton = (Button) droppedObj;
				droppedButton.setParent(parent); // Change parent
			}

			// request a layout pass
			oldParent.requestLayout();
			// If you change that to layout the layout will be correct
			parent.layout();
		}
	};

	DropTarget dropTarget = new DropTarget(parent, DND.DROP_MOVE | DND.DROP_COPY);
	dropTarget.setTransfer(new Transfer[] { transfer });
	dropTarget.addDropListener(dragAdapter);
}
 

@Override
protected Control createContents(final Composite parent) {
	this.setSize(new Point(600, 600));

	final BuiltInLibrariesLabelProvider labelProvider = new BuiltInLibrariesLabelProvider(projectExplorerhelper);
	final Composite control = new Composite(parent, NONE);
	control.setLayout(GridLayoutFactory.fillDefaults().numColumns(2).equalWidth(false).create());
	control.setLayoutData(fillDefaults().align(FILL, FILL).create());

	viewer = new TreeViewerBuilder(singletonList(""), contentProvider.get())
			.setVirtual(true)
			.setHeaderVisible(false)
			.setUseHashlookup(true)
			.setHasBorder(true)
			.setColumnWeights(asList(1))
			.setLabelProvider(new DelegatingStyledCellLabelProvider(labelProvider))
			.build(control);

	setViewerInput();

	final Composite subComposite = new Composite(control, NONE);
	subComposite.setLayout(GridLayoutFactory.fillDefaults().create());
	subComposite.setLayoutData(fillDefaults().align(END, TOP).create());

	final Button install = createEnabledPushButton(subComposite, "Install npm...",
			"Runs 'npm install' with the given package and version. Uses 'yarn add' in a yarn workspace.",
			new InstallNpmDependencyButtonListener(this::updateLocations,
					libManager, validatorHelper, semverHelper, statusHelper, this::getSelectedNodeModulesURI));

	final Button uninstall = createEnabledPushButton(subComposite, "Uninstall npm...",
			"Runs 'npm uninstall' with the given package and version. Uses 'yarn remove' in a yarn workspace.",
			new UninstallNpmDependencyButtonListener(this::updateLocations,
					libManager, validatorHelper, statusHelper, this::getSelectedNpm));

	createPlaceHolderLabel(subComposite);

	createPlaceHolderLabel(subComposite);

	createEnabledPushButton(subComposite, "Re-Build node_modules",
			"Cleans the type information from the IDE and then re-build the type information of all node_modules.",
			new RereigsterAllNpmsButtonListener(this::reregisterNpms, statusHelper));

	createEnabledPushButton(subComposite, "Clean node_modules",
			"Runs 'npm clean' on all node_modules folders. Uses 'yarn clean' in a yarn workspace.",
			new CleanAllNpmsButtonListener(this::cleanNpms, statusHelper));

	viewer.addSelectionChangedListener(new ISelectionChangedListener() {

		@Override
		public void selectionChanged(final /* @Nullable */ SelectionChangedEvent event) {
			install.setEnabled(false);
			uninstall.setEnabled(false);

			Object selectedItem = getSelectedItem();
			if (selectedItem instanceof SafeURI) {
				install.setEnabled(true);
			}
			if (selectedItem instanceof IN4JSProject) {
				uninstall.setEnabled(true);
			}
		}
	});

	control.requestLayout();

	return control;
}