bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/dnd/DragAndDropUtil.java

package org.eclipse.e4.workbench.ui.renderers.swt.dnd;

import org.eclipse.e4.ui.model.application.ui.MElementContainer;
import org.eclipse.e4.ui.model.application.ui.MUIElement;
import org.eclipse.e4.ui.workbench.swt.internal.AbstractPartRenderer;
import org.eclipse.swt.custom.CTabFolder;
import org.eclipse.swt.custom.CTabItem;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.ToolBar;
import org.eclipse.swt.widgets.ToolItem;

public class DragAndDropUtil {
	public class CursorInfo {
		MUIElement curElement;
		MUIElement itemElement;
		int itemIndex;
		Rectangle itemRect;
	}

	private Display display;

	public DragAndDropUtil(Display display) {
		this.display = display;
	}

	public CursorInfo getCursorInfo() {
		CursorInfo info = new CursorInfo();
		Control curControl = display.getCursorControl();
		if (curControl == null) {
			return info;
		}

		info.curElement = getModelElement(curControl);
		if (info.curElement instanceof MElementContainer<?>) {
			Point cursorPos = display.getCursorLocation();
			setItemElement(info, cursorPos);
		}
		return info;
	}

	private void setItemElement(CursorInfo info, Point cursorPos) {
		info.itemIndex = -1;
		info.itemRect = null;

		Control ctrl = (Control) info.curElement.getWidget();

		// KLUDGE!! Should delegate to curElement's renderer
		if (ctrl instanceof CTabFolder) {
			CTabFolder ctf = (CTabFolder) ctrl;
			cursorPos = display.map(null, ctf, cursorPos);
			CTabItem curItem = ctf.getItem(cursorPos);
			if (curItem != null) {
				info.itemElement = (MUIElement) curItem
						.getData(AbstractPartRenderer.OWNING_ME);
				CTabItem[] items = ctf.getItems();
				for (int i = 0; i < items.length; i++) {
					if (items[i] == curItem) {
						info.itemIndex = i;
						info.itemRect = curItem.getBounds();
						info.itemRect = display.map(ctf, ctf.getShell(),
								info.itemRect);
					}
				}
			}
		} else if (ctrl instanceof ToolBar) {
			ToolBar tb = (ToolBar) ctrl;
			cursorPos = display.map(null, tb, cursorPos);
			ToolItem curItem = tb.getItem(cursorPos);
			if (curItem != null) {
				info.itemElement = (MUIElement) curItem
						.getData(AbstractPartRenderer.OWNING_ME);
				ToolItem[] items = tb.getItems();
				for (int i = 0; i < items.length; i++) {
					if (items[i] == curItem) {
						info.itemIndex = i;
						info.itemRect = curItem.getBounds();
						info.itemRect = display.map(tb, tb.getShell(),
								info.itemRect);
					}
				}
			}
		}
	}

	private MUIElement getModelElement(Control ctrl) {
		if (ctrl == null)
			return null;

		MUIElement element = (MUIElement) ctrl
				.getData(AbstractPartRenderer.OWNING_ME);
		if (element != null)
			return element;

		return getModelElement(ctrl.getParent());
	}
}