/* * Smart GWT (GWT for SmartClient) * Copyright 2008 and beyond, Isomorphic Software, Inc. * * Smart GWT is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License version 3 * as published by the Free Software Foundation. Smart GWT is also * available under typical commercial license terms - see * http://smartclient.com/license * * This software is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. */ import com.smartgwt.client.types.Alignment; import com.smartgwt.client.types.DragAppearance; import com.smartgwt.client.types.Overflow; import com.smartgwt.client.types.Visibility; import com.smartgwt.client.util.EventHandler; import com.smartgwt.client.widgets.Canvas; import com.smartgwt.client.widgets.Img; import com.smartgwt.client.widgets.Label; import com.smartgwt.client.widgets.events.*; import com.google.gwt.core.client.EntryPoint; public class DragEventsSample implements EntryPoint { public void onModuleLoad() { Canvas canvas = new Canvas(); final Img img = new Img("pieces/48/pawn_green.png", 48, 48) { @Override protected boolean setDragTracker() { Canvas c = new Canvas(); String html = Canvas.imgHTML("pieces/24/pawn_green.png", 24, 24, null, null, null); EventHandler.setDragTracker(html); return false; } }; img.setCanDrag(true); img.setCanDrop(true); img.setDragAppearance(DragAppearance.TRACKER); final DropLabel label = new DropLabel(); label.setLeft(100); label.setWidth(300); label.setHeight(300); label.setBackgroundColor("#C3D9FF"); label.setAlign(Alignment.CENTER); label.setContents("Show Drop Reticle"); label.setOverflow(Overflow.HIDDEN); label.setCanAcceptDrop(true); canvas.addChild(img); canvas.addChild(label); canvas.draw(); } class DropLabel extends Label { private Canvas crossHairX; private Canvas crossHairY; @Override protected void onInit() { crossHairX = createCrossHair(); crossHairY = createCrossHair(); addChild(crossHairX); addChild(crossHairY); this.addDropOverHandler(new DropOverHandler() { public void onDropOver(DropOverEvent event) { getCrossHairX().show(); getCrossHairY().show(); updateCrossHairs(); } }); this.addDropMoveHandler(new DropMoveHandler() { public void onDropMove(DropMoveEvent event) { updateCrossHairs(); } }); this.addDropOutHandler(new DropOutHandler() { public void onDropOut(DropOutEvent event) { getCrossHairX().hide(); getCrossHairY().hide(); } }); } private Canvas createCrossHair() { Canvas canvas = new Canvas(); canvas.setWidth(this.getWidth() + 2); canvas.setHeight(this.getHeight() + 2); canvas.setBorder("1px solid #6a6a6a"); canvas.setVisibility(Visibility.HIDDEN); return canvas; } public Canvas getCrossHairX() { return crossHairX; } public Canvas getCrossHairY() { return crossHairY; } public void updateCrossHairs() { int x = getOffsetX(); int y = getOffsetY(); // crossHairX is the -X and +Y axis of the crossHair crossHairX.setLeft(x - getWidth() - 1); crossHairX.setTop(y - getHeight() - 1); // crossHairY is +X, -Y crossHairY.setLeft(x); crossHairY.setTop(y); } } }