DragDropUtils.java :  » GWT » gwtwindowmanager » org » gwm » splice » client » util » js » Java Open Source

/*
 * Copyright (c) 2006/2007 Flipperwing Ltd. (http://www.flipperwing.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package org.gwm.splice.client.util.js;

import org.gwm.splice.client.desktop.DesktopManager;

import com.google.gwt.user.client.Element;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Widget;

public class DragDropUtils {

  private static boolean initialized = false;
  private static Element dragElement = null;
  private static int startX;
  private static int startY;
  private static int offsetX;
  private static int offsetY;
  private static int height;
  private static int width;
  
  private static boolean elementMoved = false;
  private static int orgZindex;
  
  private static int minLeft;
  private static int minTop;
  private static int maxRight;
  private static int maxBottom;
  
  
  ////////////////////////////////////////////////////////////////////////////////////////////////////
  
  public static void makeDraggable(Widget w) {
    makeDraggable(w, null);
  }
  public static void makeDraggable(Widget w, IMouseClickListener listener) {
    init();
    ElementMouseHandler handler = new ElementMouseHandler(w, listener);
    MouseUtils.setMouseDownHandler(w, handler);
    MouseUtils.setMouseUpHandler(w, handler);
  }
  
  ////////////////////////////////////////////////////////////////////////////////////////////////////
  
  private static void init() {
    if(initialized) {
      return;
    }
    IMouseHandler handler = new PageMouseHandler();
    MouseUtils.setMouseMoveHandler(handler);
    MouseUtils.setMouseUpHandler(handler);
  }
  
  private static class ElementMouseHandler extends MouseHandler {
    Widget w;
    IMouseClickListener listener;
    
    ElementMouseHandler(Widget w, IMouseClickListener listener) {
      this.w = w;
      this.listener = listener;
    }
    
    public boolean onMouseDown(int x, int y, int button) {
      if(button == MouseUtils.LEFT_BUTTON) {
        // only on left button
        dragElement = w.getElement();
        startX = x;
        startY = y;
        width = w.getOffsetWidth();
        height = w.getOffsetHeight();
        offsetX = x - w.getAbsoluteLeft();
        offsetY = y - w.getAbsoluteTop();
        _setElementZIndex(dragElement, 100);
        
        DesktopManager dt = DesktopManager.getInstance();
        minLeft = dt.getLeftMargin();
        minTop = dt.getTopMargin();
        maxRight = Window.getClientWidth() - dt.getRightMargin();
        maxBottom = Window.getClientHeight() - dt.getBottomMargin();
        
        return false;
      }
      return true;
    }

    public boolean onMouseUp(int x, int y, int button) {
      _setElementZIndex(dragElement, orgZindex);
      dragElement = null;
      if(elementMoved) {
        elementMoved = false;
        return false;
      }
      elementMoved = false;
      if(listener != null) {
        listener.onClick(x, y, button);
      }
      return true;
    }
  }
  
  private static class PageMouseHandler extends MouseHandler {

    public boolean onMouseMove(int x, int y) {
      if(dragElement == null || (x == startX && y == startY)) {
        return true;
      }
      int left = x - offsetX;
      int top = y - offsetY;
      int right = left + width;
      int bottom = top + height;
      
      if(left <= minLeft || top <= minTop || right >= maxRight || bottom >= maxBottom) {
        dragElement = null;
        return true;
      }
      
      // move stuff here
      _setElementPosition(dragElement, x - offsetX, y - offsetY);
      elementMoved = true;
      return false;
    }

    
  }

  ////////////////////////////////////////////////////////////////////////////////////////////////////
  
  /**
   * Sets style to 'absolute' and sets postion.
   */
  public static void setWidgetPosition(Widget widget, int x, int y) {
    _setElementPosition(widget.getElement(), x, y);
  }
  
  ////////////////////////////////////////////////////////////////////////////////////////////////////
  
  private static native void _setElementPosition(Element obj, int x, int y) /*-{
  obj.style.position = 'absolute';
  obj.style.top = y;
  obj.style.left = x;
}-*/; 

  private static native void _setElementZIndex(Element obj, int val) /*-{
  obj.style.zIndex = val;
}-*/; 


}