com.kk_electronic.kkportal.core.dnd.MousePanel.java Source code

Introduction

Here is the source code for com.kk_electronic.kkportal.core.dnd.MousePanel.java

Source

/*
 * Copyright 2010 kk-electronic a/s. 
 * 
 * This file is part of KKPortal.
 *
 * KKPortal is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * KKPortal 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.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with KKPortal.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
package com.kk_electronic.kkportal.core.dnd;

import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.event.dom.client.MouseDownEvent;
import com.google.gwt.event.dom.client.MouseMoveEvent;
import com.google.gwt.event.dom.client.MouseMoveHandler;
import com.google.gwt.event.dom.client.MouseUpEvent;
import com.google.gwt.event.dom.client.MouseUpHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.ui.LayoutPanel;
import com.google.gwt.user.client.ui.RootLayoutPanel;
import com.google.gwt.user.client.ui.Widget;

public class MousePanel implements MouseMoveHandler, MouseUpHandler {
    private HandlerRegistration handlerRegistration;
    private HandlerRegistration handlerRegistration2;
    private LayoutPanel parent;
    private Widget widget;
    private int height;
    private int width;
    private int offsetX;
    private int offsetY;
    private MouseUpHandler mouseUpHandler;
    private MouseMoveHandler mouseMoveHandler;

    public MousePanel() {
        parent = RootLayoutPanel.get();
    }

    public void attachWidgetToMouse(MouseDownEvent event, Widget w, MouseMoveHandler mouseMoveHandler,
            MouseUpHandler mouseUpHandler) {
        this.mouseMoveHandler = mouseMoveHandler;
        this.mouseUpHandler = mouseUpHandler;
        if (widget == w)
            return;

        clearWidgetFromMouse();
        widget = w;

        if (widget != null) {
            height = w.getOffsetHeight();
            width = w.getOffsetWidth();
            offsetX = event.getRelativeX(w.getElement());
            offsetY = event.getRelativeY(w.getElement());
            parent.add(widget);
            parent.setWidgetTopHeight(widget, event.getClientY() - offsetY, Unit.PX, height, Unit.PX);
            parent.setWidgetLeftWidth(widget, event.getClientX() - offsetX, Unit.PX, width, Unit.PX);
            attachHandlers();
        }
    }

    public void clearWidgetFromMouse() {
        if (widget != null) {
            detachHandlers();
            /*
             * Do not use widget.removeFromParent() since the parent might not
             * be "parent" if the widget has been attached to another parent
             * meanwhile (which is very likely)
             */
            parent.remove(widget);
            widget = null;
        }
    }

    public void attachHandlers() {
        if (handlerRegistration != null)
            return;
        handlerRegistration = parent.addDomHandler(this, MouseMoveEvent.getType());
        handlerRegistration2 = parent.addDomHandler(this, MouseUpEvent.getType());
        DOM.setCapture(parent.getElement());
    }

    public void detachHandlers() {
        /*
         * We remove the handlers to make sure unnecessary processing is not done
         */
        if (handlerRegistration == null)
            return;
        handlerRegistration.removeHandler();
        handlerRegistration2.removeHandler();
        handlerRegistration = null;
        handlerRegistration2 = null;
        DOM.releaseCapture(parent.getElement());
    }

    @Override
    public void onMouseMove(MouseMoveEvent event) {
        parent.setWidgetTopHeight(widget, event.getClientY() - offsetY, Unit.PX, height, Unit.PX);
        parent.setWidgetLeftWidth(widget, event.getClientX() - offsetX, Unit.PX, width, Unit.PX);
        parent.forceLayout();
        if (mouseMoveHandler != null) {
            mouseMoveHandler.onMouseMove(event);
        }
    }

    @Override
    public void onMouseUp(MouseUpEvent event) {
        if (mouseUpHandler != null) {
            mouseUpHandler.onMouseUp(event);
        }
    }
}