Splitter.java

/*
 * Copyright 2015 JBoss, by Red Hat, Inc
 *
 * 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.uberfire.ext.plugin.client.widget.split;

import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.Style;
import com.google.gwt.event.dom.client.MouseDownEvent;
import com.google.gwt.event.dom.client.MouseDownHandler;
import com.google.gwt.event.dom.client.MouseUpEvent;
import com.google.gwt.event.dom.client.MouseUpHandler;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.FlowPanel;

public abstract class Splitter extends FlowPanel {

    protected static Element glassElem = null;

    protected boolean mouseDown;

    public Splitter() {
        if (glassElem == null) {
            glassElem = Document.get().createDivElement();
            glassElem.getStyle().setPosition(Style.Position.ABSOLUTE);
            glassElem.getStyle().setTop(0,
                                        Style.Unit.PX);
            glassElem.getStyle().setLeft(0,
                                         Style.Unit.PX);
            glassElem.getStyle().setMargin(0,
                                           Style.Unit.PX);
            glassElem.getStyle().setPadding(0,
                                            Style.Unit.PX);
            glassElem.getStyle().setBorderWidth(0,
                                                Style.Unit.PX);

            // We need to set the background color or mouse events will go right
            // through the glassElem. If the SplitPanel contains an iframe, the
            // iframe will capture the event and the slider will stop moving.
            glassElem.getStyle().setProperty("background",
                                             "white");
            glassElem.getStyle().setOpacity(0.0);
        }

        sinkEvents(Event.ONMOUSEDOWN | Event.ONMOUSEUP | Event.ONMOUSEMOVE | Event.ONDBLCLICK);
        addDomHandler(new MouseDownHandler() {
                          @Override
                          public void onMouseDown(final MouseDownEvent event) {
                              mouseDown = true;
                              int width = Math.max(Window.getClientWidth(),
                                                   Document.get().getScrollWidth());
                              int height = Math.max(Window.getClientHeight(),
                                                    Document.get().getScrollHeight());
                              glassElem.getStyle().setHeight(height,
                                                             Style.Unit.PX);
                              glassElem.getStyle().setWidth(width,
                                                            Style.Unit.PX);
                              Document.get().getBody().appendChild(glassElem);

                              buildOffset(event);
                              Event.setCapture(getElement());
                              event.preventDefault();
                          }
                      },
                      MouseDownEvent.getType());

        addDomHandler(new MouseUpHandler() {
                          @Override
                          public void onMouseUp(final MouseUpEvent event) {
                              mouseDown = false;

                              glassElem.removeFromParent();

                              Event.releaseCapture(getElement());
                          }
                      },
                      MouseUpEvent.getType());
    }

    protected abstract void buildOffset(MouseDownEvent event);
}