ReplacePanel.java

/*
 * Copyright 2015 ArcBees 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 com.arcbees.ui;

import com.google.gwt.dom.client.Element;
import com.google.gwt.user.client.ui.HTMLPanel;
import com.google.gwt.user.client.ui.HasOneWidget;
import com.google.gwt.user.client.ui.HasVisibility;
import com.google.gwt.user.client.ui.IsWidget;
import com.google.gwt.user.client.ui.SimplePanel;
import com.google.gwt.user.client.ui.Widget;

/*
 * Panel that wraps a GWT simple panel to be replaced by the widgetToAttach. This will make sure that the DIV element
 * is being replaced rather than having the widget inserted in it.
 *
 * The result of this will be to have a better, cleaner, dom.
 */
public class ReplacePanel implements IsWidget, HasOneWidget, HasVisibility {
    static class WrongParentTypeException extends RuntimeException {
        WrongParentTypeException(String message) {
            super(message);
        }
    }

    private IsWidget widget;

    private String style;

    public ReplacePanel() {
        widget = new SimplePanel();
    }

    @Override
    public Widget asWidget() {
        return widget.asWidget();
    }

    @Override
    public Widget getWidget() {
        return widget.asWidget();
    }

    @Override
    public void setWidget(Widget widgetToAttach) {
        Widget parentAsWidget = widget.asWidget().getParent();
        if (!(parentAsWidget instanceof HTMLPanel)) {
            throw new WrongParentTypeException("The parent of ReplacePanel must be of type HTMLPanel");
        }

        HTMLPanel parent = (HTMLPanel) parentAsWidget;

        if (widgetToAttach == null) {
            widgetToAttach = new SimplePanel();
        }

        parent.addAndReplaceElement(widgetToAttach, (Element) widget.asWidget().getElement());

        widget = widgetToAttach;

        if (style != null && !style.isEmpty()) {
            widget.asWidget().addStyleName(style);
        }
    }

    @Override
    public void setWidget(IsWidget widget) {
        if (widget == null) {
            widget = new SimplePanel();
        }

        setWidget(widget.asWidget());
    }

    @Override
    public boolean isVisible() {
        return asWidget().isVisible();
    }

    @Override
    public void setVisible(boolean visible) {
        asWidget().setVisible(visible);
    }

    public void setAddStyleName(String style) {
        this.style = style;
    }
}