com.google.gwt.user.client.ui.SimpleLayoutPanel.java Source code

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Here is the source code for com.google.gwt.user.client.ui.SimpleLayoutPanel.java

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/*
 * Copyright 2011 Google 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.google.gwt.user.client.ui;

import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.layout.client.Layout;
import com.google.gwt.layout.client.Layout.Layer;

/**
 * A simple panel that {@link ProvidesResize} to its one child.
 */
public class SimpleLayoutPanel extends SimplePanel implements RequiresResize, ProvidesResize {

    private Layer layer;
    private final Layout layout;

    public SimpleLayoutPanel() {
        layout = new Layout(getElement());
    }

    public void onResize() {
        if (widget instanceof RequiresResize) {
            ((RequiresResize) widget).onResize();
        }
    }

    @Override
    public boolean remove(Widget w) {
        // Validate.
        if (widget != w) {
            return false;
        }

        // Orphan.
        try {
            orphan(w);
        } finally {
            // Physical detach.
            layout.removeChild(layer);
            layer = null;

            // Logical detach.
            widget = null;
        }
        return true;
    }

    @Override
    public void setWidget(Widget w) {
        // Validate
        if (w == widget) {
            return;
        }

        // Detach new child.
        if (w != null) {
            w.removeFromParent();
        }

        // Remove old child.
        if (widget != null) {
            remove(widget);
        }

        // Logical attach.
        widget = w;

        if (w != null) {
            // Physical attach.
            layer = layout.attachChild(widget.getElement(), widget);
            layer.setTopHeight(0.0, Unit.PX, 100.0, Unit.PCT);
            layer.setLeftWidth(0.0, Unit.PX, 100.0, Unit.PCT);

            adopt(w);

            // Update the layout.
            layout.layout();
            onResize();
        }
    }

    @Override
    protected void onLoad() {
        layout.onAttach();
    }

    @Override
    protected void onUnload() {
        layout.onDetach();
    }
}