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

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

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/*
 * Copyright 2008 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.user.client.DOM;
import com.google.gwt.user.client.Element;

/**
 * A panel that lays all of its widgets out in a single horizontal column.
 * 
 * <p>
 * <img class='gallery' src='doc-files/HorizontalPanel.png'/>
 * </p>
 */
public class HorizontalPanel extends CellPanel implements HasAlignment, InsertPanel.ForIsWidget {

    private HorizontalAlignmentConstant horzAlign = ALIGN_DEFAULT;
    private Element tableRow;
    private VerticalAlignmentConstant vertAlign = ALIGN_TOP;

    /**
     * Creates an empty horizontal panel.
     */
    public HorizontalPanel() {
        tableRow = DOM.createTR();
        DOM.appendChild(getBody(), tableRow);

        DOM.setElementProperty(getTable(), "cellSpacing", "0");
        DOM.setElementProperty(getTable(), "cellPadding", "0");
    }

    @Override
    public void add(Widget w) {
        Element td = createAlignedTd();
        DOM.appendChild(tableRow, td);
        add(w, td);
    }

    public HorizontalAlignmentConstant getHorizontalAlignment() {
        return horzAlign;
    }

    public VerticalAlignmentConstant getVerticalAlignment() {
        return vertAlign;
    }

    public void insert(IsWidget w, int beforeIndex) {
        insert(asWidgetOrNull(w), beforeIndex);
    }

    public void insert(Widget w, int beforeIndex) {
        checkIndexBoundsForInsertion(beforeIndex);

        /*
         * The case where we reinsert an already existing child is tricky.
         * 
         * For the WIDGET, it ultimately removes first and inserts second, so we
         * have to adjust the index within ComplexPanel.insert(). But for the DOM,
         * we insert first and remove second, which means we DON'T need to adjust
         * the index.
         */
        Element td = createAlignedTd();
        DOM.insertChild(tableRow, td, beforeIndex);
        insert(w, td, beforeIndex, false);
    }

    @Override
    public boolean remove(Widget w) {
        // Get the TD to be removed, before calling super.remove(), because
        // super.remove() will detach the child widget's element from its parent.
        Element td = DOM.getParent(w.getElement());
        boolean removed = super.remove(w);
        if (removed) {
            DOM.removeChild(tableRow, td);
        }
        return removed;
    }

    /**
     * Sets the default horizontal alignment to be used for widgets added to this
     * panel. It only applies to widgets added after this property is set.
     * 
     * @see HasHorizontalAlignment#setHorizontalAlignment(HasHorizontalAlignment.HorizontalAlignmentConstant)
     */
    public void setHorizontalAlignment(HorizontalAlignmentConstant align) {
        horzAlign = align;
    }

    /**
     * Sets the default vertical alignment to be used for widgets added to this
     * panel. It only applies to widgets added after this property is set.
     * 
     * @see HasVerticalAlignment#setVerticalAlignment(HasVerticalAlignment.VerticalAlignmentConstant)
     */
    public void setVerticalAlignment(VerticalAlignmentConstant align) {
        vertAlign = align;
    }

    /**
     * <b>Affected Elements:</b>
     * <ul>
     * <li>-# = the cell at the given index.</li>
     * </ul>
     * 
     * @see UIObject#onEnsureDebugId(String)
     */
    @Override
    protected void onEnsureDebugId(String baseID) {
        super.onEnsureDebugId(baseID);
        int numChildren = getWidgetCount();
        for (int i = 0; i < numChildren; i++) {
            ensureDebugId(getWidgetTd(getWidget(i)), baseID, "" + i);
        }
    }

    private Element createAlignedTd() {
        Element td = DOM.createTD();
        setCellHorizontalAlignment(td, horzAlign);
        setCellVerticalAlignment(td, vertAlign);
        return td;
    }
}