com.google.gwt.user.cellview.client.Header.java Source code

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Here is the source code for com.google.gwt.user.cellview.client.Header.java

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/*
 * Copyright 2010 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.cellview.client;

import com.google.gwt.cell.client.Cell;
import com.google.gwt.cell.client.Cell.Context;
import com.google.gwt.cell.client.ValueUpdater;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;

/**
 * A table column header or footer.
 * 
 * @param <H> the {@link Cell} type
 */
public abstract class Header<H> {

    private final Cell<H> cell;

    private ValueUpdater<H> updater;

    /**
     * Construct a Header with a given {@link Cell}.
     * 
     * @param cell the {@link Cell} responsible for rendering items in the header
     */
    public Header(Cell<H> cell) {
        this.cell = cell;
    }

    /**
     * Return the {@link Cell} responsible for rendering items in the header.
     * 
     * @return the header Cell
     */
    public Cell<H> getCell() {
        return cell;
    }

    /**
     * Get the key for the header value. By default, the key is the same as the
     * value. Override this method to return a custom key.
     * 
     * @return the key associated with the value
     */
    public Object getKey() {
        return getValue();
    }

    /**
     * Return the header value.
     * 
     * @return the header value
     */
    public abstract H getValue();

    /**
     * Handle a browser event that took place within the header.
     * 
     * @param context the context of the header
     * @param elem the parent Element
     * @param event the native browser event
     */
    public void onBrowserEvent(Context context, Element elem, NativeEvent event) {
        cell.onBrowserEvent(context, elem, getValue(), event, updater);
    }

    /**
     * Render the header.
     * 
     * @param context the context of the header
     * @param sb a {@link SafeHtmlBuilder} to render into
     */
    public void render(Context context, SafeHtmlBuilder sb) {
        cell.render(context, getValue(), sb);
    }

    /**
     * Set the {@link ValueUpdater}.
     * 
     * @param updater the value updater to use
     */
    public void setUpdater(ValueUpdater<H> updater) {
        this.updater = updater;
    }
}