com.google.gwt.user.cellview.client.Header Maven / Gradle / Ivy
/*
* 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 the {@link Cell} type
*/
public abstract class Header {
private final Cell cell;
private String headerStyleNames = null;
private ValueUpdater updater;
/**
* Construct a Header with a given {@link Cell}.
*
* @param cell the {@link Cell} responsible for rendering items in the header
*/
public Header(Cell cell) {
this.cell = cell;
}
/**
* Return the {@link Cell} responsible for rendering items in the header.
*
* @return the header Cell
*/
public Cell getCell() {
return cell;
}
/**
* Get extra style names that should be applied to a cell in this header. May be overridden to
* get value dependent styles by calling {@link #getValue}.
*
* @return the extra styles of the given row in a space-separated list, or
* {@code null} if there are no extra styles for the cells in this
* header
*/
public String getHeaderStyleNames() {
return headerStyleNames;
}
/**
* 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);
}
/**
* Preview a browser event that may trigger a column sort event. Return true if the
* {@link CellTable} should proceed with sorting the column. Subclasses can override this method
* to disable column sort for some click events, or particular header/footer sections.
*
* This method will be invoked even if the header's cell does not consume a click event.
*
*
* @param context the context of the header
* @param elem the parent Element
* @param event the native browser event
* @return true if the {@link CellTable} should continue respond to the event (i.e., if this is
* a click event on a sortable column's header, fire {@link ColumnSortEvent}). False if
* the {@link CellTable} should stop respond to the event.
*/
public boolean onPreviewColumnSortEvent(Context context, Element elem, NativeEvent event) {
return true;
}
/**
* 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 extra style names that should be applied to every cell in this header.
*
*
* If you want to apply style names based on the header value, override
* {@link #getHeaderStyleNames(Object)} directly.
*
*
* @param styleNames the extra style names to apply in a space-separated list,
* or {@code null} if there are no extra styles for this cell
*/
public void setHeaderStyleNames(String styleNames) {
this.headerStyleNames = styleNames;
}
/**
* Set the {@link ValueUpdater}.
*
* @param updater the value updater to use
*/
public void setUpdater(ValueUpdater updater) {
this.updater = updater;
}
}