/*
* 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.cell.client;
import com.google.gwt.dom.client.BrowserEvents;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.InputElement;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.safehtml.shared.SafeHtml;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
import com.google.gwt.safehtml.shared.SafeHtmlUtils;
/**
* A {@link Cell} used to render a checkbox. The value of the checkbox may be
* toggled using the ENTER key as well as via mouse click.
*/
public class CheckboxCell extends AbstractEditableCell<Boolean, Boolean> {
/**
* An html string representation of a checked input box.
*/
private static final SafeHtml INPUT_CHECKED = SafeHtmlUtils.fromSafeConstant("<input type=\"checkbox\" tabindex=\"-1\" checked/>");
/**
* An html string representation of an unchecked input box.
*/
private static final SafeHtml INPUT_UNCHECKED = SafeHtmlUtils.fromSafeConstant("<input type=\"checkbox\" tabindex=\"-1\"/>");
private final boolean dependsOnSelection;
private final boolean handlesSelection;
/**
* Construct a new {@link CheckboxCell}.
*/
public CheckboxCell() {
this(false);
}
/**
* Construct a new {@link CheckboxCell} that optionally controls selection.
*
* @param isSelectBox true if the cell controls the selection state
* @deprecated use {@link #CheckboxCell(boolean, boolean)} instead
*/
@Deprecated
public CheckboxCell(boolean isSelectBox) {
this(isSelectBox, isSelectBox);
}
/**
* Construct a new {@link CheckboxCell} that optionally controls selection.
*
* @param dependsOnSelection true if the cell depends on the selection state
* @param handlesSelection true if the cell modifies the selection state
*/
public CheckboxCell(boolean dependsOnSelection, boolean handlesSelection) {
super(BrowserEvents.CHANGE, BrowserEvents.KEYDOWN);
this.dependsOnSelection = dependsOnSelection;
this.handlesSelection = handlesSelection;
}
@Override
public boolean dependsOnSelection() {
return dependsOnSelection;
}
@Override
public boolean handlesSelection() {
return handlesSelection;
}
@Override
public boolean isEditing(Context context, Element parent, Boolean value) {
// A checkbox is never in "edit mode". There is no intermediate state
// between checked and unchecked.
return false;
}
@Override
public void onBrowserEvent(Context context, Element parent, Boolean value,
NativeEvent event, ValueUpdater<Boolean> valueUpdater) {
String type = event.getType();
boolean enterPressed = BrowserEvents.KEYDOWN.equals(type)
&& event.getKeyCode() == KeyCodes.KEY_ENTER;
if (BrowserEvents.CHANGE.equals(type) || enterPressed) {
InputElement input = parent.getFirstChild().cast();
Boolean isChecked = input.isChecked();
/*
* Toggle the value if the enter key was pressed and the cell handles
* selection or doesn't depend on selection. If the cell depends on
* selection but doesn't handle selection, then ignore the enter key and
* let the SelectionEventManager determine which keys will trigger a
* change.
*/
if (enterPressed && (handlesSelection() || !dependsOnSelection())) {
isChecked = !isChecked;
input.setChecked(isChecked);
}
/*
* Save the new value. However, if the cell depends on the selection, then
* do not save the value because we can get into an inconsistent state.
*/
if (value != isChecked && !dependsOnSelection()) {
setViewData(context.getKey(), isChecked);
} else {
clearViewData(context.getKey());
}
if (valueUpdater != null) {
valueUpdater.update(isChecked);
}
}
}
@Override
public void render(Context context, Boolean value, SafeHtmlBuilder sb) {
// Get the view data.
Object key = context.getKey();
Boolean viewData = getViewData(key);
if (viewData != null && viewData.equals(value)) {
clearViewData(key);
viewData = null;
}
if (value != null && ((viewData != null) ? viewData : value)) {
sb.append(INPUT_CHECKED);
} else {
sb.append(INPUT_UNCHECKED);
}
}
}