com.google.gwt.i18n.client.AutoDirectionHandler Maven / Gradle / Ivy
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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.i18n.client;
import com.google.gwt.event.dom.client.HasKeyUpHandlers;
import com.google.gwt.event.dom.client.KeyUpEvent;
import com.google.gwt.event.dom.client.KeyUpHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.i18n.client.HasDirection.Direction;
import com.google.gwt.i18n.shared.DirectionEstimator;
import com.google.gwt.i18n.shared.HasDirectionEstimator;
import com.google.gwt.i18n.shared.WordCountDirectionEstimator;
/**
* Utility class for handling auto-direction adjustment.
*
* This class is useful for automatically adjusting the direction of an object
* that takes text input, while the text is being entered.
*/
public class AutoDirectionHandler implements KeyUpHandler,
HasDirectionEstimator {
/**
* The interface an object must implement in order to add an
* AutoDirectionHandler to it.
*
* TODO(tomerigo): add Paste and Input events once they're available in GWT.
*/
public interface Target extends HasDirection, HasKeyUpHandlers {
/**
* Gets this object's text.
*/
String getText();
/**
* Sets this object's text.
*
* @param text the object's new text
*/
void setText(String text);
}
/**
* Operates like {@link #addTo(Target, DirectionEstimator)}, but always uses
* a default DirectionEstimator, {@link
* com.google.gwt.i18n.shared.WordCountDirectionEstimator}.
*
* @param target Object whose direction should be automatically adjusted on
* relevant events.
* @return AutoDirectionHandler An instance of AutoDirectionHandler for the
* given object.
*/
public static AutoDirectionHandler addTo(Target target) {
return addTo(target, true);
}
/**
* Operates like {@link #addTo(Target, DirectionEstimator)}, but uses a
* default DirectionEstimator, {@link
* com.google.gwt.i18n.shared.WordCountDirectionEstimator} if {@code enabled},
* or else a null DirectionEstimator, which means disabling direction
* estimation.
*
* @param target Object whose direction should be automatically adjusted on
* relevant events.
* @param enabled Whether the handler is enabled upon creation.
* @return AutoDirectionHandler An instance of AutoDirectionHandler for the
* given object.
*/
public static AutoDirectionHandler addTo(Target target, boolean enabled) {
return addTo(target, enabled ? WordCountDirectionEstimator.get() : null);
}
/**
* Adds auto-direction adjustment to a given object:
* - Creates an AutoDirectionHandler.
* - Initializes it with the given DirectionEstimator.
* - Adds it as an event handler for the relevant events on the given object.
* - Returns the AutoDirectionHandler, so its setAutoDir() method can be
* called when the object's text changes by means other than the handled
* events.
*
* @param target Object whose direction should be automatically adjusted on
* relevant events.
* @param directionEstimator A DirectionEstimator object used for direction
* estimation (use null to disable direction estimation).
* @return AutoDirectionHandler An instance of AutoDirectionHandler for the
* given object.
*/
public static AutoDirectionHandler addTo(Target target, DirectionEstimator
directionEstimator) {
return new AutoDirectionHandler(target, directionEstimator);
}
/**
* A DirectionEstimator object used for direction estimation.
*/
private DirectionEstimator directionEstimator;
/**
* A HandlerRegistration object used to remove this handler.
*/
private HandlerRegistration handlerRegistration;
/**
* The object being handled.
*/
private Target target;
/**
* Private constructor. Instantiate using one of the addTo() methods.
*
* @param target Object whose direction should be automatically adjusted on
* relevant events.
* @param directionEstimator A DirectionEstimator object used for direction
* estimation.
*/
private AutoDirectionHandler(Target target, DirectionEstimator
directionEstimator) {
this.target = target;
this.handlerRegistration = null;
setDirectionEstimator(directionEstimator);
}
/**
* Returns the DirectionEstimator object.
*/
public DirectionEstimator getDirectionEstimator() {
return directionEstimator;
}
/**
* Automatically adjusts hasDirection's direction on KeyUpEvent events.
* Implementation of KeyUpHandler interface method.
*/
public void onKeyUp(KeyUpEvent event) {
refreshDirection();
}
/**
* Adjusts target's direction according to the estimated direction of the text
* it supplies.
*/
public void refreshDirection() {
if (directionEstimator != null) {
Direction dir = directionEstimator.estimateDirection(target.getText());
if (dir != target.getDirection()) {
target.setDirection(dir);
}
}
}
/**
* Toggles direction estimation on (using a default estimator) and off.
*/
public void setDirectionEstimator(boolean enabled) {
setDirectionEstimator(enabled ? WordCountDirectionEstimator.get() : null);
}
/**
* Sets the DirectionEstimator object.
*/
public void setDirectionEstimator(DirectionEstimator directionEstimator) {
this.directionEstimator = directionEstimator;
if ((directionEstimator == null) != (handlerRegistration == null)) {
if (directionEstimator == null) {
handlerRegistration.removeHandler();
handlerRegistration = null;
} else {
handlerRegistration = target.addKeyUpHandler(this);
}
}
refreshDirection();
}
}