com.google.gwt.user.client.ui.LayoutCommand Maven / Gradle / Ivy
/*
* Copyright 2009 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.core.client.Scheduler;
import com.google.gwt.core.client.Scheduler.ScheduledCommand;
import com.google.gwt.layout.client.Layout;
import com.google.gwt.layout.client.Layout.AnimationCallback;
import com.google.gwt.layout.client.Layout.Layer;
/**
* A scheduled command used by animated layouts to ensure that only layout is
* ever performed for a panel within a given user event.
*
*
* Note: This class assumes that {@link com.google.gwt.layout.client.Layout.Layer#getUserObject Layer.getUserObject()} will
* return the widget associated with a given layer.
*
*/
public class LayoutCommand implements ScheduledCommand {
private boolean scheduled, canceled;
private int duration;
private Layout.AnimationCallback callback;
private final Layout layout;
/**
* Creates a new command for the given layout object.
*
* @param layout
*/
public LayoutCommand(Layout layout) {
this.layout = layout;
}
/**
* Cancels this command. A subsequent call to
* {@link #schedule(int, Layout.AnimationCallback)} will re-enable it.
*/
public void cancel() {
// There's no way to "unschedule" a command, so we use a canceled flag.
canceled = true;
}
public final void execute() {
scheduled = false;
if (canceled) {
return;
}
doBeforeLayout();
layout.layout(duration, new Layout.AnimationCallback() {
public void onAnimationComplete() {
// Chain to the passed callback.
if (callback != null) {
callback.onAnimationComplete();
}
}
public void onLayout(Layer layer, double progress) {
// Inform the child associated with this layer that its size may
// have changed.
Widget child = (Widget) layer.getUserObject();
if (child instanceof RequiresResize) {
((RequiresResize) child).onResize();
}
// Chain to the passed callback.
if (callback != null) {
callback.onLayout(layer, progress);
}
}
});
}
/**
* Schedules a layout. The duration and callback passed to this method will
* supercede any previous call that has not yet been executed.
*
* @param duration
* @param callback
*/
public void schedule(int duration, AnimationCallback callback) {
this.duration = duration;
this.callback = callback;
canceled = false;
if (!scheduled) {
scheduled = true;
Scheduler.get().scheduleFinally(this);
}
}
/**
* Called before the layout is executed. Override this method to perform any
* work that needs to happen just before it.
*/
protected void doBeforeLayout() {
}
}