56 lines
1.8 KiB
Java
56 lines
1.8 KiB
Java
// Copyright (C) 2009 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package com.google.gwtexpui.user.client;
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import com.google.gwt.user.client.ui.Composite;
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import com.google.gwt.user.client.ui.Widget;
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/**
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* Widget to display within a {@link ViewSite}.
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*
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* <p>Implementations must override {@code protected void onLoad()} and arrange for {@link
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* #display()} to be invoked once the DOM within the view is consistent for presentation to the
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* user. Typically this means that the subclass can start RPCs within {@code onLoad()} and then
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* invoke {@code display()} from within the AsyncCallback's {@code onSuccess(Object)} method.
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*/
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public abstract class View extends Composite {
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ViewSite<? extends View> site;
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@Override
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protected void onUnload() {
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site = null;
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super.onUnload();
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}
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/** true if this is the current view of its parent view site */
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public final boolean isCurrentView() {
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Widget p = getParent();
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while (p != null) {
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if (p instanceof ViewSite<?>) {
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return ((ViewSite<?>) p).getView() == this;
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}
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p = p.getParent();
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}
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return false;
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}
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/** Replace the current view in the parent ViewSite with this view. */
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public final void display() {
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if (site != null) {
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site.swap(this);
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}
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}
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}
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