294 lines
10 KiB
Java
294 lines
10 KiB
Java
/*
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* Copyright (C) 2008 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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*/
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package android.view;
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import android.content.Context;
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import android.content.res.TypedArray;
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import android.graphics.Canvas;
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import android.util.AttributeSet;
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import com.android.internal.R;
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import java.lang.ref.WeakReference;
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/**
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* A ViewStub is an invisible, zero-sized View that can be used to lazily inflate
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* layout resources at runtime.
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*
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* When a ViewStub is made visible, or when {@link #inflate()} is invoked, the layout resource
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* is inflated. The ViewStub then replaces itself in its parent with the inflated View or Views.
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* Therefore, the ViewStub exists in the view hierarchy until {@link #setVisibility(int)} or
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* {@link #inflate()} is invoked.
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*
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* The inflated View is added to the ViewStub's parent with the ViewStub's layout
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* parameters. Similarly, you can define/override the inflate View's id by using the
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* ViewStub's inflatedId property. For instance:
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*
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* <pre>
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* <ViewStub android:id="@+id/stub"
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* android:inflatedId="@+id/subTree"
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* android:layout="@layout/mySubTree"
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* android:layout_width="120dip"
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* android:layout_height="40dip" />
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* </pre>
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*
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* The ViewStub thus defined can be found using the id "stub." After inflation of
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* the layout resource "mySubTree," the ViewStub is removed from its parent. The
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* View created by inflating the layout resource "mySubTree" can be found using the
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* id "subTree," specified by the inflatedId property. The inflated View is finally
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* assigned a width of 120dip and a height of 40dip.
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*
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* The preferred way to perform the inflation of the layout resource is the following:
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*
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* <pre>
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* ViewStub stub = (ViewStub) findViewById(R.id.stub);
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* View inflated = stub.inflate();
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* </pre>
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*
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* When {@link #inflate()} is invoked, the ViewStub is replaced by the inflated View
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* and the inflated View is returned. This lets applications get a reference to the
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* inflated View without executing an extra findViewById().
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*
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* @attr ref android.R.styleable#ViewStub_inflatedId
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* @attr ref android.R.styleable#ViewStub_layout
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*/
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public final class ViewStub extends View {
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private int mLayoutResource = 0;
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private int mInflatedId;
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private WeakReference<View> mInflatedViewRef;
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private OnInflateListener mInflateListener;
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public ViewStub(Context context) {
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initialize(context);
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}
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/**
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* Creates a new ViewStub with the specified layout resource.
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*
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* @param context The application's environment.
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* @param layoutResource The reference to a layout resource that will be inflated.
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*/
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public ViewStub(Context context, int layoutResource) {
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mLayoutResource = layoutResource;
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initialize(context);
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}
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public ViewStub(Context context, AttributeSet attrs) {
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this(context, attrs, 0);
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}
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@SuppressWarnings({"UnusedDeclaration"})
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public ViewStub(Context context, AttributeSet attrs, int defStyle) {
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TypedArray a = context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.ViewStub,
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defStyle, 0);
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mInflatedId = a.getResourceId(R.styleable.ViewStub_inflatedId, NO_ID);
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mLayoutResource = a.getResourceId(R.styleable.ViewStub_layout, 0);
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a.recycle();
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a = context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.View, defStyle, 0);
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mID = a.getResourceId(R.styleable.View_id, NO_ID);
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a.recycle();
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initialize(context);
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}
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private void initialize(Context context) {
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mContext = context;
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setVisibility(GONE);
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setWillNotDraw(true);
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}
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/**
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* Returns the id taken by the inflated view. If the inflated id is
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* {@link View#NO_ID}, the inflated view keeps its original id.
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*
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* @return A positive integer used to identify the inflated view or
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* {@link #NO_ID} if the inflated view should keep its id.
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*
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* @see #setInflatedId(int)
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* @attr ref android.R.styleable#ViewStub_inflatedId
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*/
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public int getInflatedId() {
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return mInflatedId;
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}
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/**
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* Defines the id taken by the inflated view. If the inflated id is
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* {@link View#NO_ID}, the inflated view keeps its original id.
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*
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* @param inflatedId A positive integer used to identify the inflated view or
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* {@link #NO_ID} if the inflated view should keep its id.
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*
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* @see #getInflatedId()
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* @attr ref android.R.styleable#ViewStub_inflatedId
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*/
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public void setInflatedId(int inflatedId) {
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mInflatedId = inflatedId;
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}
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/**
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* Returns the layout resource that will be used by {@link #setVisibility(int)} or
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* {@link #inflate()} to replace this StubbedView
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* in its parent by another view.
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*
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* @return The layout resource identifier used to inflate the new View.
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*
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* @see #setLayoutResource(int)
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* @see #setVisibility(int)
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* @see #inflate()
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* @attr ref android.R.styleable#ViewStub_layout
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*/
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public int getLayoutResource() {
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return mLayoutResource;
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}
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/**
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* Specifies the layout resource to inflate when this StubbedView becomes visible or invisible
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* or when {@link #inflate()} is invoked. The View created by inflating the layout resource is
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* used to replace this StubbedView in its parent.
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*
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* @param layoutResource A valid layout resource identifier (different from 0.)
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*
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* @see #getLayoutResource()
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* @see #setVisibility(int)
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* @see #inflate()
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* @attr ref android.R.styleable#ViewStub_layout
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*/
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public void setLayoutResource(int layoutResource) {
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mLayoutResource = layoutResource;
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}
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@Override
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protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
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setMeasuredDimension(0, 0);
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}
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@Override
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public void draw(Canvas canvas) {
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}
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@Override
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protected void dispatchDraw(Canvas canvas) {
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}
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/**
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* When visibility is set to {@link #VISIBLE} or {@link #INVISIBLE},
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* {@link #inflate()} is invoked and this StubbedView is replaced in its parent
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* by the inflated layout resource.
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*
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* @param visibility One of {@link #VISIBLE}, {@link #INVISIBLE}, or {@link #GONE}.
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*
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* @see #inflate()
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*/
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@Override
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public void setVisibility(int visibility) {
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if (mInflatedViewRef != null) {
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View view = mInflatedViewRef.get();
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if (view != null) {
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view.setVisibility(visibility);
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} else {
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throw new IllegalStateException("setVisibility called on un-referenced view");
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}
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} else {
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super.setVisibility(visibility);
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if (visibility == VISIBLE || visibility == INVISIBLE) {
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inflate();
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}
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}
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}
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/**
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* Inflates the layout resource identified by {@link #getLayoutResource()}
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* and replaces this StubbedView in its parent by the inflated layout resource.
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*
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* @return The inflated layout resource.
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*
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*/
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public View inflate() {
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final ViewParent viewParent = getParent();
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if (viewParent != null && viewParent instanceof ViewGroup) {
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if (mLayoutResource != 0) {
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final ViewGroup parent = (ViewGroup) viewParent;
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final LayoutInflater factory = LayoutInflater.from(mContext);
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final View view = factory.inflate(mLayoutResource, parent,
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false);
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if (mInflatedId != NO_ID) {
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view.setId(mInflatedId);
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}
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final int index = parent.indexOfChild(this);
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parent.removeViewInLayout(this);
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final ViewGroup.LayoutParams layoutParams = getLayoutParams();
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if (layoutParams != null) {
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parent.addView(view, index, layoutParams);
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} else {
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parent.addView(view, index);
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}
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mInflatedViewRef = new WeakReference<View>(view);
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if (mInflateListener != null) {
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mInflateListener.onInflate(this, view);
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}
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return view;
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} else {
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throw new IllegalArgumentException("ViewStub must have a valid layoutResource");
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}
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} else {
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throw new IllegalStateException("ViewStub must have a non-null ViewGroup viewParent");
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}
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}
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/**
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* Specifies the inflate listener to be notified after this ViewStub successfully
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* inflated its layout resource.
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*
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* @param inflateListener The OnInflateListener to notify of successful inflation.
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*
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* @see android.view.ViewStub.OnInflateListener
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*/
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public void setOnInflateListener(OnInflateListener inflateListener) {
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mInflateListener = inflateListener;
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}
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/**
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* Listener used to receive a notification after a ViewStub has successfully
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* inflated its layout resource.
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*
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* @see android.view.ViewStub#setOnInflateListener(android.view.ViewStub.OnInflateListener)
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*/
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public static interface OnInflateListener {
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/**
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* Invoked after a ViewStub successfully inflated its layout resource.
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* This method is invoked after the inflated view was added to the
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* hierarchy but before the layout pass.
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*
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* @param stub The ViewStub that initiated the inflation.
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* @param inflated The inflated View.
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*/
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void onInflate(ViewStub stub, View inflated);
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}
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}
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