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