It seems that when inflating a ViewStub in a ConstraintLayout, the resulting view has lost all its constraints. I guess we can define the constraints for the inflated view using ConstraintSet, but that kind of defeats the purpose of ViewStub.
Is there a good way to do this?
There's a simple solution:
in your ViewStub let the inflatedId attribute as the same as id
like this:
<ViewStub
android:id="@+id/pocket_view"
android:inflatedId="@+id/pocket_view"
android:layout="@layout/game_pocket_view"
android:layout_width="@dimen/game_pocket_max_width"
android:layout_height="@dimen/game_pocket_max_height"
app:layout_constraintLeft_toLeftOf="@id/avatar_view"
app:layout_constraintRight_toRightOf="@id/avatar_view"
app:layout_constraintTop_toTopOf="@id/avatar_view"
app:layout_constraintBottom_toBottomOf="@id/avatar_view"
/>
id is handle for the ViewSub and inflatedId is handle for the resulting layout that takes its place. –
Howlan I've run into the same problem and found a code workaround. Just iterate over each child of the ConstraintLayout (the parent of the ViewStub) and change the references from the stub id to the inflated id.
I implemented my own ViewStub because the IDE preview is not working otherwise. Here is the class I'm using. I copied the code from the android project and changed it to allow the IDE preview to display properly.
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.ViewStub;
import androidx.annotation.LayoutRes;
import androidx.annotation.Nullable;
import androidx.constraintlayout.widget.ConstraintHelper;
import androidx.constraintlayout.widget.ConstraintLayout;
import java.lang.ref.WeakReference;
import rocks.tbog.tblauncher.R;
/**
* Copy of {@link android.view.ViewStub} so that we can see something in the preview
*/
public final class ViewStubPreview extends View {
private int mLayoutResource;
private int mInflatedId;
private WeakReference<View> mInflatedViewRef = null;
private LayoutInflater mInflater = null;
private OnInflateListener mInflateListener = null;
public ViewStubPreview(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public ViewStubPreview(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ViewStubPreview,
defStyle, 0);
mInflatedId = a.getResourceId(R.styleable.ViewStubPreview_inflatedId, NO_ID);
mLayoutResource = a.getResourceId(R.styleable.ViewStubPreview_layout, 0);
setId(a.getResourceId(R.styleable.ViewStubPreview_id, NO_ID));
a.recycle();
if (!isInEditMode()) {
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.
* @attr name android:inflatedId
* @see #setInflatedId(int)
*/
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.
* @attr name android:inflatedId
* @see #getInflatedId()
*/
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.
* @attr name android:layout
* @see #setLayoutResource(int)
* @see #setVisibility(int)
* @see #inflate()
*/
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.)
* @attr name android:layout
* @see #getLayoutResource()
* @see #setVisibility(int)
* @see #inflate()
*/
public void setLayoutResource(int layoutResource) {
mLayoutResource = layoutResource;
}
/**
* Set {@link LayoutInflater} to use in {@link #inflate()}, or {@code null}
* to use the default.
*/
public void setLayoutInflater(LayoutInflater inflater) {
mInflater = inflater;
}
/**
* Get current {@link LayoutInflater} used in {@link #inflate()}.
*/
public LayoutInflater getLayoutInflater() {
return mInflater;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (isInEditMode()) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
return;
}
setMeasuredDimension(0, 0);
}
@Override
public void draw(Canvas canvas) {
if (isInEditMode())
super.draw(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. After that calls to this function are passed
* through to the inflated view.
*
* @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 instanceof ViewGroup) {
if (mLayoutResource != 0) {
final ViewGroup parent = (ViewGroup) viewParent;
final LayoutInflater factory;
if (mInflater != null) {
factory = mInflater;
} else {
factory = LayoutInflater.from(getContext());
}
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);
}
// update parent ConstraintLayout constraints
if (parent instanceof ConstraintLayout)
updateConstraintsAfterStubInflate((ConstraintLayout) parent, getId(), view.getId());
mInflatedViewRef = new WeakReference<>(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;
}
@Nullable
public static View inflateStub(@Nullable View view) {
return inflateStub(view, 0);
}
@Nullable
public static View inflateStub(@Nullable View view, @LayoutRes int layoutRes) {
if (view instanceof ViewStubPreview) {
if (layoutRes != 0)
((ViewStubPreview) view).setLayoutResource(layoutRes);
// ViewStubPreview already calls updateConstraintsAfterStubInflate
return ((ViewStubPreview) view).inflate();
}
if (!(view instanceof ViewStub))
return view;
ViewStub stub = (ViewStub) view;
int stubId = stub.getId();
// get parent before the call to inflate
ConstraintLayout constraintLayout = stub.getParent() instanceof ConstraintLayout ? (ConstraintLayout) stub.getParent() : null;
if (layoutRes != 0)
stub.setLayoutResource(layoutRes);
View inflatedView = stub.inflate();
int inflatedId = inflatedView.getId();
updateConstraintsAfterStubInflate(constraintLayout, stubId, inflatedId);
return inflatedView;
}
private static void updateConstraintsAfterStubInflate(@Nullable ConstraintLayout constraintLayout, int stubId, int inflatedId) {
if (inflatedId == View.NO_ID)
return;
// change parent ConstraintLayout constraints
if (constraintLayout != null && stubId != inflatedId) {
int childCount = constraintLayout.getChildCount();
for (int childIdx = 0; childIdx < childCount; childIdx += 1) {
View child = constraintLayout.getChildAt(childIdx);
if (child instanceof ConstraintHelper) {
// get a copy of the id list
int[] refIds = ((ConstraintHelper) child).getReferencedIds();
boolean changed = false;
// change constraint reference IDs
for (int idx = 0; idx < refIds.length; idx += 1) {
if (refIds[idx] == stubId) {
refIds[idx] = inflatedId;
changed = true;
}
}
if (changed)
((ConstraintHelper) child).setReferencedIds(refIds);
}
ConstraintLayout.LayoutParams params = (ConstraintLayout.LayoutParams) child.getLayoutParams();
if (changeConstraintLayoutParamsTarget(params, stubId, inflatedId))
child.setLayoutParams(params);
}
}
}
private static boolean changeConstraintLayoutParamsTarget(ConstraintLayout.LayoutParams params, int fromId, int toId) {
boolean changed = false;
if (params.leftToLeft == fromId) {
params.leftToLeft = toId;
changed = true;
}
if (params.leftToRight == fromId) {
params.leftToRight = toId;
changed = true;
}
if (params.rightToLeft == fromId) {
params.rightToLeft = toId;
changed = true;
}
if (params.rightToRight == fromId) {
params.rightToRight = toId;
changed = true;
}
if (params.topToTop == fromId) {
params.topToTop = toId;
changed = true;
}
if (params.topToBottom == fromId) {
params.topToBottom = toId;
changed = true;
}
if (params.bottomToTop == fromId) {
params.bottomToTop = toId;
changed = true;
}
if (params.bottomToBottom == fromId) {
params.bottomToBottom = toId;
changed = true;
}
if (params.baselineToBaseline == fromId) {
params.baselineToBaseline = toId;
changed = true;
}
if (params.baselineToTop == fromId) {
params.baselineToTop = toId;
changed = true;
}
if (params.circleConstraint == fromId) {
params.circleConstraint = toId;
changed = true;
}
if (params.startToEnd == fromId) {
params.startToEnd = toId;
changed = true;
}
if (params.startToStart == fromId) {
params.startToStart = toId;
changed = true;
}
if (params.endToStart == fromId) {
params.endToStart = toId;
changed = true;
}
if (params.endToEnd == fromId) {
params.endToEnd = toId;
changed = true;
}
return changed;
}
/**
* 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 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(ViewStubPreview stub, View inflated);
}
}
Note: The inflateStub static method will also work with a android.view.ViewStub.
Consider NOT using the same id and inflatedId, as that could lead to undefined behavior and crashes, such as:
java.lang.IllegalArgumentException: Wrong state class... This usually happens when two views of different type have the same id in the same hierarchy. (This one can occur when restoring state after rotating or coming back from the background, depending on where your inflation is taking place.)
If you wish NOT to modify the parent ConstraintLayout's ConstraintSet, there is an alternative - androidx.costraintlayout.widget.Barrier
For example, lets say your views are:
<ScrollView
android:id="@+id/some_scroll_view"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toTopOf="@+id/some_view_stub">
<ViewStub
android:id="@+id/some_view_stub"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inflatedId="@+id/some_view"
android:layout="@layout/some_view_layout"
app:layout_constraintBottom_toBottomOf="parent" />
When the view stub becomes inflated, some_scroll_view's constraint will no longer be valid.
We can introduce a Barrier like so:
<ScrollView
android:id="@+id/some_scroll_view"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toTopOf="@+id/some_barrier">
<androidx.constraintlayout.widget.Barrier
android:id="@+id/some_barrier"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:barrierDirection="top"
app:constraint_referenced_ids="some_view_stub,some_view" />
<ViewStub
android:id="@+id/some_view_stub"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inflatedId="@+id/some_view"
android:layout="@layout/some_view_layout"
app:layout_constraintBottom_toBottomOf="parent" />
Note that the app:constraint_referenced_ids includes BOTH the ViewStub's id and its inflatedId.
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