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/*
 * Copyright (C) 2013 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.annotation.NonNull;
import android.content.Context;
import android.graphics.drawable.Drawable;


A group overlay is an extra layer that sits on top of a ViewGroup
(the "host view") which is drawn after all other content in that view
(including the view group's children). Interaction with the overlay
layer is done by adding and removing views and drawables.

ViewGroupOverlay is a subclass of ViewOverlay, adding the ability to manage views for overlays on ViewGroups, in addition to the drawable support in ViewOverlay.


See Also:
/**
 * A group overlay is an extra layer that sits on top of a ViewGroup
 * (the "host view") which is drawn after all other content in that view
 * (including the view group's children). Interaction with the overlay
 * layer is done by adding and removing views and drawables.
 *
 * <p>ViewGroupOverlay is a subclass of {@link ViewOverlay}, adding the ability to
 * manage views for overlays on ViewGroups, in addition to the drawable
 * support in ViewOverlay.</p>
 *
 * @see ViewGroup#getOverlay()
 */
public class ViewGroupOverlay extends ViewOverlay {

    ViewGroupOverlay(Context context, View hostView) {
        super(context, hostView);
    }

    
Adds a View to the overlay. The bounds of the added view should be relative to the host view. Any view added to the overlay should be removed when it is no longer needed or no longer visible. 
Views in the overlay are visual-only; they do not receive input
events and do not participate in focus traversal. Overlay views
are intended to be transient, such as might be needed by a temporary
animation effect.


If the view has a parent, the view will be removed from that parent
before being added to the overlay. Also, if that parent is attached
in the current view hierarchy, the view will be repositioned
such that it is in the same relative location inside the activity. For
example, if the view's current parent lies 100 pixels to the right
and 200 pixels down from the origin of the overlay's
host view, then the view will be offset by (100, 200).


Views added with this API will be drawn in the order they were added. Drawing of the overlay views will happen before drawing of any of the Drawables added with ViewOverlay.add(Drawable) API even if a call to this API happened after the call to ViewOverlay.add(Drawable).


Passing null parameter will result in an IllegalArgumentException being thrown.


Params:
  • view – The View to be added to the overlay. The added view will be drawn when the overlay is drawn.
See Also:
/**
     * Adds a {@code View} to the overlay. The bounds of the added view should be
     * relative to the host view. Any view added to the overlay should be
     * removed when it is no longer needed or no longer visible.
     *
     * <p>Views in the overlay are visual-only; they do not receive input
     * events and do not participate in focus traversal. Overlay views
     * are intended to be transient, such as might be needed by a temporary
     * animation effect.</p>
     *
     * <p>If the view has a parent, the view will be removed from that parent
     * before being added to the overlay. Also, if that parent is attached
     * in the current view hierarchy, the view will be repositioned
     * such that it is in the same relative location inside the activity. For
     * example, if the view's current parent lies 100 pixels to the right
     * and 200 pixels down from the origin of the overlay's
     * host view, then the view will be offset by (100, 200).</p>
     *
     * <p>{@code View}s added with this API will be drawn in the order they were
     * added. Drawing of the overlay views will happen before drawing of any of the
     * {@code Drawable}s added with {@link #add(Drawable)} API even if a call to
     * this API happened after the call to {@link #add(Drawable)}.</p>
     *
     * <p>Passing <code>null</code> parameter will result in an
     * {@link IllegalArgumentException} being thrown.</p>
     *
     * @param view The {@code View} to be added to the overlay. The added view will be
     * drawn when the overlay is drawn.
     * @see #remove(View)
     * @see ViewOverlay#add(Drawable)
     */
    public void add(@NonNull View view) {
        mOverlayViewGroup.add(view);
    }

    
Removes the specified View from the overlay. Passing null parameter will result in an IllegalArgumentException being thrown. 
Params:
  • view – The View to be removed from the overlay.
See Also:
/**
     * Removes the specified {@code View} from the overlay. Passing <code>null</code> parameter
     * will result in an {@link IllegalArgumentException} being thrown.
     *
     * @param view The {@code View} to be removed from the overlay.
     * @see #add(View)
     * @see ViewOverlay#remove(Drawable)
     */
    public void remove(@NonNull View view) {
        mOverlayViewGroup.remove(view);
    }
}