1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package android.view; 17 18 import android.annotation.NonNull; 19 import android.content.Context; 20 import android.graphics.drawable.Drawable; 21 22 /** 23 * A group overlay is an extra layer that sits on top of a ViewGroup 24 * (the "host view") which is drawn after all other content in that view 25 * (including the view group's children). Interaction with the overlay 26 * layer is done by adding and removing views and drawables. 27 * 28 * <p>ViewGroupOverlay is a subclass of {@link ViewOverlay}, adding the ability to 29 * manage views for overlays on ViewGroups, in addition to the drawable 30 * support in ViewOverlay.</p> 31 * 32 * @see ViewGroup#getOverlay() 33 */ 34 public class ViewGroupOverlay extends ViewOverlay { 35 ViewGroupOverlay(Context context, View hostView)36 ViewGroupOverlay(Context context, View hostView) { 37 super(context, hostView); 38 } 39 40 /** 41 * Adds a {@code View} to the overlay. The bounds of the added view should be 42 * relative to the host view. Any view added to the overlay should be 43 * removed when it is no longer needed or no longer visible. 44 * 45 * <p>Views in the overlay are visual-only; they do not receive input 46 * events and do not participate in focus traversal. Overlay views 47 * are intended to be transient, such as might be needed by a temporary 48 * animation effect.</p> 49 * 50 * <p>If the view has a parent, the view will be removed from that parent 51 * before being added to the overlay. Also, if that parent is attached 52 * in the current view hierarchy, the view will be repositioned 53 * such that it is in the same relative location inside the activity. For 54 * example, if the view's current parent lies 100 pixels to the right 55 * and 200 pixels down from the origin of the overlay's 56 * host view, then the view will be offset by (100, 200).</p> 57 * 58 * <p>{@code View}s added with this API will be drawn in the order they were 59 * added. Drawing of the overlay views will happen before drawing of any of the 60 * {@code Drawable}s added with {@link #add(Drawable)} API even if a call to 61 * this API happened after the call to {@link #add(Drawable)}.</p> 62 * 63 * <p>Passing <code>null</code> parameter will result in an 64 * {@link IllegalArgumentException} being thrown.</p> 65 * 66 * @param view The {@code View} to be added to the overlay. The added view will be 67 * drawn when the overlay is drawn. 68 * @see #remove(View) 69 * @see ViewOverlay#add(Drawable) 70 */ add(@onNull View view)71 public void add(@NonNull View view) { 72 mOverlayViewGroup.add(view); 73 } 74 75 /** 76 * Removes the specified {@code View} from the overlay. Passing <code>null</code> parameter 77 * will result in an {@link IllegalArgumentException} being thrown. 78 * 79 * @param view The {@code View} to be removed from the overlay. 80 * @see #add(View) 81 * @see ViewOverlay#remove(Drawable) 82 */ remove(@onNull View view)83 public void remove(@NonNull View view) { 84 mOverlayViewGroup.remove(view); 85 } 86 } 87