1 /* 2 * Copyright 2012 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 17 package com.example.android.animationsdemo; 18 19 import android.content.Context; 20 import android.content.res.TypedArray; 21 import android.graphics.Canvas; 22 import android.graphics.Rect; 23 import android.graphics.drawable.Drawable; 24 import android.util.AttributeSet; 25 import android.widget.ImageButton; 26 27 /** 28 * An image button that uses a blue highlight (@link android.R.attr.selectableItemBackground} to 29 * indicate pressed and focused states. 30 */ 31 public class TouchHighlightImageButton extends ImageButton { 32 /** 33 * The highlight drawable. This generally a {@link android.graphics.drawable.StateListDrawable} 34 * that's transparent in the default state, and contains a semi-transparent overlay 35 * for the focused and pressed states. 36 */ 37 private Drawable mForegroundDrawable; 38 39 /** 40 * The cached bounds of the view. 41 */ 42 private Rect mCachedBounds = new Rect(); 43 TouchHighlightImageButton(Context context)44 public TouchHighlightImageButton(Context context) { 45 super(context); 46 init(); 47 } 48 TouchHighlightImageButton(Context context, AttributeSet attrs)49 public TouchHighlightImageButton(Context context, AttributeSet attrs) { 50 super(context, attrs); 51 init(); 52 } 53 TouchHighlightImageButton(Context context, AttributeSet attrs, int defStyle)54 public TouchHighlightImageButton(Context context, AttributeSet attrs, int defStyle) { 55 super(context, attrs, defStyle); 56 init(); 57 } 58 59 /** 60 * General view initialization used common to all constructors of the view. 61 */ init()62 private void init() { 63 // Reset default ImageButton background and padding. 64 setBackgroundColor(0); 65 setPadding(0, 0, 0, 0); 66 67 // Retrieve the drawable resource assigned to the android.R.attr.selectableItemBackground 68 // theme attribute from the current theme. 69 TypedArray a = getContext() 70 .obtainStyledAttributes(new int[]{android.R.attr.selectableItemBackground}); 71 mForegroundDrawable = a.getDrawable(0); 72 mForegroundDrawable.setCallback(this); 73 a.recycle(); 74 } 75 76 @Override drawableStateChanged()77 protected void drawableStateChanged() { 78 super.drawableStateChanged(); 79 80 // Update the state of the highlight drawable to match 81 // the state of the button. 82 if (mForegroundDrawable.isStateful()) { 83 mForegroundDrawable.setState(getDrawableState()); 84 } 85 86 // Trigger a redraw. 87 invalidate(); 88 } 89 90 @Override onDraw(Canvas canvas)91 protected void onDraw(Canvas canvas) { 92 // First draw the image. 93 super.onDraw(canvas); 94 95 // Then draw the highlight on top of it. If the button is neither focused 96 // nor pressed, the drawable will be transparent, so just the image 97 // will be drawn. 98 mForegroundDrawable.setBounds(mCachedBounds); 99 mForegroundDrawable.draw(canvas); 100 } 101 102 @Override onSizeChanged(int w, int h, int oldw, int oldh)103 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 104 super.onSizeChanged(w, h, oldw, oldh); 105 106 // Cache the view bounds. 107 mCachedBounds.set(0, 0, w, h); 108 } 109 } 110