Home | History | Annotate | Download | only in animationsdemo 
      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 
     44     public TouchHighlightImageButton(Context context) {
     45         super(context);
     46         init();
     47     }
     48 
     49     public TouchHighlightImageButton(Context context, AttributeSet attrs) {
     50         super(context, attrs);
     51         init();
     52     }
     53 
     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      */
     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
     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
     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
    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