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 
17 package com.example.android.crossfading;
18 
19 import android.app.Activity;
20 import android.graphics.Bitmap;
21 import android.graphics.Canvas;
22 import android.graphics.Color;
23 import android.graphics.drawable.BitmapDrawable;
24 import android.graphics.drawable.TransitionDrawable;
25 import android.os.Bundle;
26 import android.view.View;
27 import android.widget.ImageView;
28 
29 /**
30  * This example shows how to use TransitionDrawable to perform a simple cross-fade effect
31  * between two drawables.
32  *
33  * Watch the associated video for this demo on the DevBytes channel of developer.android.com
34  * or on YouTube at https://www.youtube.com/watch?v=atH3o2uh_94.
35  */
36 public class CrossFading extends Activity {
37 
38     int mCurrentDrawable = 0;
39 
40     @Override
onCreate(Bundle savedInstanceState)41     public void onCreate(Bundle savedInstanceState) {
42         super.onCreate(savedInstanceState);
43         setContentView(R.layout.activity_cross_fading);
44 
45         final ImageView imageview = (ImageView) findViewById(R.id.imageview);
46 
47         // Create red and green bitmaps to cross-fade between
48         Bitmap bitmap0 = Bitmap.createBitmap(500, 500, Bitmap.Config.ARGB_8888);
49         Bitmap bitmap1 = Bitmap.createBitmap(500, 500, Bitmap.Config.ARGB_8888);
50         Canvas canvas = new Canvas(bitmap0);
51         canvas.drawColor(Color.RED);
52         canvas = new Canvas(bitmap1);
53         canvas.drawColor(Color.GREEN);
54         BitmapDrawable drawables[] = new BitmapDrawable[2];
55         drawables[0] = new BitmapDrawable(getResources(), bitmap0);
56         drawables[1] = new BitmapDrawable(getResources(), bitmap1);
57 
58         // Add the red/green bitmap drawables to a TransitionDrawable. They are layered
59         // in the transition drawalbe. The cross-fade effect happens by fading one out and the
60         // other in.
61         final TransitionDrawable crossfader = new TransitionDrawable(drawables);
62         imageview.setImageDrawable(crossfader);
63 
64         // Clicking on the drawable will cause the cross-fade effect to run. Depending on
65         // which drawable is currently being shown, we either 'start' or 'reverse' the
66         // transition, which determines which drawable is faded out/in during the transition.
67         imageview.setOnClickListener(new View.OnClickListener() {
68 
69             @Override
70             public void onClick(View v) {
71                 if (mCurrentDrawable == 0) {
72                     crossfader.startTransition(500);
73                     mCurrentDrawable = 1;
74                 } else {
75                     crossfader.reverseTransition(500);
76                     mCurrentDrawable = 0;
77                 }
78             }
79         });
80     }
81 }
82