Android 杂谈---帧动画

Android中的动画有

• 帧动画
• 属性动画
• 补间动画

大体思路

1.需要定义存放每一帧的xml文件,放在drawable文件夹下

设置图片路径和duration,以及shot属性,false--->只播放一次,true----->播放多次

<?xml version="1.0" encoding="utf-8"?>
<animation-list android:oneshot="false"

  xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:duration="50" android:drawable="@drawable/progressbar34" />
    <item android:duration="50" android:drawable="@drawable/progressbar33" />
    <item android:duration="50" android:drawable="@drawable/progressbar32" />
    <item android:duration="50" android:drawable="@drawable/progressbar31" />
    <item android:duration="50" android:drawable="@drawable/progressbar30" />
    <item android:duration="50" android:drawable="@drawable/progressbar29" />
    <item android:duration="50" android:drawable="@drawable/progressbar28" />
    <item android:duration="50" android:drawable="@drawable/progressbar27" />
    <item android:duration="50" android:drawable="@drawable/progressbar26" />
    <item android:duration="50" android:drawable="@drawable/progressbar25" />
    <item android:duration="50" android:drawable="@drawable/progressbar24" />
    <item android:duration="50" android:drawable="@drawable/progressbar23" />
    <item android:duration="50" android:drawable="@drawable/progressbar22" />
    <item android:duration="50" android:drawable="@drawable/progressbar21" />
    <item android:duration="50" android:drawable="@drawable/progressbar20" />
    <item android:duration="50" android:drawable="@drawable/progressbar19" />
    <item android:duration="50" android:drawable="@drawable/progressbar18" />
    <item android:duration="50" android:drawable="@drawable/progressbar17" />
    <item android:duration="50" android:drawable="@drawable/progressbar16" />
    <item android:duration="50" android:drawable="@drawable/progressbar15" />
    <item android:duration="50" android:drawable="@drawable/progressbar14" />
    <item android:duration="50" android:drawable="@drawable/progressbar13" />
    <item android:duration="50" android:drawable="@drawable/progressbar12" />
    <item android:duration="50" android:drawable="@drawable/progressbar11" />
    <item android:duration="50" android:drawable="@drawable/progressbar10" />
    <item android:duration="50" android:drawable="@drawable/progressbar9" />
    <item android:duration="50" android:drawable="@drawable/progressbar8" />
    <item android:duration="50" android:drawable="@drawable/progressbar7" />
    <item android:duration="50" android:drawable="@drawable/progressbar6" />
    <item android:duration="50" android:drawable="@drawable/progressbar5" />
    <item android:duration="50" android:drawable="@drawable/progressbar4" />
    <item android:duration="50" android:drawable="@drawable/progressbar3" />
    <item android:duration="50" android:drawable="@drawable/progressbar2" />
    <item android:duration="50" android:drawable="@drawable/progressbar1" />
</animation-list>

2.指定存放该动画的容器,使用imageView来充当

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.jing.www.loginlightdemo.MainActivity">
    <ImageView
        android:id="@+id/animation_iv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_margin="10dp"
        android:src="@drawable/progress" />

</android.support.constraint.ConstraintLayout>

3.使用代码来播放帧动画

注意:不能再onCreate()方法中进行动画的播放,动画依附于window,在onCreate()时期,window还没有初始化完成

会使动画没有运行而是停留在第一帧，那是因为AnimationDrawable播放动画是依附在window上面，而在Activity onCreate方法中调用时Window还未初始化完毕，所有才会停留在第一帧，要想实现播放必须在onWindowFocusChanged中添加如下代码：

public class MainActivity extends AppCompatActivity {

    private ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imageView = (ImageView) findViewById(R.id.animation_iv);

    }

    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        imageView.setImageResource(R.drawable.progress);
        AnimationDrawable animationDrawable = (AnimationDrawable) imageView.getDrawable();
        animationDrawable.start();

    }
}