开始逐帧动画

Question

我有一个关于开始逐帧动画的基本问题.

当我直接从我的代码调用AnimationDrawable.start()方法时,它似乎不起作用.

public void onCreate(Bundle savedInstanceState) {  
   ...  
   mAnimation.start();  
   ...  
}

但是如果我把这一行放在按钮的onClick()回调方法中,按下按钮就会启动动画.

为什么这行不在代码中？

谢谢!

码:

public class MyAnimation extends Activity {
@Override

public void onCreate(Bundle savedInstanceState) {

    AnimationDrawable mframeAnimation = null;
    super.onCreate(savedInstanceState);
    setContentView(R.layout.my_animation);

    ImageView img = (ImageView) findViewById(R.id.imgMain);

    BitmapDrawable frame1 = (BitmapDrawable) getResources().getDrawable(
            R.drawable.splash1);
    BitmapDrawable frame2 = (BitmapDrawable) getResources().getDrawable(
            R.drawable.splash2);

    int reasonableDuration = 250;
    mframeAnimation = new AnimationDrawable();
    mframeAnimation.setOneShot(false);
    mframeAnimation.addFrame(frame1, reasonableDuration);
    mframeAnimation.addFrame(frame2, reasonableDuration);

    img.setBackgroundDrawable(mframeAnimation);

    mframeAnimation.setVisible(true, true);
    //If this line is inside onClick(...) method of a button, animation works!!
    mframeAnimation.start(); 
}

}

Answer 1

重要的是要注意,在Activity的onCreate()方法中,无法调用在AnimationDrawable上调用的start()方法,因为AnimationDrawable尚未完全附加到窗口.如果您想立即播放动画而不需要交互,那么您可能希望从Activity中的onWindowFocusChanged()方法调用它,当Android将窗口置于焦点时将调用它.页面的最后 http://developer.android.com/guide/topics/graphics/2d-graphics.html

 ImageView img = (ImageView)findViewById(R.id.some layout);
 AnimationDrawable frameAnimation =    (AnimationDrawable)img.getDrawable();
 frameAnimation.setCallback(img);
 frameAnimation.setVisible(true, true);
 frameAnimation.start();

并添加动画,你可以做类似的事情

<animation-list   android:id="@+id/my_animation" android:oneshot="false" 
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/frame1" android:duration="150" />
    <item android:drawable="@drawable/frame2" android:duration="150" />

 </animation-list>  

Answer 2

使用Runnable将start()消息插入消息队列,只需添加此LOC即可替换mFrameAnimation.start();

img.post(new Starter());

助手内班:

class Starter implements Runnable {
        public void run() {
            mFrameAnimation.start();
        }
}

Answer 3

在onCreate(...)中播放动画添加:

ImageView mImageView=(ImageView) findViewById(R.id.image);          
mImageView.setBackgroundResource(R.anim.film);    
mFrameAnimation = (AnimationDrawable) mImageView.getBackground();    
mImageView.post(new Runnable(){    
    public void run(){    
        mFrameAnimation.start();        
}
});