Android使用淡入/淡出动画更改背景图像

问题描述：

我编写了可以每5秒随机更改背景图像的代码.现在我想使用淡入/淡出动画来更改背景图像，但是我不知道如何使用此动画.

I wrote code which can change background image random every 5 second.now i want to use fade in/out animation to change background image,but I do not know how I can use this animation.

这是我的消息来源:

void handlechange() {

    Handler hand = new Handler();
    hand.postDelayed(new Runnable() {

        @Override
        public void run() {
            // TODO Auto-generated method stub

            // change image here
            change();

        }

        private void change() {
            // TODO Auto-generated method stub

            Random rand = new Random();

            int index = rand.nextInt(image_rundow.length);

            mapimg.setBackgroundResource(image_rundow[index]);

            handlechange();
        }
    }, 4000);

}

目前，一切正常.我可以随机更改背景图像，但是我不知道如何使用动画淡入/淡出.

At the moment everything is OK. I can change background image random,but I don't know how can I use animation fade in/out.

如果有人知道解决方案，请帮助我，谢谢.

If anyone knows solution please help me, thanks.

答

您需要调用这些代码.

首先，您必须制作两个xml文件以用于淡入&这样的动画.

First, you have to make two xml files for fade in & out animation like this.

fade_in.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<alpha
        android:fromAlpha="0.0"
        android:toAlpha="1.0"
        android:fillAfter="true"
        android:duration="2000"
        />
</set>

fade_out.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<alpha
        android:fromAlpha="1.0"
        android:toAlpha="0.0"
        android:fillAfter="true"
        android:duration="2000"
        />
</set>

第二，您必须运行如下所示的imageView动画，并且还必须设置AnimationListener以在淡入完成时更改淡出.

Second, you have to run animation of imageView like below and also you have to set AnimationListener to change fadeout when fadein finish.

Animation fadeOut = AnimationUtils.loadAnimation(YourActivity.this, R.anim.fade_out);
imageView.startAnimation(fadeOut);

fadeOut.setAnimationListener(new Animation.AnimationListener() {
      @Override
      public void onAnimationStart(Animation animation) {
      }
      @Override
      public void onAnimationEnd(Animation animation) {
          Animation fadeIn = AnimationUtils.loadAnimation(YourActivity.this, R.anim.fade_in);
          imageView.startAnimation(fadeIn);
      }
      @Override
      public void onAnimationRepeat(Animation animation) {
      }
});

Android使用淡入/淡出动画更改背景图像

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