Android 使用淡入/淡出动画更改背景图像

Android change background image with fade in/out animation

提问by BekaKK

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.

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，但我不知道如何使用此动画。

This is a my source:

这是我的来源：

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);

}

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.

目前一切正常。我可以随机更改背景图像，但我不知道如何使用动画淡入/淡出。

If anyone knows solution please help me, thanks.

如果有人知道解决方案，请帮助我，谢谢。

回答by kimkevin

You need to call these codes.

您需要调用这些代码。

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

首先，您必须为这样的淡入淡出动画制作两个 xml 文件。

fade_in.xml

淡入淡出.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

淡出.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>

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

其次，您必须像下面一样运行 imageView 的动画，并且您还必须设置 AnimationListener 以在淡入完成时更改淡出。

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) {
      }
});

回答by akshay7692

For fade in animation , create new folder named 'anim' in your res folder and inside it, create 'fade_in.xml' with following code

对于淡入动画，在 res 文件夹中创建名为“anim”的新文件夹，并在其中使用以下代码创建“fade_in.xml”

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" >

    <alpha
        android:duration="@android:integer/config_mediumAnimTime"
        android:fromAlpha="0.0"
        android:interpolator="@android:anim/decelerate_interpolator"
        android:toAlpha="1.0" />

</set>

now to run this animation on your imageview, use following code in your activity

现在要在您的 imageview 上运行此动画，请在您的活动中使用以下代码

Animation anim = AnimationUtils.loadAnimation(YourActivity.this, R.anim.fade_in);
imageView.setAnimation(anim);
anim.start();

for fadeout animation, just swap values of android:fromAlpha and android:toAlpha

对于淡出动画，只需交换 android:fromAlpha 和 android:toAlpha 的值

Hope this helps.

希望这可以帮助。

回答by Ziwei Zeng

You can use relativeLayout, and add one layer of background view which set both height and width match_parent. All other UI element should put on top of this view. In your code. Define fadeOut and fadeIn animation. Find that background view by id, then do this:

您可以使用 relativeLayout，并添加一层设置高度和宽度 match_parent 的背景视图。所有其他 UI 元素都应放在此视图之上。在你的代码中。定义fadeOut 和fadeIn 动画。通过 id 找到该背景视图，然后执行以下操作：

 xxxBackground.startAnimation(fadeOut);
 xxxBackground.setBackgroundResource(R.drawable.your_random_pic);
 xxxBackground.startAnimation(fadeIn);

You can use some interpolator to tune the performance.

您可以使用一些插值器来调整性能。

回答by Cabezas

You need AnimationDrawable with animation.

您需要带有动画的 AnimationDrawable。

First step AnimationDrawable

第一步 AnimationDrawable

-Create a file /res/anim/anim_android.xml

- 创建一个文件/res/anim/anim_android.xml

<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android"android:oneshot="false">
    <item android:drawable="@drawable/android_1"
          android:duration="100"/>
    <item android:drawable="@drawable/android_2"
          android:duration="100"/>
    <item android:drawable="@drawable/android_3"
          android:duration="100"/>
    <item android:drawable="@drawable/android_4"
          android:duration="100"/>
    <item android:drawable="@drawable/android_5"
          android:duration="100"/>
    <item android:drawable="@drawable/android_6"
          android:duration="100"/>
    <item android:drawable="@drawable/android_7"
          android:duration="100"/>
</animation-list>

-Add a ImageView with android:src="@anim/anim_android".

- 添加一个带有 android:src="@anim/anim_android" 的 ImageView。

<ImageView
    android:id="@+id/myanimation"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@anim/anim_android" />

Second step

第二步

-In your activity create AnimationDrawable and Animation

- 在您的活动中创建 AnimationDrawable 和 Animation

AnimationDrawable animationDrawable = (AnimationDrawable) imageView.getDrawable();
            animationDrawable.setOneShot(true);
            animationDrawable.start();

    Animation animation = AnimationUtils.loadAnimation(YourActivity.this, android.R.anim.fade_in);

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

you don't need Handler.

你不需要处理程序。

回答by Bugs Happen

Answer by kimkevinanimates a View(be it an ImageView, TextViewetc.) and not a background of a View. Which means if you want to just highlight any View, you'll have to add another Viewbehind it (lets call it backgroundView) and animate that backgroundView.

由回答kimkevin动画一个View（可以是一个ImageView，TextView等等），而不是一个的背景View。这意味着如果您只想突出显示 any View，则必须View在其后面添加另一个（我们称之为 backgroundView）并为该 backgroundView 设置动画。

Use the following code for animating background of a view

使用以下代码为视图的背景设置动画

val startColor = view.solidColor
val endColor = ContextCompat.getColor(context, R.color.your_color)

val colorAnim = ObjectAnimator.ofInt(view, "backgroundColor", startColor, endColor, startColor)
colorAnim.duration = 2000
colorAnim.setEvaluator(ArgbEvaluator())
colorAnim.start()