An object used to create frame-by-frame animations, defined by a series of Drawable objects, which can be used as a View object's background.
The simplest way to create a frame-by-frame animation is to define the animation in an XML file, placed in the res/drawable/ folder, and set it as the background to a View object. Then, call run()
to start the animation.
An AnimationDrawable defined in XML consists of a single <animation-list>
element, and a series of nested <item>
tags. Each item defines a frame of the animation. See the example below.
spin_animation.xml file in res/drawable/ folder: //AnimotionDrawable布局文件
<!-- Animation frames are wheel0.png -- wheel5.png files inside the res/drawable/ folder --> <animation-list android:id="selected" android:oneshot="false"> <item android:drawable="@drawable/wheel0" android:duration="50" /> <item android:drawable="@drawable/wheel1" android:duration="50" /> <item android:drawable="@drawable/wheel2" android:duration="50" /> <item android:drawable="@drawable/wheel3" android:duration="50" /> <item android:drawable="@drawable/wheel4" android:duration="50" /> <item android:drawable="@drawable/wheel5" android:duration="50" /> </animation-list>
Here is the code to load and play this animation. //事例代码
// Load the ImageView that will host the animation and // set its background to our AnimationDrawable XML resource. ImageView img = (ImageView)findViewById(R.id.spinning_wheel_image); img.setBackgroundResource(R.drawable.spin_animation); // Get the background, which has been compiled to an AnimationDrawable object. AnimationDrawable frameAnimation = (AnimationDrawable) img.getBackground(); // Start the animation (looped playback by default). frameAnimation.start()
android与逐帧动画:
效果图:
当我们点击按钮时,该图片会不停的旋转,当再次点击按钮时,会停止在当前的状态。
activity代码:
package cn.com.chenzheng_java.animation;
import android.app.Activity;
import android.graphics.drawable.AnimationDrawable;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
/**
* @description android中的逐帧动画.
* 逐帧动画的原理很简单,跟电影的播放一样,一张张类似的图片不停的切换,当切换速度达到一定值时,
* 我们的视觉就会出现残影,残影的出现保证了视觉上变化的连续性,这时候图片的切换看在我们眼中就跟真实的一样了。
* 想使用逐帧动画:
* 第一步:需要在res/drawable文件夹下新建一个xml文件,该文件详细定义了动画播放时所用的图片、切换每张图片
* 所用的时间、是否为连续播放等等。(有些文章说,在res/anim文件夹下放置该文件,事实证明,会出错哦)
* 第二步:在代码中,将该动画布局文件,赋值给特定的图片展示控件,如本例子中的ImageView。
* 第三步:通过imageView.getBackGround()获取相应的AnimationDrawable对象,然后通过该对象的方法进行控制动画
* @author chenzheng_java
*
*/
public class Animation1Activity extends Activity {
ImageView imageView ;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.animation1);
imageView = (ImageView) findViewById(R.id.imageView_animation1);
imageView.setBackgroundResource(R.drawable.animation1_drawable);
}
public void myClickHandler(View targetButton){
// 获取AnimationDrawable对象
AnimationDrawable animationDrawable = (AnimationDrawable)imageView.getBackground();
// 动画是否正在运行
if(animationDrawable.isRunning()){
//停止动画播放
animationDrawable.stop();
}
else{
//开始或者继续动画播放
animationDrawable.start();
}
}
}
animation1.xml文件:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:orientation="vertical">
<Button android:id="@+id/button_animation1" android:text="动画开始"
android:layout_gravity="center_horizontal" android:layout_width="wrap_content"
android:layout_height="wrap_content" android:onClick="myClickHandler"></Button>
<ImageView android:id="@+id/imageView_animation1"
android:layout_width="fill_parent"
android:layout_height="wrap_content" android:layout_weight="1"></ImageView>
</LinearLayout>
存放动画文件的xml文件:
<?xml version="1.0" encoding="utf-8"?>
<!--
根标签为animation-list,其中oneshot代表着是否只展示一遍,设置为false会不停的循环播放动画
根标签下,通过item标签对动画中的每一个图片进行声明
android:duration 表示展示所用的该图片的时间长度
-->
<animation-list
xmlns:android="http://schemas.android.com/apk/res/android"
android:oneshot="false"
>
<item android:drawable="@drawable/a1" android:duration="50"></item>
<item android:drawable="@drawable/a2" android:duration="50"></item>
<item android:drawable="@drawable/a3" android:duration="50"></item>
<item android:drawable="@drawable/a4" android:duration="50"></item>
<item android:drawable="@drawable/a5" android:duration="50"></item>
<item android:drawable="@drawable/a6" android:duration="50"></item>
</animation-list>
除此之外:在AnimationDrawable中,我们还可以看到如下的几个重要方法:
setOneShot(boolean flag) 和在配置文件中进行配置一样,可以设置动画是否播放一次,false为连续播放;
addFrame (Drawable frame, int duration) 动态的添加一个图片进入该动画中