First introduction to animation in android-java类库-php.cn

Animation effects can greatly improve the interactive effect of the interface. Therefore, animation application scenarios are more common in mobile development. Mastering basic animation effects is indispensable in mature software development. In addition, users are much more receptive to animation than text and pictures. Using animation effects can deepen users’ impression of the product. Therefore, this article gives several common animation effects in Android design.

. Picture special effects include graphics scaling, mirroring, reflection, rotation, translation, etc. The special effects processing method of pictures is achieved by multiplying the graphics matrix of the original picture by a special effects matrix to form a new graphics matrix. The Matrix class maintains a 3*3 matrix to change the coordinates of pixels. The screen coordinate system of the Android phone takes the upper left corner as the origin, from left to right as the positive x-axis direction, and from top to bottom as the positive y-axis direction. The first line represents the x coordinate of the pixel: x = 1*x + 0*y + 0*z, the second line represents the y coordinate of the pixel: y = 0*x + 1*y + 0*z, and the third line The rows represent the z-coordinates of the pixels: z = 0*x + 0*y + 1*z. The special effects processing of pictures is achieved by changing the value of the graphics matrix. Under Android, the Matrix class helps us encapsulate some basic usage of matrices, so we can use it directly. When editing images with code, it is best to process a copy of the image in memory instead of processing the original image. Therefore, you need to use Bitmap to create a blank bitmap with the same size and format as the original image.

Basic steps for operating photos:

1. Create a blank bitmap, save the width and height information consistent with the original image;

2. Create a drawing board;

3. Create a brush;

4. Settings matrix matrix；

5. Draw exactly the same look on the drawing paper according to the original picture.

The codes for image scaling, translation, rotation, and mirror operations are given below.

/**
     * 图片缩放
     * 
     */
    private void zoom() {
        Bitmap srcBitmap = BitmapFactory.decodeFile("mnt/sdcard/b.jpg");
        iv_src.setImageBitmap(srcBitmap);
        Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(), srcBitmap.getHeight(), srcBitmap.getConfig());
        Canvas canvas = new Canvas(copyBitmap);
        Paint paint = new Paint();
        paint.setColor(Color.BLACK);
        Matrix matrix = new Matrix();
        matrix.setScale(0.6f, 0.6f);
        canvas.drawBitmap(srcBitmap, matrix, paint);
        iv_dest.setImageBitmap(copyBitmap);
    }
    
    /**
     * 图片平移
     * 
     */
    public void translation(){
        Options ops = new Options();
        ops.inSampleSize = 4;   //等比放缩
        Bitmap srcBitmap = BitmapFactory.decodeFile("/mnt/sdcard/b.jpg",ops);
        iv_src.setImageBitmap(srcBitmap);
        Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(), srcBitmap.getHeight(), srcBitmap.getConfig());
        Canvas canvas = new Canvas(copyBitmap);
        Paint paint = new Paint();
        paint.setColor(Color.BLACK);
        Matrix matrix = new Matrix();
        matrix.setTranslate(100, 100);
        canvas.drawBitmap(srcBitmap, matrix, paint);
        iv_dest.setImageBitmap(copyBitmap);
    }
    /**
     * 旋转
     * 
     */
    public void scole(){
        Bitmap srcBitmap = BitmapFactory.decodeFile("/mnt/sdcard/b.jpg");
        iv_src.setImageBitmap(srcBitmap); 
        Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(), srcBitmap.getHeight(), srcBitmap.getConfig());
        Canvas canvas = new Canvas(copyBitmap);
        Paint paint = new Paint();
        paint.setColor(Color.BLACK);
        Matrix matrix = new Matrix();
        matrix.setRotate(180, srcBitmap.getWidth()/2, srcBitmap.getHeight()/2);//绕原点旋转
        canvas.drawBitmap(srcBitmap, matrix, paint);
        iv_dest.setImageBitmap(copyBitmap);
    }
    /**
     * 镜面特效/倒影特效
     * 原理一样，一个关于x轴旋转，一个关于y轴旋转
     */
    public void mirror(){
        Bitmap srcBitmap = BitmapFactory.decodeFile("/mnt/sdcard/b.jpg");
        iv_src.setImageBitmap(srcBitmap);
        Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(), srcBitmap.getHeight(), srcBitmap.getConfig());
        Canvas canvas = new Canvas(copyBitmap);
        Paint paint = new Paint();
        paint.setColor(Color.BLACK);
        Matrix matrix = new Matrix();
        matrix.setScale(-1, 1);
        matrix.postTranslate(srcBitmap.getWidth(), 0);
        canvas.drawBitmap(srcBitmap, matrix, paint);
        iv_dest.setImageBitmap(copyBitmap);
    }

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Next let’s get into today’s topic. Animation under Android is divided into three types: frame animation, View animation (tween animation), and attribute animation. These three animations are introduced below.

Frame animation:

Frame animation is the most common of these three animations, which refers to animation played frame by frame. To put it more bluntly, it is the effect of quickly switching pictures. It is implemented through animation-list and creates a Drawable sequence. These Drawables can be displayed one by one according to the specified time interval, that is, the pre-made images are played in sequence.基 Basic steps used in frame animation:

1. Create pictures required for each frame of frame animation, put in the corresponding Drawable-XXX or Drawable directory

2. In the DRAWABLE directory, create frame animation XML files, root nodes Select animation-list. The oneshot attribute represents the automatic execution of frame animation. If true, it means that the animation will only play once and stop on the last frame. If set to false, it means the animation will play in a loop.

3. Enable animation in JAVA code. Set it to the Background of View or the src of ImageView, then obtain the AnimationDrawable object of the control, and start the animation through the AnimationDrawable.start() method

- to be set to the src of the View or the src of the ImageView, then get the AnimationDrawable object of the control and start the animation through the AnimationDrawable.start() method.

use use using use use using using using ’s out through out out out out out out out out out out out outmb out out out out out out out out out out off ’s That is to say, systems running above API-11. Property animation will change the position of the current view and produce animation effects by dynamically changing the width, height, coordinates and other properties of the control.

Achieve animation effects by controlling the properties of controls. Property animation is much more flexible and powerful than tweening animation. It should be noted that property animation does not actually distinguish between displacement, scaling, transparency, rotation and other animations. Its core idea is just to modify the properties of a control. We can achieve the four effects of tween animation by modifying different properties.

属性动画跟补间动画比，属性动画是真正改变了控件的属性，会改变当前的视图所在的位置，因此当控件的位置改变后只要点击到了控件“身上”就能触发onClick 事件。而补间动画则并没用改变控件的真实属性，因此不管属性动画执行后将控件移动到了哪个位置，只能通过点击该控件的原始位置才能触发onClick 事件。

通过xml 文件实现属性动画步骤：

1. 在res 下创建属性动画文件。在res 目录下创建animator 文件夹，然后创建一个objectAnimator 资源文件。资源名称自定义即可。

2. 编写属性动画文件。指定属性值。

3. 编写代码使用属性动画文件。通过AnimatorInflater加载图片资源，指定要显示动画的控件，并开启动画。

属性动画可以通过xml文件实现，但通常属性动画是通过JAVA代码实现。这里仅给出用xml文件实现淡化动画的案例，其他案例均以JAVA代码的方式实现。

JAVA代码的方式实现属性动画。

public class MainActivity extends Activity {
    private ImageView iv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        iv = (ImageView) findViewById(R.id.iv);
    }
    /**
     * 淡化动画
     * @param view
     */
    public void alpha(View view) {
        ObjectAnimator oa = ObjectAnimator.ofFloat(iv, "alpha", new float[] {
                0.0f, 0.2f, 0.4f, 0.6f, 0.8f, 1.0f });
        oa.setDuration(3000);
        oa.setRepeatCount(ObjectAnimator.INFINITE);
        oa.setRepeatMode(ObjectAnimator.REVERSE);
        oa.start();
    }
    /**
     * 平移动画
     * @param view
     */
    public void trans(View view) {
        ObjectAnimator oa = ObjectAnimator.ofFloat(iv, "translationX",
                new float[] { 10f, 20f, 30f, 40f, 60f, 80f });
        oa.setDuration(3000);
        oa.setRepeatCount(ObjectAnimator.INFINITE);
        oa.setRepeatMode(ObjectAnimator.REVERSE);
        oa.start();
    }
    /**
     * 缩放动画
     */
    public void scale(View view) {
        ObjectAnimator oa = ObjectAnimator.ofFloat(iv, "scaleX", new float[] {
                1f, 2f, 3f, 4f, 5f, 6f });
        oa.setDuration(3000);
        oa.setRepeatCount(ObjectAnimator.INFINITE);
        oa.setRepeatMode(ObjectAnimator.REVERSE);
        oa.start();
    }

    /**
     * 旋转动画
     */
    public void rotate(View view) {
        ObjectAnimator oa = ObjectAnimator.ofFloat(iv, "rotationY",
                new float[] { 90f, 180f, 270f, 360f });
        oa.setDuration(3000);
        oa.setRepeatCount(ObjectAnimator.INFINITE);
        oa.setRepeatMode(ObjectAnimator.REVERSE);
        oa.start();
    }

    /**
     * 水平平移 + 竖直平移
     */
    public void set(View view) {
        AnimatorSet set = new AnimatorSet();
        ObjectAnimator oa = ObjectAnimator.ofFloat(iv, "translationX",
                new float[] { 10f, 20f, 30f, 40f, 60f, 80f });
        oa.setDuration(3000);
        ObjectAnimator oa2 = ObjectAnimator.ofFloat(iv, "translationY",
                new float[] { -10f, -20f, -30f, -40f, -60f, -80f });
        oa2.setDuration(3000);
        set.playTogether(oa, oa2);
        set.start();
    }

}

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xml文件实现淡化效果：

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然后在java代码中实现这样一段代码：

      public void alpha(View view) {
          Animator animator = AnimatorInflater.loadAnimator(this,
                  R.animator.alpha);
          animator.setTarget(iv);
          animator.start();
      }

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View动画：

渐变动画也叫补间动画。补间动画通过对View 的内容进行一系列的图形变换(包括平移、缩放、旋转、改变透明度)来实现动画效果。动画效果的定义可以采用XML 文件来做也可以采用java 代码来做。

使用XML 文件实现View动画的步骤：

1. 在res 目录下创建anim 文件夹。

2. 在anim 文件夹中创建xml文件，文件名可以自定义。

3. 编辑xml文件。定义不同的标签，表示不同的动画效果。alpha表示淡化，

4. 添加Java 逻辑代码，使用AnimationUtils 工具类加载xml 文件，获取Animation 对象，调用startAnimation 让ImageView 执行此动画。

View动画中常用属性的含义：

duration 动画时长

fromAlpha 起始透明度，1 为完全不透明，0 为完全透明

repeatCount 重复次数，INFINITE表示无限重复

toAlpha 目标透明度

repeatMode 重复模式，restart 为重新开始，reverse表示来回播放

渐变动画在代码中使用的是AlphaAnimation 类来定义，在XML 文件中使用节点来定义。旋转动画在代码中使用的是RotateAnimation 类来定义，在XML 文件中使用节点来定义。伸缩动画在代码中使用的是ScaleAnimation 类来定义，在XML 文件中使用节点来定义。平移动画在代码中使用的是TranslateAnimation 类来定义，在XML 文件中使用节点来定义。Android 提供了AnimationSet 动画集合用于将多种补间动画联合起来一起使用，这样就能实现更多复杂的动画效果。动画集合既可以使用AnimationSet 类来定义也可以在XML 文件中使用节点来定义。任何复杂的动画均是通过简单的动画集合在一起的。

使用编码方式同样可以实现view动画，直接创建相应的动画对象，然后添加相应的属。代使用编码方式实现view动画跟用XML 文件实现View动画其实是一模一样的，无非就是在JAVA代码中设定相关的属性罢了。

使用XML 文件实现View动画的代码：

1 . 在anim文件夹下新建下列文件：

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2 . 在java代码中实现下列逻辑：

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;

public class MainActivity extends Activity {
    private ImageView iv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        iv = (ImageView) findViewById(R.id.iv);
    }
    /**
     * 淡化动画
     * @param view
     */
     public void alpha(View view){
         Animation aa = AnimationUtils.loadAnimation(this, R.anim.alpha_demo);
         iv.startAnimation(aa);
     }

     /**
      * 平移动画
      * @param view
      */
     public void trans(View view){
         Animation ta = AnimationUtils.loadAnimation(this, R.anim.trans_demo);
         iv.startAnimation(ta);
     }
     /**
      * 缩放动画
      */
     public void scale(View view){
         Animation sa = AnimationUtils.loadAnimation(this, R.anim.scale_demo);
         iv.startAnimation(sa);
     }
     /**
      * 旋转动画
      */
     public void rotate(View view){
         Animation ra = AnimationUtils.loadAnimation(this, R.anim.rotate_demo);
         iv.startAnimation(ra);
     }
     /**
      * 旋转 + 放缩
      */
     public void set(View view){
         Animation set = AnimationUtils.loadAnimation(this, R.anim.set_demo);
         iv.startAnimation(set);
     }
}

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使用java代码实现View动画的代码

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.AnimationSet;
import android.view.animation.AnimationUtils;
import android.view.animation.RotateAnimation;
import android.view.animation.ScaleAnimation;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;

public class MainActivity extends Activity {
     private ImageView iv;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         iv = (ImageView) findViewById(R.id.iv);
     }
     /**
      * 渐变动画
      * @param view
      */
     public void alpha(View view) {
         AlphaAnimation aa = new AlphaAnimation(0.0f, 1.0f);
         aa.setDuration(2000);
         aa.setRepeatCount(Animation.INFINITE);
         aa.setRepeatMode(Animation.REVERSE);
         iv.startAnimation(aa);
     }
     /**
      * 平移动画
      * @param view
      */
     public void trans(View view) {
         TranslateAnimation ta = new TranslateAnimation(
                 Animation.RELATIVE_TO_SELF, 0, Animation.RELATIVE_TO_SELF, 1f,
                 Animation.RELATIVE_TO_SELF, 0, Animation.RELATIVE_TO_SELF, 1f);
         ta.setDuration(2000);
         ta.setRepeatCount(Animation.INFINITE);
         ta.setRepeatMode(Animation.REVERSE);
         iv.startAnimation(ta);
     }
     /**
      * 缩放动画
      */
     public void scale(View view) {
         ScaleAnimation sa = new ScaleAnimation(0.2f, 2.0f, 0.2f, 2.0f,
                 Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
                 0.5f);
         sa.setDuration(2000);
         sa.setRepeatCount(Animation.INFINITE);
         sa.setRepeatMode(Animation.REVERSE);
         iv.startAnimation(sa);
     }

     /**
      * 旋转动画
      */
     public void rotate(View view) {
         RotateAnimation ra = new RotateAnimation(0, 360,
                 Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
                 0.5f);
         ra.setDuration(2000);
         ra.setRepeatCount(Animation.INFINITE);
         ra.setRepeatMode(Animation.REVERSE);
         iv.startAnimation(ra);
     }

     /**
      *  旋转 + 平移 + 放缩
      *  AnimationSet添加各个动画
      */
     public void set(View view) {
         AnimationSet set = new AnimationSet(false);
         RotateAnimation ra = new RotateAnimation(0, 360,
                 Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
                 0.5f);
         ra.setDuration(2000);
         ra.setRepeatCount(Animation.INFINITE);
         ra.setRepeatMode(Animation.REVERSE);
         ScaleAnimation sa = new ScaleAnimation(0.2f, 2.0f, 0.2f, 2.0f,
                 Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
                 0.5f);
         sa.setDuration(2000);
         sa.setRepeatCount(Animation.INFINITE);
         sa.setRepeatMode(Animation.REVERSE);
         TranslateAnimation ta = new TranslateAnimation(
                 Animation.RELATIVE_TO_SELF, 0, Animation.RELATIVE_TO_SELF, 1f,
                 Animation.RELATIVE_TO_SELF, 0, Animation.RELATIVE_TO_SELF, 1f);
         ta.setDuration(2000);
         ta.setRepeatCount(Animation.INFINITE);
         ta.setRepeatMode(Animation.REVERSE);
         set.addAnimation(ta);
         set.addAnimation(sa);
         set.addAnimation(ra);
         iv.startAnimation(set);
     }
}

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自此Android下的三种动画全部讲解完毕。