详解Android动画之Tween Animation
前面讲了动画中的Frame动画,今天就来详细讲解一下Tween动画的使用。
同样,在开始实例演示之前,先引用官方文档中的一段话:
Tween动画是操作某个控件让其展现出旋转、渐变、移动、缩放的这么一种转换过程,我们成为补间动画。我们可以以XML形式定义动画,也可以编码实现。
如果以XML形式定义一个动画,我们按照动画的定义语法完成XML,并放置于/res/anim目录下,文件名可以作为资源ID被引用;如果由编码实现,我们需要使用到Animation对象。
如果用定义XML方式实现动画,我们需要熟悉一下动画XML语法:
ImageView image = (ImageView) findViewById(R.id.image); Animation testAnim = AnimationUtils.loadAnimation(this, R.anim.test); image.startAnimation(testAnim);
ImageView image = (ImageView) findViewById(R.id.image); Animation testAnim = AnimationUtils.loadAnimation(this, R.anim.test); image.startAnimation(testAnim);
下面重点介绍一下插值器的概念:
首先要了解为什么需要插值器,因为在补间动画中,我们一般只定义关键帧(首帧或尾帧),然后由系统自动生成中间帧,生成中间帧的这个过程可以成为“插值”。插值器定义了动画变化的速率,提供不同的函数定义变化值相对于时间的变化规则,可以定义各种各样的非线性变化函数,比如加速、减速等。下面是几种常见的插值器:
| AccelerateDecelerateInterpolator | @android:anim/accelerate_decelerate_interpolator | 先加速再减速 |
| AccelerateInterpolator | @android:anim/accelerate_interpolator | 加速 |
| AnticipateInterpolator | @android:anim/anticipate_interpolator | 先回退一小步然后加速前进 |
| AnticipateOvershootInterpolator | @android:anim/anticipate_overshoot_interpolator | 在上一个基础上超出终点一小步再回到终点 |
| BounceInterpolator | @android:anim/bounce_interpolator | 最后阶段弹球效果 |
| CycleInterpolator | @android:anim/cycle_interpolator | 周期运动 |
| DecelerateInterpolator | @android:anim/decelerate_interpolator | 减速 |
| LinearInterpolator | @android:anim/linear_interpolator | 匀速 |
| OvershootInterpolator | @android:anim/overshoot_interpolator | 快速到达终点并超出一小步最后回到终点 |
然后我们可以这样使用一个插值器:
public float getInterpolation(float input) {
return input;
} public float getInterpolation(float input) {
return input;
}加速减速插值器定义如下:public float getInterpolation(float input) {
return (float)(Math.cos((input + 1) * Math.PI) / 2.0f) + 0.5f;
} public float getInterpolation(float input) {
return (float)(Math.cos((input + 1) * Math.PI) / 2.0f) + 0.5f;
}有兴趣的话,大家可以尝试一下自定义一个插值器。讲了这么久的概念,下面我们就结合实例来演示一下几种Tween动画的应用。
先来介绍一下旋转动画的使用,布局文件/res/layout/rotate.xml如下:
package com.scott.anim;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;
public class RotateActivity extends Activity {
private int currAngle;
private View piechart;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.rotate);
piechart = findViewById(R.id.piechart);
Animation animation = AnimationUtils.loadAnimation(this, R.anim.rotate);
piechart.startAnimation(animation);
}
public void positive(View v) {
Animation anim = new RotateAnimation(currAngle, currAngle + 180, Animation.RELATIVE_TO_SELF, 0.5f,
Animation.RELATIVE_TO_SELF, 0.5f);
/** 匀速插值器 */
LinearInterpolator lir = new LinearInterpolator();
anim.setInterpolator(lir);
anim.setDuration(1000);
/** 动画完成后不恢复原状 */
anim.setFillAfter(true);
currAngle += 180;
if (currAngle > 360) {
currAngle = currAngle - 360;
}
piechart.startAnimation(anim);
}
public void negative(View v) {
Animation anim = new RotateAnimation(currAngle, currAngle - 180, Animation.RELATIVE_TO_SELF, 0.5f,
Animation.RELATIVE_TO_SELF, 0.5f);
/** 匀速插值器 */
LinearInterpolator lir = new LinearInterpolator();
anim.setInterpolator(lir);
anim.setDuration(1000);
/** 动画完成后不恢复原状 */
anim.setFillAfter(true);
currAngle -= 180;
if (currAngle < -360) {
currAngle = currAngle + 360;
}
piechart.startAnimation(anim);
}
} package com.scott.anim;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;
public class RotateActivity extends Activity {
private int currAngle;
private View piechart;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.rotate);
piechart = findViewById(R.id.piechart);
Animation animation = AnimationUtils.loadAnimation(this, R.anim.rotate);
piechart.startAnimation(animation);
}
public void positive(View v) {
Animation anim = new RotateAnimation(currAngle, currAngle + 180, Animation.RELATIVE_TO_SELF, 0.5f,
Animation.RELATIVE_TO_SELF, 0.5f);
/** 匀速插值器 */
LinearInterpolator lir = new LinearInterpolator();
anim.setInterpolator(lir);
anim.setDuration(1000);
/** 动画完成后不恢复原状 */
anim.setFillAfter(true);
currAngle += 180;
if (currAngle > 360) {
currAngle = currAngle - 360;
}
piechart.startAnimation(anim);
}
public void negative(View v) {
Animation anim = new RotateAnimation(currAngle, currAngle - 180, Animation.RELATIVE_TO_SELF, 0.5f,
Animation.RELATIVE_TO_SELF, 0.5f);
/** 匀速插值器 */
LinearInterpolator lir = new LinearInterpolator();
anim.setInterpolator(lir);
anim.setDuration(1000);
/** 动画完成后不恢复原状 */
anim.setFillAfter(true);
currAngle -= 180;
if (currAngle < -360) {
currAngle = currAngle + 360;
}
piechart.startAnimation(anim);
}
}然后,看一下渐变动画,布局文件/res/layout/alpha.xml如下:package com.scott.anim;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
public class AlphaActivity extends Activity implements AnimationListener {
private ImageView splash;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.alpha);
splash = (ImageView) findViewById(R.id.splash);
Animation anim = AnimationUtils.loadAnimation(this, R.anim.alpha);
anim.setAnimationListener(this);
splash.startAnimation(anim);
}
public void alpha(View view) {
Animation anim = new AlphaAnimation(1.0f, 0.0f);
anim.setDuration(3000);
anim.setFillAfter(true);
splash.startAnimation(anim);
}
@Override
public void onAnimationStart(Animation animation) {
Log.i("alpha", "onAnimationStart called.");
}
@Override
public void onAnimationEnd(Animation animation) {
Log.i("alpha", "onAnimationEnd called");
}
@Override
public void onAnimationRepeat(Animation animation) {
Log.i("alpha", "onAnimationRepeat called");
}
} package com.scott.anim;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
public class AlphaActivity extends Activity implements AnimationListener {
private ImageView splash;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.alpha);
splash = (ImageView) findViewById(R.id.splash);
Animation anim = AnimationUtils.loadAnimation(this, R.anim.alpha);
anim.setAnimationListener(this);
splash.startAnimation(anim);
}
public void alpha(View view) {
Animation anim = new AlphaAnimation(1.0f, 0.0f);
anim.setDuration(3000);
anim.setFillAfter(true);
splash.startAnimation(anim);
}
@Override
public void onAnimationStart(Animation animation) {
Log.i("alpha", "onAnimationStart called.");
}
@Override
public void onAnimationEnd(Animation animation) {
Log.i("alpha", "onAnimationEnd called");
}
@Override
public void onAnimationRepeat(Animation animation) {
Log.i("alpha", "onAnimationRepeat called");
}
}接着看一下位移动画,布局文件/res/layout/translate.xml如下:package com.scott.anim;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.OvershootInterpolator;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;
public class TranslateActivity extends Activity {
private ImageView trans_iamge;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.tanslate);
trans_iamge = (ImageView) findViewById(R.id.trans_image);
Animation anim = AnimationUtils.loadAnimation(this, R.anim.translate);
anim.setFillAfter(true);
trans_iamge.startAnimation(anim);
}
public void translate(View view) {
Animation anim = new TranslateAnimation(200, 0, 300, 0);
anim.setDuration(2000);
anim.setFillAfter(true);
OvershootInterpolator overshoot = new OvershootInterpolator();
anim.setInterpolator(overshoot);
trans_iamge.startAnimation(anim);
}
} package com.scott.anim;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.OvershootInterpolator;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;
public class TranslateActivity extends Activity {
private ImageView trans_iamge;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.tanslate);
trans_iamge = (ImageView) findViewById(R.id.trans_image);
Animation anim = AnimationUtils.loadAnimation(this, R.anim.translate);
anim.setFillAfter(true);
trans_iamge.startAnimation(anim);
}
public void translate(View view) {
Animation anim = new TranslateAnimation(200, 0, 300, 0);
anim.setDuration(2000);
anim.setFillAfter(true);
OvershootInterpolator overshoot = new OvershootInterpolator();
anim.setInterpolator(overshoot);
trans_iamge.startAnimation(anim);
}
}最后,我们再来看以下缩放动画,布局文件/res/layout/scale.xml如下:package com.scott.anim;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.BounceInterpolator;
import android.view.animation.ScaleAnimation;
import android.widget.ImageView;
public class ScaleActivity extends Activity {
private ImageView scale_iamge;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.scale);
scale_iamge = (ImageView) findViewById(R.id.scale_image);
Animation anim = AnimationUtils.loadAnimation(this, R.anim.scale);
anim.setFillAfter(true);
scale_iamge.startAnimation(anim);
}
public void sclae(View view) {
Animation anim = new ScaleAnimation(2.0f, 1.0f, 2.0f, 1.0f,
Animation.RELATIVE_TO_SELF, 0.5f,
Animation.RELATIVE_TO_SELF, 0.5f);
anim.setDuration(2000);
anim.setFillAfter(true);
BounceInterpolator bounce = new BounceInterpolator();
anim.setInterpolator(bounce);
scale_iamge.startAnimation(anim);
}
} package com.scott.anim;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.BounceInterpolator;
import android.view.animation.ScaleAnimation;
import android.widget.ImageView;
public class ScaleActivity extends Activity {
private ImageView scale_iamge;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.scale);
scale_iamge = (ImageView) findViewById(R.id.scale_image);
Animation anim = AnimationUtils.loadAnimation(this, R.anim.scale);
anim.setFillAfter(true);
scale_iamge.startAnimation(anim);
}
public void sclae(View view) {
Animation anim = new ScaleAnimation(2.0f, 1.0f, 2.0f, 1.0f,
Animation.RELATIVE_TO_SELF, 0.5f,
Animation.RELATIVE_TO_SELF, 0.5f);
anim.setDuration(2000);
anim.setFillAfter(true);
BounceInterpolator bounce = new BounceInterpolator();
anim.setInterpolator(bounce);
scale_iamge.startAnimation(anim);
}
}几种动画运行效果如下图所示:



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