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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