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Android動(dòng)畫之3D翻轉(zhuǎn)效果實(shí)現(xiàn)函數(shù)分析

更新時(shí)間：2013年01月20日 15:26:05 作者：

Android中的翻轉(zhuǎn)動(dòng)畫效果的實(shí)現(xiàn),Android中并沒有提供直接做3D翻轉(zhuǎn)的動(dòng)畫，所以關(guān)于3D翻轉(zhuǎn)的動(dòng)畫效果需要我們自己實(shí)現(xiàn)，那么我們首先來分析一下Animation 和 Transformation,感興趣的朋友可以了解下啊

Android中的翻轉(zhuǎn)動(dòng)畫效果的實(shí)現(xiàn)，首先看一下運(yùn)行效果如上圖所示.
Android中并沒有提供直接做3D翻轉(zhuǎn)的動(dòng)畫，所以關(guān)于3D翻轉(zhuǎn)的動(dòng)畫效果需要我們自己實(shí)現(xiàn)，那么我們首先來分析一下Animation 和 Transformation。

Animation動(dòng)畫的主要接口，其中主要定義了動(dòng)畫的一些屬性比如開始時(shí)間，持續(xù)時(shí)間，是否重復(fù)播放等等。而Transformation中則包含一個(gè)矩陣和alpha值，矩陣是用來做平移，旋轉(zhuǎn)和縮放動(dòng)畫的，而alpha值是用來做alpha動(dòng)畫的，要實(shí)現(xiàn)3D旋轉(zhuǎn)動(dòng)畫我們需要繼承自Animation類來實(shí)現(xiàn)，我們需要重載getTransformation和applyTransformation，在getTransformation中Animation會(huì)根據(jù)動(dòng)畫的屬性來產(chǎn)生一系列的差值點(diǎn)，然后將這些差值點(diǎn)傳給applyTransformation，這個(gè)函數(shù)將根據(jù)這些點(diǎn)來生成不同的Transformation。下面是具體實(shí)現(xiàn)：

復(fù)制代碼代碼如下:

 
package com.example.textviewtest; 
import android.graphics.Camera; 
import android.graphics.Matrix; 
import android.view.animation.Animation; 
import android.view.animation.Transformation; 
public class Rotate3dAnimation extends Animation { 
// 開始角度 
private final float mFromDegrees; 
// 結(jié)束角度 
private final float mToDegrees; 
// 中心點(diǎn) 
private final float mCenterX; 
private final float mCenterY; 
private final float mDepthZ; 
// 是否需要扭曲 
private final boolean mReverse; 
// 攝像頭 
private Camera mCamera; 
public Rotate3dAnimation(float fromDegrees, float toDegrees, float centerX, 
float centerY, float depthZ, boolean reverse) { 
mFromDegrees = fromDegrees; 
mToDegrees = toDegrees; 
mCenterX = centerX; 
mCenterY = centerY; 
mDepthZ = depthZ; 
mReverse = reverse; 
} 
@Override 
public void initialize(int width, int height, int parentWidth, 
int parentHeight) { 
super.initialize(width, height, parentWidth, parentHeight); 
mCamera = new Camera(); 
} 
// 生成Transformation 
@Override 
protected void applyTransformation(float interpolatedTime, Transformation t) { 
final float fromDegrees = mFromDegrees; 
// 生成中間角度 
float degrees = fromDegrees 
+ ((mToDegrees - fromDegrees) * interpolatedTime); 
final float centerX = mCenterX; 
final float centerY = mCenterY; 
final Camera camera = mCamera; 
final Matrix matrix = t.getMatrix(); 
camera.save(); 
if (mReverse) { 
camera.translate(0.0f, 0.0f, mDepthZ * interpolatedTime); 
} else { 
camera.translate(0.0f, 0.0f, mDepthZ * (1.0f - interpolatedTime)); 
} 
camera.rotateY(degrees); 
// 取得變換后的矩陣 
camera.getMatrix(matrix); 
camera.restore(); 
matrix.preTranslate(-centerX, -centerY); 
matrix.postTranslate(centerX, centerY); 
} 
} 

其中包括了旋轉(zhuǎn)的開始和結(jié)束角度，中心點(diǎn)、是否扭曲、和一個(gè)Camera，這里我們主要分析applyTransformation函數(shù)，其中第一個(gè)參數(shù)就是通過getTransformation函數(shù)傳遞的差指點(diǎn)，然后我們根據(jù)這個(gè)差值通過線性差值算法計(jì)算出一個(gè)中間角度degrees，Camera類是用來實(shí)現(xiàn)繞Y軸旋轉(zhuǎn)后透視投影的，因此我們首先通過t.getMatrix()取得當(dāng)前的矩陣，然后通過camera.translate來對(duì)矩陣進(jìn)行平移變換操作，camera.rotateY進(jìn)行旋轉(zhuǎn)。這樣我們就可以很輕松的實(shí)現(xiàn)3D旋轉(zhuǎn)效果了。

下面是布局文件main.xml:

復(fù)制代碼代碼如下:

 
View Code 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:background="@drawable/main_screen_bg" 
android:gravity="center_horizontal" 
android:orientation="vertical" 
tools:context=".MainActivity" > 
<Button 
android:id="@+id/next_btn" 
android:layout_width="wrap_content" 
android:layout_height="wrap_content" 
android:layout_marginTop="20dip" 
android:drawableTop="@drawable/qiangpiao_dropdown" 
android:text="下一個(gè)" /> 
<TextView 
android:id="@+id/tv" 
android:layout_width="300dip" 
android:layout_height="300dip" 
android:layout_gravity="center" 
android:background="@drawable/call_show_frame_safe" 
android:gravity="center" 
android:textColor="#ffffff" 
android:textSize="15sp" /> 
</LinearLayout> 

MainActivity的代碼如下：

復(fù)制代碼代碼如下:

 
View Code 
package com.example.textviewtest; 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.View; 
import android.view.animation.AccelerateInterpolator; 
import android.view.animation.Animation; 
import android.view.animation.DecelerateInterpolator; 
import android.widget.Button; 
import android.widget.TextView; 
public class MainActivity extends Activity { 
private TextView tv; 
private Button btn; 
private int count = 1; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_main); 
tv = (TextView) findViewById(R.id.tv); 
tv.setText(String.valueOf(count)); 
btn = (Button) findViewById(R.id.next_btn); 
applyRotation(0, 90); 
btn.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
applyRotation(0, 90); 
} 
}); 
} 
private void applyRotation(float start, float end) { 
// 計(jì)算中心點(diǎn) 
final float centerX = tv.getWidth() / 2.0f; 
final float centerY = tv.getHeight() / 2.0f; 
final Rotate3dAnimation rotation = new Rotate3dAnimation(start, end, 
centerX, centerY, 310.0f, true); 
rotation.setDuration(500); 
rotation.setFillAfter(true); 
rotation.setInterpolator(new AccelerateInterpolator()); 
// 設(shè)置監(jiān)聽 
rotation.setAnimationListener(new DisplayNextView()); 
tv.startAnimation(rotation); 
} 
private final class DisplayNextView implements Animation.AnimationListener { 
public void onAnimationStart(Animation animation) { 
} 
// 動(dòng)畫結(jié)束 
public void onAnimationEnd(Animation animation) { 
tv.post(new SwapViews()); 
} 
public void onAnimationRepeat(Animation animation) { 
} 
} 
private final class SwapViews implements Runnable { 
public void run() { 
final float centerX = tv.getWidth() / 2.0f; 
final float centerY = tv.getHeight() / 2.0f; 
Rotate3dAnimation rotation = null; 
tv.requestFocus(); 
rotation = new Rotate3dAnimation(90, 0, centerX, centerY, 310.0f, 
false); 
rotation.setDuration(500); 
rotation.setFillAfter(true); 
rotation.setInterpolator(new DecelerateInterpolator()); 
// 開始動(dòng)畫 
tv.startAnimation(rotation); 
tv.setText(String.valueOf(count++)); 
} 
} 
@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
getMenuInflater().inflate(R.menu.activity_main, menu); 
return true; 
} 
} 