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Android\OPhone动画分析之翻转效果
来源:互联网   发布日期:2015-10-03 11:21:00   浏览:6247次  

导读:看到很多人在问如何实现三维的翻转效果,所以今天在这里简单的给大家分析一下,其实在APIDemo中就有这样一个例子,那么我们就以其为例来学习Android中的翻转动画效果的实现,首先看一下运行效果如下图所示。Andr......

看到很多人在问如何实现三维的翻转效果,所以今天在这里简单的给大家分析一下,其实在APIDemo中就有这样一个例子,那么我们就以其为例来学习Android中的翻转动画效果的实现,首先看一下运行效果如下图所示。

Android中并没有提供直接做3D翻转的动画,所以关于3D翻转的动画效果需要我们自己实现,那么我们首先来分析一下Animation 和 Transformation。

Animation动画的主要接口,其中主要定义了动画的一 些属性比如开始时间,持续时间,是否重复播放等等。而Transformation中则包含一个矩阵和alpha值,矩阵是用来做平移,旋转和缩放动画 的,而alpha值是用来做alpha动画的,要实现3D旋转动画我们需要继承自Animation类来实现,我们需要重载 getTransformation和applyTransformation,在getTransformation中Animation会根据动画的 属性来产生一系列的差值点,然后将这些差值点传给applyTransformation,这个函数将根据这些点来生成不同的 Transformation。下面是具体实现:

public class Rotate3dAnimation extends Animation {

//开始角度

private final float mFromDegrees;

//结束角度

private final float mToDegrees;

//中心点

private final float mCenterX;

private final float mCenterY;

private final float mDepthZ;

//是否需要扭曲

private final boolean mReverse;

//摄像头

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;

//生成中间角度

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);

//取得变换后的矩阵

camera.getMatrix(matrix);

camera.restore();

matrix.preTranslate(-centerX, -centerY);

matrix.postTranslate(centerX, centerY);

}

}

其中包括了旋转的开始和结束角度,中心点、是否扭曲、和一个 Camera,这里我们主要分析applyTransformation函数,其中第一个参数就是通过getTransformation函数传递的差指 点,然后我们根据这个差值通过线性差值算法计算出一个中间角度degrees,Camera类是用来实现绕Y轴旋转后透视投影的,因此我们首先通过 t.getMatrix()取得当前的矩阵,然后通过camera.translate来对矩阵进行平移变换操作,camera.rotateY进行旋 转。这样我们就可以很轻松的实现3D旋转效果了,该例子的原意是通过一个列表来供用户选择要实现翻转的图像,所以我们分析至少需要定义两个控 件:ListView和ImageView(要翻转的图像),主界面的xml布局定义如下所示:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:id="@+id/container"

android:layout_width="match_parent"

android:layout_height="match_parent">

<ListView

android:id="@android:id/list"

android:persistentDrawingCache="animation|scrolling"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:layoutAnimation="@anim/layout_bottom_to_top_slide" />

<ImageView

android:id="@+id/picture"

android:scaleType="fitCenter"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:visibility="gone" />

</FrameLayout>

然后准备好需要的资源,在onCreate函数中准备好 ListView和ImageView,因为要旋转所以我们需要保存视图的缓存信息,通过 setPersistentDrawingCache(ViewGroup.PERSISTENT_ANIMATION_CACHE);可以设置该功能, 当我们选择列表中的图像资源后在onItemClick中将选择的资源Id对应的图像设置到ImageView中,然后通过applyRotation来 启动一个动画,前面有了Rotate3dAnimation的实现,我们要完成3D翻转动画就很简单,直接构建一个Rotate3dAnimation对 象,设置其属性(包括动画监听),这里将动画的监听设置为DisplayNextView,可以用来显示下一个视图,在其中的动画结束监听 (onAnimationEnd)中,通过一个县城SwapViews来交换两个画面,交换过程则是设置ImageView和ListView的显示相关 属性,并构建一个Rotate3dAnimation对象,对另一个界面进行旋转即可,然后启动动画,整个转换过程实际上就是将第一个界面从0度转好90 度,然后就爱你过第二个界面从90度转到0度,这样就形成了一个翻转动画,完整代码如下,我们也加入了一些必要的注解,大家也可以参考APIDemo中的 Transition3d例子:

public class Transition3d extends Activity implements

AdapterView.OnItemClickListener, View.OnClickListener {

//照片列表

private ListView mPhotosList;

private ViewGroup mContainer;

private ImageView mImageView;

// 照片的名字,用于显示在list中

private static final String[] PHOTOS_NAMES = new String[] {

"Lyon",

"Livermore",

"Tahoe Pier",

"Lake Tahoe",

"Grand Canyon",

"Bodie"

};

// 资源id

private static final int[] PHOTOS_RESOURCES = new int[] {

R.drawable.photo1,

R.drawable.photo2,

R.drawable.photo3,

R.drawable.photo4,

R.drawable.photo5,

R.drawable.photo6

};

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.animations_main_screen);

mPhotosList = (ListView) findViewById(android.R.id.list);

mImageView = (ImageView) findViewById(R.id.picture);

mContainer = (ViewGroup) findViewById(R.id.container);

// 准备ListView

final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,

android.R.layout.simple_list_item_1, PHOTOS_NAMES);

mPhotosList.setAdapter(adapter);

mPhotosList.setOnItemClickListener(this);

// 准备ImageView

mImageView.setClickable(true);

mImageView.setFocusable(true);

mImageView.setOnClickListener(this);

//设置需要保存缓存

mContainer.setPersistentDrawingCache(ViewGroup.PERSISTENT_ANIMATION_CACHE);

}

/**

* Setup a new 3D rotation on the container view.

*

* @param position the item that was clicked to show a picture, or -1 to show the list

* @param start the start angle at which the rotation must begin

* @param end the end angle of the rotation

*/

private void applyRotation(int position, float start, float end) {

// 计算中心点

final float centerX = mContainer.getWidth() / 2.0f;

final float centerY = mContainer.getHeight() / 2.0f;

// Create a new 3D rotation with the supplied parameter

// The animation listener is used to trigger the next animation

final Rotate3dAnimation rotation =

new Rotate3dAnimation(start, end, centerX, centerY, 310.0f, true);

rotation.setDuration(500);

rotation.setFillAfter(true);

rotation.setInterpolator(new AccelerateInterpolator());

//设置监听

rotation.setAnimationListener(new DisplayNextView(position));

mContainer.startAnimation(rotation);

}

public void onItemClick(AdapterView parent, View v, int position, long id) {

// 设置ImageView

mImageView.setImageResource(PHOTOS_RESOURCES[position]);

applyRotation(position, 0, 90);

}

//点击图像时,返回listview

public void onClick(View v) {

applyRotation(-1, 180, 90);

}

/**

* This class listens for the end of the first half of the animation.

* It then posts a new action that effectively swaps the views when the container

* is rotated 90 degrees and thus invisible.

*/

private final class DisplayNextView implements Animation.AnimationListener {

private final int mPosition;

private DisplayNextView(int position) {

mPosition = position;

}

public void onAnimationStart(Animation animation) {

}

//动画结束

public void onAnimationEnd(Animation animation) {

mContainer.post(new SwapViews(mPosition));

}

public void onAnimationRepeat(Animation animation) {

}

}

/**

* This class is responsible for swapping the views and start the second

* half of the animation.

*/

private final class SwapViews implements Runnable {

private final int mPosition;

public SwapViews(int position) {

mPosition = position;

}

public void run() {

final float centerX = mContainer.getWidth() / 2.0f;

final float centerY = mContainer.getHeight() / 2.0f;

Rotate3dAnimation rotation;

if (mPosition > -1) {

//显示ImageView

mPhotosList.setVisibility(View.GONE);

mImageView.setVisibility(View.VISIBLE);

mImageView.requestFocus();

rotation = new Rotate3dAnimation(90, 180, centerX, centerY, 310.0f, false);

} else {

//返回listview

mImageView.setVisibility(View.GONE);

mPhotosList.setVisibility(View.VISIBLE);

mPhotosList.requestFocus();

rotation = new Rotate3dAnimation(90, 0, centerX, centerY, 310.0f, false);

}

rotation.setDuration(500);

rotation.setFillAfter(true);

rotation.setInterpolator(new DecelerateInterpolator());

//开始动画

mContainer.startAnimation(rotation);

}

}

}

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相关热词: 翻转 效果 动画 OPhone

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