今天在网上看到一篇文章写关于Android实现3D旋转（http://www.ibm.com/developerworks/cn/opensource/os-cn-android-anmt2/index.html?ca=drs-），出于好奇就写了一个，运行效果如下：

下面我们就开始一步步完成这个效果吧。

实现水平滑动

package com.example.rotation3dview;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewDebug.HierarchyTraceType;
import android.view.ViewGroup;
import android.widget.ImageView;

public class Rote3DView extends ViewGroup{

public Rote3DView(Context context, AttributeSet attrs) {  
    super(context, attrs);  
    initScreens();  
}

public void initScreens(){  
    ViewGroup.LayoutParams p = new ViewGroup.LayoutParams(  
            ViewGroup.LayoutParams.MATCH\_PARENT,ViewGroup.LayoutParams.MATCH\_PARENT);  
     for (int i = 0; i < 3; i++) {  
         this.addView(new ImageView(this.getContext()), i, p);  
     }  
     ((ImageView)this.getChildAt(0)).setImageResource(R.drawable.page1);  
     ((ImageView)this.getChildAt(1)).setImageResource(R.drawable.page2);  
     ((ImageView)this.getChildAt(2)).setImageResource(R.drawable.page3);  
}

@Override  
protected void onLayout(boolean changed, int l, int t, int r, int b) {  
    int childLeft = 0;  
    final int childCount = getChildCount();  
    for(int i = 0; i< childCount; i++){  
        final View childView = getChildAt(i);  
        if(childView.getVisibility() != View.GONE){  
            final int childWidth = childView.getMeasuredWidth();  
            childView.layout(childLeft, 0, childLeft + childWidth, childView.getMeasuredHeight());  
            childLeft += childWidth;  
        }  
    }  
}

@Override  
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);  
    final int width = MeasureSpec.getSize(widthMeasureSpec);  
    final int widthMode = MeasureSpec.getMode(widthMeasureSpec);  
    if(widthMode != MeasureSpec.EXACTLY){  
        throw new IllegalStateException("仅支持精确尺寸");  
    }  
    final int heightMode = MeasureSpec.getMode(heightMeasureSpec);  
    if(heightMode != MeasureSpec.EXACTLY){  
        throw new IllegalStateException("仅支持精确尺寸");  
    }  
    final int count = getChildCount();  
    for(int i = 0; i < count; i++){  
        getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);  
    }  
}

private float mDownX;  
@Override  
public boolean onTouchEvent(MotionEvent event) {  
    float x = event.getX();  
    switch (event.getAction()) {  
    case MotionEvent.ACTION\_DOWN:  
        mDownX = x;  
        break;  
    case MotionEvent.ACTION\_MOVE:  
        int disX = (int)(mDownX - x);  
        mDownX = x;  
        scrollBy(disX, 0);  
        break;  
    case MotionEvent.ACTION\_UP:

        break;

    default:  
        break;  
    }

    return true;  
}

}

上面的滑动还不太流畅，我们在手势抬起的时候进行判断并处理，代码如下：

package com.example.rotation3dview;

import android.content.Context;
import android.graphics.Camera;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewDebug.HierarchyTraceType;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.Scroller;

public class Rote3DView extends ViewGroup{
private int mCurScreen = 1;
// 滑动的速度
private static final int SNAP_VELOCITY = 500;
private VelocityTracker mVelocityTracker;
private int mWidth;
private Scroller mScroller;
private Camera mCamera;
private Matrix mMatrix;
// 旋转的角度，可以进行修改来观察效果
private float angle = 90;
public Rote3DView(Context context, AttributeSet attrs) {
super(context, attrs);
mScroller = new Scroller(context);
mCamera = new Camera();
mMatrix = new Matrix();
initScreens();
}

public void initScreens(){  
    ViewGroup.LayoutParams p = new ViewGroup.LayoutParams(  
            ViewGroup.LayoutParams.MATCH\_PARENT,ViewGroup.LayoutParams.MATCH\_PARENT);  
     for (int i = 0; i < 3; i++) {  
         this.addView(new ImageView(this.getContext()), i, p);  
     }  
     ((ImageView)this.getChildAt(0)).setImageResource(R.drawable.page1);  
     ((ImageView)this.getChildAt(1)).setImageResource(R.drawable.page2);  
     ((ImageView)this.getChildAt(2)).setImageResource(R.drawable.page3);  
}

@Override  
protected void onLayout(boolean changed, int l, int t, int r, int b) {  
    int childLeft = 0;  
    final int childCount = getChildCount();  
    for(int i = 0; i< childCount; i++){  
        final View childView = getChildAt(i);  
        if(childView.getVisibility() != View.GONE){  
            final int childWidth = childView.getMeasuredWidth();  
            childView.layout(childLeft, 0, childLeft + childWidth, childView.getMeasuredHeight());  
            childLeft += childWidth;  
        }  
    }  
}

@Override  
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);  
    final int width = MeasureSpec.getSize(widthMeasureSpec);  
    final int widthMode = MeasureSpec.getMode(widthMeasureSpec);  
    if(widthMode != MeasureSpec.EXACTLY){  
        throw new IllegalStateException("仅支持精确尺寸");  
    }  
    final int heightMode = MeasureSpec.getMode(heightMeasureSpec);  
    if(heightMode != MeasureSpec.EXACTLY){  
        throw new IllegalStateException("仅支持精确尺寸");  
    }  
    final int count = getChildCount();  
    for(int i = 0; i < count; i++){  
        getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);  
    }  
    scrollTo(mCurScreen \* width, 0);  
}

private float mDownX;  
@Override  
public boolean onTouchEvent(MotionEvent event) {  
    if(mVelocityTracker == null){  
        mVelocityTracker = VelocityTracker.obtain();  
    }  
    //将当前的触摸事件传递给VelocityTracker对象  
    mVelocityTracker.addMovement(event);  
    float x = event.getX();  
    switch (event.getAction()) {  
    case MotionEvent.ACTION\_DOWN:  
        if(!mScroller.isFinished()){  
            mScroller.abortAnimation();  
        }  
        mDownX = x;  
        break;  
    case MotionEvent.ACTION\_MOVE:  
        int disX = (int)(mDownX - x);  
        mDownX = x;  
        scrollBy(disX, 0);  
        break;  
    case MotionEvent.ACTION\_UP:  
        final VelocityTracker velocityTracker = mVelocityTracker;  
        velocityTracker.computeCurrentVelocity(1000);  
        int velocityX = (int) velocityTracker.getXVelocity();  
        if(velocityX > SNAP\_VELOCITY && mCurScreen > 0){  
            snapToScreen(mCurScreen - 1);  
        }else if(velocityX < -SNAP\_VELOCITY && mCurScreen < getChildCount() - 1){  
            snapToScreen(mCurScreen + 1);  
        }else{  
            snapToDestination();  
        }  
        if(mVelocityTracker != null){  
            mVelocityTracker.recycle();  
            mVelocityTracker = null;  
        }  
        break;  
    }  
    return true;  
}

@Override  
public void computeScroll() {  
    if (mScroller.computeScrollOffset()) {  
        scrollTo(mScroller.getCurrX(), mScroller.getCurrY());  
        postInvalidate();  
    }  
}

public void snapToDestination(){  
    setMWidth();  
    final int destScreen = (getScrollX() + mWidth / 2) / mWidth;  
    snapToScreen(destScreen);  
}

public void snapToScreen(int whichScreen){  
    whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));  
    setMWidth();  
    int scrollX = getScrollX();  
    int startWidth = whichScreen \* mWidth;  
    if(scrollX != startWidth){  
        int delta = 0;  
        int startX = 0;  
        if(whichScreen > mCurScreen){  
            setPre();  
            delta = startWidth - scrollX;  
            startX = mWidth - startWidth + scrollX;  
        }else if(whichScreen < mCurScreen){  
            setNext();  
            delta = -scrollX;  
            startX = scrollX + mWidth;  
        }else{  
            startX = scrollX;  
            delta = startWidth - scrollX;  
        }  
        mScroller.startScroll(startX, 0, delta, 0, Math.abs(delta) \* 2);  
        invalidate();  
    }  
}

private void setNext(){  
    int count = this.getChildCount();  
    View view = getChildAt(count - 1);  
    removeViewAt(count - 1);  
    addView(view, 0);  
}

private void setPre(){  
    int count = this.getChildCount();  
    View view = getChildAt(0);  
    removeViewAt(0);  
    addView(view, count - 1);  
}

private void setMWidth(){  
    if(mWidth == 0){  
        mWidth = getWidth();  
    }  
}  

}

实现立体效果

添加如下代码：

/\*  
 \* 当进行View滑动时，会导致当前的View无效，该函数的作用是对View进行重新绘制 调用drawScreen函数  
 \*/  
@Override  
protected void dispatchDraw(Canvas canvas) {  
    final long drawingTime = getDrawingTime();  
    final int count = getChildCount();  
    for (int i = 0; i < count; i++) {  
        drawScreen(canvas, i, drawingTime);  
    }  
}

public void drawScreen(Canvas canvas, int screen, long drawingTime) {  
    // 得到当前子View的宽度  
    final int width = getWidth();  
    final int scrollWidth = screen \* width;  
    final int scrollX = this.getScrollX();  
    // 偏移量不足的时  
    if (scrollWidth > scrollX + width || scrollWidth + width < scrollX) {  
        return;  
    }  
    final View child = getChildAt(screen);  
    final int faceIndex = screen;  
    final float currentDegree = getScrollX() \* (angle / getMeasuredWidth());  
    final float faceDegree = currentDegree - faceIndex \* angle;  
    if (faceDegree > 90 || faceDegree < -90) {  
        return;  
    }  
    final float centerX = (scrollWidth < scrollX) ? scrollWidth + width  
            : scrollWidth;  
    final float centerY = getHeight() / 2;  
    final Camera camera = mCamera;  
    final Matrix matrix = mMatrix;  
    canvas.save();  
    camera.save();  
    camera.rotateY(-faceDegree);  
    camera.getMatrix(matrix);  
    camera.restore();  
    matrix.preTranslate(-centerX, -centerY);  
    matrix.postTranslate(centerX, centerY);  
    canvas.concat(matrix);  
    drawChild(canvas, child, drawingTime);  
    canvas.restore();  
}

项目完整源代码下载：https://code.csdn.net/lxq_xsyu/rotation3dview

Git下载地址：git@code.csdn.net:lxq_xsyu/rotation3dview.git