CustomFlingView 翻轉頁面

public class CustomFlingView extends FrameLayout implements ChangePage {
private static final String TAG = "FlingLayout";
// 用於滑動的類
private Scroller mScroller;
// 用來跟蹤觸摸速度的類
private VelocityTracker mVelocityTracker;
// 當前的屏幕視圖
private int mCurScreen;
// 默認的顯示視圖
private int mDefaultScreen = 0;
// 無事件的狀態
private static final int TOUCH_STATE_REST = 0;
// 處於拖動的狀態
private static final int TOUCH_STATE_SCROLLING = 1;
// 滑動的速度
private static final int SNAP_VELOCITY = 600;


private int mTouchState = TOUCH_STATE_REST;
private int mTouchSlop; // 溢出
private float mLastMotionX;
private float mTouchDownEventX;


// 用來處理立體效果的類
private Camera mCamera;
private Matrix mMatrix;
// 旋轉的角度
private float angle = 100;
// 滑動效果類型
private Boolean mNormal = false;


private ChangePage mChangePage;
private InterceptTouchEvent mInterceptEvent;


public void setNormal(Boolean mNormal) {
this.mNormal = mNormal;
}

public void setInterceptTouchEvent(InterceptTouchEvent interceptEvent) {
this.mInterceptEvent = interceptEvent;
}


public void setChangePage(ChangePage mChangePage) {
this.mChangePage = mChangePage;
}


public CustomFlingView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
// TODO Auto-generated constructor stub
}


public CustomFlingView(Context context) {
this(context, null, 0);
// TODO Auto-generated constructor stub
}


public CustomFlingView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
mScroller = new Scroller(context);


mCurScreen = mDefaultScreen;
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();


mCamera = new Camera();
mMatrix = new Matrix();
}


/*
* 爲子View指定位置
*/
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// TODO Auto-generated method stub
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;
}
}
}


// 重寫此方法用來計算高度和寬度
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);


final int width = MeasureSpec.getSize(widthMeasureSpec);
// The children are given the same width and height as the scrollLayout
final int count = getChildCount();
for (int i = 0; i < count; i++) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
scrollTo(mCurScreen * width, 0);
}


/*
* 當進行View滑動時，會導致當前的View無效，該函數的作用是對View進行重新繪製 調用drawScreen函數
*/
protected void dispatchDraw(Canvas canvas) {
// TODO Auto-generated method stub
if (!mNormal) {
final long drawingTime = getDrawingTime();
final int count = getChildCount();
for (int i = 0; i < count; i++) {
drawScreen(canvas, i, drawingTime);
}
} else {
super.dispatchDraw(canvas);
}
}


/*
* 立體效果的實現函數 ,screen爲哪一個子View
*/
public void drawScreen(Canvas canvas, int screen, long drawingTime) {
// 得到當前子View的寬度
final int width = getWidth();
final int scrollWidth = screen * width;
final int scrollX = this.getScrollX();
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();
}


/*
* 當進行View滑動時，會導致當前的View無效
*/
public void snapToDestination() {
final int screenWidth = getWidth();
final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;
snapToScreen(destScreen);
}


public void snapToScreen(int whichScreen) {
whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
if (getScrollX() != (whichScreen * getWidth())) {


final int delta = whichScreen * getWidth() - getScrollX();
mScroller.startScroll(getScrollX(), 0, delta, 0,
Math.abs(delta));
mCurScreen = whichScreen;
invalidate(); // 刷新頁面


if (mChangePage != null) {
mChangePage.changePage(whichScreen);
}


}
}


public void setToScreen(int whichScreen) {
whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
mCurScreen = whichScreen;
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
scrollTo(whichScreen * getWidth(), 0);
if (mChangePage != null) {
mChangePage.changePage(whichScreen);
}
}


public int getCurScreen() {
return mCurScreen;
}


public void setCurScreen(int whichScreen) {
mCurScreen = whichScreen;
}


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


@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub


if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(event);


final int action = event.getAction();
final float x = event.getX();
final float y = event.getY();


switch (action) {
case MotionEvent.ACTION_DOWN:
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
mLastMotionX = x;
break;


case MotionEvent.ACTION_MOVE:
int deltaX = (int) (mLastMotionX - x);
mLastMotionX = x;
int moveX = (int) Math.abs(mLastMotionX - mTouchDownEventX);
if (moveX > mTouchSlop) {
scrollBy(deltaX, 0);
}
break;


case MotionEvent.ACTION_UP:
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000);
int velocityX = (int) velocityTracker.getXVelocity();


if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
// Fling enough to move left
snapToScreen(mCurScreen - 1);
} else if (velocityX < -SNAP_VELOCITY
&& mCurScreen < getChildCount() - 1) {
// Fling enough to move right
snapToScreen(mCurScreen + 1);
} else {
snapToDestination();
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
mTouchState = TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_CANCEL:
mTouchState = TOUCH_STATE_REST;
break;
}


return true;
}


@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
// TODO Auto-generated method stub


if (ev.getAction() == MotionEvent.ACTION_DOWN) {
if (mInterceptEvent != null) {
mInterceptEvent.revert();
}
}


if (mInterceptEvent != null && mInterceptEvent.interceptTouchEvent()) {
mTouchState = TOUCH_STATE_REST;
return false;
}


final int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE)
&& (mTouchState != TOUCH_STATE_REST)) {
return true;
}


final float x = ev.getX();
final float y = ev.getY();


switch (action) {
case MotionEvent.ACTION_MOVE:
final int xDiff = (int) Math.abs(mLastMotionX - x);
if (xDiff > mTouchSlop) {
mTouchState = TOUCH_STATE_SCROLLING;
}
break;


case MotionEvent.ACTION_DOWN:
mLastMotionX = x;
mTouchDownEventX = x;
mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST
: TOUCH_STATE_SCROLLING;
break;


case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
mTouchState = TOUCH_STATE_REST;
break;
}


return mTouchState != TOUCH_STATE_REST;
}


@Override
public void changePage(int pageNumber) {
if (pageNumber < getChildCount() && mCurScreen != pageNumber) {
snapToScreen(pageNumber);
}
}


}