仿多看滑动翻页

来源：互联网发布：mac os 修改开机密码编辑：程序博客网时间：2024/05/17 23:35
本文是在http://blog.csdn.net/zhongkejingwang/article/details/38728119的基础上改的
仿多看滑动
看了原作者的思路，觉得很好，就按照自己的理解写了一遍，这里做个记录，后期再补充完善
public class MyScanView extends ViewGroup {    private static final int VELOCITY_SLIDE_THRESHOLD = 20;    private View mPreView;    private View mCurView;    private View mNextView;    private PageAdapter mAdapter;    private int mPageIndex;    private int mPrePageLeft;    private int mCurPageLeft;    private int mNextPageLeft;    private boolean mIsInit;    private int mWidth;    private int mHeight;    private int mLastX;    private int mLastY;    private int mTouchSlop;    private VelocityTracker mVelocityTracker;    private Scroller mScroller;    private boolean mIsActionUp = false;    private enum SlideState{        NONE, PRE, CURRENT    }    private SlideState mState = SlideState.NONE;    public MyScanView(Context context) {        this(context, null);    }    public MyScanView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public MyScanView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        init(context, attrs);    }    private void init(Context context, AttributeSet attrs){        mPageIndex = 1;        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();        mScroller = new Scroller(context);    }    public void setAdapter(PageAdapter adapter){        if(adapter == null){            return;        }        removeAllViews();        mAdapter = adapter;        mPreView = adapter.getView();        adapter.addContent(mPreView, mPageIndex - 1);        addView(mPreView, 0, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));        mCurView = adapter.getView();        adapter.addContent(mCurView, mPageIndex);        addView(mCurView, 0, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));        mNextView = adapter.getView();        adapter.addContent(mNextView, mPageIndex + 1);        addView(mNextView, 0, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));    }    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {        DebugTools.d("view2 dispatchTouchEvent action: " + ev.getAction());        switch(ev.getAction()){        case MotionEvent.ACTION_DOWN:            mIsActionUp = false;            addVelocityTracker(ev);            mLastX = (int)ev.getX();            mLastY = (int)ev.getY();            if(mIsLayouting){                if(mAnim != null){                    mAnim.cancel();                }                mIsLayouting = false;            }            break;        case MotionEvent.ACTION_MOVE:            addVelocityTracker(ev);            mIsActionUp = false;            int deltaX = (int)ev.getX() - mLastX;            int deltaY = (int)ev.getY() - mLastY;            if(Math.abs(deltaX) > Math.abs(deltaY)){                DebugTools.d("page2 mPageIndex: " + mPageIndex + " count: " + mAdapter.getCount());                if((deltaX < 0 && mState == SlideState.NONE && mPageIndex < mAdapter.getCount()) || (mState == SlideState.CURRENT && !mIsLayouting)){                    mCurPageLeft += deltaX;                    DebugTools.d("view2 dispatchTouchEvent mCurPageLeft: " + mCurPageLeft);                    mState = SlideState.CURRENT;                    requestLayout();                }else if((deltaX > 0 && mState == SlideState.NONE && mPageIndex > 1) || (mState == SlideState.PRE && !mIsLayouting)){                    mPrePageLeft += deltaX;                    mState = SlideState.PRE;                    requestLayout();                }            }            mLastX = (int)ev.getX();            mLastY = (int)ev.getY();            break;        case MotionEvent.ACTION_UP:        case MotionEvent.ACTION_CANCEL:            if(mState == SlideState.CURRENT && !mIsLayouting){                float speed = getVelocity();                DebugTools.d("view2 speed: " + speed);                if(mCurPageLeft < -mWidth / 2 || speed < -VELOCITY_SLIDE_THRESHOLD){                    startScroll(mCurPageLeft, -mWidth);                }else{                    startScroll(mCurPageLeft, 0);                }                invalidate();            }else if(mState == SlideState.PRE && !mIsLayouting){                float speed = getVelocity();                if(mPrePageLeft > -mWidth / 2 || speed > VELOCITY_SLIDE_THRESHOLD){                    startScroll(mPrePageLeft, 0);                }else{                    startScroll(mPrePageLeft, -mWidth);                }                invalidate();            }            recycleVelocityTracker();            mIsActionUp = true;            break;        }        super.dispatchTouchEvent(ev);        return true;    }    private ValueAnimator mAnim = null;    private void startScroll(final int start, final int end){        mAnim = ValueAnimator.ofInt(start, end);        mAnim.setDuration(400);        mAnim.addUpdateListener(new AnimatorUpdateListener() {            @Override            public void onAnimationUpdate(ValueAnimator animation) {                int value = (Integer) animation.getAnimatedValue();                     boolean isScrolling = value != end;                handleScroll(isScrolling, value);            }        });        mAnim.start();    }    private float getVelocity(){        if(mVelocityTracker == null){            return 0;        }        mVelocityTracker.computeCurrentVelocity(1000);        return mVelocityTracker.getXVelocity();    }    private boolean mIsLayouting = false;    private void handleScroll(boolean isScrolling, int value){        if(isScrolling){            if(mState == SlideState.CURRENT){                mCurPageLeft = value;                requestLayout();                mIsLayouting = true;            }else if(mState == SlideState.PRE){                mPrePageLeft = value;                requestLayout();                mIsLayouting = true;            }        }else{            if(mIsActionUp){                DebugTools.d("view2 computeScroll mState: " + mState + " mCurPageLeft: " + mCurPageLeft);                if(mState == SlideState.CURRENT){                    mPageIndex++;                    addNextPage();                }else if(mState == SlideState.PRE){                    mPageIndex--;                    addPrePage();                }                mState = SlideState.NONE;            }            mIsLayouting = false;        }    }    private void addNextPage(){        removeView(mPreView);        addView(mPreView, 0, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));        mAdapter.addContent(mPreView, mPageIndex + 1);        View temp = mCurView;        mCurView = mNextView;        mNextView = mPreView;        mPreView = temp;        mCurPageLeft = 0;    }    private void addPrePage(){        removeView(mNextView);        addView(mNextView, -1, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));        mAdapter.addContent(mNextView, mPageIndex - 1);        View temp = mCurView;        mCurView = mPreView;        mPreView = mNextView;        mNextView = temp;        mPrePageLeft = -mWidth;    }    private void addVelocityTracker(MotionEvent event){        if(mVelocityTracker == null){            mVelocityTracker = VelocityTracker.obtain();        }        mVelocityTracker.addMovement(event);    }    private void recycleVelocityTracker(){        if(mVelocityTracker != null){            mVelocityTracker.clear();            mVelocityTracker = null;        }    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        measureChildren(widthMeasureSpec, heightMeasureSpec);        mWidth = getMeasuredWidth();        mHeight = getMeasuredHeight();        if(!mIsInit){            mPrePageLeft = -mWidth;            mCurPageLeft = 0;            mNextPageLeft = 0;            mIsInit = true;        }    }    @Override    protected void onLayout(boolean changed, int l, int t, int r, int b) {        if(mAdapter == null){            return;        }        mNextView.layout(mNextPageLeft, 0, mNextPageLeft + mNextView.getMeasuredWidth(), mNextView.getMeasuredHeight());        mCurView.layout(mCurPageLeft, 0, mCurPageLeft + mCurView.getMeasuredWidth(), mCurView.getMeasuredHeight());        mPreView.layout(mPrePageLeft, 0, mPrePageLeft + mPreView.getMeasuredWidth(), mPreView.getMeasuredHeight());        invalidate();    }}
demo地址：http://download.csdn.net/detail/paddyy/9392718
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