ViewDragHelper实现QQ5.0侧滑并处理与ViewPager的滑动冲突

QQ5.0的侧滑效果有多种实现方式，

如http://blog.csdn.net/lmj623565791/article/details/39257409 就是利用HorizontalScrollView实现的,简单实用;

如http://blog.csdn.net/manoel/article/details/39013095/ 通过改造SlidingMenu实现，没有改变原有SlidingMenu功能，屏幕边缘侧滑也可以....

相对来说ViewDragHelper实现方式最为复杂，但灵活性也更高，可以应对各种需求，毕竟google的DrawerLayout也是用ViewDragHelper实现的。

先看下效果：

分析：主面板有个ViewPager,需要注意的是viewpager的滑动肯定与侧滑相互冲突，一般我们让viewpager的第一页是可以向右拖出侧滑菜单，其他页则响应viewpager的滑动。

代码：

自定义侧滑控件DragLayout ，代码量不少，不过关键地方都加了注释。

package com.liujing.draglayoutdemo;/**
 * 通过ViewDragHelper实现的侧滑控件
 * @author liujing
 * 
 */
public class DragLayout extends FrameLayout {

    private View mLeftContent;
    private View mMainContent;
    private int mWidth;
    private int mDragRange;
    private ViewDragHelper mDragHelper;
    private int mMainLeft;
    private int mHeight;

    private Status mStatus = Status.Close;
    private GestureDetectorCompat mDetectorCompat;

    public DragLayout(Context context) {
        this(context, null);
    }

    public DragLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }
    
    public DragLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        //ViewDragHelper.create(forParent, sensitivity, cb);
        //对应参数：父布局、敏感度、回调
        mDragHelper = ViewDragHelper.create(this, mCallBack);
        mDetectorCompat = new GestureDetectorCompat(getContext(),
                mGestureListener);

    }
    
    private boolean isDrag = true;
    
    public void setDrag(boolean isDrag) {
        this.isDrag = isDrag;
        if(isDrag){
            //这里有个Bug,当isDrag从false变为true是，mDragHelper的mCallBack在
            //首次滑动时不响应，再次滑动才响应，只好在此调用下，让mDragHelper恢复下状态
            mDragHelper.abort();
        }
    }

    SimpleOnGestureListener mGestureListener = new SimpleOnGestureListener() {
        public boolean onScroll(MotionEvent e1, MotionEvent e2,
                float distanceX, float distanceY) {
　　　　　　　　
            if((Math.abs(distanceX) > Math.abs(distanceY))&&distanceX<0&&isDrag!=false&&mStatus==Status.Close){
                return true;
            }else if((Math.abs(distanceX) > Math.abs(distanceY))&&distanceX>0&&isDrag!=false&&mStatus==Status.Open){
                return true;
            }else {
                return false;
            }
        };
    };

    ViewDragHelper.Callback mCallBack = new ViewDragHelper.Callback() {
        public void onEdgeTouched(int edgeFlags, int pointerId) {
            
            
        };
        
        public void onEdgeDragStarted(int edgeFlags, int pointerId) {
             mDragHelper.captureChildView(mMainContent, pointerId); 
        };
        // 决定child是否可被拖拽。返回true则进行拖拽。
        @Override
        public boolean tryCaptureView(View child, int pointerId) {
            return child == mMainContent || child == mLeftContent;
        }

        // 当capturedChild被拖拽时
        @Override
        public void onViewCaptured(View capturedChild, int activePointerId) {
            super.onViewCaptured(capturedChild, activePointerId);
        }

        // 横向拖拽的范围，大于0时可拖拽，等于0无法拖拽
        // 此方法只用于计算如view释放速度，敏感度等
        // 实际拖拽范围由clampViewPositionHorizontal方法设置
        @Override
        public int getViewHorizontalDragRange(View child) {
            return mDragRange;
        }

        // 此处设置view的拖拽范围。（实际移动还未发生）
        @Override
        public int clampViewPositionHorizontal(View child, int left, int dx) {
            // 拖动前oldLeft + 变化量dx == left
            if (mMainLeft + dx < 0) {
                return 0;
            } else if (mMainLeft + dx > mDragRange) {
                return mDragRange;
            }
            return left;
        }

        // 决定了当View位置改变时，希望发生的其他事情。（此时移动已经发生）
        // 高频实时的调用，在这里设置左右面板的联动
        @Override
        public void onViewPositionChanged(View changedView, int left, int top,
                int dx, int dy) {
            //如果拖动的是主面板
            if (changedView == mMainContent) {
                mMainLeft = left;
            } else {
                mMainLeft += dx;
            }

            // 进行值的修正
            if (mMainLeft < 0) {
                mMainLeft = 0;
            } else if (mMainLeft > mDragRange) {
                mMainLeft = mDragRange;
            }
            // 如果拖拽的是左面板，强制在指定位置绘制Content
            if (changedView == mLeftContent) {
                layoutContent();
            }

            dispatchDragEvent(mMainLeft);

        }

        // View被释放时,侧滑打开或恢复
        @Override
        public void onViewReleased(View releasedChild, float xvel, float yvel) {
            if (xvel > 0) {
                open();
            } else if (xvel == 0 && mMainLeft > mDragRange * 0.5f) {
                open();
            } else {
                close();
            }

        }

        //当拖拽状态改变的时，IDLE/DRAGGING/SETTLING
        @Override
        public void onViewDragStateChanged(int state) {
            super.onViewDragStateChanged(state);
        }

    };

    private void layoutContent() {
        mMainContent.layout(mMainLeft, 0, mMainLeft + mWidth, mHeight);
        mLeftContent.layout(0, 0, mWidth, mHeight);
    }

    /**
     * 每次更新都会调用 根据当前执行的位置计算百分比percent
     */
    protected void dispatchDragEvent(int mainLeft) {
        float percent = mainLeft / (float) mDragRange;
        animViews(percent);

        if (mListener != null) {
            mListener.onDraging(percent);
        }

        Status lastStatus = mStatus;
        if (updateStatus(mainLeft) != lastStatus) {
            if (mListener == null) {
                return;
            }
            if (lastStatus == Status.Draging) {
                if (mStatus == Status.Close) {
                    mListener.onClose();
                } else if (mStatus == Status.Open) {
                    mListener.onOpen();
                }

            }
        }
    }

    public static interface OnLayoutDragingListener {
        void onOpen();

        void onClose();

        void onDraging(float percent);
    }

    private OnLayoutDragingListener mListener;

    public void setOnLayoutDragingListener(OnLayoutDragingListener l) {
        mListener = l;
    }

    private Status updateStatus(int mainLeft) {
        if (mainLeft == 0) {
            mStatus = Status.Close;
        } else if (mainLeft == mDragRange) {
            mStatus = Status.Open;
        } else {
            mStatus = Status.Draging;
        }
        return mStatus;
    }

    public static enum Status {
        Open, Close, Draging
    }

    public Status getStatus() {
        return mStatus;
    }

    public void setStatus(Status mStatus) {
        this.mStatus = mStatus;
    }
    
    /**
     * 伴随动画：
     * @param percent
     */
    private void animViews(float percent) {
        // 主面板：缩放
        float inverse = 1 - percent * 0.2f;
        ViewHelper.setScaleX(mMainContent, inverse);
        ViewHelper.setScaleY(mMainContent, inverse);

        // 左面板：缩放、平移、透明度
        ViewHelper.setScaleX(mLeftContent, 0.5f + 0.5f * percent);
        ViewHelper.setScaleY(mLeftContent, 0.5f + 0.5f * percent);

        ViewHelper.setTranslationX(mLeftContent, -mWidth / 2.0f + mWidth / 2.0f
                * percent);
        ViewHelper.setAlpha(mLeftContent, percent);
        // 背景：颜色渐变
        getBackground().setColorFilter(
                evaluate(percent, Color.BLACK, Color.TRANSPARENT),
                PorterDuff.Mode.SRC_OVER);
    }

    private int evaluate(float fraction, int startValue, int endValue) {
        int startInt = (Integer) startValue;
        int startA = (startInt >> 24) & 0xff;
        int startR = (startInt >> 16) & 0xff;
        int startG = (startInt >> 8) & 0xff;
        int startB = startInt & 0xff;

        int endInt = (Integer) endValue;
        int endA = (endInt >> 24) & 0xff;
        int endR = (endInt >> 16) & 0xff;
        int endG = (endInt >> 8) & 0xff;
        int endB = endInt & 0xff;

        return (int) ((startA + (int) (fraction * (endA - startA))) << 24)
                | (int) ((startR + (int) (fraction * (endR - startR))) << 16)
                | (int) ((startG + (int) (fraction * (endG - startG))) << 8)
                | (int) ((startB + (int) (fraction * (endB - startB))));
    }

    @Override
    public boolean onInterceptTouchEvent(android.view.MotionEvent ev) {
        boolean onTouchEvent = mDetectorCompat.onTouchEvent(ev);
        //将Touch事件传递给ViewDragHelper
        return mDragHelper.shouldInterceptTouchEvent(ev) & onTouchEvent;
    };
    
    @Override
    public boolean onTouchEvent(MotionEvent event) {

        try {
            //将Touch事件传递给ViewDragHelper
            mDragHelper.processTouchEvent(event);
        } catch (Exception e) {
        }
        return true;
    }

    public void close() {
        close(true);
    };

    public void open() {
        open(true);
    }

    public void close(boolean isSmooth) {
        mMainLeft = 0;
        if (isSmooth) {
            // 执行动画，返回true代表有未完成的动画, 需要继续执行
            if (mDragHelper.smoothSlideViewTo(mMainContent, mMainLeft, 0)) {
                // 注意：参数传递根ViewGroup
                ViewCompat.postInvalidateOnAnimation(this);
            }
        } else {
            layoutContent();
        }
    }

    public void open(boolean isSmooth) {
        mMainLeft = mDragRange;
        if (isSmooth) {
            if (mDragHelper.smoothSlideViewTo(mMainContent, mMainLeft, 0)) {
                ViewCompat.postInvalidateOnAnimation(this);
            }
        } else {
            layoutContent();
        }
    }

    @Override
    public void computeScroll() {
        // 高频率调用，决定是否有下一个变动等待执行
        if (mDragHelper.continueSettling(true)) {
            ViewCompat.postInvalidateOnAnimation(this);
        }
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right,
            int bottom) {
        mMainContent.layout(mMainLeft, 0, mMainLeft + mWidth, mHeight);
        mLeftContent.layout(0, 0, mWidth, mHeight);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        //拿到宽高
        mWidth = getMeasuredWidth();
        mHeight = getMeasuredHeight();
        //设置拖动范围
        mDragRange = (int) (mWidth * 0.6f);
    }

    /**
     * 填充结束时获得两个子布局的引用
     */
    @Override
    protected void onFinishInflate() {

        int childCount = getChildCount();
        // 必要的检验
        if (childCount < 2) {
            throw new IllegalStateException(
                    "You need two childrens in your content");
        }

        if (!(getChildAt(0) instanceof ViewGroup)
                || !(getChildAt(1) instanceof ViewGroup)) {
            throw new IllegalArgumentException(
                    "Your childrens must be an instance of ViewGroup");
        }

        mLeftContent = getChildAt(0);
        mMainContent = getChildAt(1);
    }

}

我设置了一个isDrag的标签来控制是否允许侧滑；

在SimpleOnGestureListener的onScroll方法中判断，如果是横向向右滑动，且侧滑是关闭状态，且isDrag的tag为true时，让ViewDragHelper响应对应滑动事件（滑出），

如果是横向向左滑动，且侧滑是开启状态，且isDrag的tag为true时，让ViewDragHelper响应对应滑动事件（滑入），

其余情况，都不处理；

在onViewPositionChanged里通过dispatchDragEvent方法，计算移动百分比，据此执行相应的伴随动画，同时也将该值通过回调传递到外面，执行动画用了nineoldandroids来兼容之前版本。

MainContentLayout是为了处理当侧滑菜单打开后，主面板便不再响应内部的Touch事件了。

package com.liujing.draglayoutdemo;public class MainContentLayout extends RelativeLayout {

    private DragLayout mDragLayout;

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

    public MainContentLayout(Context context) {
        super(context);
    }

    public void setDragLayout(DragLayout mDragLayout) {
        this.mDragLayout = mDragLayout;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        if(mDragLayout.getStatus() == Status.Close){
            return super.onInterceptTouchEvent(ev);
        }else {
            return true;
        }

    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if(mDragLayout.getStatus() == Status.Close){
            return super.onTouchEvent(event);
        }else {
            if(MotionEventCompat.getActionMasked(event) == MotionEvent.ACTION_UP){
                mDragLayout.close();
            }
            return true;
        }
        
    }

}

DragLayout设置回调监听：

mDragLayout.setOnLayoutDragingListener(new OnLayoutDragingListener() {

            @Override
            public void onOpen() {
                //打开
            }
            @Override
            public void onDraging(float percent) {
                //滑动中
            }
            @Override
            public void onClose() {
                //关闭
            }
        });

当ViewPager切换时，只要给DragLayout设置是否允许侧滑即可

public void onPageSelected(int postion) {
            switch (postion) {
            case 0:
                mDragLayout.setDrag(true);
                break;
            case 1:
                mDragLayout.setDrag(false);
                break;
            case 2:
                mDragLayout.setDrag(false);
                break;
            }
        }

布局示例：

<com.liujing.draglayoutdemo.DragLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/dl"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/img_frame_background" >

    <LinearLayout
        android:id="@+id/fl_menu"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:paddingBottom="40dp"
        android:paddingLeft="10dp"
        android:paddingTop="50dp" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="#ffffff"
            android:textSize="18sp"
            android:text="这是左面板" >
        </TextView>
    </LinearLayout>

    <com.liujing.draglayoutdemo.MainContentLayout
        android:id="@+id/mainContent"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/tab_bg"
        android:orientation="vertical" >

        <android.support.v4.view.ViewPager
            android:id="@+id/pager_view"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_below="@id/topbar" />
    </com.liujing.draglayoutdemo.MainContentLayout>

</com.liujing.draglayoutdemo.DragLayout>

Demo下载：http://files.cnblogs.com/files/liujingg/DragLayoutDemo.rar