侧滑、ViewDragHelper、属性动画

<com.drag.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/bg"
    tools:context=".MainActivity" >
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:paddingBottom="50dp"
        android:paddingLeft="10dp"
        android:paddingRight="50dp"
        android:paddingTop="50dp" >
        <ImageView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:src="@drawable/head" />
        <ListView
            android:id="@+id/lv_left"
            android:layout_width="match_parent"
            android:layout_height="match_parent" >
        </ListView>
    </LinearLayout>
    <com.drag.MyLinearLayout
        android:id="@+id/mll"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#ffffff"
        android:orientation="vertical" >
        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:background="#18B6EF"
            android:gravity="center_vertical" >
            <ImageView
                android:id="@+id/iv_header"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_marginLeft="15dp"
                android:src="@drawable/head" />
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerHorizontal="true"
                android:text="Header" />
        </RelativeLayout>
        <ListView
            android:id="@+id/lv_main"
            android:layout_width="match_parent"
            android:layout_height="match_parent" >
        </ListView>
    </com.drag.MyLinearLayout>
</com.drag.DragLayout>

public class Utils {
    public static Toast mToast;
    public static void showToast(Context mContext, String msg) {
        if (mToast == null) {
            mToast = Toast.makeText(mContext, "", Toast.LENGTH_SHORT);
        }
        mToast.setText(msg);
        mToast.show();
    }
     
    /**
     * dip 转换成 px
     * @param dip
     * @param context
     * @return
     */
    public static float dip2Dimension(float dip, Context context) {
        DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
        return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dip, displayMetrics);
    }
    /**
     * @param dip
     * @param context
     * @param complexUnit {@link TypedValue#COMPLEX_UNIT_DIP} {@link TypedValue#COMPLEX_UNIT_SP}}
     * @return
     */
    public static float toDimension(float dip, Context context, int complexUnit) {
        DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
        return TypedValue.applyDimension(complexUnit, dip, displayMetrics);
    }
    /** 获取状态栏高度
     * @param v
     * @return
     */
    public static int getStatusBarHeight(View v) {
        if (v == null) {
            return 0;
        }
        Rect frame = new Rect();
        v.getWindowVisibleDisplayFrame(frame);
        return frame.top;
    }
    public static String getActionName(MotionEvent event) {
        String action = "unknow";
        switch (MotionEventCompat.getActionMasked(event)) {
        case MotionEvent.ACTION_DOWN:
            action = "ACTION_DOWN";
            break;
        case MotionEvent.ACTION_MOVE:
            action = "ACTION_MOVE";
            break;
        case MotionEvent.ACTION_UP:
            action = "ACTION_UP";
            break;
        case MotionEvent.ACTION_CANCEL:
            action = "ACTION_CANCEL";
            break;
        case MotionEvent.ACTION_SCROLL:
            action = "ACTION_SCROLL";
            break;
        case MotionEvent.ACTION_OUTSIDE:
            action = "ACTION_SCROLL";
            break;
        default:
            break;
        }
        return action;
    }
}

/**
 * 侧滑面板
 * @author poplar
 *
 */
public class DragLayout extends FrameLayout {
    private static final String TAG = "TAG";
    private ViewDragHelper mDragHelper;
    private ViewGroup mLeftContent;
    private ViewGroup mMainContent;
    private OnDragStatusChangeListener mListener;
    private Status mStatus = Status.Close;
     
    /**
     * 状态枚举
     */
    public static enum Status {
        Close, Open, Draging;
    }
    public interface OnDragStatusChangeListener{
        void onClose();
        void onOpen();
        void onDraging(float percent);
    }
     
    public Status getStatus() {
        return mStatus;
    }
    public void setStatus(Status mStatus) {
        this.mStatus = mStatus;
    }
    public void setDragStatusListener(OnDragStatusChangeListener mListener){
        this.mListener = mListener;
    }
     
    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);
         
        // a.初始化 (通过静态方法)
        mDragHelper = ViewDragHelper.create(this , mCallback);
         
    }
     
    ViewDragHelper.Callback mCallback = new ViewDragHelper.Callback() {
        // c. 重写事件
         
        // 1. 根据返回结果决定当前child是否可以拖拽
        // child 当前被拖拽的View
        // pointerId 区分多点触摸的id
        @Override
        public boolean tryCaptureView(View child, int pointerId) {
            Log.d(TAG, "tryCaptureView: " + child);
            return true;
        };
         
        @Override
        public void onViewCaptured(View capturedChild, int activePointerId) {
            Log.d(TAG, "onViewCaptured: " + capturedChild);
            // 当capturedChild被捕获时,调用.
            super.onViewCaptured(capturedChild, activePointerId);
        }
        @Override
        public int getViewHorizontalDragRange(View child) {
            // 返回拖拽的范围, 不对拖拽进行真正的限制. 仅仅决定了动画执行速度
            return mRange;
        }
         
        // 2. 根据建议值 修正将要移动到的(横向)位置   (重要)
        // 此时没有发生真正的移动
        public int clampViewPositionHorizontal(View child, int left, int dx) {
            // child: 当前拖拽的View
            // left 新的位置的建议值, dx 位置变化量
            // left = oldLeft + dx;
            Log.d(TAG, "clampViewPositionHorizontal: "
                    + "oldLeft: " + child.getLeft() + " dx: " + dx + " left: " +left);
             
            if(child == mMainContent){
                left = fixLeft(left);
            }
            return left;
        }
        // 3. 当View位置改变的时候, 处理要做的事情 (更新状态, 伴随动画, 重绘界面)
        // 此时,View已经发生了位置的改变
        @Override
        public void onViewPositionChanged(View changedView, int left, int top,
                int dx, int dy) {
            // changedView 改变位置的View
            // left 新的左边值
            // dx 水平方向变化量
            super.onViewPositionChanged(changedView, left, top, dx, dy);
            Log.d(TAG, "onViewPositionChanged: " + "left: " + left + " dx: " + dx);
             
            int newLeft = left;
            if(changedView == mLeftContent){
                // 把当前变化量传递给mMainContent
                newLeft = mMainContent.getLeft() + dx;
            }
             
            // 进行修正
            newLeft = fixLeft(newLeft);
             
            if(changedView == mLeftContent) {
                // 当左面板移动之后, 再强制放回去.
                mLeftContent.layout(0, 0, 0 + mWidth, 0 + mHeight);
                mMainContent.layout(newLeft, 0, newLeft + mWidth, 0 + mHeight);
            }
            // 更新状态,执行动画
            dispatchDragEvent(newLeft);
             
            // 为了兼容低版本, 每次修改值之后, 进行重绘
            invalidate();
        }
        // 4. 当View被释放的时候, 处理的事情(执行动画)
        @Override
        public void onViewReleased(View releasedChild, float xvel, float yvel) {
            // View releasedChild 被释放的子View
            // float xvel 水平方向的速度, 向右为+
            // float yvel 竖直方向的速度, 向下为+
            Log.d(TAG, "onViewReleased: " + "xvel: " + xvel + " yvel: " + yvel);
            super.onViewReleased(releasedChild, xvel, yvel);
             
            // 判断执行 关闭/开启
            // 先考虑所有开启的情况,剩下的就都是关闭的情况
            if(xvel == 0 && mMainContent.getLeft() > mRange / 2.0f){
                open();
            }else if (xvel > 0) {
                open();
            }else {
                close();
            }
             
        }
        @Override
        public void onViewDragStateChanged(int state) {
            // TODO Auto-generated method stub
            super.onViewDragStateChanged(state);
        }
    };
     
    /**
     * 根据范围修正左边值
     * @param left
     * @return
     */
    private int fixLeft(int left) {
        if(left < 0){
            return 0;
        }else if (left > mRange) {
            return mRange;
        }
        return left;
    }
     
    protected void dispatchDragEvent(int newLeft) {
        float percent = newLeft * 1.0f/ mRange;
        //0.0f -> 1.0f
        Log.d(TAG, "percent: " + percent);
         
        if(mListener != null){
            mListener.onDraging(percent);
        }
         
        // 更新状态, 执行回调
        Status preStatus = mStatus;
        mStatus = updateStatus(percent);
        if(mStatus != preStatus){
            // 状态发生变化
            if(mStatus == Status.Close){
                // 当前变为关闭状态
                if(mListener != null){
                    mListener.onClose();
                }
            }else if (mStatus == Status.Open) {
                if(mListener != null){
                    mListener.onOpen();
                }
            }
        }
         
//      * 伴随动画:
        animViews(percent);
         
    }
    private Status updateStatus(float percent) {
        if(percent == 0f){
            return Status.Close;
        }else if (percent == 1.0f) {
            return Status.Open;
        }
        return Status.Draging;
    }
    private void animViews(float percent) {
        //      > 1. 左面板: 缩放动画, 平移动画, 透明度动画
                    // 缩放动画 0.0 -> 1.0 >>> 0.5f -> 1.0f  >>> 0.5f * percent + 0.5f
            //      mLeftContent.setScaleX(0.5f + 0.5f * percent);
            //      mLeftContent.setScaleY(0.5f + 0.5f * percent);
                    ViewHelper.setScaleX(mLeftContent, evaluate(percent, 0.5f, 1.0f));
                    ViewHelper.setScaleY(mLeftContent, 0.5f + 0.5f * percent);
                    // 平移动画: -mWidth / 2.0f -> 0.0f
                    ViewHelper.setTranslationX(mLeftContent, evaluate(percent, -mWidth / 2.0f, 0));
                    // 透明度: 0.5 -> 1.0f
                    ViewHelper.setAlpha(mLeftContent, evaluate(percent, 0.5f, 1.0f));
                 
        //      > 2. 主面板: 缩放动画
                    // 1.0f -> 0.8f
                    ViewHelper.setScaleX(mMainContent, evaluate(percent, 1.0f, 0.8f));
                    ViewHelper.setScaleY(mMainContent, evaluate(percent, 1.0f, 0.8f));
                     
        //      > 3. 背景动画: 亮度变化 (颜色变化)
                    getBackground().setColorFilter((Integer)evaluateColor(percent, Color.BLACK, Color.TRANSPARENT), Mode.SRC_OVER);
    }
     
    /**
     * 估值器，0-100,一半50百分之=50,10-100
     * @param fraction
     * @param startValue
     * @param endValue
     * @return
     */
    public Float evaluate(float fraction, Number startValue, Number endValue) {
        float startFloat = startValue.floatValue();
        return startFloat + fraction * (endValue.floatValue() - startFloat);
    }
    /**
     * 颜色变化过度
     * @param fraction
     * @param startValue
     * @param endValue
     * @return
     */
    public Object evaluateColor(float fraction, Object startValue, Object 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 void computeScroll() {
        super.computeScroll();
         
        // 2. 持续平滑动画 (高频率调用)
        if(mDragHelper.continueSettling(true)){
            //  如果返回true, 动画还需要继续执行
            ViewCompat.postInvalidateOnAnimation(this);
        }
    }
     
    public void close(){
        close(true);
    }
    /**
     * 关闭
     */
    public void close(boolean isSmooth) {
        int finalLeft = 0;
        if(isSmooth){
            // 1. 触发一个平滑动画
            if(mDragHelper.smoothSlideViewTo(mMainContent, finalLeft, 0)){
                // 返回true代表还没有移动到指定位置, 需要刷新界面.
                // 参数传this(child所在的ViewGroup)
                ViewCompat.postInvalidateOnAnimation(this);
            }
        }else {
            mMainContent.layout(finalLeft, 0, finalLeft + mWidth, 0 + mHeight);
        }
    }
     
    public void open(){
        open(true);
    }
    /**
     * 开启
     */
    public void open(boolean isSmooth) {
        int finalLeft = mRange;
        if(isSmooth){
            // 1. 触发一个平滑动画
            if(mDragHelper.smoothSlideViewTo(mMainContent, finalLeft, 0)){
                // 返回true代表还没有移动到指定位置, 需要刷新界面.
                // 参数传this(child所在的ViewGroup)
                ViewCompat.postInvalidateOnAnimation(this);
            }
        }else {
            mMainContent.layout(finalLeft, 0, finalLeft + mWidth, 0 + mHeight);
        }
    }
    private int mHeight;
    private int mWidth;
    private int mRange;
     
    // b.传递触摸事件
    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        // 传递给mDragHelper
        return mDragHelper.shouldInterceptTouchEvent(ev);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        try {
            mDragHelper.processTouchEvent(event);
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 返回true, 持续接受事件
        return true;
    }
     
    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        // Github
        // 写注释
        // 容错性检查 (至少有俩子View, 子View必须是ViewGroup的子类)
         
        if(getChildCount() < 2){
            throw new IllegalStateException("布局至少有俩孩子. Your ViewGroup must have 2 children at least.");
        }
        if(!(getChildAt(0) instanceof ViewGroup && getChildAt(1) instanceof ViewGroup)){
            throw new IllegalArgumentException("子View必须是ViewGroup的子类. Your children must be an instance of ViewGroup");
        }
         
        mLeftContent = (ViewGroup) getChildAt(0);
        mMainContent = (ViewGroup) getChildAt(1);
    }
     
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        // 当尺寸有变化的时候调用
         
        mHeight = getMeasuredHeight();
        mWidth = getMeasuredWidth();
         
        // 移动的范围
        mRange = (int) (mWidth * 0.6f);
         
    }
     
}

public class MyLinearLayout extends LinearLayout {
    private DragLayout mDragLayout;
    public MyLinearLayout(Context context) {
        super(context);
    }
    public MyLinearLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
     
    public void setDraglayout(DragLayout mDragLayout){
        this.mDragLayout = mDragLayout;
    }
     
    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        // 如果当前是关闭状态, 按之前方法判断
        if(mDragLayout.getStatus() == Status.Close){
            return super.onInterceptTouchEvent(ev);
        }else {
            return true;
        }
    }
     
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // 如果当前是关闭状态, 按之前方法处理
        if(mDragLayout.getStatus() == Status.Close){
            return super.onTouchEvent(event);
        }else {
            // 手指抬起, 执行关闭操作
            if(event.getAction() == MotionEvent.ACTION_UP){
                mDragLayout.close();
            }
             
            return true;
        }
    }
}

public class MainActivity extends Activity {
    private static final String TAG = "TAG";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);
         
        final ListView mLeftList = (ListView) findViewById(R.id.lv_left);
        final ListView mMainList = (ListView) findViewById(R.id.lv_main);
        final ImageView mHeaderImage = (ImageView) findViewById(R.id.iv_header);
        MyLinearLayout mLinearLayout = (MyLinearLayout) findViewById(R.id.mll);
         
        // 查找Draglayout, 设置监听
        DragLayout mDragLayout = (DragLayout) findViewById(R.id.dl);
        // 设置引用
        mLinearLayout.setDraglayout(mDragLayout);
         
        mDragLayout.setDragStatusListener(new OnDragStatusChangeListener() {
             
            @Override
            public void onOpen() {
                Utils.showToast(MainActivity.this, "onOpen");
                // 左面板ListView随机设置一个条目
                Random random = new Random();
                 
                int nextInt = random.nextInt(50);
                mLeftList.smoothScrollToPosition(nextInt);
                 
            }
             
            @Override
            public void onDraging(float percent) {
                Log.d(TAG, "onDraging: " + percent);// 0 -> 1
                // 更新图标的透明度
                // 1.0 -> 0.0
                ViewHelper.setAlpha(mHeaderImage, 1 - percent);
            }
             
            @Override
            public void onClose() {
                Utils.showToast(MainActivity.this, "onClose");
                // 让图标晃动
//              mHeaderImage.setTranslationX(translationX)
                ObjectAnimator mAnim = ObjectAnimator.ofFloat(mHeaderImage, "translationX", 15.0f);
                mAnim.setInterpolator(new CycleInterpolator(4));
                mAnim.setDuration(500);
                mAnim.start();
            }
        });
         
        mLeftList.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, Cheeses.sCheeseStrings){//Cheeses自己定义的，存放的一些字符串
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                View view = super.getView(position, convertView, parent);
                TextView mText = ((TextView)view);
                mText.setTextColor(Color.WHITE);
                return view;
            }
        });
         
        mMainList.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, Cheeses.NAMES));
         
         
         
    }
}