viewDragHelper的用法 至实用

本文主要是介绍viewDragHelper的用法 至实用，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

[2019年的草稿]不负责任的发出去吧.我想不出来直播的view 翻页 看上一个下一个直播是怎么做的,我实在搞不明白怎么实现的呢..

想过viewpager,但是发现用fragment出现了很多问题  做循环滚动设置currentItem为中间值就是oom，

int half = Integer.MAX_VALUE / 2; int needPosition = 1; int realPosition = half % mViewList.size(); while (realPosition != needPosition) { if (realPosition > needPosition) { --half; } else { ++half; } realPosition = half % mViewList.size(); } Log.i(TAG, "real position:" + realPosition + ",position:" + half); mViewPager.setCurrentItem(0);

暂时不设置currteim等于half的值 那么滑动超过了fragment数量是空白了往回滑动就崩溃了。

 java.lang.IllegalStateException: Fragment already activeat android.support.v4.app.Fragment.setInitialSavedState(Fragment.java:571)at android.support.v4.app.FragmentStatePagerAdapter.instantiateItem(FragmentStatePagerAdapter.java:110)at space.qssq.dragdemo.BaseFragmentAdapter.instantiateItem(BaseFragmentAdapter.java:47)

那么set

package space.qssq.dragdemo;import android.annotation.TargetApi;
import android.content.Context;
import android.os.Build;
import android.support.v4.view.GestureDetectorCompat;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.ViewDragHelper;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;/**
 * Created by luozheng on 2016/5/16.  qssq.space
 */
public class LiveViewGroup extends FrameLayout {private static final String TAG = "LiveViewGroup";private ViewDragHelper mDragger;private View mCurrentLiveUi;/**
     * 下一个直播的封面图
     */
    private View mNextLiveUi;/**
     * 聊天在线人数 送花交互view
     */
    private View mInteractiveUi;private int mWidth;private GestureDetectorCompat gestureDetector;private float criticalVel;public LiveViewGroup(Context context) {super(context);init(context);}public LiveViewGroup(Context context, AttributeSet attrs) {super(context, attrs);init(context);}@TargetApi(Build.VERSION_CODES.HONEYCOMB)public LiveViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);init(context);}/**
     * 不允许垂直 y方向滚动 所以 y的最大值必须 小于x的大小
     */
    class YScrollDetector extends GestureDetector.SimpleOnGestureListener {@Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float dx, float dy) {return Math.abs(dy) <= Math.abs(dx);}}public void init(Context context) {criticalVel = getResources().getDisplayMetrics().density * 200;gestureDetector = new GestureDetectorCompat(context, new YScrollDetector());mDragger = ViewDragHelper.create(this, 1.0f, new ViewDragHelper.Callback() {@Override
                    public boolean tryCaptureView(View child, int pointerId) {return true;}@Override
                    public int clampViewPositionHorizontal(View child, int left, int dx) {//dx表示滑动的距离大于0表示右滑动  小于0 表示向左边滑动 left表示距离屏幕左边的距离
                        Log.i("clampViewPositionHorizontal", "left:" + left + ",dx:" + dx);if (child == mInteractiveUi) {//不能向左边滑动只能向右边滑动 右边滑动之后就把直播展示出来了
                            if (left < 0) {return 0;} else if (left > mWidth) {//往右边滑动不可超过直播的宽度
                                return mWidth;}} else if (child == mCurrentLiveUi) { //
                            if (left < 0 && left < -mWidth) {//拉得太过了肯定不行
                                return -mWidth;} else if (left > mWidth) {//往右边滑动不可超过直播的宽度  直播ui往右边拉可以，但是在下一步要撤销回去。
                                return mWidth;}} else if (child == mNextLiveUi) {//自己不动 不能右边滑动 了, 另外左边滑动其实是把 直播view滑动出来
                            if (left > 0) {return 0;} else if (left < 0 && left < -mWidth) {//往右边滑动不可超过直播的宽度
                                return -mWidth;}}return left;}@Override
                    public void onViewPositionChanged(View changedView, int left, int top, int dx,int dy) {super.onViewPositionChanged(changedView, left, top, dx, dy);Log.d("3 onViewPositionChanged", String.format("changedView %s ,left %s ,top %s ,dx %s ,dy %s", changedView.getTag(), left, top, dx, dy));if (changedView == mCurrentLiveUi) {
//                            // 验证移动的范围对不对，如果不对就啥都不做
                            if (dx < 0) {//往右边 那么左边变成复数 拉自己不动
                                int tmpXLeft = mInteractiveUi.getLeft() + dx;if (tmpXLeft <= mWidth) {if (left < 0) {//自己都没滑动回来
                                        mInteractiveUi.offsetLeftAndRight(dx);}}if (left < 0) {mCurrentLiveUi.offsetLeftAndRight(-dx);//自己撤销回去？拉多少撤销多少 除非自己都没考左边
                                }} else {
//
                            }} else if (changedView == mNextLiveUi) {int tmpXLeft = mCurrentLiveUi.getLeft() + dx;if (dx < 0) {if (tmpXLeft > 0) {mCurrentLiveUi.offsetLeftAndRight(dx);//这里应该是负数
                                }} else {if (tmpXLeft <= mWidth) {mCurrentLiveUi.offsetLeftAndRight(dx);//这里应该是正数
                                }}mNextLiveUi.offsetLeftAndRight(-dx);//自己撤销回去？拉多少撤销多少
                        }}
//                        if (changedView == mCurrentLiveUi) {
//                            // 验证移动的范围对不对，如果不对就啥都不做
//                            int tmpXLeft = mInteractiveUi.getLeft() + dx;
//                            if (tmpXLeft < mWidth) {
//
//                                mInteractiveUi.offsetLeftAndRight(dx);
//                            }
//                            mCurrentLiveUi.offsetLeftAndRight(-dx);//撤销回去？
//
//                        }

                    @Override
                    public int clampViewPositionVertical(View child, int top, int dy) {Log.i("clampViewPositionVertical", "left:" + top + ",dx:" + dy);return 0;}/*！ 一般用来进行动画效果
                         * 当view的位置发生变化的时候会调用此方法
                         * changedView 位置发生变化的view
                         * left 当前changedView的left边的位置
                         * top  当前changedView的top边的位置
                         * dx   left边在  移动  前后的变化值
                         * dy   top边在  移动  前后的变化值
                         *
                         */
                    @Override
                    public void onViewDragStateChanged(int state) {super.onViewDragStateChanged(state);Log.i(TAG, "onViewDragStateChanged");switch (state) {case ViewDragHelper.STATE_IDLE:
//                                if (mInteractiveUi.getLeft() > mWidth / 2) {
//                                    currentView = CURRENT_VIEW.VIEW_TWO;
//                                } else if (mInteractiveUi.getLeft() > 0) {
//                                    currentView = CURRENT_VIEW.VIEW_THERE;
//                                } else if (mNextLiveUi.getLeft() > -mWidth / 2) {
//                                    currentView = CURRENT_VIEW.VIEW_TWO;
//                                } else if (mInteractiveUi.getLeft() < 0) {
//                                    currentView = CURRENT_VIEW.VIEW_THERE;
//                                    break;
//                                } else {
//                                    currentView = CURRENT_VIEW.VIEW_TWO;
//                                }
//                                Log.i(TAG, "CURRENT state:" + currentView);
//                                break;

                        }}/*
                     *
                     * 当手指抬起的时候，会被调用，表示view被释放
                     * releasedChild
                     * 速度的值是由记速器VelocityTracker对象提供的
                     * xvel 释放时水平方向的速度，单位是像素/秒
                     * yvel 释放时垂直方向的速度，单位是像素/秒
                     */
                    @Override
                    public void onViewReleased(View releasedChild, float xvel, float yvel) {Log.i(TAG, "onViewReleased");Log.w("onViewReleased", String.format("releasedChild %s,xvel %s,yvel %s", releasedChild.getTag(), xvel, yvel));judgeState(xvel);}});}public void judgeState(float xvel) {
//        if (true) {
//            return;
//        }
        if (mInteractiveUi.getLeft() != mWidth) {//如果原来是 显示 互动界面的
            if (Math.abs(xvel) >= criticalVel) {if (xvel > 0) {//从左往右边滑动
                    hiddenInteractiveUi();currentView = CURRENT_VIEW.VIEW_TWO;} else {showInteractiveUi();currentView = CURRENT_VIEW.VIEW_THERE;}return;}if (mInteractiveUi.getLeft() < mWidth / 2) {//表明 往右边拉 还没拉到1半 所以回弹
                showInteractiveUi();} else if (mInteractiveUi.getLeft() > mWidth / 2) {//表明 往右边拉 拉到1半了
                currentView = CURRENT_VIEW.VIEW_TWO;hiddenInteractiveUi();}} else if (mCurrentLiveUi.getLeft() != 0) {if (Math.abs(xvel) >= criticalVel) {if (xvel > 0) {//从左往右边滑动
                    showCurrentUi();currentView = CURRENT_VIEW.VIEW_TWO;} else {hiddenCurrentUi();currentView = CURRENT_VIEW.VIEW_ONE;}return;}int value = mCurrentLiveUi.getLeft();if (Math.abs(value) > mWidth / 2) {//说明负数很大了
                hiddenCurrentUi();currentView = CURRENT_VIEW.VIEW_ONE;} else {showCurrentUi();currentView = CURRENT_VIEW.VIEW_TWO;}/*
            value永远不可能大于0
        解决ui问题但是现在 改变判断条件了不需要再这里做了
         if (value == 0) {//dengyu 0
                if (mInteractiveUi.getLeft() != mWidth) {
                    if (mInteractiveUi.getLeft() < mWidth / 2) {
                        hiddenInteractiveUi();
                    } else {
                        hiddenCurrentUi();
                        showInteractiveUi();
                    }
                } else {
                }
            }
            */
        }}@Override
    public boolean onInterceptTouchEvent(MotionEvent event) {return mDragger.shouldInterceptTouchEvent(event);}@Override
    public boolean onTouchEvent(MotionEvent event) {mDragger.processTouchEvent(event);return true;}@Override
    protected void onFinishInflate() {super.onFinishInflate();mNextLiveUi = getChildAt(0);mCurrentLiveUi = getChildAt(1);mInteractiveUi = getChildAt(2);mCurrentLiveUi.post(new Runnable() {@Override
            public void run() {mWidth = mCurrentLiveUi.getWidth();}});/**
         * 首页是这样的 最顶层 放的是直播评论  刚开始点击应该滑动的是mLiveComment
         */
    }/**
     * 是否还需要移动
     */
    @Override
    public void computeScroll() {if (mDragger.continueSettling(true)) {ViewCompat.postInvalidateOnAnimation(this);} else {if (mDragger.continueSettling(true)) {ViewCompat.postInvalidateOnAnimation(this);} else {if (onPageChangeListener != null) {if (mInteractiveUi.getLeft() == 0) {onPageChangeListener.onPageNext();} else if (mCurrentLiveUi.getLeft() == mWidth) {onPageChangeListener.onPagePre();} else {onPageChangeListener.onPageCurrent();}Log.i(TAG, "执行完毕");}}}}public void showInteractiveUi() {//租后的左边和定边
        if (mDragger.smoothSlideViewTo(mInteractiveUi, 0, 0)) {ViewCompat.postInvalidateOnAnimation(this);}}public void hiddenInteractiveUi() {if (mDragger.smoothSlideViewTo(mInteractiveUi, mWidth, 0)) {ViewCompat.postInvalidateOnAnimation(this);}}public void showCurrentUi() {//租后的左边和定边
        if (mDragger.smoothSlideViewTo(mCurrentLiveUi, 0, 0)) {ViewCompat.postInvalidateOnAnimation(this);}}public void setOnPageChangeListener(LiveViewGroup.onPageChangeListener onPageChangeListener) {this.onPageChangeListener = onPageChangeListener;}onPageChangeListener onPageChangeListener = null;public interface onPageChangeListener {public void onPageNext();public void onPagePre();public void onPageCurrent();}public void hiddenCurrentUi() {if (mDragger.smoothSlideViewTo(mCurrentLiveUi, mWidth, 0)) {ViewCompat.postInvalidateOnAnimation(this);}}//    public void showNextUi() {
//        //租后的左边和定边
//        if (mDragger.smoothSlideViewTo(mNextLiveUi, 0, 0)) {
//            ViewCompat.postInvalidateOnAnimation(this);
//        }
//    }
//
//    public void hiddenNextUi() {
//        if (mDragger.smoothSlideViewTo(mNextLiveUi, -mWidth, 0)) {
//            ViewCompat.postInvalidateOnAnimation(this);
//        }
//    }

    // 使用估值器和属性动画（nineoldAndroid）(ViewHelper)
    protected void dispatchAnimation(float percent) {// 主界面有缩放动画
//    mainView.setScaleX(0.5f);
//    ViewHelper.setScaleX(mainView, 0.5f);


        // 菜单界面位移、缩放、透明
        //位移
        // 单位是像素
//        ViewHelper.setTranslationX(menuView, floatEvaluator.evaluate(percent, - leftWidth /2, 0));
      缩放
//        Float menuScale = floatEvaluator.evaluate(percent, menuMinScale, 1);
//        ViewHelper.setScaleX(menuView, menuScale);
//        ViewHelper.setScaleY(menuView, menuScale);
      透明
//        ViewHelper.setAlpha(menuView, percent);

    }/**
     * ONE 就是 往TWO也就是没有交互的页面往右边滑动显示的界面
     */
    public enum CURRENT_VIEW {VIEW_ONE, VIEW_TWO, VIEW_THERE;}public CURRENT_VIEW currentView = CURRENT_VIEW.VIEW_THERE;//默认显示 交互view

    public void setCurrentView(CURRENT_VIEW currentView, boolean needAnim) {switch (currentView) {case VIEW_ONE:if (needAnim) {if (mInteractiveUi.getLeft() != mWidth) {hiddenCurrentUi();} else if (mCurrentLiveUi.getLeft() != 0) {hiddenCurrentUi();}} else {mInteractiveUi.offsetLeftAndRight(mWidth);//这里应该是负数
                    mCurrentLiveUi.offsetLeftAndRight(mWidth);//这里应该是负数

                }break;case VIEW_TWO:if (needAnim) {if (mInteractiveUi.getLeft() != mWidth) {hiddenCurrentUi();}showCurrentUi();} else {mInteractiveUi.offsetLeftAndRight(mWidth);//这里应该是负数
                    mCurrentLiveUi.offsetLeftAndRight(0);//这里应该是负数

                }break;case VIEW_THERE:if (needAnim) {if (mCurrentLiveUi.getLeft() != 0) {showCurrentUi();}showInteractiveUi();} else {mCurrentLiveUi.offsetLeftAndRight(0);//这里应该是负数
                    mInteractiveUi.offsetLeftAndRight(mWidth);//这里应该是负数
                }break;default:return;}this.currentView = currentView;}
}

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