ViewDragHelper通用模板代码及应用

来源：互联网发布：三菱plc模拟量编程实例编辑：程序博客网时间：2024/06/05 13:32

ViewDragHelper的通用代码模板如下：

public class DragLayout extends FrameLayout {    private ViewDragHelper viewDragHelper;    public DragLayout(Context context){        super(context);        initHelper();    }    public DragLayout(Context context, AttributeSet attrs){        super(context,attrs);        initHelper();    }    public DragLayout(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        initHelper();    }    //初始化ViewDragHelper    private void initHelper(){        viewDragHelper=ViewDragHelper.create(this,callback);    }    //处理callback    ViewDragHelper.Callback callback=new ViewDragHelper.Callback() {        //何时开始触摸        @Override        public boolean tryCaptureView(View child, int pointerId) {            return false;        }        //处理水平滑动        @Override        public int clampViewPositionHorizontal(View child,int left,int dx){            return left;        }        //处理垂直滑动        @Override        public int clampViewPositionVertical(View child,int top,int dy){            return top;        }        //拖动结束后调用        @Override        public void onViewReleased(View releaseChild,float xvel,float yvel){            super.onViewReleased(releaseChild,xvel,yvel);        }        //触摸到View时调用        @Override        public void onViewCaptured(View capturedChild,int activePointerId){            super.onViewCaptured(capturedChild,activePointerId);        }        //触摸状态改变时调用，比如STATE_IDLE（没有拖动）、STATE_DRAGGING（正在拖动）、        //STATE_SETTLING（拖动结束）        @Override        public void onViewDragStateChanged(int state){            super.onViewDragStateChanged(state);        }        //触摸位置改变时调用，常用于滑动时更改scale进行缩放        @Override        public void onViewPositionChanged(View changeView,int left,int top,int dx,int dy){            super.onViewPositionChanged(changeView,left,top,dx,dy);        }    };    //重写拦截事件    @Override    public boolean onInterceptTouchEvent(MotionEvent event){        return viewDragHelper.shouldInterceptTouchEvent(event);    }    @Override    public boolean onTouchEvent(MotionEvent event){        //将触摸事件传递给ViewDragHelper        viewDragHelper.processTouchEvent(event);        return true;    }    //重写computeScroll    @Override    public void computeScroll(){        super.computeScroll();        if(viewDragHelper.continueSettling(true)){//如果需要继续滑动，就刷新界面            ViewCompat.postInvalidateOnAnimation(this);        }    }}

下面使用ViewDragHelper实现类似QQ的滑动侧边栏，具体代码如下：

public class DragLayout extends FrameLayout {    private ViewDragHelper viewDragHelper;    private View mainView,menuView;    private int menuViewWidth;    public DragLayout(Context context){        super(context);        initHelper();    }    public DragLayout(Context context, AttributeSet attrs){        super(context,attrs);        initHelper();    }    public DragLayout(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        initHelper();    }    //初始化ViewDragHelper    private void initHelper(){        viewDragHelper=ViewDragHelper.create(this,callback);    }    //处理callback    ViewDragHelper.Callback callback=new ViewDragHelper.Callback() {        //何时开始触摸        @Override        public boolean tryCaptureView(View child, int pointerId) {            return mainView==child;        }        //处理水平滑动        @Override        public int clampViewPositionHorizontal(View child,int left,int dx){            return left;        }        //处理垂直滑动        @Override        public int clampViewPositionVertical(View child,int top,int dy){            return 0;        }        //拖动结束后调用        @Override        public void onViewReleased(View releaseChild,float xvel,float yvel){            super.onViewReleased(releaseChild,xvel,yvel);            if(mainView.getLeft()<menuViewWidth/2){//关闭菜单                viewDragHelper.smoothSlideViewTo(mainView,0,0);            }else {//打开菜单                viewDragHelper.smoothSlideViewTo(mainView,menuViewWidth,0);            }            ViewCompat.postInvalidateOnAnimation(DragLayout.this);        }    };    //重写拦截事件    @Override    public boolean onInterceptTouchEvent(MotionEvent event){        return viewDragHelper.shouldInterceptTouchEvent(event);    }    @Override    public boolean onTouchEvent(MotionEvent event){        //将触摸事件传递给ViewDragHelper        viewDragHelper.processTouchEvent(event);        return true;    }    //重写computeScroll    @Override    public void computeScroll(){        super.computeScroll();        if(viewDragHelper.continueSettling(true)){            ViewCompat.postInvalidateOnAnimation(this);        }    }    @Override    public void onFinishInflate(){        super.onFinishInflate();        menuView=getChildAt(0);        mainView=getChildAt(1);    }    @Override    public void onSizeChanged(int w,int h,int oldW,int oldH){        super.onSizeChanged(w,h,oldW,oldH);        menuViewWidth=menuView.getMeasuredWidth();    }}

activity_main布局如下：

<?xml version="1.0" encoding="utf-8"?><com.example.draghelperdemo.DragLayout    xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/activity_main"    android:layout_width="match_parent"    android:layout_height="match_parent">    <LinearLayout        android:layout_width="400dp"        android:layout_height="match_parent"        android:gravity="center"        android:background="@color/colorAccent">        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="菜单布局"/>    </LinearLayout>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="match_parent"        android:gravity="center"        android:background="@color/colorPrimary">        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="主页布局"/>    </LinearLayout></com.example.draghelperdemo.DragLayout>

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