机器人的WebView：检测滚动 [英] Android webview : detect scroll

问题描述

我需要知道如何检测，如果用户不能在web视图不再滚动。我想，当用户扫描到左边或右边，以产生一个动作，但只有在用户不能滚动：

 如果用户扫描的左侧和web视图不能滚动到左​​，那么
 做一点事
其他
 让web视图滚动
 

解决方案

我发现这对我的工作，我检查类的WebView源$ C ​​$ C在2.3 API，并找到如何与2.1 API做一个解决方案。也许它可以与旧的API工作：

 公共类CustomWebView扩展的WebView {

    私人浮动oldX;

 //说明是否水平滚动条不能走得更向左
    私人布尔overScrollLeft = FALSE;

 //说明是否水平滚动条不能去到右侧
    私人布尔overScrollRight = FALSE;

 //说明是否水平滚动条不能去更多地向左或向右
    私人布尔isScrolling = FALSE;

    公共CustomWebView（上下文的背景下）{
        超（上下文）;
        // TODO自动生成构造函数存根
    }



    公共CustomWebView（上下文的背景下，ATTRS的AttributeSet，诠释defStyle）{
        超（背景下，ATTRS，defStyle）;
        // TODO自动生成构造函数存根
    }



    公共CustomWebView（上下文的背景下，ATTRS的AttributeSet）{
        超（背景下，ATTRS）;
        // TODO自动生成构造函数存根
    }

    @覆盖
    公共布尔的onTouchEvent（MotionEvent事件）{
        //宽的垂直滚动条
  INT scrollBarWidth = getVerticalScrollbarWidth（）;

  //宽取决于你的观点的设置布局
  INT viewWidth = computeHorizo​​ntalScrollExtent（）;

  //宽度网页的根据变焦的
        INT innerWidth = computeHorizo​​ntalScrollRange（）;

  //水平滚动条左侧的位置
        INT scrollBarLeftPos = computeHorizo​​ntalScrollOffset（）;

  //右侧水平滚动条的位置时，涡旋的宽度的视图宽度减去垂直滚动条的宽度
        INT scrollBarRightPos = scrollBarLeftPos + viewWidth  -  scrollBarWidth;

        //如果滚动条左pos是0剩下的滚动是真实的
        如果（scrollBarLeftPos == 0）{
            overScrollLeft = TRUE;
        } 其他 {
            overScrollLeft = FALSE;
        }

        //如果滚动条右侧POS优于网页宽度：对在滚动是真实的
        如果（scrollBarRightPos＆GT; = innerWidth）{
            overScrollRight = TRUE;
        } 其他 {
            overScrollRight = FALSE;
        }

        开关（event.getAction（））{
        案例MotionEvent.ACTION_DOWN：//当用户触摸屏幕
   //如果滚动条被左或右最
            如果（overScrollLeft || overScrollRight）{
                isScrolling = FALSE;
            } 其他 {
                isScrolling = TRUE;
            }
            oldX = event.getX（）;
            打破;

        案例MotionEvent.ACTION_UP：//当用户停止触摸屏
   //如果滚动条不能去更多地向左或向右
   //这使强迫用户做另一种姿态，当他到达侧
            如果（！isScrolling）{
                如果（event.getX（）＆GT; oldX＆安培;＆安培; overScrollLeft）{
                    //左行动
                }

                如果（event.getX（）＆其中; oldX＆安培;＆安培; overScrollRight）{
     //权之诉
                }
            }

            打破;
        默认：
            打破;
        }
        返回super.onTouchEvent（事件）;
    }

}
 

I need to know how to detect if the user can't scroll anymore in a webView. I want to generate an action when the user swipes to the left or right, but only if the user can't scroll:

IF the user swipes to the left AND the webview can't scroll to left THEN
 do something
ELSE
 let the webview scroll

解决方案

I found a solution which work for me, I check the source code of class WebView in 2.3 API and find how to do it with a 2.1 API. Maybe it can work with older API:

public class CustomWebView extends WebView {

    private float oldX;

 // indicate if horizontal scrollbar can't go more to the left
    private boolean overScrollLeft = false;

 // indicate if horizontal scrollbar can't go more to the right
    private boolean overScrollRight = false;

 // indicate if horizontal scrollbar can't go more to the left OR right
    private boolean isScrolling = false;

    public CustomWebView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }



    public CustomWebView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
    }



    public CustomWebView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // width of the vertical scrollbar
  int scrollBarWidth = getVerticalScrollbarWidth();

  // width of the view depending of you set in the layout
  int viewWidth = computeHorizontalScrollExtent();

  // width of the webpage depending of the zoom
        int innerWidth = computeHorizontalScrollRange();

  // position of the left side of the horizontal scrollbar
        int scrollBarLeftPos = computeHorizontalScrollOffset();

  // position of the right side of the horizontal scrollbar, the width of scroll is the width of view minus the width of vertical scrollbar
        int scrollBarRightPos = scrollBarLeftPos + viewWidth - scrollBarWidth;

        // if left pos of scroll bar is 0 left over scrolling is true
        if(scrollBarLeftPos == 0) {
            overScrollLeft = true;
        } else {
            overScrollLeft = false;
        }

        // if right pos of scroll bar is superior to webpage width: right over scrolling is true
        if(scrollBarRightPos >= innerWidth) {
            overScrollRight = true;
        } else {
            overScrollRight = false;
        }

        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN: // when user touch the screen
   // if scrollbar is the most left or right
            if(overScrollLeft || overScrollRight) {
                isScrolling = false;
            } else {
                isScrolling = true;
            }
            oldX = event.getX();
            break;

        case MotionEvent.ACTION_UP: // when user stop to touch the screen
   // if scrollbar can't go more to the left OR right 
   // this allow to force the user to do another gesture when he reach a side
            if(!isScrolling) {
                if(event.getX() > oldX && overScrollLeft) {
                    // left action
                }

                if(event.getX() < oldX && overScrollRight) {
     // right actio
                }
            }

            break;
        default:
            break;
        }
        return super.onTouchEvent(event);
    }

}

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