android - 如何在 android kotlin 中更改 onScrollChanged 上的选项卡

Question

我在屏幕上工作，其中有 scrollview，其中包含 4 个 view，并且我有四个选项卡代表该部分。最初 view1 tab 在我滚动 view2 时处于 Activity 状态 visible 那时 view2 tab 应该处于 Activity 状态。让我知道如果有人有解决方案。

Answer 1

首先应该将 ScrollViewListener 添加到您的 ScrollView 中

yourscrollview.setScrollViewListener(this)//replace yourscrollview with your scrollview and override onScrollChanged

然后为所有四个 View 创建变量

现在是主要部分。在这里我们得到所有四个的高度。虽然滚动 position 和 views heights 我们检查当前是哪个 View 可见 在屏幕上然后您可以激活 选项卡。

现在在onScrollChanged 方法中

override fun onScrollChanged(scrollView: ScrollViewExt?, x: Int, y: Int, oldx: Int, oldy: Int) {
    val scrollBounds = Rect()
    scrollView?.getDrawingRect(scrollBounds)
    var top4 = 0f
    var temp4:View = view4
    while (temp4 !is ScrollView){
        top4 += (temp4).y
        temp4 = temp4.parent as View
    }

    var top3 = 0f
    var temp3:View = view3
    while (temp3 !is ScrollView){
        top3 += (temp3).y
        temp3 = temp3.parent as View
    }
    var top2 = 0f
    var temp2:View = view2
    while (temp2 !is ScrollView){
        top2 += (temp2).y
        temp2 = temp2.parent as View
    }
    var top1 = 0f
    var temp1:View = view1
    while (temp1 !is ScrollView){
        top1 += (temp1).y
        temp1 = temp1.parent as View
    }

//this are the height of four views
    view1_height = top1 + view1.height
    view2_height = top2 + view2.height
    view3_height = top3 + view3.height
    view4_height = top4 + view4.height

//now check which view is visible . we go in descending order
    if (scrollBounds.bottom + view4.height >= view4_height {
            //4th view is visible
            //active your 4th tab    
        } else if (scrollBounds.bottom + view3.height >= view3_height {
          //3th view is visible
          //active your 3rd tab     
        } else if (scrollBounds.bottom + view2.height >= view2_height) {
          //2th view is visible
          //active your 2th tab 
        } else if ( scrollBounds.bottom + view1.height >= view1_height) {
              //1th view is visible
            //active your 1st tab   
        }
    }

我希望这对你有用。