自定义视图未在 BottomSheetDialogFragment 中绘制，有时在无效后调用 onSizeChanged

Question

我正在开发一个自定义图表视图，显示在底部 sheet 对话框片段中，它没有绘制，当我添加数据并在调用 onSizeChanged() 之前调用 invalidate() 时.有时会出现这种情况，我不知道如何解决。

我在我的 BottomSheetDialogFragment 的 onViewCreated(...) 中添加了数据，它是 LiveData，所以在 Observer 调用 ChartView 的 setDataPoints() 之前肯定需要一些时间。

我还在两个普通片段中使用了图表，在那里工作正常。

我的自定义视图：

class MonthlyTrendChart @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) : View(context, attrs, defStyleAttr) {

    //region Variables

    private val data = mutableListOf<DateDataPoint>()
    private val points = mutableListOf<PointF>()

    private val path = Path()

    private val pathPaint: Paint

    //endregion

    //region Constructor

    init {
        pathPaint = Paint().apply {
            isAntiAlias = true
            color = Color.WHITE
            strokeWidth = 5.0f
            style = Paint.Style.STROKE
        }

        setWillNotDraw(false)
    }

    //endregion

    //region View

    override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
        super.onSizeChanged(w, h, oldw, oldh)

        println("MB: onSizeChanged: ${data.size}")
    }

    override fun onDraw(canvas: Canvas?) {
        super.onDraw(canvas)

        computePath()

        canvas?.drawPath(path, pathPaint)
    }

    //endregion

    //region Methods

    fun setDataPoints(dataPoints: List<DateDataPoint>) = GlobalScope.launch(Dispatchers.Main) {
        val min = dataPoints.minByOrNull { it.value }?.value ?: 0.0f

        val positiveDataPoints: List<DateDataPoint> = List(dataPoints.size) { i -> DateDataPoint(dataPoints[i].date, dataPoints[i].value - min) }

        data.clear()
        data.addAll(positiveDataPoints)

        computePoints()

        postInvalidate()
        println("MB: invalidate: ${data.size}")
    }

    private fun computePoints() {
        points.clear()

        val graphHeight = height.toFloat()

        val maxValue: Float = data.maxByOrNull { it.value }!!.value

        val xStep: Float = width.toFloat() / (data.size - 1)

        for (i in 0 until data.size) {
            val xVal = xStep * i
            val yVal = graphHeight - data[i].value / maxValue * graphHeight

            points.add(PointF(xVal, yVal))
        }
    }

    private fun computePath() {
        if (points.isEmpty()) return

        with(path) {
            reset()

            moveTo(points.first().x, points.first().y)

            for (i in 0 until points.size) {
                lineTo(points[i].x, points[i].y)
            }
        }
    }

    //endregion

    companion object {

    }
}

这是输出：

2021-02-19 18:13:25.210 29400-29400/at.guger.moneybook.dev I/System.out: MB: invalidate: 28
2021-02-19 18:13:30.146 29400-29400/at.guger.moneybook.dev I/System.out: MB: onSizeChanged: 0
2021-02-19 18:13:30.153 29400-29400/at.guger.moneybook.dev I/System.out: MB: invalidate: 28
2021-02-19 18:13:32.424 29400-29400/at.guger.moneybook.dev I/System.out: MB: onSizeChanged: 0
2021-02-19 18:13:32.429 29400-29400/at.guger.moneybook.dev I/System.out: MB: invalidate: 28
2021-02-19 18:13:34.897 29400-29400/at.guger.moneybook.dev I/System.out: MB: onSizeChanged: 0
2021-02-19 18:13:34.900 29400-29400/at.guger.moneybook.dev I/System.out: MB: invalidate: 28
2021-02-19 18:13:37.077 29400-29400/at.guger.moneybook.dev I/System.out: MB: onSizeChanged: 0
2021-02-19 18:13:37.083 29400-29400/at.guger.moneybook.dev I/System.out: MB: invalidate: 28
2021-02-19 18:13:38.689 29400-29400/at.guger.moneybook.dev I/System.out: MB: invalidate: 28  <---- this is the case when it doesn't draw
2021-02-19 18:13:38.697 29400-29400/at.guger.moneybook.dev I/System.out: MB: onSizeChanged: 28 <---- doesn't draw

我已经尝试在 onSizeChanged() 中调用 invalidate()，设置 setWillNotDraw(false) 或使用 postInvalidateDelayed(100) 延迟 invalidate() 的调用。

Answer 1

我找到了解决该问题的方法：

为了检查 onSizeChanged 是否已经被调用，我在我的方法 setDataPoints.

中检查 height * width > 0

如果这个条件不成立，我会设置一个标志来重新计算尺寸变化时的绘图数据。

在 onSizeChanged 中，我检查了那个标志并再次调用了我的 setDataPoints 方法，这现在有效了。

自定义视图未在 BottomSheetDialogFragment 中绘制，有时在无效后调用 onSizeChanged

Custom View is not drawing in BottomSheetDialogFragment, when sometimes onSizeChanged is called after invalidate

android

kotlin

view

bottom-sheet

android-bottomsheetdialog