如果在 onViewCreated() 之后运行，自定义视图将不会更新

Question

我构建了一个名为 progressCircle 的自定义 view class，它是一个类似于 snapchat 的圆形进度条 - 它位于约束布局内，位于圆形按钮上方。

此视图具有参数 angle，当从 onViewCreated() 调用时，如果运行

将完美运行

progressCircle.angle = 100f

但是，我正在尝试为这个 onClick 设置动画。如果我运行这个相同的代码，onClick，progressCircle不会出现？！经过反复试验，我发现在这里更新背景颜色使视图可见并且已更新。即;

 button.setOnClickListener {
      progressCircle.setBackgroundColor(android.R.color.transparent)
      progressCircle.angle = 270f
 }

这是怎么回事，我怎样才能解决这个问题，以便我可以正确地制作动画...

编辑：

class ProgressCircle(context: Context, attrs: AttributeSet) : View(context, attrs) {

    private val paint: Paint
    private val rect: RectF

    private val fillPaint: Paint
    private val fillRect: RectF

    var angle: Float
    var startAngle: Float = 0f

    init {

        val typedArray = context.obtainStyledAttributes(attrs, R.styleable.ProgressCircle)
        angle = typedArray.getFloat(R.styleable.ProgressCircle_angle, 0f)
        typedArray.recycle()

        val offsetAngle = 0f
        val color = getColor(context, R.color.outputON)
        val strokeWidth = 15f
        val circleSize = 276f

        paint = Paint().apply {
            setAntiAlias(true)
            setStyle(Paint.Style.STROKE)
            setStrokeWidth(strokeWidth)
            setColor(color)
        }

        rect = RectF(
            strokeWidth,
            strokeWidth,
            (circleSize - strokeWidth),
            (circleSize - strokeWidth)
        )

        fillPaint = Paint().apply {
            setAntiAlias(true)
            setStyle(Paint.Style.FILL)
            setColor(getColor(context, R.color.flat_blue_1))
        }

        val offsetFill = strokeWidth
        fillRect = RectF(
            offsetFill,
            offsetFill,
            (circleSize - offsetFill),
            (circleSize - offsetFill)
        )

        //Initial Angle (optional, it can be zero)
        angle = offsetAngle
    }

    override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        if (getColor(context, R.color.flat_blue_1) > 0) {
            canvas.drawArc(rect, 0f, 360f, false, fillPaint)
        }
        canvas.drawArc(rect, startAngle, angle, false, paint)
    }
}

TIA

Answer 1

默认情况下，视图仅在某些内容发生更改时才重绘自身 - 即，根据 View documentation:

视图“无效”时

Drawing is handled by walking the tree and recording the drawing commands of any View that needs to update. After this, the drawing commands of the entire tree are issued to screen, clipped to the newly damaged area.

如果您希望自定义视图在 angle 属性更改时自行重绘，您需要调用 invalidate():

var angle: Float
    set(value) {
        // Do the default behavior of setting the value
        field = value

        // Then call invalidate() to force a redraw
        invalidate()
    }
}

如果在 onViewCreated() 之后运行，自定义视图将不会更新

Custom view will not update if run after onViewCreated()

animation

android

view

kotlin

如果在 onViewCreated() 之后 运行，自定义视图将不会更新

Custom view will not update if run after onViewCreated()

animation

android

view

kotlin

如果在 onViewCreated() 之后运行，自定义视图将不会更新