How to draw a circle with animation in android with circle size based on a value

Question

I want to develop a custom component which draws part of the circle based on different values. e.g draw 1/4 cirle, 1/2 circle etc. The component needs to be animated to disp

Answer 1

Added code for calculating correct circle measurements

import android.content.Context
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.graphics.RectF
import android.util.AttributeSet
import android.view.View
import androidx.core.content.ContextCompat

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

    private val paint: Paint
    private val rect: RectF

    var angle = 0f

    companion object {
        private val START_ANGLE_POINT = 270f
    }

    init {
        val strokeWidth = resources.getDimension(R.dimen.toast_circle_stroke_width)

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

        val circleSize = resources.getDimension(R.dimen.toast_circle_size)

        rect = RectF(
            strokeWidth,
            strokeWidth,
            circleSize + strokeWidth,
            circleSize + strokeWidth
        )
    }

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        val circleSize = resources.getDimension(R.dimen.toast_circle_size).toInt()
        val strokeWidth = resources.getDimension(R.dimen.toast_circle_stroke_width).toInt()

        super.onMeasure(
            MeasureSpec.makeMeasureSpec(circleSize + 2 * strokeWidth, MeasureSpec.EXACTLY),
            MeasureSpec.makeMeasureSpec(circleSize + 2 * strokeWidth, MeasureSpec.EXACTLY));
    }

    override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        canvas.drawArc(rect, START_ANGLE_POINT, angle, false, paint)
    }

}