RoundedBackgroundSpan

RoundedBackgroundSpan.kt

import android.content.Context
import android.graphics.*
import android.text.style.ReplacementSpan
import kotlin.math.roundToInt

class RoundedBackgroundSpan(
    private val context: Context,
    private val borderRadius: Float = 0f,
    private val backgroundColorInt: Int? = null,
    private val textColorInt: Int = Color.BLACK,
    private val textSizePx: Float = R.dimen._12sdp.dimen2Pixel(context).toFloat()
) : ReplacementSpan() {
    private val paddingHorizontal = R.dimen._3sdp.dimen2Pixel(context)
    private val paddingVertical = R.dimen._1sdp.dimen2Pixel(context)
    private val marginVertical = R.dimen._1sdp.dimen2Pixel(context)

    private val textPaint = Paint().apply {
        color = textColorInt
        textSize = textSizePx
        flags = Paint.ANTI_ALIAS_FLAG
        typeface = Typeface.create(Typeface.DEFAULT, Typeface.BOLD)
    }

    private val backgroundPaint = Paint().apply {
        backgroundColorInt?.apply { color = this }
        flags = Paint.ANTI_ALIAS_FLAG
    }

    override fun getSize(
        paint: Paint,
        text: CharSequence?,
        start: Int,
        end: Int,
        fm: Paint.FontMetricsInt?
    ): Int {
        return (paint.measureText(text, start, end) + paddingHorizontal * 2).toInt()
    }

    private fun measureTextWidth(paint: Paint, text: CharSequence?, start: Int, end: Int): Float {
        return paint.measureText(text, start, end)
    }

    override fun draw(
        canvas: Canvas,
        text: CharSequence?,
        start: Int,
        end: Int,
        x: Float,
        top: Int,
        y: Int,
        bottom: Int,
        paint: Paint
    ) {
        val rect = RectF(
            x,
            top + paddingVertical.toFloat() + marginVertical,
            x + measureTextWidth(paint, text, start, end) + paddingHorizontal * 2,
            bottom - paddingVertical.toFloat() - marginVertical
        )
        canvas.drawRoundRect(
            rect,
            borderRadius,
            borderRadius,
            backgroundPaint
        )
        canvas.drawText(
            text ?: "",
            start,
            end,
            x + paddingHorizontal + paddingHorizontal / 2,
            y.toFloat() - paddingVertical * 2,
            textPaint
        )
    }
}