Center Icon and Text in Button

CenteredImageButton.kt

import android.content.Context
import android.graphics.Canvas
import android.graphics.Paint
import android.graphics.Rect
import android.graphics.Typeface
import android.graphics.drawable.Drawable
import android.support.annotation.ColorRes
import android.support.annotation.DrawableRes
import android.support.v4.content.ContextCompat
import android.util.AttributeSet
import android.widget.Button

/**
 * Created by Fandi Akhmad on 8/2/18.
 */
class CenteredImageButton(context: Context, attrs: AttributeSet) : Button(context, attrs) {
    private var mTextPaint: Paint? = null
    private var mIconDrawable: Drawable? = null
    private var mIconSize = resources.getDimensionPixelSize(R.dimen.icon_size_24)
    private var mButtonText: String? = null
    private val bounds = Rect()

    init {
        //...
        mTextPaint = Paint().apply {
            isAntiAlias = true
            color = ContextCompat.getColor(context, android.R.color.black)
            textSize = resources.getDimension(R.dimen.text_size_14)
        }
    }

    fun setIconResource(@DrawableRes resource: Int) {
        mIconDrawable = ContextCompat.getDrawable(context, resource)
    }

    fun setButtonText(text: String) {
        mButtonText = text
    }

    fun setButtonTextColor(@ColorRes color: Int) {
        mTextPaint?.color = ContextCompat.getColor(context, color)
    }

    fun setBoldText() {
        mTextPaint?.typeface = Typeface.DEFAULT_BOLD
    }

    override fun onDraw(canvas: Canvas?) {
        super.onDraw(canvas)
        mIconDrawable?.setBounds(getLeftPosition(), getTopPosition(), 
                                 mIconSize + getLeftPosition(), mIconSize + getTopPosition())
        mIconDrawable?.draw(canvas)

        mButtonText?.let {
            mTextPaint?.getTextBounds(it, 0, it.length, bounds)
        }
        canvas?.drawText(mButtonText, (mIconSize + getLeftPosition() + 16).toFloat(), 
                         ((height / 2) - bounds.centerY() + 5).toFloat(), mTextPaint)
    }

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        val paddingLeft = resources.getDimensionPixelSize(R.dimen.margin_padding_48)
        val paddingRight = resources.getDimensionPixelSize(R.dimen.margin_padding_32)
        val desiredWidth = suggestedMinimumWidth + paddingLeft + paddingRight
    }

    private fun getTopPosition(): Int {
        val halfHeightOfDrawable = mIconSize.div(2)
        val halfHeightOfView = height / 2

        return halfHeightOfView - halfHeightOfDrawable
    }

    private fun getLeftPosition(): Int {
        val halfWidthOfDrawable = (getCompoundPosition() / 2).toInt()
        val halfWidthOfView = width / 2

        return halfWidthOfView - halfWidthOfDrawable
    }

    private fun getCompoundPosition(): Float {
        val textWidth = mTextPaint?.measureText(mButtonText) ?: 0f
        val gapWidth = resources.getDimensionPixelSize(R.dimen.margin_padding_16)

        return mIconSize + gapWidth + textWidth
    }
}