jetpack compose - Draw rectangle on canvas

MainActivity.kt

package com.cfsuman.jetpackcompose

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.activity.compose.setContent
import androidx.compose.foundation.Canvas
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.*
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.geometry.Size
import androidx.compose.ui.graphics.*
import androidx.compose.ui.graphics.drawscope.Stroke
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContent {
            MainContent()
        }
    }


    @Composable
    fun MainContent(){
        Canvas(
            modifier = Modifier
                .fillMaxSize()
                .background(Color(0xFFFFDAE9))
        )
        {
            drawRect(
                color = Color(0xFF9D2933),
                size = Size(
                    width = 300.dp.toPx(),
                    height = 150.dp.toPx()
                ),
                topLeft = Offset(
                    x = 50.dp.toPx(),
                    y = 50.dp.toPx()
                )
            )

            drawRect(
                color = Color(0xFF26619C),
                size = Size(
                    width = 300.dp.toPx(),
                    height = 125.dp.toPx()
                ),
                topLeft = Offset(
                    x = 50.dp.toPx(),
                    y = 250.dp.toPx()
                ),
                style = Stroke(
                    width = 8.dp.toPx(),
                    miter = 15.dp.toPx(),
                    cap = StrokeCap.Round,
                    pathEffect = PathEffect.cornerPathEffect(8.dp.toPx())
                )
            )
        }
    }


    @Preview
    @Composable
    fun ComposablePreview(){
        //MainContent()
    }
}