A Christmas tree in Jetpack Compose

ChristmasTreeActivity.kt

package com.thomaskuenneth.christmastreecompose

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.foundation.shape.GenericShape
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.RectangleShape
import androidx.compose.ui.platform.setContent
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.dp
import androidx.ui.tooling.preview.Preview
import com.thomaskuenneth.christmastreecompose.ui.ChristmasTreeComposeTheme

// A Christmas tree in Jetpack Compose
class ChristmasTreeActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            ChristmasTreeComposeTheme {
                ChristmasTree()
            }
        }
    }
}

@Composable
fun ChristmasTree() {
    val purple = Color(148, 0, 211)
    Box(
        modifier = Modifier.fillMaxSize(),
        alignment = Alignment.Center
    ) {
        Column(
            horizontalAlignment = Alignment.CenterHorizontally,
        ) {
            Box(
                alignment = Alignment.TopCenter
            ) {
                Box(
                    alignment = Alignment.TopCenter,
                ) {
                    Triangle(100.dp, 100.dp, Color.Green)
                    Box(
                        modifier = Modifier.padding(top = 50.dp)
                    ) {
                        Triangle(150.dp, 120.dp, Color.Green)
                    }
                    Box(modifier = Modifier.padding(top = 100.dp))
                    {
                        Triangle(200.dp, 140.dp, Color.Green)
                    }
                }
                Box(modifier = Modifier.align(alignment = Alignment.Center)) {
                    Star(0.dp, -120.dp, 20.dp, 20.dp, Color.Yellow)
                    Circle(0.dp, -80.dp, 15.dp, 15.dp, Color.Red)
                    Circle(-20.dp, -40.dp, 18.dp, 18.dp, purple)
                    Circle(30.dp, -50.dp, 20.dp, 20.dp, Color.Red)
                    Circle(30.dp, 0.dp, 22.dp, 22.dp, purple)
                    Circle(-20.dp, 30.dp, 24.dp, 24.dp, Color.Red)
                    Circle(60.dp, 45.dp, 18.dp, 18.dp, Color.Red)
                    Circle(-30.dp, 90.dp, 26.dp, 26.dp, purple)
                    Circle(40.dp, 100.dp, 26.dp, 26.dp, Color.Red)
                }
            }
            Rectangle(20.dp, 30.dp, Color(0.6f, 0.4f, 0.2f))
        }
    }
}

@Composable
fun Triangle(width: Dp, height: Dp, color: Color) {
    Box(
        modifier = Modifier.preferredSize(width = width, height = height)
            .clip(
                GenericShape { size ->
                    moveTo(size.width / 2f, 0f)
                    lineTo(size.width, size.height)
                    lineTo(0f, size.height)
                })
            .background(color)
    )
}

@Composable
fun Rectangle(width: Dp, height: Dp, color: Color) {
    Box(
        modifier = Modifier.preferredSize(width = width, height = height)
            .clip(
                RectangleShape
            )
            .background(color)
    )
}

@Composable
fun Circle(x: Dp, y: Dp, width: Dp, height: Dp, color: Color) {
    Box(
        modifier = Modifier.preferredSize(width = width, height = height)
            .offset(x = x, y = y)
            .clip(
                CircleShape
            )
            .background(color)
    )
}

@Composable
fun Star(x: Dp, y: Dp, width: Dp, height: Dp, color: Color) {
    Box(
        modifier = Modifier.preferredSize(width = width, height = height)
            .offset(x = x, y = y)
            .clip(
                GenericShape { size ->
                    val halfX = size.width / 2f
                    val halfY = size.height / 2f
                    val fl = halfX / 2
                    moveTo(0f, halfY)
                    lineTo(halfX + fl, 0f)
                    lineTo(halfX + fl, size.height)
                    lineTo(0f, halfY)
                })
            .background(color)
    )
    Box(
        modifier = Modifier.preferredSize(width = width, height = height)
            .offset(x = x, y = y)
            .clip(
                GenericShape { size ->
                    val halfX = size.width / 2f
                    val halfY = size.height / 2f
                    val fl = halfX / 2
                    moveTo(size.width, halfY)
                    lineTo(halfX - fl, 0F)
                    lineTo(halfX - fl, size.height)
                    lineTo(size.width, halfY)
                })
            .background(color)
    )
}


@Preview
@Composable
fun Preview() {
    ChristmasTree()
}