MainActivity.kt
package com.cfsuman.kotlintutorials
import android.app.Activity
import android.graphics.*
import android.os.Bundle
import android.widget.ImageView
class MainActivity : Activity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// get the widgets reference from XML layout
val imageView = findViewById<ImageView>(R.id.imageView)
// draw triangle on canvas
val bitmap = drawTriangle(
sideLength = 650F,
yOffsetTopPoint = 150F,
xOffsetTopPoint = 750F,
xOffsetLeftPoint = 200F,
yOffsetBottomHand = 150F,
strokeWidth = 20F,
strokeColor = Color.parseColor("#F0FFFF"),
fillColor = Color.parseColor("#333399"),
canvasColor = Color.parseColor("#A2A2D0")
)
// show triangle drawing on image view
imageView.setImageBitmap(bitmap)
}
}
// function to draw triangle on canvas
fun drawTriangle(
sideLength : Float = 600F,
yOffsetTopPoint : Float = 100F,
xOffsetTopPoint : Float = 600F,
xOffsetLeftPoint : Float = 200F,
yOffsetBottomHand : Float = 150F,
strokeWidth : Float = 15F,
strokeColor : Int = Color.BLACK,
fillColor : Int = Color.CYAN,
canvasColor : Int = Color.LTGRAY
):Bitmap?{
val bitmap = Bitmap.createBitmap(
1500,
850,
Bitmap.Config.ARGB_8888
)
// canvas to draw triangle
val canvas = Canvas(bitmap).apply {
drawColor(canvasColor)
}
// paint to draw triangle fill color
val paint = Paint().apply {
isAntiAlias = true
color = fillColor
this.strokeWidth = strokeWidth
style = Paint.Style.FILL
}
// create a path to draw triangle
val path = Path().apply {
fillType = Path.FillType.EVEN_ODD
// draw rectangle on canvas
moveTo(xOffsetLeftPoint,
canvas.height - yOffsetBottomHand)
lineTo(xOffsetTopPoint, yOffsetTopPoint)
lineTo(xOffsetTopPoint + sideLength,
canvas.height - yOffsetBottomHand)
close()
}
// draw path on canvas
// it will draw triangle fill color
canvas.drawPath(path, paint)
// change paint color to draw triangle border
paint.apply {
color = strokeColor
style = Paint.Style.STROKE
}
// it will draw triangle border on canvas
canvas.drawPath(path,paint)
return bitmap
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/rootLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#DCDCDC"
android:padding="24dp">
<ImageView
android:id="@+id/imageView"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
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