MainActivity.kt
package com.cfsuman.kotlintutorials
import android.app.Activity
import android.graphics.*
import android.os.Bundle
import android.text.TextPaint
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 text on canvas inside rectangle and get bitmap
val bitmap = drawTextInsideRectangle(
textToDraw = "Text to draw inside rectangle",
textSize = 185F,
textColor = Color.parseColor("#F0FFFF"),
rectangleColor = Color.parseColor("#333399"),
canvasColor = Color.parseColor("#A2A2D0")
)
// show drawing on image view
imageView.setImageBitmap(bitmap)
}
}
// function to draw text inside rectangle
fun drawTextInsideRectangle(
textToDraw:String = "Text to draw in rectangle",
textSize:Float = 100F,
textColor:Int = Color.BLACK,
rectangleColor:Int = Color.LTGRAY,
canvasColor:Int = Color.DKGRAY
):Bitmap?{
val bitmap = Bitmap.createBitmap(
1500,
850,
Bitmap.Config.ARGB_8888
)
// canvas to drawing
val canvas = Canvas(bitmap).apply {
drawColor(canvasColor)
}
// draw rectangle on canvas
val rectF = RectF(
200f,
180f,
canvas.width - 80F,
canvas.height - 120F
)
canvas.drawRect(rectF,Paint().apply { color = rectangleColor })
// text paint to draw text
val textPaint = TextPaint().apply {
color = textColor
textAlign = Paint.Align.CENTER
this.textSize = textSize
isAntiAlias = true
}
// calculate text y offset to center it vertically
val textHeight = textPaint.descent() - textPaint.ascent()
val textOffset = textHeight / 2 - textPaint.descent()
// rectangle margin to draw text
val margin = 130F
// number of characters can draw inside rectangle
var text = textToDraw
val numOfChars = textPaint.breakText(
text,
true,
rectF.width() - margin,
null
)
if (text.length > numOfChars){
text = text.substring(0, numOfChars) + ".."
}
// finally, draw the text inside rectangle
canvas.drawText(
text,
rectF.centerX(),
rectF.centerY() + textOffset,
textPaint
)
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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