MainActivity.kt
package com.cfsuman.kotlintutorials
import android.app.Activity
import android.graphics.*
import android.os.Bundle
import android.widget.ImageView
import android.widget.SeekBar
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)
val seekBar = findViewById<SeekBar>(R.id.seekBar)
// show initial drawing on image view
imageView.setImageBitmap(
drawDottedLine(seekBar.progress + 10F)
)
// update drawing on seek bar change
seekBar.setOnSeekBarChangeListener(object :
SeekBar.OnSeekBarChangeListener{
override fun onProgressChanged(
seekBar: SeekBar?, progress: Int, fromUser: Boolean) {
val bitmap = drawDottedLine(progress + 10F)
imageView.setImageBitmap(bitmap)
}
override fun onStartTrackingTouch(seekBar: SeekBar?) {
}
override fun onStopTrackingTouch(seekBar: SeekBar?) {
}
})
}
}
// function to draw dotted line on canvas
fun drawDottedLine(
dotWidth : Float = 25F
):Bitmap?{
val bitmap = Bitmap.createBitmap(
1500,
850,
Bitmap.Config.ARGB_8888
)
// canvas for drawing
val canvas = Canvas(bitmap).apply {
drawColor(Color.parseColor("#A2A2D0"))
}
// paint to draw dotted line
val paint = Paint().apply {
isAntiAlias = true
color = Color.parseColor("#333399")
strokeWidth = dotWidth
style = Paint.Style.STROKE
strokeCap = Paint.Cap.ROUND
pathEffect = DashPathEffect(
// try to make nearly rounded shape / dot
floatArrayOf
(dotWidth / 12,
dotWidth * 2
),
0F // phase
)
}
// draw a line path
val path = Path().apply {
// move to line starting point
moveTo(100F,canvas.height / 2F)
// draw line
// add a quadratic bezier
quadTo(
100F, // x1
canvas.height / 2F, // y1
canvas.width - 100F, // x2
canvas.height / 2F // y2
)
}
// finally, draw the path (dotted line) 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" />
<SeekBar
android:id="@+id/seekBar"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:max="200"
android:progress="20"
android:layout_marginTop="16dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/imageView" />
</androidx.constraintlayout.widget.ConstraintLayout>


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