Sunday, August 9, 2020

android kotlin - Convert pixels to dp programmatically

MainActivity.kt

package com.example.jetpack

import android.content.Context
import android.os.Bundle
import android.util.DisplayMetrics
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*
import kotlin.random.Random


class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // generate a random integer number in range
        val pixels = Random.nextInt(50,200)

        // convert pixels to equivalent dp value
        val dp = pixels.pixelsToDp(this)
        val dpInt = pixels.pixelsToDpInt(this)

        // show pixels to dp actual float value
        textView.text = "Return float value"
        textView.append("\n$pixels pixels = $dp dp")

        // pixels to dp integer conversion result
        textView.append("\n\nReturn integer value")
        textView.append("\n$pixels pixels = $dpInt dp")
    }
}


// extension function to convert pixels to dp
// this method return dp perfect float value
fun Int.pixelsToDp(context: Context):Float{
    return this / (context.resources
        .displayMetrics.densityDpi / DisplayMetrics.DENSITY_DEFAULT).toFloat()
}


// extension function to convert pixels value to dp value
// this method return integer dp value
fun Int.pixelsToDpInt(context: Context):Int{
    return this / (context.resources
        .displayMetrics.densityDpi / DisplayMetrics.DENSITY_DEFAULT)
}
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"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:background="#E5E4E2">

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="32dp"
        android:layout_marginEnd="16dp"
        tools:text="TextView"
        android:fontFamily="sans-serif-condensed"
        android:textSize="30sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>