Generate PDF File in Android using Kotlin

Most of the applications provide users with the facility of bills to be downloaded from the mobile applications. This type of application gets the data from the APIS or data within the application and this data is used to generate the PDF files. PDF files within android are generated using canvas. In this article, we will take a look at How to generate a PDF file in android using Kotlin. 

Note: If you are looking to generate PDF files in an Android application using Java. Check out the following article: How to generate PDF files in Android using Java

Step by Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Kotlin as the programming language.

Step 2: Working with the activity_main.xml file

Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file. Comments are added inside the code to understand the code in more detail.

XML

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <!--on below line we are creating
        a simple text view for heading-->
    <TextView
        android:id="@+id/idTVHead"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="20dp"
        android:layout_marginTop="50dp"
        android:layout_marginEnd="20dp"
        android:gravity="center"
        android:padding="8dp"
        android:text="PDF Generator"
        android:textAlignment="center"
        android:textColor="@color/purple_200"
        android:textSize="20sp"
        android:textStyle="bold" />

    <!--on below line we are creating a
        button to generate a pdf file-->
    <Button
        android:id="@+id/idBtnGeneratePdf"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:layout_margin="20dp"
        android:padding="4dp"
        android:text="Generate PDF"
        android:textAllCaps="false" />

</RelativeLayout>

Step 3: Add permission for reading and writing in the External Storage

Navigate to the app > AndroifManifest.xml file and add the below permissions to it.  

XML

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Step 4: Adding images to the drawable folder

Copy your image and then Navigate to app >res >drawable > Right-click on it and simply paste your images within the drawable folder. 

Step 5: Working with the MainActivity.kt file

Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

Kotlin

package com.gtappdevelopers.kotlingfgproject

import android.Manifest.permission.READ_EXTERNAL_STORAGE
import android.Manifest.permission.WRITE_EXTERNAL_STORAGE
import android.content.pm.PackageManager
import android.graphics.*
import android.graphics.pdf.PdfDocument
import android.os.Build
import android.os.Bundle
import android.os.Environment
import android.widget.Button
import android.widget.Toast
import androidx.annotation.RequiresApi
import androidx.appcompat.app.AppCompatActivity
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import java.io.File
import java.io.FileOutputStream

class MainActivity : AppCompatActivity() {

    // on below line we are creating
    // a variable for our image view.
    lateinit var generatePDFBtn: Button

    // declaring width and height
    // for our PDF file.
    var pageHeight = 1120
    var pageWidth = 792

    // creating a bitmap variable
    // for storing our images
    lateinit var bmp: Bitmap
    lateinit var scaledbmp: Bitmap

    // on below line we are creating a
    // constant code for runtime permissions.
    var PERMISSION_CODE = 101

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

        // on below line we are initializing our button with its id.
        generatePDFBtn = findViewById(R.id.idBtnGeneratePdf)

        // on below line we are initializing our bitmap and scaled bitmap.
        bmp = BitmapFactory.decodeResource(resources, R.drawable.android)
        scaledbmp = Bitmap.createScaledBitmap(bmp, 140, 140, false)

        // on below line we are checking permission
        if (checkPermissions()) {
            // if permission is granted we are displaying a toast message.
            Toast.makeText(this, "Permissions Granted..", Toast.LENGTH_SHORT).show()
        } else {
            // if the permission is not granted
            // we are calling request permission method.
            requestPermission()
        }

        // on below line we are adding on click listener for our generate button.
        generatePDFBtn.setOnClickListener {
            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {
                // on below line we are calling generate
                // PDF method to generate our PDF file.
                generatePDF()
            }
        }
    }

    // on below line we are creating a generate PDF method
    // which is use to generate our PDF file.
    @RequiresApi(Build.VERSION_CODES.KITKAT)
    fun generatePDF() {
        // creating an object variable
        // for our PDF document.
        var pdfDocument: PdfDocument = PdfDocument()

        // two variables for paint "paint" is used
        // for drawing shapes and we will use "title"
        // for adding text in our PDF file.
        var paint: Paint = Paint()
        var title: Paint = Paint()

        // we are adding page info to our PDF file
        // in which we will be passing our pageWidth,
        // pageHeight and number of pages and after that
        // we are calling it to create our PDF.
        var myPageInfo: PdfDocument.PageInfo? =
            PdfDocument.PageInfo.Builder(pageWidth, pageHeight, 1).create()

        // below line is used for setting
        // start page for our PDF file.
        var myPage: PdfDocument.Page = pdfDocument.startPage(myPageInfo)

        // creating a variable for canvas
        // from our page of PDF.
        var canvas: Canvas = myPage.canvas

        // below line is used to draw our image on our PDF file.
        // the first parameter of our drawbitmap method is
        // our bitmap
        // second parameter is position from left
        // third parameter is position from top and last
        // one is our variable for paint.
        canvas.drawBitmap(scaledbmp, 56F, 40F, paint)

        // below line is used for adding typeface for
        // our text which we will be adding in our PDF file.
        title.setTypeface(Typeface.create(Typeface.DEFAULT, Typeface.NORMAL))

        // below line is used for setting text size
        // which we will be displaying in our PDF file.
        title.textSize = 15F

        // below line is sued for setting color
        // of our text inside our PDF file.
        title.setColor(ContextCompat.getColor(this, R.color.purple_200))

        // below line is used to draw text in our PDF file.
        // the first parameter is our text, second parameter
        // is position from start, third parameter is position from top
        // and then we are passing our variable of paint which is title.
        canvas.drawText("A portal for IT professionals.", 209F, 100F, title)
        canvas.drawText("Geeks for Geeks", 209F, 80F, title)
        title.setTypeface(Typeface.defaultFromStyle(Typeface.NORMAL))
        title.setColor(ContextCompat.getColor(this, R.color.purple_200))
        title.textSize = 15F

        // below line is used for setting
        // our text to center of PDF.
        title.textAlign = Paint.Align.CENTER
        canvas.drawText("This is sample document which we have created.", 396F, 560F, title)

        // after adding all attributes to our
        // PDF file we will be finishing our page.
        pdfDocument.finishPage(myPage)

        // below line is used to set the name of
        // our PDF file and its path.
        val file: File = File(Environment.getExternalStorageDirectory(), "GFG.pdf")

        try {
            // after creating a file name we will
            // write our PDF file to that location.
            pdfDocument.writeTo(FileOutputStream(file))

            // on below line we are displaying a toast message as PDF file generated..
            Toast.makeText(applicationContext, "PDF file generated..", Toast.LENGTH_SHORT).show()
        } catch (e: Exception) {
            // below line is used
            // to handle error
            e.printStackTrace()

            // on below line we are displaying a toast message as fail to generate PDF
            Toast.makeText(applicationContext, "Fail to generate PDF file..", Toast.LENGTH_SHORT)
                .show()
        }
        // after storing our pdf to that
        // location we are closing our PDF file.
        pdfDocument.close()
    }

    fun checkPermissions(): Boolean {
        // on below line we are creating a variable for both of our permissions.

        // on below line we are creating a variable for
        // writing to external storage permission
        var writeStoragePermission = ContextCompat.checkSelfPermission(
            applicationContext,
            WRITE_EXTERNAL_STORAGE
        )

        // on below line we are creating a variable
        // for reading external storage permission
        var readStoragePermission = ContextCompat.checkSelfPermission(
            applicationContext,
            READ_EXTERNAL_STORAGE
        )

        // on below line we are returning true if both the
        // permissions are granted and returning false
        // if permissions are not granted.
        return writeStoragePermission == PackageManager.PERMISSION_GRANTED
                  && readStoragePermission == PackageManager.PERMISSION_GRANTED
    }

    // on below line we are creating a function to request permission.
    fun requestPermission() {

        // on below line we are requesting read and write to
        // storage permission for our application.
        ActivityCompat.requestPermissions(
            this,
            arrayOf(READ_EXTERNAL_STORAGE, WRITE_EXTERNAL_STORAGE), PERMISSION_CODE
        )
    }

    // on below line we are calling
    // on request permission result.
    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)

        // on below line we are checking if the
        // request code is equal to permission code.
        if (requestCode == PERMISSION_CODE) {

            // on below line we are checking if result size is > 0
            if (grantResults.size > 0) {

                // on below line we are checking
                // if both the permissions are granted.
                if (grantResults[0] == PackageManager.PERMISSION_GRANTED && grantResults[1]
                                            == PackageManager.PERMISSION_GRANTED) {

                    // if permissions are granted we are displaying a toast message.
                    Toast.makeText(this, "Permission Granted..", Toast.LENGTH_SHORT).show()

                } else {

                    // if permissions are not granted we are
                    // displaying a toast message as permission denied.
                    Toast.makeText(this, "Permission Denied..", Toast.LENGTH_SHORT).show()
                    finish()
                }
            }
        }
    }
}

Now run your application to see the output of it.

Output: