Hay muchas aplicaciones en las que los datos de la aplicación se proporcionan a los usuarios en formato de archivo PDF descargable. Entonces, en este caso, tenemos que crear un archivo PDF a partir de los datos presentes dentro de nuestra aplicación y representar esos datos correctamente dentro de nuestra aplicación. Entonces, al usar esta técnica, podemos crear fácilmente un nuevo PDF de acuerdo con nuestros requisitos. En este artículo, veremos cómo crear un nuevo archivo PDF a partir de los datos presentes en nuestra aplicación de Android usando Jetpack Compose en Android.
Implementación paso a paso
Paso 1: crea un nuevo proyecto en Android Studio
Para crear un nuevo proyecto en Android Studio, consulte Cómo crear/iniciar un nuevo proyecto en Android Studio . Al elegir la plantilla, seleccione Actividad de composición vacía . Si no encuentra esta plantilla, intente actualizar Android Studio a la última versión. Demostramos la aplicación en Kotlin, así que asegúrese de seleccionar Kotlin como idioma principal al crear un nuevo proyecto.
Paso 2: Agregar un nuevo color en el archivo Color.kt
Vaya a aplicación>java>nombre del paquete de su aplicación>ui.theme>archivo Color.kt y agregue el código a continuación. Se agregan comentarios en el código para conocer en detalle.
Kotlin
package com.example.newcanaryproject.ui.theme import androidx.compose.ui.graphics.Color val Purple200 = Color(0xFF0F9D58) val Purple500 = Color(0xFF0F9D58) val Purple700 = Color(0xFF3700B3) val Teal200 = Color(0xFF03DAC5) // on below line we are adding different colors. val greenColor = Color(0xFF0F9D58)
Paso 3: agregar imágenes a la carpeta dibujable
Copie la imagen que desea agregar a su archivo PDF. Vaya a aplicación> res> dibujable. Haga clic derecho sobre él y pegue todas las imágenes en la carpeta dibujable.
Paso 4: Agregar permisos en AndroidManifest.xml
Vaya a app>manifest>AndroidManifest.xml y agregue el siguiente permiso para leer y escribir en el almacenamiento externo.
XML
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
Paso 5: trabajar con el archivo MainActivity.kt
Vaya al archivo MainActivity.kt y consulte el siguiente código. A continuación se muestra el código del archivo MainActivity.kt . Se agregan comentarios dentro del código para comprender el código con más detalle.
Kotlin
package com.example.newcanaryproject
import android.app.Activity
import android.content.Context
import android.content.Intent
import android.Manifest
import android.content.SharedPreferences
import android.content.pm.PackageManager
import android.graphics.*
import android.graphics.pdf.PdfDocument
import android.net.Uri
import android.os.Build
import android.os.Bundle
import android.os.Environment
import android.util.Log
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.annotation.RequiresApi
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Email
import androidx.compose.material.icons.filled.Password
import androidx.compose.runtime.*
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.font.FontFamily
import androidx.compose.ui.text.font.FontStyle
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.input.PasswordVisualTransformation
import androidx.compose.ui.text.input.TextFieldValue
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.unit.*
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import com.example.newcanaryproject.ui.theme.*
import java.io.File
import java.io.FileOutputStream
class MainActivity : ComponentActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContent {
NewCanaryProjectTheme {
// on below line we are specifying background
// color for our application
Surface(
// on below line we are specifying
// modifier and color for our app
modifier = Modifier.fillMaxSize(),
color = MaterialTheme.colors.background
) {
// on below line we are specifying theme as scaffold.
Scaffold(
// in scaffold we are specifying top bar.
topBar = {
// inside top bar we are specifying background color.
TopAppBar(backgroundColor = greenColor,
// along with that we are specifying
// title for our top bar.
title = {
// in the top bar we are specifying tile as a text
Text(
// on below line we are specifying
// text to display in top app bar.
text = "PDF Generator",
// on below line we are specifying
// modifier to fill max width.
modifier = Modifier.fillMaxWidth(),
// on below line we are
// specifying text alignment.
textAlign = TextAlign.Center,
// on below line we are
// specifying color for our text.
color = Color.White
)
}
)
}
) {
// on below line we are calling pdf generator
// method for generating a pdf file.
pdfGenerator()
}
}
}
}
}
// on below line we are calling on
// request permission result method.
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 == 101) {
// 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()
}
}
}
}
}
// on below line we are creating a
// pdf generator composable function for ui.
@Composable
fun pdfGenerator() {
// on below line we are creating a variable for
// our context and activity and initializing it.
val ctx = LocalContext.current
val activity = (LocalContext.current as? Activity)
// on below line we are checking permission
if (checkPermissions(ctx)) {
// if permission is granted we are displaying a toast message.
Toast.makeText(ctx, "Permissions Granted..", Toast.LENGTH_SHORT).show()
} else {
// if the permission is not granted
// we are calling request permission method.
requestPermission(activity!!)
}
// on below line we are creating a column for our ui.
Column(
// in this column we are adding a modifier for our
// column and specifying max width, height and size.
modifier = Modifier
.fillMaxWidth()
.fillMaxHeight()
.fillMaxSize()
// on below line we are adding padding
// from all sides to our column.
.padding(6.dp),
// on below line we are adding vertical
// arrangement for our column as center
verticalArrangement = Arrangement.Center,
// on below line we are adding
// horizontal alignment for our column.
horizontalAlignment = Alignment.CenterHorizontally
) {
// on below line we are creating a simple text as a PDF Generator.
Text(
// on below line we are setting text to our text
text = "PDF Generator",
// on below line we are
// setting color for our text
color = greenColor,
// on below line we are setting
// font weight for our text
fontWeight = FontWeight.Bold,
// on below line we are setting
// alignment for our text as center.
textAlign = TextAlign.Center,
// on below line we are
// setting font size for our text
fontSize = 20.sp
)
// on below line we are adding
// spacer between text and a button.
Spacer(modifier = Modifier.height(60.dp))
// on the below line we are creating a button.
Button(
// on below line we are adding a modifier
// to it and specifying max width to it.
modifier = Modifier
.fillMaxWidth()
// on below line we are adding
// padding for our button.
.padding(20.dp),
// on below line we are adding
// on click for our button.
onClick = {
// inside on click we are calling our
// generate PDF method to generate our PDF
generatePDF(ctx)
}) {
// on the below line we are displaying a text for our button.
Text(modifier = Modifier.padding(6.dp), text = "Generate PDF")
}
}
}
// 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(context: Context) {
// 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
// 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()
// on below line we are initializing our bitmap and scaled bitmap.
bmp = BitmapFactory.decodeResource(context.resources, R.drawable.android)
scaledbmp = Bitmap.createScaledBitmap(bmp, 140, 140, false)
// 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(context, 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(context, 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(context, "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(context, "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(context: Context): 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(
context,
Manifest.permission.WRITE_EXTERNAL_STORAGE
)
// on below line we are creating a variable for
// reading external storage permission
var readStoragePermission = ContextCompat.checkSelfPermission(
context,
Manifest.permission.READ_EXTERNAL_STORAGE
)
// on below line we are returning true if both the
// permissions are granted anf 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(activity: Activity) {
// on below line we are requesting read and write to
// storage permission for our application.
ActivityCompat.requestPermissions(
activity,
arrayOf(
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE
), 101
)
}
Ahora ejecute su aplicación para ver el resultado.
Producción:
Publicación traducida automáticamente
Artículo escrito por chaitanyamunje y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA