Generate a PDF in Kotlin for Android

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/*
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 *   Copyright © 2020-2025 PSPDFKit GmbH. All rights reserved.
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 *
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 *   The PSPDFKit Sample applications are licensed with a modified BSD license.
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 *   Please see License for details. This notice may not be removed from this file.
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 */
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package com.pspdfkit.catalog.examples.kotlin
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import android.content.Context
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import android.graphics.Canvas
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import android.graphics.Paint
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import android.graphics.Path
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import android.net.Uri
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import android.util.Log
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import com.pspdfkit.catalog.R
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import com.pspdfkit.catalog.SdkExample
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import com.pspdfkit.catalog.SdkExample.Companion.TAG
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import com.pspdfkit.configuration.activity.PdfActivityConfiguration
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import com.pspdfkit.document.processor.NewPage
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import com.pspdfkit.document.processor.PdfProcessor
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import com.pspdfkit.document.processor.PdfProcessorTask
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import com.pspdfkit.ui.PdfActivityIntentBuilder
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import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers
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import io.reactivex.rxjava3.disposables.Disposable
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import io.reactivex.rxjava3.schedulers.Schedulers
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import java.io.File
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import java.io.IOException
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/**
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 * This example shows how to create a document from [Canvas] drawing.
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 */
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class DocumentFromCanvasExample(context: Context) : SdkExample(context, R.string.documentFromCanvasExampleTitle, R.string.documentFromCanvasExampleDescription) {
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    private var documentProcessingDisposable: Disposable? = null
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    override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) {
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        // Turn off saving, so we have the clean original document every time the example is launched.
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        configuration.autosaveEnabled(false)
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        // Create a canvas based on a A4 page.
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        val pageCanvas = NewPage.fromCanvas(NewPage.PAGE_SIZE_A4) { canvas ->
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            val paint = Paint().apply {
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                style = Paint.Style.STROKE
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            }
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            val path = Path().apply {
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                cubicTo(0f, 0f, 100f, 300f, 400f, 300f)
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            }
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            canvas.drawPath(path, paint)
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        }.build()
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        val task = PdfProcessorTask.newPage(pageCanvas)
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        val outputFile = try {
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            File(getCatalogCacheDirectory(context), "Canvas.pdf").canonicalFile
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        } catch (exception: IOException) {
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            throw IllegalStateException("Couldn't create Canvas.pdf file.", exception)
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        }
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        documentProcessingDisposable = PdfProcessor.processDocumentAsync(task, outputFile)
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            // Ignore PdfProcessor progress.
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            .ignoreElements()
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            .subscribeOn(Schedulers.io())
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            .observeOn(AndroidSchedulers.mainThread())
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            .subscribe(
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                {
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                    val intent = PdfActivityIntentBuilder.fromUri(context, Uri.fromFile(outputFile))
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                        .configuration(configuration.build())
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                        .build()
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                    context.startActivity(intent)
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                },
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                { throwable ->
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                    Log.e(TAG, "Error while trying to create PDF document.", throwable)
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                }
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            )
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    }
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    override fun onDestroy() {
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        super.onDestroy()
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        documentProcessingDisposable?.dispose()
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        documentProcessingDisposable = null
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    }
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    companion object {
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        private const val PSPDFKIT_DIRECTORY_NAME = "catalog-pspdfkit"
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        @Throws(IOException::class)
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        private fun getCatalogCacheDirectory(ctx: Context): File {
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            val dir = File(ctx.cacheDir, PSPDFKIT_DIRECTORY_NAME)
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            if (!dir.exists()) {
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                if (!dir.mkdirs()) {
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                    throw IOException("Failed to create Catalog cache directory.")
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                }
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            }
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            return dir
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        }
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    }
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}