--- title: "Kiosk Grid" canonical_url: "https://www.nutrient.io/guides/android/samples/kiosk-grid-kotlin/" md_url: "https://www.nutrient.io/guides/android/samples/kiosk-grid-kotlin.md" last_updated: "2026-05-15T19:10:04.916Z" description: "Browse documents from the assets folder in a grid with thumbnail previews." --- # Kiosk Grid Browse documents from the assets folder in a grid with thumbnail previews. [Get Started](https://www.nutrient.io/sdk/android/getting-started.md) [All Samples](https://www.nutrient.io/guides/android/samples.md) [Download](https://www.nutrient.io/guides/android/downloads.md) [Launch Demo](https://www.nutrient.io/demo/) --- ```kotlin /* * Copyright © 2020-2026 PSPDFKit GmbH. All rights reserved. * * The PSPDFKit Sample applications are licensed with a modified BSD license. * Please see License for details. This notice may not be removed from this file. */ package com.pspdfkit.catalog.examples.kotlin import android.content.Context import android.content.Intent import android.graphics.Bitmap import android.os.Bundle import android.text.TextUtils import android.util.Log import android.view.LayoutInflater import android.view.View import android.view.ViewGroup import android.widget.AdapterView.OnItemClickListener import android.widget.ArrayAdapter import android.widget.GridView import android.widget.ImageView import android.widget.ProgressBar import android.widget.TextView import android.widget.Toast import androidx.appcompat.app.AppCompatActivity import androidx.collection.LruCache import com.pspdfkit.catalog.R import com.pspdfkit.catalog.SdkExample import com.pspdfkit.catalog.SdkExample.Companion.TAG import com.pspdfkit.configuration.activity.PdfActivityConfiguration import com.pspdfkit.document.DocumentSource import com.pspdfkit.document.PdfDocument import com.pspdfkit.document.PdfDocumentLoader import com.pspdfkit.document.providers.AssetDataProvider import com.pspdfkit.ui.PdfActivityIntentBuilder import com.pspdfkit.utils.Size import com.pspdfkit.utils.getSupportParcelableExtra import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers import io.reactivex.rxjava3.core.BackpressureStrategy import io.reactivex.rxjava3.core.Flowable import io.reactivex.rxjava3.core.FlowableEmitter import io.reactivex.rxjava3.core.FlowableOnSubscribe import io.reactivex.rxjava3.disposables.Disposable import io.reactivex.rxjava3.schedulers.Schedulers import java.io.File import java.io.IOException import java.util.ArrayDeque import java.util.Locale /** * This example lists all documents found in the assets and presents them with their previews in a grid. */ class KioskExample(context: Context) : SdkExample(context, R.string.kioskExampleTitle, R.string.kioskExampleDescription) { override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) { val intent = Intent(context, KioskActivity::class.java) // Pass the configuration to our activity. intent.putExtra(KioskActivity.CONFIGURATION_ARG, configuration.build()) context.startActivity(intent) } } /** * This activity displays all documents found in the assets folder of the app. */ class KioskActivity : AppCompatActivity() { private lateinit var configuration: PdfActivityConfiguration private var listAssetsDisposable: Disposable? = null public override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_kiosk) configuration = intent.getSupportParcelableExtra(CONFIGURATION_ARG, PdfActivityConfiguration::class.java)?: throw NullPointerException("Extras bundle was missing configuration") val documentGrid = findViewById(android.R.id.list) val documentAdapter: DocumentAdapter = DocumentAdapter(this) documentGrid.adapter = documentAdapter documentGrid.onItemClickListener = OnItemClickListener { _, _, position, _ -> val dataProvider = documentAdapter.getItem(position)?.documentSource?.dataProvider?: return@OnItemClickListener // Open the touched document. val intent = PdfActivityIntentBuilder.fromDataProvider(this@KioskActivity, dataProvider).configuration(configuration).build() startActivity(intent) } val progressBar = findViewById(android.R.id.progress) // Load the documents on a background thread. listAssetsDisposable = listAllAssets() // List assets on the background (I/O) thread..subscribeOn(Schedulers.io()) // Filter PDF files only..filter { it.lowercase(Locale.getDefault()).endsWith(".pdf") } // The second observe on is necessary so opening the documents runs on a different thread as listing the assets..observeOn(Schedulers.io()).flatMap { asset -> PdfDocumentLoader.openDocumentAsync(this@KioskActivity, DocumentSource(AssetDataProvider(asset))).toFlowable().doOnError { throwable -> // This example catches any error that happens while opening the document (e.g. if a password would be needed). // If an exception is thrown, the document will not be shown. Log.w( TAG, String.format("Could not open document '%s' from assets. See exception for reason.", asset), throwable, ) }.onErrorResumeNext { Flowable.empty() } }.observeOn(AndroidSchedulers.mainThread()).doOnComplete { progressBar.visibility = View.GONE }.toSortedList { document: PdfDocument, document2: PdfDocument -> val title = document.title val title2 = document2.title return@toSortedList when { document === document2 -> 0 title == null -> -1 title2 == null -> 1 else -> title.compareTo(title2, ignoreCase = true) } }.subscribe({ collection: List -> documentAdapter.addAll(collection) }) { throwable -> progressBar.visibility = View.GONE Log.e(TAG, "Error while trying to list all catalog app assets.", throwable) Toast.makeText( this@KioskActivity, "Error listing asset files - see logcat for detailed error message.", Toast.LENGTH_LONG, ).show() } } override fun onDestroy() { super.onDestroy() listAssetsDisposable?.dispose() listAssetsDisposable = null } /** * Lists all assets in the assets directory. * * @return A observable sending all file paths in the assets folder. */ private fun listAllAssets(): Flowable { return Flowable.create( object : FlowableOnSubscribe { override fun subscribe(emitter: FlowableEmitter) { try { val pathsToCheck = ArrayDeque() pathsToCheck.addAll(assets.list("")?: arrayOf()) while (!pathsToCheck.isEmpty()) { val currentPath = pathsToCheck.poll()?: break val children = getChildren(currentPath) if (children.isNullOrEmpty()) { // This is just a file, tell our subscriber about it. emitter.onNext(currentPath) } else { // Check all other sub paths. for (child in children) { pathsToCheck.add(currentPath + File.separator + child) } } } emitter.onComplete() } catch (e: IOException) { emitter.onError(e) } } @Throws(IOException::class) private fun getChildren(path: String): Array { // Since listing assets is really really slow we assume everything with a '.' in it is a file. return if (path.contains(".")) { arrayOf() } else { assets.list(path)?: arrayOf() } } }, BackpressureStrategy.BUFFER, ) } private class ViewHolder(val view: View) { val itemPreviewImageView: ImageView = view.findViewById(R.id.itemPreviewImageView) val itemTitleView: TextView = view.findViewById(R.id.itemTileView) var previewRenderDisposable: Disposable? = null companion object { operator fun get(convertView: View?, parent: ViewGroup): ViewHolder { var view = convertView val holder: ViewHolder if (view!= null) { holder = view.tag as ViewHolder } else { view = LayoutInflater.from(parent.context).inflate(R.layout.item_kiosk_item, parent, false) holder = ViewHolder(view) view.tag = holder } return holder } } } private inner class DocumentAdapter(context: Context) : ArrayAdapter(context, View.NO_ID) { private val previewImageCache: LruCache private val previewImageSize: Size override fun getView(position: Int, convertView: View?, parent: ViewGroup): View { val holder: ViewHolder = ViewHolder[convertView, parent] holder.previewRenderDisposable?.dispose() val document = getItem(position)?: throw IllegalStateException("Invalid position!") // We only want to render a new preview image if we don't already have one in the cache. val cachedPreview = previewImageCache[document.uid] holder.itemPreviewImageView.setImageBitmap(cachedPreview) if (cachedPreview == null) { // Calculate the size of the rendered preview image. val size = calculateBitmapSize(document, previewImageSize) // Render page to bitmap. holder.previewRenderDisposable = document.renderPageToBitmapAsync( parent.context, 0, size.width.toInt(), size.height.toInt(), ).observeOn(AndroidSchedulers.mainThread()).subscribe { bitmap -> holder.itemPreviewImageView.setImageBitmap(bitmap) previewImageCache.put(document.uid, bitmap) } } if (!TextUtils.isEmpty(document.title)) { holder.itemTitleView.text = document.title } else { holder.itemTitleView.text = resources.getText(com.pspdfkit.R.string.pspdf__activity_title_unnamed_document) } return holder.view } private fun calculateBitmapSize(document: PdfDocument, availableSpace: Size): Size { val pageSize = document.getPageSize(0) val ratio: Float ratio = if (pageSize.width > pageSize.height) { availableSpace.width / pageSize.width } else { availableSpace.height / pageSize.height } return Size(pageSize.width * ratio, pageSize.height * ratio) } init { previewImageCache = object : LruCache((Runtime.getRuntime().maxMemory() / 1024 / 8).toInt()) { override fun sizeOf(key: String, value: Bitmap): Int { // The cache size will be measured in kilobytes rather than number of items. return value.byteCount / 1024 } } previewImageSize = Size( context.resources.getDimensionPixelSize(R.dimen.kiosk_previewimage_width).toFloat(), context.resources.getDimensionPixelSize(R.dimen.kiosk_previewimage_height).toFloat(), ) } } companion object { const val CONFIGURATION_ARG = "configuration" } } ``` This code sample is an example that illustrates how to use our SDK. Please adapt it to your specific use case. --- ## Related pages - [Application Policy](/guides/android/samples/application-policy-kotlin.md) - [Custom Form Highlight Color](/guides/android/samples/custom-form-highlight-color-java.md) - [Custom Page Templates](/guides/android/samples/custom-page-templates-java.md) - [Digital Signature (Basic)](/guides/android/samples/digital-signature-basic-kotlin.md) - [Disabled Annotation Property](/guides/android/samples/disabled-annotation-property-java.md) - [Image Document](/guides/android/samples/image-document-kotlin.md) - [Compose Image Document](/guides/android/samples/compose-image-document-kotlin.md) - [Inline Multimedia](/guides/android/samples/inline-multimedia-kotlin.md) - [JavaScript Form Filling](/guides/android/samples/javascript-form-filling-kotlin.md) - [Overlay Visibility](/guides/android/samples/overlay-visibility-kotlin.md) - [PdfFragment](/guides/android/samples/pdffragment-kotlin.md) - [Reader View](/guides/android/samples/reader-view-kotlin.md) - [Playground](/guides/android/samples/playground-kotlin.md) - [JavaScript Calculator](/guides/android/samples/javascript-calculator-kotlin.md) - [Text Field Suggestions](/guides/android/samples/text-field-suggestions-kotlin.md) - [Thumbnail Bar Modes](/guides/android/samples/thumbnail-bar-modes-kotlin.md) - [Signature Storage Database](/guides/android/samples/signature-storage-database-kotlin.md) - [Selection Customization](/guides/android/samples/selection-customization-java.md) - [Password Protected PDF](/guides/android/samples/password-protected-pdf-kotlin.md) - [Scientific Paper](/guides/android/samples/scientific-paper-kotlin.md) - [Try Instant](/guides/android/samples/try-instant-kotlin.md) - [Merge Documents](/guides/android/samples/merge-documents-kotlin.md) - [Annotation Rendering](/guides/android/samples/annotation-rendering-kotlin.md) - [Custom Data Provider](/guides/android/samples/custom-data-provider-kotlin.md) - [Annotations with Transparency](/guides/android/samples/annotations-with-transparency-kotlin.md) - [Annotation Flags](/guides/android/samples/annotation-flags-kotlin.md) - [AI Assistant (Multiple Documents, ViewPager)](/guides/android/samples/ai-assistant-multiple-documents-viewpager-kotlin.md) - [Custom Sharing Menu](/guides/android/samples/custom-sharing-menu-java.md) - [Add LTV to Existing Signature](/guides/android/samples/add-ltv-to-existing-signature-kotlin.md) - [Custom Toolbar Grouping](/guides/android/samples/custom-toolbar-grouping-java.md) - [Custom Layout](/guides/android/samples/custom-layout-kotlin.md) - [Custom ActionBar Actions](/guides/android/samples/custom-actionbar-actions-kotlin.md) - [Custom Activity Toolbars](/guides/android/samples/custom-activity-toolbars-java.md) - [Custom Note Hinter](/guides/android/samples/custom-note-hinter-kotlin.md) - [Custom Main Toolbar](/guides/android/samples/custom-main-toolbar-kotlin.md) - [Annotation Configuration](/guides/android/samples/annotation-configuration-kotlin.md) - [Annotation Selection Styling](/guides/android/samples/annotation-selection-styling-kotlin.md) - [Custom Search UI (Compose)](/guides/android/samples/custom-search-ui-compose-kotlin.md) - [Document Switcher](/guides/android/samples/document-switcher-java.md) - [File Annotation Creation](/guides/android/samples/file-annotation-creation-kotlin.md) - [Dynamic Pages on Scroll](/guides/android/samples/dynamic-pages-on-scroll-kotlin.md) - [Custom Activity Form Editing](/guides/android/samples/custom-activity-form-editing-java.md) - [Custom Stamp Annotations](/guides/android/samples/custom-stamp-annotations-java.md) - [Custom Outline Provider](/guides/android/samples/custom-outline-provider-kotlin.md) - [Compose Navigation](/guides/android/samples/compose-navigation-kotlin.md) - [Fragment Runtime Configuration](/guides/android/samples/fragment-runtime-configuration-kotlin.md) - [Annotation Overlay](/guides/android/samples/annotation-overlay-java.md) - [Instant Document JSON](/guides/android/samples/instant-document-json-kotlin.md) - [DocumentView Composable](/guides/android/samples/documentview-composable-kotlin.md) - [Form Creation](/guides/android/samples/form-creation-kotlin.md) - [Document Download](/guides/android/samples/document-download-kotlin.md) - [JavaScript Actions](/guides/android/samples/javascript-actions-kotlin.md) - [Instant JSON Attachment](/guides/android/samples/instant-json-attachment-kotlin.md) - [Digital Signature (Manual)](/guides/android/samples/digital-signature-manual-kotlin.md) - [Digital Signature (Third-Party)](/guides/android/samples/digital-signature-third-party-kotlin.md) - [Inline Search](/guides/android/samples/inline-search-java.md) - [Form Filling](/guides/android/samples/form-filling-kotlin.md) - [Form Click Intercept (Compose)](/guides/android/samples/form-click-intercept-compose-kotlin.md) - [Document Sharing](/guides/android/samples/document-sharing-java.md) - [Custom Download Dialog](/guides/android/samples/custom-download-dialog-java.md) - [Download Progress](/guides/android/samples/download-progress-kotlin.md) - [Popup Toolbar Customization](/guides/android/samples/popup-toolbar-customization-kotlin.md) - [Custom Sharing Dialog](/guides/android/samples/custom-sharing-dialog-java.md) - [PDF from Image](/guides/android/samples/pdf-from-image-kotlin.md) - [Digital Signature (Two-Step)](/guides/android/samples/digital-signature-two-step-kotlin.md) - [Remote URL](/guides/android/samples/remote-url-kotlin.md) - [PdfUiFragment](/guides/android/samples/pdfuifragment-kotlin.md) - [Runtime Configuration](/guides/android/samples/runtime-configuration-kotlin.md) - [Sound Extraction](/guides/android/samples/sound-extraction-kotlin.md) - [Document from Canvas](/guides/android/samples/document-from-canvas-kotlin.md) - [Tabbed Documents](/guides/android/samples/tabbed-documents-kotlin.md) - [Watermarks](/guides/android/samples/watermarks-kotlin.md) - [Programmatic Zoom](/guides/android/samples/programmatic-zoom-kotlin.md) - [Signature Parcelize](/guides/android/samples/signature-parcelize-kotlin.md) - [OCR](/guides/android/samples/ocr-kotlin.md) - [Vertical Scrollbar](/guides/android/samples/vertical-scrollbar-java.md) - [Split View](/guides/android/samples/split-view-java.md) - [XFDF Import/Export](/guides/android/samples/xfdf-import-export-kotlin.md) - [UI View Modes](/guides/android/samples/ui-view-modes-kotlin.md) - [LTV Signature](/guides/android/samples/ltv-signature-kotlin.md) - [Bookmark Highlighting](/guides/android/samples/bookmark-highlighting-kotlin.md) - [Custom Annotation Inspector](/guides/android/samples/custom-annotation-inspector-java.md) - [Annotation Sidebar](/guides/android/samples/annotation-sidebar-kotlin.md) - [AI Assistant (Single Document)](/guides/android/samples/ai-assistant-single-document-kotlin.md) - [AI Assistant (Multiple Documents, Compose)](/guides/android/samples/ai-assistant-multiple-documents-compose-kotlin.md) - [Document Comparison](/guides/android/samples/document-comparison-kotlin.md) - [Document Processing](/guides/android/samples/document-processing-kotlin.md) - [Custom Annotation Creation Toolbar](/guides/android/samples/custom-annotation-creation-toolbar-java.md) - [Custom Electronic Signature](/guides/android/samples/custom-electronic-signature-java.md) - [E-Learning](/guides/android/samples/e-learning-kotlin.md) - [Electronic + Digital Signing](/guides/android/samples/electronic-digital-signing-kotlin.md) - [Generate PDF Report](/guides/android/samples/generate-pdf-report-kotlin.md) - [Multimedia Annotations](/guides/android/samples/multimedia-annotations-kotlin.md) - [Forms with JavaScript](/guides/android/samples/forms-with-javascript-kotlin.md) - [External Document](/guides/android/samples/external-document-kotlin.md) - [Overlay Views](/guides/android/samples/overlay-views-kotlin.md) - [Search Indexing](/guides/android/samples/search-indexing-kotlin.md) - [Annotation Creation](/guides/android/samples/annotation-creation-kotlin.md) - [Filterable Thumbnail Grid](/guides/android/samples/filterable-thumbnail-grid-kotlin.md) - [Tabbed Documents (Persistent)](/guides/android/samples/tabbed-documents-persistent-kotlin.md) - [Measurement Tools](/guides/android/samples/measurement-tools-kotlin.md) - [HTML-to-PDF Conversion](/guides/android/samples/html-to-pdf-conversion-kotlin.md) - [AES Encrypted File](/guides/android/samples/aes-encrypted-file-java.md) - [Construction Floor Plan](/guides/android/samples/construction-floor-plan-kotlin.md) - [Hide and Reveal Areas](/guides/android/samples/hide-and-reveal-areas-kotlin.md) - [Multiple Documents (Compose Pager)](/guides/android/samples/multiple-documents-compose-pager-kotlin.md) - [Screen Reader](/guides/android/samples/screen-reader-java.md) - [Custom Search UI (Views)](/guides/android/samples/custom-search-ui-views-java.md)