Compose PDF Viewer

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/*
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 *   Copyright © 2026 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.composeviewer
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import android.content.Context
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import android.content.Intent
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import android.net.Uri
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import android.os.Bundle
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import androidx.activity.compose.setContent
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import androidx.activity.enableEdgeToEdge
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import androidx.appcompat.app.AppCompatActivity
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import androidx.compose.foundation.isSystemInDarkTheme
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import androidx.compose.runtime.Composable
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import androidx.compose.runtime.LaunchedEffect
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import androidx.compose.runtime.collectAsState
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import androidx.compose.runtime.getValue
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import androidx.lifecycle.viewmodel.compose.viewModel
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import androidx.navigation.compose.NavHost
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import androidx.navigation.compose.composable
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import androidx.navigation.compose.rememberNavController
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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.tasks.ExtractAssetTask
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import com.pspdfkit.catalog.ui.theming.CatalogTheme
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import com.pspdfkit.configuration.activity.PdfActivityConfiguration
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import com.pspdfkit.utils.getSupportParcelableExtra
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import java.io.File
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/**
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 * A complete Jetpack Compose PDF viewer app in one catalog example — the in-catalog successor
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 * of the standalone `simple-compose` app:
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 *
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 * - **Library**: recent documents as a grid of live page-1 thumbnails (rendered with
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 *   `PdfDocumentLoader`), with system file import (SAF).
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 * - **Viewer** ([ViewerScreen]): `DocumentView` with a host-rendered `NutrientMainToolbar`,
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 *   the content/viewport inset bookkeeping a custom main toolbar requires, custom toolbar
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 *   items, `DefaultListeners` wiring, and a live demonstration of
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 *   [com.pspdfkit.jetpack.compose.interactors.DocumentState.setCustomPdfSource]'s async
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 *   completion and view-state restore.
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 * - **Settings**: light/dark/system theme and Material You dynamic color, persisted in a
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 *   DataStore; the choice drives both the app chrome and the document theme.
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 *
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 * State lives in [ComposeViewerViewModel] — plain `ViewModel` + DataStore, no DI framework or
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 * database, so the whole example is copy-paste-able.
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 */
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class ComposePdfViewerExample(context: Context) :
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    SdkExample(context, R.string.composePdfViewerExampleTitle, R.string.composePdfViewerExampleDescription) {
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    override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) {
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        // Extract the bundled demo document so a fresh install starts with a library entry.
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        ExtractAssetTask.extract(WELCOME_DOC, title, context) { documentFile ->
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            val intent = Intent(context, ComposePdfViewerActivity::class.java)
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                .putExtra(ComposePdfViewerActivity.EXTRA_DEMO_DOCUMENT, Uri.fromFile(documentFile))
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            context.startActivity(intent)
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        }
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    }
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}
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class ComposePdfViewerActivity : AppCompatActivity() {
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    override fun onCreate(savedInstanceState: Bundle?) {
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        enableEdgeToEdge()
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        super.onCreate(savedInstanceState)
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        val demoDocument = intent.getSupportParcelableExtra(EXTRA_DEMO_DOCUMENT, Uri::class.java)
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        setContent {
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            val viewModel: ComposeViewerViewModel = viewModel()
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            // Seed the library with the bundled demo document on every launch — recordOpened
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            // upserts, so an existing entry only refreshes its timestamp. Label it with the asset
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            // name: ExtractAssetTask writes the file as "<asset>_<sha1-of-title>", which is not a
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            // name to show a reader.
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            LaunchedEffect(viewModel) {
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                demoDocument?.path?.let { viewModel.recordOpened(File(it), name = SdkExample.WELCOME_DOC) }
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            }
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            val darkMode by viewModel.darkMode.collectAsState()
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            val dynamicColor by viewModel.dynamicColor.collectAsState()
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            // The catalog's own theme (brand palette + typography), driven by this example's
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            // persisted settings rather than CatalogTheme's system defaults — so the Settings
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            // screen's theme and dynamic-color controls still work while the viewer looks like
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            // the rest of the catalog.
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            CatalogTheme(darkTheme = viewerDarkMode(darkMode), dynamicColor = dynamicColor) {
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                ViewerNavHost(viewModel)
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            }
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        }
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    }
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    companion object {
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        const val EXTRA_DEMO_DOCUMENT = "ComposePdfViewerActivity.DemoDocument"
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    }
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}
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/** The app's three destinations; the viewer takes the document's file path as its argument. */
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@Composable
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private fun ViewerNavHost(viewModel: ComposeViewerViewModel) {
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    val navController = rememberNavController()
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    NavHost(navController = navController, startDestination = "library") {
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        composable("library") {
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            LibraryScreen(
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                viewModel = viewModel,
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                onOpenDocument = { document ->
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                    viewModel.recordOpened(File(document.path))
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                    navController.navigate("viewer/${Uri.encode(document.path)}")
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                },
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                onOpenSettings = { navController.navigate("settings") },
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            )
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        }
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        composable("settings") {
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            SettingsScreen(viewModel = viewModel, onBack = { navController.popBackStack() })
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        }
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        composable("viewer/{path}") { backStackEntry ->
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            val path = Uri.decode(backStackEntry.arguments?.getString("path").orEmpty())
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            ViewerScreen(
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                path = path,
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                isDark = viewerInDarkTheme(viewModel),
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                onBack = { navController.popBackStack() },
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            )
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        }
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    }
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}
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/** Resolves the effective dark flag from the tri-state setting. */
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@Composable
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internal fun viewerInDarkTheme(viewModel: ComposeViewerViewModel): Boolean {
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    val darkMode by viewModel.darkMode.collectAsState()
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    return viewerDarkMode(darkMode)
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}
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/** Resolves the tri-state [ViewerDarkMode] setting into the effective dark flag. */
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@Composable
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private fun viewerDarkMode(darkMode: Int): Boolean = when (darkMode) {
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    ViewerDarkMode.DARK -> true
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    ViewerDarkMode.LIGHT -> false
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    else -> isSystemInDarkTheme()
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}