Simple PDF ViewPager

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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
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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 android.view.View
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import android.view.ViewGroup
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import androidx.appcompat.app.AppCompatActivity
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import androidx.core.net.toUri
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import androidx.core.view.ViewCompat
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import androidx.core.view.WindowInsetsCompat
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import androidx.core.view.updateLayoutParams
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import androidx.fragment.app.Fragment
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import androidx.fragment.app.FragmentActivity
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import androidx.viewpager2.adapter.FragmentStateAdapter
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import androidx.viewpager2.widget.ViewPager2
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import com.google.android.material.tabs.TabLayout
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import com.google.android.material.tabs.TabLayoutMediator
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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.WELCOME_DOC
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import com.pspdfkit.catalog.examples.kotlin.ViewPager2Activity.Companion.selectedPage
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import com.pspdfkit.configuration.activity.PdfActivityConfiguration
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import com.pspdfkit.ui.PdfUiFragmentBuilder
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/**
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 * Simple example showing how to use PdfUiFragment with ViewPager2 and TabLayout.
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 * This demonstrates a basic setup with 4 PDF documents in a swipeable tab interface.
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 */
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class SimplePdfViewPagerExample(context: Context) :
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    SdkExample(context, R.string.simplePdfViewPagerExampleTitle, R.string.simplePdfViewPagerExampleDescription) {
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    override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) {
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        context.startActivity(Intent(context, SimplePdfViewPagerActivity::class.java))
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    }
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}
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/**
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 * Activity that hosts a ViewPager2 with 4 PdfUiFragments and a TabLayout for navigation.
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 */
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class SimplePdfViewPagerActivity : AppCompatActivity() {
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    override fun onCreate(savedInstanceState: Bundle?) {
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        super.onCreate(savedInstanceState)
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        setContentView(R.layout.activity_simple_pdf_view_pager)
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        // Setup TabLayout with ViewPager2
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        val tabLayout: TabLayout = findViewById(R.id.tabLayout)
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        val viewPager: ViewPager2 = findViewById(R.id.viewPager)
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        val rootView = this.findViewById<View>(android.R.id.content)
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        ViewCompat.setOnApplyWindowInsetsListener(rootView) { v, windowInsets ->
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            val insets = windowInsets.getInsets(WindowInsetsCompat.Type.systemBars())
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            v.updateLayoutParams<ViewGroup.MarginLayoutParams> {
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                leftMargin = insets.left
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                topMargin = insets.top
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                rightMargin = insets.right
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                bottomMargin = insets.bottom
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            }
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            WindowInsetsCompat.CONSUMED
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        }
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        viewPager.registerOnPageChangeCallback(
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            object : ViewPager2.OnPageChangeCallback() {
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                override fun onPageSelected(position: Int) {
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                    super.onPageSelected(position)
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                    // Update the globally tracked selected page
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                    selectedPage = position
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                }
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                override fun onPageScrollStateChanged(state: Int) {
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                    super.onPageScrollStateChanged(state)
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                    // Refresh the current fragment when scrolling stops
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                    if (state == ViewPager2.SCROLL_STATE_IDLE) {
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                        refresh(selectedPage)
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                    }
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                }
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            },
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        )
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        // Setup ViewPager2
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        val adapter = SimplePdfPagerAdapter(this)
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        viewPager.adapter = adapter
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        TabLayoutMediator(tabLayout, viewPager) { tab, position ->
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            tab.text = "PDF ${position + 1}"
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        }.attach()
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    }
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}
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/**
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 * Adapter that provides PdfUiFragment instances for each page.
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 */
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class SimplePdfPagerAdapter(private val fragmentActivity: FragmentActivity) : FragmentStateAdapter(fragmentActivity) {
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    // List of PDF files to display
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    private val pdfFiles =
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        listOf(
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            WELCOME_DOC,
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            "Scientific-paper.pdf",
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            "Teacher.pdf",
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            "The-Cosmic-Context-for-Life.pdf",
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        )
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    override fun getItemCount(): Int = pdfFiles.size
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    override fun createFragment(position: Int): Fragment {
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        // Get the PDF URI from assets
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        val pdfUri: Uri = "file:///android_asset/${pdfFiles[position]}".toUri()
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        val activityConfiguration =
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            PdfActivityConfiguration
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                .Builder(fragmentActivity.applicationContext)
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                // Content editing is disabled because PDFs loaded from assets (file:///android_asset/)
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                // are read-only. To enable content editing, PDFs must be extracted from assets to
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                // writable storage using ExtractAssetTask before loading them.
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                .contentEditingEnabled(false)
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                .build()
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        // Build and return PdfUiFragment
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        return PdfUiFragmentBuilder
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            .fromUri(fragmentActivity, pdfUri)
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            .configuration(activityConfiguration)
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            .build()
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    }
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}