Memory Pressure Recovery

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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 androidx.appcompat.app.AlertDialog
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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.ui.DocumentPickerActivity
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import com.pspdfkit.configuration.activity.PdfActivityConfiguration
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import com.pspdfkit.document.PdfDocument
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import com.pspdfkit.ui.PdfActivity
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/**
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 * Exercises the SDK's native memory-pressure handling on heavy documents, with the full
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 * [PdfActivity] UI (including the thumbnail bar) active.
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 *
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 * Under sustained memory pressure the SDK sends critical memory notifications into core,
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 * which trims page caches and aborts in-flight page-content parses; an aborted page backs
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 * off (blank, no auto-retry) and is re-rendered automatically once memory recovers. A
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 * rasterisation that already started is allowed to finish. If pressure persists despite
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 * the automatic recovery, [com.pspdfkit.listeners.OnSustainedMemoryPressureListener]
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 * fires (once per episode) so the host can offer to close the document — demonstrated
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 * here with a dialog.
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 *
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 * Open a large document and scroll through its high-resolution pages to drive the device
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 * into real memory pressure, then watch the SDK trim caches, blank and re-render pages, and
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 * — if pressure persists — fire the host advisory dialog. Observe with:
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 * `adb logcat -s PSPDF.MemTrace MemoryHandling DocumentProvider PSPDF.MemoryNotHandler`.
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 */
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class MemoryPressureExample(context: Context) :
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    SdkExample(
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        context,
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        R.string.memoryPressureExampleTitle,
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        R.string.memoryPressureExampleDescription,
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    ) {
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    override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) {
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        val intent = Intent(context, MemoryPressureExamplePickerActivity::class.java)
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        intent.putExtra(DocumentPickerActivity.EXTRA_CONFIGURATION, configuration.build())
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        context.startActivity(intent)
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    }
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}
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/** Activity that lets the user choose between picking a PDF and using the default document. */
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class MemoryPressureExamplePickerActivity : DocumentPickerActivity() {
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    override val targetActivityClass = MemoryPressureActivity::class.java
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}
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class MemoryPressureActivity : PdfActivity() {
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    override fun onDocumentLoaded(document: PdfDocument) {
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        super.onDocumentLoaded(document)
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        // The advisory only fires when critical pressure persists across several memory
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        // polls despite the SDK's automatic recovery — transient episodes stay silent.
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        // The recommended host response is to release the document.
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        pdfFragment?.setOnSustainedMemoryPressureListener {
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            AlertDialog.Builder(this)
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                .setTitle("Device is low on memory")
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                .setMessage(
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                    "This document needs more memory than the device can sustain. Some pages may " +
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                        "stay blank until memory recovers. Closing the document is recommended.",
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                )
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                .setPositiveButton("Close document") { _, _ -> finish() }
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                .setNegativeButton("Keep viewing", null)
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                .show()
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        }
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    }
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}