--- title: "Programmatic Zoom" canonical_url: "https://www.nutrient.io/guides/android/samples/programmatic-zoom-kotlin/" md_url: "https://www.nutrient.io/guides/android/samples/programmatic-zoom-kotlin.md" last_updated: "2026-05-15T19:10:04.916Z" description: "Navigate between annotations with animated zoom using PdfFragment.zoomTo()." --- # Programmatic Zoom Navigate between annotations with animated zoom using PdfFragment.zoomTo(). [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.view.Menu import android.view.MenuItem import androidx.activity.viewModels import androidx.annotation.UiThread import androidx.lifecycle.lifecycleScope import com.pspdfkit.annotations.Annotation import com.pspdfkit.annotations.AnnotationType import com.pspdfkit.catalog.R import com.pspdfkit.catalog.SdkExample import com.pspdfkit.catalog.ui.DocumentPickerActivity import com.pspdfkit.configuration.activity.PdfActivityConfiguration import com.pspdfkit.document.PdfDocument import com.pspdfkit.ui.PdfActivity import com.pspdfkit.ui.PdfFragment import kotlinx.coroutines.Dispatchers import kotlinx.coroutines.Job import kotlinx.coroutines.launch import kotlinx.coroutines.withContext import kotlin.math.max import kotlin.math.min /** * Simple example that shows how to zoom to page annotations, using the [PdfFragment.zoomTo] method. */ class ZoomExample(context: Context) : SdkExample(context, R.string.zoomExampleTitle, R.string.zoomExampleDescription) { override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) { // This example uses a custom activity which adds some option menu items. // The default menu items are deactivated for simplicity. configuration.searchEnabled(false).outlineEnabled(false).thumbnailGridEnabled(false) // Launch the picker activity to let users choose between default or custom document. val intent = Intent(context, ZoomExamplePickerActivity::class.java) intent.putExtra(DocumentPickerActivity.EXTRA_CONFIGURATION, configuration.build()) context.startActivity(intent) } } /** * Activity that lets the user choose between picking a PDF and using the default document. */ class ZoomExamplePickerActivity : DocumentPickerActivity() { override val targetActivityClass = ZoomExampleActivity::class.java } /** * This example shows how to zoom/animate between annotations of a document using the [PdfFragment.zoomTo] method. */ class ZoomExampleActivity : PdfActivity() { companion object { /** Padding around annotation bounding box used when zooming. */ private const val ANNOTATION_BOUNDING_BOX_PADDING_PX = 16 } /** * This list holds all annotations of the loaded document. It is populated in onDocumentLoaded(). */ private val documentAnnotations = mutableListOf() /** This holds reference to the currently zoomed annotation. */ private var currentAnnotation: Annotation? = null private var annotationLoadingJob: Job? = null private val viewModel: AnnotationCreationViewModel by viewModels() /** * Once the document is loaded, we extract all the annotations and put them into our list. * That way we can easily move forth and back between the annotations. */ @UiThread override fun onDocumentLoaded(document: PdfDocument) { viewModel.createObjects { annotationLoadingJob = lifecycleScope.launch { val annotations = withContext(Dispatchers.IO) { document.annotationProvider.getAllAnnotationsOfType( AnnotationType.entries.toSet(), ) } documentAnnotations.addAll(annotations) } } } override fun onDestroy() { super.onDestroy() // Cancel the annotation loading job. annotationLoadingJob?.cancel() annotationLoadingJob = null } /** * Creates our custom navigation menu. */ override fun onCreateOptionsMenu(menu: Menu): Boolean { // It's important to call super before inflating the // custom menu, or the custom menu won't be shown. super.onCreateOptionsMenu(menu) // Inflate our custom menu items, for navigation between annotations. menuInflater.inflate(R.menu.activity_zoom_example, menu) return true } /** * Handles clicks on the navigation option menu items. */ override fun onOptionsItemSelected(item: MenuItem): Boolean = when (item.itemId) { R.id.nextAnnotation -> { zoomToNextAnnotation() true } R.id.previousAnnotation -> { zoomToPreviousAnnotation() true } else -> { super.onOptionsItemSelected(item) } } /** * Called when pressing the "next annotation" button. Finds the next annotation and issues a call * to [PdfFragment.zoomTo]. */ private fun zoomToNextAnnotation() { if (documentAnnotations.isEmpty()) return var currentAnnotation = this.currentAnnotation val currentAnnotationIndex = if (currentAnnotation == null) { -1 } else { documentAnnotations.indexOf(currentAnnotation) } val nextAnnotationIndex = min(currentAnnotationIndex + 1, documentAnnotations.size - 1) if (nextAnnotationIndex!= currentAnnotationIndex) { currentAnnotation = documentAnnotations[nextAnnotationIndex] this.currentAnnotation = currentAnnotation val boundingBox = currentAnnotation.boundingBox boundingBox.inset(-ANNOTATION_BOUNDING_BOX_PADDING_PX.toFloat(), -ANNOTATION_BOUNDING_BOX_PADDING_PX.toFloat()) requirePdfFragment().zoomTo(boundingBox, currentAnnotation.pageIndex, 300) } } /** * Called when pressing the "previous annotation" button. Finds the previous annotation and issues a call * to [PdfFragment.zoomTo]. */ private fun zoomToPreviousAnnotation() { if (documentAnnotations.isEmpty()) return var currentAnnotation = this.currentAnnotation?: return val currentAnnotationIndex = documentAnnotations.indexOf(currentAnnotation) val nextAnnotationIndex = max(currentAnnotationIndex - 1, 0) if (nextAnnotationIndex!= currentAnnotationIndex) { currentAnnotation = documentAnnotations[nextAnnotationIndex] this.currentAnnotation = currentAnnotation val boundingBox = currentAnnotation.boundingBox boundingBox.inset(-ANNOTATION_BOUNDING_BOX_PADDING_PX.toFloat(), -ANNOTATION_BOUNDING_BOX_PADDING_PX.toFloat()) requirePdfFragment().zoomTo(boundingBox, currentAnnotation.pageIndex, 300) } } } ``` 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) - 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