Customizing PDF annotation note hints in Kotlin for Android

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/*
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 *   Copyright © 2020-2025 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.graphics.Canvas
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import android.graphics.ColorFilter
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import android.graphics.Matrix
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import android.graphics.PixelFormat
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import android.graphics.PointF
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import android.graphics.Rect
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import android.graphics.RectF
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import android.graphics.drawable.Drawable
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import android.net.Uri
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import android.os.Bundle
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import android.text.TextUtils
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import androidx.annotation.IntRange
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import androidx.core.content.ContextCompat
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import androidx.core.graphics.drawable.DrawableCompat
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import com.pspdfkit.annotations.Annotation
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import com.pspdfkit.annotations.AnnotationProvider.OnAnnotationUpdatedListener
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import com.pspdfkit.annotations.AnnotationType
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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.utils.Utils
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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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import com.pspdfkit.ui.PdfActivityIntentBuilder
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import com.pspdfkit.ui.drawable.PdfDrawable
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import com.pspdfkit.ui.drawable.PdfDrawableProvider
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/**
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 * Shows how to create a custom annotation note hinter extending [PdfDrawableProvider].
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 */
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class CustomAnnotationNoteHinterProviderExample(context: Context) : SdkExample(
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    context,
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    R.string.customAnnotationNoteHinterProviderExampleTitle,
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    R.string.customAnnotationNoteHinterProviderExampleDescription
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) {
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    override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) {
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        // Disable default annotation hinter provider.
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        configuration.setAnnotationNoteHintingEnabled(false)
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        // We use a custom utility class to extract the example document from the assets.
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        ExtractAssetTask.extract(WELCOME_DOC, title, context) { documentFile ->
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            // To start the CustomAnnotationNoteHinterProviderActivity create a launch intent using the builder.
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            val intent = PdfActivityIntentBuilder.fromUri(context, Uri.fromFile(documentFile))
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                .configuration(configuration.build())
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                .activityClass(CustomAnnotationNoteHinterProviderActivity::class)
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                .build()
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            // Start the activity for the extracted document.
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            context.startActivity(intent)
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        }
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    }
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}
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class CustomAnnotationNoteHinterProviderActivity : PdfActivity() {
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    override fun onCreate(savedInstanceState: Bundle?) {
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        super.onCreate(savedInstanceState)
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        val customAnnotationNoteHinter = CustomAnnotationNoteHinter(this)
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        // Inject our custom hinter to the framework.
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        requirePdfFragment().apply {
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            // We need to register custom drawable provider so we can provide our custom hint drawables.
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            addDrawableProvider(customAnnotationNoteHinter)
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            //  We also want to react to annotation updated events in our hinter.
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            requirePdfFragment().addOnAnnotationUpdatedListener(customAnnotationNoteHinter)
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        }
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    }
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}
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/**
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 * A custom annotation note hinter provider that works only for ink annotations.
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 */
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private class CustomAnnotationNoteHinter(private val pdfActivity: PdfActivity) : PdfDrawableProvider(), OnAnnotationUpdatedListener {
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    private val noteIcon: Drawable = ContextCompat.getDrawable(pdfActivity, R.drawable.ic_pin_drop)
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        ?: throw IllegalStateException("Can't retrieve note drawable from resources.")
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    override fun getDrawablesForPage(
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        context: Context,
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        document: PdfDocument,
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        @IntRange(from = 0) pageIndex: Int
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    ): List<PdfDrawable> {
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        return document.annotationProvider.getAnnotations(pageIndex)
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            .asSequence()
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            .filter { it.type == AnnotationType.INK }
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            .map { NoteInkHinterDrawable(pdfActivity, noteIcon, it) }
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            .toList()
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    }
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    // We notify change to provided drawables whenever any ink annotation changes (is created, updated or removed).
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    override fun onAnnotationCreated(annotation: Annotation) = notifyDrawablesChangedIfSupported(annotation)
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    override fun onAnnotationUpdated(annotation: Annotation) = notifyDrawablesChangedIfSupported(annotation)
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    override fun onAnnotationRemoved(annotation: Annotation) = notifyDrawablesChangedIfSupported(annotation)
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    private fun notifyDrawablesChangedIfSupported(annotation: Annotation) {
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        if (annotation.type == AnnotationType.INK) {
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            notifyDrawablesChanged()
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        }
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    }
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    // There's no need to update note hinter drawables on Annotation Z-order changes. This method is a no-op.
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    override fun onAnnotationZOrderChanged(pageIndex: Int, oldOrder: List<Annotation>, newOrder: List<Annotation>) = Unit
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}
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private class NoteInkHinterDrawable internal constructor(
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    private val activity: PdfActivity,
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    private val noteIcon: Drawable,
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    private val annotation: Annotation
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) : PdfDrawable() {
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    private val viewBoundingBoxRounded: Rect = Rect()
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    private val pdfBoundingBox: RectF = RectF()
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    private val viewPoint: PointF = PointF()
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    private val viewBoundingBox: RectF = RectF()
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    private val widthPx: Int
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    private val heightPx: Int
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    private val halfWidthPx: Int
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    private val halfHeightPx: Int
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    init {
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        annotation.getBoundingBox(pdfBoundingBox)
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        widthPx = Utils.dpToPx(activity, 24)
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        heightPx = Utils.dpToPx(activity, 24)
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        halfWidthPx = widthPx / 2
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        halfHeightPx = heightPx / 2
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    }
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    override fun draw(canvas: Canvas) {
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        invalidateSelf()
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        if (TextUtils.isEmpty(annotation.contents)) {
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            return
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        }
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        DrawableCompat.setTint(noteIcon, annotation.color)
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        noteIcon.bounds = viewBoundingBoxRounded
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        noteIcon.draw(canvas)
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    }
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    override fun setAlpha(@IntRange(from = 0, to = 255) alpha: Int) {
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        noteIcon.alpha = ALPHA
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    }
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    override fun setColorFilter(colorFilter: ColorFilter?) {
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        noteIcon.colorFilter = colorFilter
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    }
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    @Deprecated("Deprecated in Java")
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    override fun getOpacity(): Int {
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        return PixelFormat.TRANSLUCENT
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    }
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    override fun updatePdfToViewTransformation(matrix: Matrix) {
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        super.updatePdfToViewTransformation(matrix)
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        annotation.getBoundingBox(pdfBoundingBox)
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        viewPoint.set(pdfBoundingBox.centerX(), pdfBoundingBox.centerY())
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        activity.requirePdfFragment().viewProjection.toViewPoint(viewPoint, annotation.pageIndex)
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        viewBoundingBox.set(
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            viewPoint.x - halfWidthPx,
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            viewPoint.y - halfHeightPx,
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            viewPoint.x + halfWidthPx,
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            viewPoint.y + halfHeightPx
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        )
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        viewBoundingBox.round(viewBoundingBoxRounded)
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    }
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    companion object {
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        private const val ALPHA = 255
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    }
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}