Guides

Using CPDFReaderView

CPDFReaderView is the viewer component provided by ComPDF Android PDF SDK for displaying PDF content inside an Android screen. This page covers the minimum integration flow, including layout setup, instance binding, and document attachment.

Use this page when

This page is intended for the following scenarios:

• Embedding a PDF viewer in an Activity or Fragment.
• Opening a local PDF file and displaying its content.
• Establishing the base integration for later viewer state, navigation, search, and mode configuration.

Complete these prerequisites first

Before starting the integration, confirm that the following items are already in place:

• SDK integration is complete.
• License configuration is valid.
• The current screen has access to a readable PDF file path or source.
• The screen layout is ready to host the viewer component.

Add CPDFReaderView to the layout

Add CPDFReaderView to the screen layout first.

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  tools:context=".MainActivity">

  <com.compdfkit.ui.reader.CPDFReaderView
    android:id="@+id/readerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

In screens that also include toolbars, bottom bars, or business UI panels, CPDFReaderView is usually placed in the primary reading area rather than assigned a fixed size.

Get the viewer instance and open the document

After adding the view to the layout, complete the following steps in order:

1. Get the CPDFReaderView instance.
2. Create CPDFDocument.
3. Call open(...) on the document.
4. Bind the document to CPDFReaderView after the open call succeeds.

The following example shows a minimum working setup.

java

private CPDFReaderView readerView;
private CPDFDocument document;

@Override
protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  readerView = findViewById(R.id.readerView);

  String filePath = "/storage/emulated/0/Download/sample.pdf";
  document = new CPDFDocument(this);

  PDFDocumentError error = document.open(filePath);
  if (error == PDFDocumentError.PDFDocumentErrorSuccess) {
    readerView.setPDFDocument(document);
  } else {
    Log.e("ComPDF", "Open document failed: " + error);
  }
}

kotlin

private lateinit var readerView: CPDFReaderView
private var document: CPDFDocument? = null

override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)
  setContentView(R.layout.activity_main)

  readerView = findViewById(R.id.readerView)

  val filePath = "/storage/emulated/0/Download/sample.pdf"
  val pdfDocument = CPDFDocument(this)
  val error = pdfDocument.open(filePath)

  if (error == PDFDocumentError.PDFDocumentErrorSuccess) {
    document = pdfDocument
    readerView.setPDFDocument(pdfDocument)
  } else {
    Log.e("ComPDF", "Open document failed: $error")
  }
}

Follow the integration sequence

CPDFReaderView is responsible for rendering document content, while CPDFDocument is the object that actually opens the file. The correct sequence is:

1. Create CPDFDocument.
2. Call document.open(...).
3. Check whether the result is PDFDocumentErrorSuccess.
4. Call readerView.setPDFDocument(document).

If the document is bound to the viewer before it is opened successfully, the screen will not enter a valid display state.

Keep these points in mind

• open(...) failures are usually caused by invalid paths, missing permissions, corrupted files, or inaccessible file sources.
• If the document comes from a Uri, download directory, or sandbox path, verify read access before opening it.
• It is usually easier to configure display modes, navigation, search, and themes after the document is displayed successfully.
• Production screens generally also need document loading state and error handling logic.

Related pages

• For document loading state, error prompts, and viewer interaction events, see Document State and Error Callbacks.
• For single-page, double-page, and scroll direction settings, see Display Modes.