pdfrx 0.4.37

pdfrx is a rich and fast PDF viewer implementation built on the top of pdfium. The plugin supports Android, iOS, Windows, macOS, Linux, and Web.

pdfrx

pdfrx is a rich and fast PDF viewer implementation built on the top of pdfium. The plugin supports Android, iOS, Windows, macOS, Linux, and Web.

Main Features

• Zoomable and scrollable PDF document viewer

• PDF Link Handling support

• Document Outline (a.k.a Bookmarks) support

• Text Selection (still experimental) support

• Text Search support

• Flexibily customizable

• Multi-platform support

  • Android
  • iOS
  • Windows
  • macOS
  • Linux (even on Raspberry PI)
  • Web (*using PDF.js)

• Three layers of APIs:

  • Easy to use Flutter widgets
    • PdfViewer
    • PdfDocumentViewBuilder
    • PdfPageView
  • Easy to use PDF APIs
    • PdfDocument
  • pdfium bindings
    • Not encouraged but you can import package:pdfrx/src/pdfium/pdfium_bindings.dart

Demo site

• A demo site using Flutter Web

Getting Started

The following fragment illustrates the easiest way to show a PDF file in assets:

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Pdfrx example'),
        ),
        body: PdfViewer.asset('assets/hello.pdf'),
      ),
    );
  }
}

Installation

Add this to your package's pubspec.yaml file and execute flutter pub get:

dependencies:
  pdfrx: ^0.4.37

Windows

• Ensure your Windows installation enables Developer Mode

  The build process internally uses symblic link and it requires Developer Mode to be enabled. Without this, you may encounter errors like this.

Web

pdf.js is now automatically loaded and no modification to index.html is required.

It's not required but you can customize download URLs for pdf.js by setting PdfJsConfiguration.configuration:

// place the code on main function or somewhere that is executed before the actual
// app code.
PdfJsConfiguration.configuration = const PdfJsConfiguration(
  pdfJsSrc: 'https://cdnjs.cloudflare.com/ajax/libs/pdf.js/3.11.174/pdf.min.mjs',
  workerSrc: 'https://cdnjs.cloudflare.com/ajax/libs/pdf.js/3.11.174/pdf.worker.min.js',
  cMapUrl: 'https://cdnjs.cloudflare.com/ajax/libs/pdf.js/3.11.174/cmaps/',
);

Please note that pdf.js 4.X is not supported yet and use 3.X versions.

macOS

For macOS, Flutter app restrict its capability by enabling App Sandbox by default. You can change the behavior by editing your app's entitlements files depending on your configuration. See the discussion below.

• macos/Runner/Release.entitlements
• macos/Runner/DebugProfile.entitlements

Deal with App Sandbox

The easiest option to access files on your disk, set com.apple.security.app-sandbox to false on your entitlements file though it is not recommended for releasing apps because it completely disables App Sandbox.

Another option is to use com.apple.security.files.user-selected.read-only along with file_selector_macos. The option is better in security than the previous option.

Anyway, the example code for the plugin illustrates how to download and preview internet hosted PDF file. It uses com.apple.security.network.client along with flutter_cache_manager:

<dict>
  <key>com.apple.security.app-sandbox</key>
  <true/>
  <key>com.apple.security.network.client</key>
  <true/>
</dict>

Open PDF File

PdfViewer supports following functions to open PDF file on specific medium:

• PdfViewer.asset
  • Open PDF of Flutter's asset
• PdfViewer.file
  • Open PDF from file
• PdfViewer.uri
  • Open PDF from URI (https://... or relative path)
  • On Flutter Web, it may be blocked by CORS

Deal with Password Protected PDF Files

To support password protected PDF files, use passwordProvider to supply passwords interactively:

PdfViewer.asset(
  'assets/test.pdf',
  // Set password provider to show password dialog
  passwordProvider: _passwordDialog,

  ...
),

And, _passwordDialog function is defined like this:

Future<String?> _passwordDialog() async {
  final textController = TextEditingController();
  return await showDialog<String?>(
    context: context,
    barrierDismissible: false,
    builder: (context) {
      return AlertDialog(
        title: const Text('Enter password'),
        content: TextField(
          controller: textController,
          autofocus: true,
          keyboardType: TextInputType.visiblePassword,
          obscureText: true,
          onSubmitted: (value) => Navigator.of(context).pop(value),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(context).pop(null),
            child: const Text('Cancel'),
          ),
          TextButton(
            onPressed: () => Navigator.of(context).pop(textController.text),
            child: const Text('OK'),
          ),
        ],
      );
    },
  );
}

When PdfViewer tries to open a password protected document, it calls the function passed to passwordProvider (except the first attempt; see below) repeatedly to get a new password until the document is successfully opened. And if the function returns null, the viewer will give up the password trials and the function is no longer called.

firstAttemptByEmptyPassword

By default, the first password attempt uses empty password. This is because encrypted PDF files frequently use empty password for viewing purpose. It's normally useful but if you want to use authoring password, it can be disabled by setting firstAttemptByEmptyPassword to false.

Customizations

You can customize the behaviour and visual by configuring PdfViewerParams.

Text Selection

Text selection feature is still experimental but you can easily enable it like the following fragment:

PdfViewer.asset(
  'assets/test.pdf',
  enableTextSelection: true,
  ...
),

PDF Link Handling

To enable Link in PDF file, you should set PdfViewerParams.linkWidgetBuilder.

The following fragment creates a widget that handles user's tap on link:

linkWidgetBuilder: (context, link, size) => Material(
  color: Colors.transparent,
  child: InkWell(
    onTap: () {
      // handle URL or Dest
      if (link.url != null) {
        // TODO: implement your own isSecureUrl by yourself...
        if (await isSecureUrl(link.url!)) {
          launchUrl(link.url!);
        }
      } else if (link.dest != null) {
        controller.goToDest(link.dest);
      }
    },
    hoverColor: Colors.blue.withOpacity(0.2),
  ),
),

For URIs, you should check the validity of the URIs before opening the URI; the example code just show dialog to ask whether to open the URL or not.

For destinations, you can use PdfViewerController.goToDest to go to the destination. Or you can use PdfViewerController.calcMatrixForDest to get the matrix for it.

Document Outline (a.k.a Bookmarks)

PDF defines document outline (PdfOutlineNode), which is sometimes called as bookmarks or index. And you can access it by PdfDocument.loadOutline.

The following fragment obtains it on PdfViewerParams.onViewerReady:

onViewerReady: (document, controller) async {
  outline.value = await document.loadOutline();
},

PdfOutlineNode is tree structured data and for more information, see the usage on example code.

Horizontal Scroll View

By default, the pages are layed out vertically. You can customize the layout logic by PdfViewerParams.layoutPages:

layoutPages: (pages, params) {
  final height =
      pages.fold(0.0, (prev, page) => max(prev, page.height)) +
          params.margin * 2;
  final pageLayouts = <Rect>[];
  double x = params.margin;
  for (var page in pages) {
    pageLayouts.add(
      Rect.fromLTWH(
        x,
        (height - page.height) / 2, // center vertically
        page.width,
        page.height,
      ),
    );
    x += page.width + params.margin;
  }
  return PdfPageLayout(
    pageLayouts: pageLayouts,
    documentSize: Size(x, height),
  );
},

Showing Scroll Thumbs

By default, the viewer does never show any scroll bars nor scroll thumbs. You can add scroll thumbs by using PdfViewerParams.viewerOverlayBuilder:

viewerOverlayBuilder: (context, size) => [
  // Add vertical scroll thumb on viewer's right side
  PdfViewerScrollThumb(
    controller: controller,
    orientation: ScrollbarOrientation.right,
    thumbSize: const Size(40, 25),
    thumbBuilder:
        (context, thumbSize, pageNumber, controller) =>
            Container(
      color: Colors.black,
      // Show page number on the thumb
      child: Center(
        child: Text(
          pageNumber.toString(),
          style: const TextStyle(color: Colors.white),
        ),
      ),
    ),
  ),
  // Add horizontal scroll thumb on viewer's bottom
  PdfViewerScrollThumb(
    controller: controller,
    orientation: ScrollbarOrientation.bottom,
    thumbSize: const Size(80, 30),
    thumbBuilder:
        (context, thumbSize, pageNumber, controller) =>
            Container(
      color: Colors.red,
    ),
  ),
],

Adding Page Number on Page Bottom

If you want to add page number on each page, you can do that by PdfViewerParams.pageOverlayBuilder:

pageOverlayBuilder: (context, pageRect, page) {
  return Align(
    alignment: Alignment.bottomCenter,
    child: Text(page.pageNumber.toString(),
    style: const TextStyle(color: Colors.red)));
},

Loading Indicator

PdfViewer.uri may take long time to download PDF file and you want to show some loading indicator. You can do that by PdfViewerParams.loadingBannerBuilder:

loadingBannerBuilder: (context, bytesDownloaded, totalBytes) {
  return Center(
    child: CircularProgressIndicator(
      // totalBytes may not be available on certain case
      value: totalBytes != null ? bytesDownloaded / totalBytes : null,
      backgroundColor: Colors.grey,
    ),
  );
}

Other Features

Text Search

TextSearcher is just a helper class that helps you to implement text searching feature on your app.

The following fragment illustrates the overall structure of the TextSearcher:

class _MainPageState extends State<MainPage> {
  final controller = PdfViewerController();
  // create a PdfTextSearcher and add a listener to update the GUI on search result changes
  late final textSearcher = PdfTextSearcher(controller)..addListener(_update);

  void _update() {
    if (mounted) {
      setState(() {});
    }
  }

  @override
  void dispose() {
    // dispose the PdfTextSearcher
    textSearcher.removeListener(_update);
    textSearcher.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Pdfrx example'),
      ),
      body: PdfViewer.asset(
        'assets/hello.pdf',
        controller: controller,
        params: PdfViewerParams(
          // add pageTextMatchPaintCallback that paints search hit highlights
          pagePaintCallbacks: [
            textSearcher.pageTextMatchPaintCallback
          ],
        ),
      )
    );
  }
  ...
}

On the fragment above, it does:

• Create TextSearcher instance
• Add a listener (Using PdfTextSearcher.addListener) to update UI on search result change
• Add TextSearcher.pageTextMatchPaintCallback to PdfViewerParams.pagePaintCallbacks to show search matches

Then, you can use TextSearcher.startTextSearch to search text in the PDF document:

textSearcher.startTextSearch('hello', caseInsensitive: true);

The search starts running in background and the search progress is notified by the listener.

There are several functions that helps you to navigate user to the search matches:

• TextSearcher.goToMatchOfIndex to go to the match of the specified index
• TextSearcher.goToNextMatch to go to the next match
• TextSearcher.goToPrevMatch to go to the previous match

You can get the search result (even during the search running) in the list of PdfTextMatch by PdfTextSearcher.matches:

for (final match in textSearcher.matches) {
  print(match.pageNumber);
  ...
}

You can also cancel the background search:

textSearcher.resetTextSearch();

PdfDocumentViewBuilder/PdfPageView

PdfPageView is just another PDF widget that shows only one page. It accepts PdfDocument and page number to show a page within the document.

PdfDocumentViewBuilder is used to safely manage PdfDocument inside widget tree and it accepts builder parameter that creates child widgets.

The following fragment is a typical use of these widgets:

PdfDocumentViewBuilder.asset(
  'asset/test.pdf',
  builder: (context, document) => ListView.builder(
    itemCount: document?.pages.length ?? 0,
    itemBuilder: (context, index) {
      return Container(
        margin: const EdgeInsets.all(8),
        height: 240,
        child: Column(
          children: [
            SizedBox(
              height: 220,
              child: PdfPageView(
                document: document,
                pageNumber: index + 1,
                alignment: Alignment.center,
              ),
            ),
            Text(
              '${index + 1}',
            ),
          ],
        ),
      );
    },
  ),
),

PdfDocument management and sharing it between widgets

PdfDocumentViewBuilder can accept PdfDocumentRef from PdfViewer to safely share the same PdfDocument instance. For more information, see example/lib/thumbnails_view.dart.