pdfrx Initialization

If you use Flutter widgets like PdfViewer or PdfDocumentViewBuilder, they implicitly initialize the library by calling pdfrxFlutterInitialize.

But if you use PdfDocument directly, you should explicitly do either one of the following ways:

• Call pdfrxFlutterInitialize
• Call pdfrxInitialize
• Initialize things by yourself

The first one is the recommended and the easiest way to initialize Flutter app.

For pure Dart apps (or even some of Flutter apps), you can use pdfrxInitialize.

Initialize Things By Yourself

Basically, these initialization functions do the following things:

• Set Pdfrx.getCacheDirectory
• Map PdfDocument factory/interop functions to actual platform ones
• Set Pdfrx.loadAsset (Flutter only)
• Download PDFium binary on-demand (pdfrxInitialize only)

Cache Directory

The mechanism to locate cache directory is different between pure Dart apps and Flutter apps:

Init. Func.	Underlying API	Notes
pdfrxInitialize	Directory.systemTemp	May not be suitable for mobile apps.
pdfrxFlutterInitialize	path_provider.getTemporaryDirectory	Always app local directory.

Download PDFium Binary On-Demand

For pure Dart apps, because it is typically used on desktop environments, pdfrx downloads PDFium binary if your environment does not have it.

• PDFium binaries are downloaded from https://github.com/bblanchon/pdfium-binaries/releases
• By default, the binary is downloaded to [TMP_DIR]/pdfrx.cache
• You can explicitly specify libpdfium shared library file path/name by PDFIUM_PATH environment variable