Android Tutorial [B4XDaisyUIKit] Beautiful, High-Performance PDF Rendering Made Simple (100% Beginner Friendly!)

Hi B4X Community,

Rending PDFs natively on Android can be a daunting task, requiring complex wrappers, native .so files, and tedious permission configurations. For years, the community has relied on the outstanding work of DonManfred, who wrapped Bartosz Schiller's popular AndroidPdfViewer and PdfiumAndroid GitHub libraries. This wrapper served as the foundation for excellent community examples, such as walt61's ad-free default viewer application, PDFab.

Today, we are taking it a step further. Introducing B4XDaisyPDFView—a modern, high-level custom view that packages all of that low-level power into a clean, single B4X component. You no longer need to worry about manually configuring layouts, copying assets with boilerplate code, or handling complex configurators yourself. Our component is based on PDFab but using B4XDaisyUIKit buttons.

---

Features

• Simple Assets Loading: Load assets directly with a single line of code.
• Modern Properties: Effortlessly toggle Auto-Spacing, Horizontal Swipe, Page Snapping, and Toolbars.
• Touch Intercepting: Built-in touch handling inside scrollable parent containers.
• Clean Callback Events: Easily trap page change, load complete, and screen tap events.

---

Beginner-Friendly Code Example

Setting up B4XDaisyPDFView is incredibly simple. Below is an example of how to initialize the component programmatically, set up its properties, load a PDF, and trap its key events.

Sub Class_Globals
    Private Root As B4XView
    Private xui As XUI
   
    ' Declare our custom view component
    Private pdfViewer As B4XDaisyPDFView
    Private NAVBAR_HEIGHT As Int = 56dip
End Sub

Public Sub Initialize As Object
    Return Me
End Sub

' This is called when the B4XPage is created
Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Root.Color = xui.Color_RGB(245, 247, 250) ' Soft background
   
    ' 1. Initialize the component programmatically (or add via the Designer!)
    pdfViewer.Initialize(Me, "pdfViewer")
   
    ' 2. Programmatically add it to your root layout parent
    pdfViewer.AddToParent(Root, 0, NAVBAR_HEIGHT, Root.Width, Root.Height - NAVBAR_HEIGHT)
   
    ' 3. Configure properties easily with clean getters and setters
    pdfViewer.AutoSpacing = True        ' Enable dynamic page margins
    pdfViewer.EnableSwipe = True        ' Allow swipe gestures to turn pages
    pdfViewer.PageSnap = True           ' Automatically snap pages to borders
    pdfViewer.SwipeHorizontal = False   ' False for classic vertical scrolling
    pdfViewer.ShowToolbar = True        ' Display the built-in control toolbar
   
    ' 4. Load your PDF directly from the DirAssets folder
    ' This automatically copies the file to the safe DefaultFolder and displays it!
    pdfViewer.LoadAsset("chapter_5.pdf")
End Sub

' --- TRAP EVENT CALLBACKS ---

' Triggered automatically when the PDF document is successfully parsed
Private Sub pdfViewer_LoadComplete(Pages As Int)
    Log("Success! PDF loaded with total pages: " & Pages)
End Sub

' Triggered automatically when the user scrolls to a new page
Private Sub pdfViewer_PageChanged(Page As Int, TotalPages As Int)
    ' Page index is 0-based, so add 1 for human-friendly display
    Log("Switched to page: " & (Page + 1) & " of " & TotalPages)
End Sub

' Triggered when a user taps on the document
Private Sub pdfViewer_OnTap(Target As Object)
    Log("User tapped the PDF view panel!")
End Sub

---

The History: Where Did It Come From?

For those interested in how we got here, this project stands on the shoulders of giants:

1. AOSP Pdfium / AndroidPdfViewer: Created by Bartosz Schiller on GitHub as a high-performance rendering engine on top of PdfiumAndroid.
2. The DonManfred Wrap: He brought Bartosz's NDK binaries to B4A under a compiled library PDFium - Pdfview2.
3. The PDFab Example: Inspired by walt61's PDFab, which showed the first low-level configuration approach using a compiled configurator:

' The original low-level PDFab configuration approach
Dim cfg As Configurator = PDFView1.fromFile(xui.DefaultFolder, "chapter_5.pdf")
cfg.SetEventname("PDFium")
cfg.autoSpacing(True)
cfg.enableSwipe(True)
cfg.pageSnap(True)
cfg.swipeHorizontal(False)
cfg.addOnErrorListener
cfg.addOnLoadCompleteListener
cfg.addOnPageChangeListener
cfg.load

With B4XDaisyPDFView, all of this configuration is handled behind the scenes, leaving your main page code exceptionally clean, readable, and highly maintainable!
We hope this helps onboard beginners to native PDF rendering in B4X. Let us know if you have any questions or feedback below!