pdfviewer — `u_pbt_pdfviewer` #

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Built-in PDF viewer: displays a local document or one published on the web, straight inside your window, with pagination, zoom and printing.

▶ See it live — Demo application, PDF viewer tile: the preview, the code behind it and this page, side by side.

At a glance #

Userobject	`u_pbt_pdfviewer`
Item class	— (component without items)
Used for	Displaying an invoice, a purchase order, a contract or a manual without launching an external application
Opt-in options	—

The component replaces the classic "save the PDF to a temporary file, then call ShellExecute": the document stays inside your application, and the user never leaves the current screen.

Quick start #

// window open event : display a document stored on disk
uo_pdf.is_source = "C:\factures\FA-2026-0142.pdf"

// ue_load_completed event of uo_pdf : (string as_source)
uo_statut.of_item("main").is_text = "Document displayed"

That is all: setting is_source is enough to load and display the document.

Properties #

Property	Type	Default	Purpose
`is_source`	string	`""`	Document to display: a file path on disk (absolute or relative to the application) or a web address (`https://…`). Setting the value triggers the load; setting `""` clears the viewer
`ii_page`	integer	`0`	Page displayed, counted from 1 (`0` = the document's first page). Loading another document resets it: keeping the previous page would land the reader in the middle of a file they have just opened. Write only: reading it back gives the last page you asked for, not the one on screen. The reader is the one built into the web engine, and it reports nothing.
`ii_zoom`	integer	`0`	Zoom in percent (`0` = left to the viewer). Setting a zoom cancels `is_fit`, which contradicts it. Write only, like `ii_page`: if the user zooms with the reader's own toolbar, this property does not follow.
`is_fit`	string	`""`	Fit mode: `FIT_PAGE`, `FIT_WIDTH`, `FIT_HEIGHT`, or `""` for none. Cancels `ii_zoom`
`ib_viewer_toolbar`	boolean	`true`	Shows the viewer's own toolbar (page number, zoom, print, download). Hide it when your window carries those commands itself
`is_theme_style`	string	`fluent`	Visual style of the component (`THEME_STYLE_*` constants)
`is_theme_mode`	string	`light`	Light or dark variant (`THEME_MODE_*` constants)
`il_theme_accent`	long	`-1`	Accent color of this component (`-1` = the theme accent)

Methods #

Method	Purpose
`of_refresh ( )`	Reloads the current document — for example after the file has been regenerated on disk
`of_reset ( )`	Clears the viewer and resets every property to its default
`of_set_redraw (boolean)`	Groups a burst of changes into a single render
`of_save_as_png (string)` · `of_save_as_jpg (string)`	Exports the rendering as an image

Events #

Event	Raised when
`ue_load_completed (string as_source)`	The document has finished loading; `as_source` reminds you what was displayed
`ue_ready ( )`	The component has finished loading; everything sent beforehand has been replayed
`ue_runtime_missing ( )`	The WebView2 runtime is missing: the component stays empty
`ue_bg_color (long al_color)`	The component has computed its theme background color; the userobject has already adopted it (`backcolor`)

What the user can do, without a single line of code #

The viewer displays its built-in toolbar above the document. There is nothing for you to program: it is provided and localized by the system.

Action	How
Pagination	Mouse wheel and scroll bar, or type the page number directly in the `n / total` counter
Zoom	`+` / `−` buttons, `Ctrl` + wheel, fit to page or fit to width
Search	`Ctrl+F` within the text of the document
Printing	Printer button on the toolbar, or `Ctrl+P`
Saving	Download button, to save a copy of the document
Rotation	Page rotation from the toolbar menu

Examples #

Opening a local document #

// Absolute path, or relative to the application directory
uo_pdf.is_source = "doc\conditions-generales.pdf"

Opening a document published on the web #

// A web address loads exactly like a local file
uo_pdf.is_source = "https://www.monsite.fr/tarifs/catalogue-2026.pdf"

An internet connection is of course required; the load is asynchronous, and ue_load_completed tells you when it is done.

Displaying the PDF a DataWindow has just produced #

string ls_fichier

ls_fichier = "C:\temp\etat_" + String(Today(), "yyyymmdd") + ".pdf"

// The DataWindow produces the file...
dw_etat.SaveAs(ls_fichier, PDF!, false)

// ...and the viewer displays it immediately
uo_pdf.is_source = ls_fichier

Refreshing after the file has been regenerated #

// The file was rewritten in the same location : reload without touching is_source
uo_pdf.of_refresh()

Chaining several documents in the same viewer #

// ue_row_changed event of dw_liste : display the attachment of the current row
string ls_pdf

ls_pdf = dw_liste.GetItemString(dw_liste.GetRow(), "chemin_pdf")

if ls_pdf = "" then
    uo_pdf.of_reset()          // no attachment : empty viewer
else
    uo_pdf.is_source = ls_pdf
end if

Tracking the end of the load #

// ue_load_completed event of uo_pdf : (string as_source)
uo_attente.Hide()
uo_imprimer.ib_enabled = true

Preview in a tab, next to data entry #

// open event : the viewer takes one tab page, data entry the other
uo_tab.of_add_page("saisie",  "Entry",   uo_page_saisie)
uo_tab.of_add_page("apercu",  "Preview",   uo_page_apercu)

// The viewer sits inside uo_page_apercu like any other control
uo_pdf.is_source = is_document_courant

The component is hosted with no special precautions inside a tab or a dockcontainer panel.

Checking the file before displaying it #

string ls_chemin

ls_chemin = "C:\factures\" + is_numero + ".pdf"

if not FileExists(ls_chemin) then
    // Nothing to show : clear the viewer rather than leave the previous document
    uo_pdf.of_reset()
    uo_statut.of_item("main").is_text = "Invoice not found"
    return
end if

uo_pdf.is_source = ls_chemin

Accepted formats and paths #

Form of `is_source`	Example	Note
Absolute path	`"C:\docs\contrat.pdf"`	The most reliable
Relative path	`"doc\notice.pdf"`	Relative to the application directory
Network path	`"\\serveur\partage\bon.pdf"`	The user must have read permissions
Web address	`"https://…/catalogue.pdf"`	Asynchronous load, connection required
Empty	`""`	Clears the viewer

This component only supports PDF: for an image, use picture; for an HTML page, webbrowser.

Best practices #

Check that the file exists before assigning is_source: an invalid path simply leaves the viewer empty, with no blocking error.
Call of_reset() when no document should be displayed any more (moving to a row without an attachment): otherwise the previous document stays visible.
Prefer of_refresh() over reassigning is_source to reload the same document: it is faster and the reading position is restored cleanly.
Provide a waiting indicator for remote or large documents, and hide it on ue_load_completed.
Give the component a comfortable area (at least half the window): the built-in toolbar and the document both need room to stay readable.
To display a web page rather than a PDF, use webbrowser; for an image, picture.