Convert to PDF

convert.ConvertToPdf turns an open presentation into a UniPDF Creator, one page per slide, drawn at the presentation’s own slide size. From there it is an ordinary creator: write it to a file, write it to a stream, or keep adding to it before you do.

ppt, err := presentation.Open("table.pptx")
if err != nil {
    log.Fatalf("error opening document: %s", err)
}
defer ppt.Close()

c := convert.ConvertToPdf(ppt)
if err := c.WriteToFile("table.pdf"); err != nil {
    log.Fatalf("error saving PDF: %s", err)
}

ConvertToPdf returns no error. Anything it cannot draw is logged at debug level and skipped, so an empty or partial page is reported through the logger rather than through a return value. Turn UniOffice’s logging up while you are debugging a conversion that comes out wrong.

Page size

The PDF page size is the slide size, read straight from the presentation and converted from EMU. A 16:9 deck produces 13.33 by 7.5 inch landscape pages; a 4:3 deck produces 10 by 7.5. Nothing is scaled to fit a paper size, which is what you want for slides and is worth knowing if the output is destined for a printer. See Slide Size.

ConvertToPdfWithOptions takes an *Options whose only field is DefaultPageSize, and that applies solely when the presentation carries no slide size at all. On any file written by PowerPoint or by UniOffice the size is present, so the option has no effect and ConvertToPdf is the call to use.

Fonts

Fonts referenced by the deck are matched by name and style against the fonts registered with the converter. When a name is not found, the converter logs it and falls back to a default, which is the usual cause of a PDF whose text is the right words in the wrong typeface.

if err := convert.RegisterFontsFromDirectory("./fonts"); err != nil {
    log.Fatal(err)
}

RegisterFontsFromDirectory detects families and styles from the files it finds. RegisterFont(name, style, font) registers one font under one of FontStyle_Regular, FontStyle_Bold, FontStyle_Italic or FontStyle_BoldItalic. Register before converting; the lookup happens during the conversion.

Licensing

This is the one presentation feature that needs two license keys. UniOffice reads the file and UniPDF renders it, and each checks its own metered license, so init calls license.SetMeteredKey from github.com/unidoc/unioffice/v2/common/license and again from github.com/unidoc/unipdf/v5/common/license. Missing either one fails at the package that needs it, which can look like a UniOffice problem when it is a UniPDF one. That confusion is the most common licensing problem reported against UniOffice; see Why does my license key fail when converting to PDF?

Limitations

Speaker notes are not rendered. The converter walks the slides only, so a notes page never becomes a PDF page.

Animations, transitions and any timing on the slide are ignored. Every slide is drawn in its final state.

The conversion is documented in the source as beta, and breaking changes to the convert package are explicitly allowed. Pin your UniOffice version if the output has to stay identical between builds.

Individual drawing failures are silent by default. A table, image or text box that cannot be rendered is logged with logger.Log.Debug and left out of the page, so a PDF that is missing an element will not have told you so unless debug logging is on.

Run the example

The example converts five decks from the same directory - chart.pptx, lists.pptx, picture.pptx, several_slides.pptx and table.pptx - and writes each one into the output folder, which already exists in the examples repository.

git clone https://github.com/unidoc/unioffice-examples.git
cd unioffice-examples/presentation/convert_to_pdf
go run main.go

If this is your first time using UniOffice, follow the getting started guide to create an API key and set up your development environment.

Sample output

chart.pptx converted:

lists.pptx converted, numbered and bulleted lists over a picture background: