Use a Template

Working from a template is the normal way to produce a presentation that has to look designed. Someone builds a .pptx with the masters, layouts, theme colors and fonts already right; your program opens it, adds slides from the layouts it wants and writes text into the placeholders. Nothing about the appearance is your problem.

Two calls add a slide from a layout, and the difference matters:

AddDefaultSlideWithLayout is what PowerPoint does when you insert a slide, and it is the one to use unless you want the layout’s prompt text to survive.

Filling a layout

ppt, err := presentation.OpenTemplate("template.pptx")
if err != nil {
    log.Fatalf("unable to open template: %s", err)
}
defer ppt.Close()

l, err := ppt.GetLayoutByName("Title and Caption")
if err != nil {
    log.Fatalf("error retrieving layout: %s", err)
}
sld, err := ppt.AddDefaultSlideWithLayout(l)
if err != nil {
    log.Fatalf("error adding slide: %s", err)
}

ph, _ := sld.GetPlaceholder(pml.ST_PlaceholderTypeTitle)
ph.SetText("Using unioffice")

GetLayoutByName matches the layout’s name exactly, which is the name shown in PowerPoint’s layout gallery. It returns an error rather than a fallback when nothing matches, so a typo surfaces immediately. To find out what a template offers, iterate ppt.SlideLayouts() and print each layout’s Name() and Type(); the example does this first and its terminal output is below.

OpenTemplate is the same as Open. Use whichever reads better; there is no behavioral difference, and either works on .pptx and .potx alike.

Reaching placeholders

GetPlaceholder takes a pml.ST_PlaceholderType and returns the first placeholder of that type. The common ones are Title, CtrTitle, SubTitle, Body, Pic and Tbl. When a layout has two placeholders of the same type, as a two-content layout does, type is not enough and you want GetPlaceholderByIndex, which matches the layout’s own index attribute, or PlaceHolders() to walk them all.

SetText is the shortcut for a single-paragraph placeholder such as a title: it clears the placeholder and writes one run. For anything multi-line, clear it and build paragraphs:

ph, _ = sld.GetPlaceholderByIndex(1)
ph.ClearAll()

para := ph.AddParagraph()
para.AddRun().SetText("Adding paragraphs can create bullets depending on the placeholder")
para.AddBreak()
para.AddRun().SetText("Line breaks work as expected within a paragraph")

for i := 1; i < 5; i++ {
    para = ph.AddParagraph()
    para.Properties().SetLevel(int32(i))
    para.AddRun().SetText("Level controls indentation")
}

Whether those paragraphs come out as bullets is decided by the layout, not by your code. A body placeholder in a designed template usually carries a bullet style per level, so SetLevel picks up both the indent and the bullet character. AddBreak inserts a line break inside a paragraph, which keeps the lines under one bullet.

Run properties still work on top of the layout’s styling: SetSize, SetFont and SetSolidFill on a run override the theme for that run only.

Removing the template’s own slides

A template usually ships with example slides. Remove them before adding yours:

for _, s := range ppt.Slides() {
    if err := ppt.RemoveSlide(s); err != nil {
        log.Fatalf("error removing slide: %s", err)
    }
}

RemoveSlide drops the slide part, its relationship and its notes, which is why a removed slide does not come back as an empty page when the file is reopened.

Limitations

ClearAll leaves the placeholder with no paragraphs at all, which PowerPoint rejects. Add at least one paragraph afterwards, or use Clear, which leaves a single empty one.

Adding a slide from a layout copies only the layout’s placeholder shapes. Every picture and every non-placeholder shape in the layout is dropped from the copy, to avoid drawing it twice - the layout itself still renders behind the slide, so the design looks right, but you cannot reach those shapes through the slide.

AddDefaultSlideWithLayout removes footer, date and slide-number placeholders outright, so a design that expects you to fill a footer per slide needs AddSlideWithLayout and manual clearing instead.

Layout names are template-specific. “Title and Content” is a PowerPoint convention, not a guarantee, so a program that hardcodes names should handle the error from GetLayoutByName rather than ignore it.

Run the example

The example prints every layout in template.pptx, removes the template’s slides, then builds two: a “Title and Caption” slide filled through SetText and a “Title and Content” slide filled paragraph by paragraph. It writes mod.pptx.

git clone https://github.com/unidoc/unioffice-examples.git
cd unioffice-examples/presentation/use-template
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 input

Sample output

0  LL  Title Slide / title
1  LL  Title and Content / obj
2  LL  Section Header / secHead
3  LL  Two Content / twoObj
4  LL  Comparison / twoTxTwoObj
5  LL  Title Only / titleOnly
6  LL  Blank / blank
7  LL  Content with Caption / objTx
8  LL  Picture with Caption / picTx
9  LL  Panoramic Picture with Caption / 
10  LL  Title and Caption / 
11  LL  Quote with Caption / 
12  LL  Name Card / 
13  LL  Quote Name Card / 
14  LL  True or False / 
15  LL  Title and Vertical Text / vertTx
16  LL  Vertical Title and Text / vertTitleAndTx