Presentations and Slides

Create and configure presentations with Podium.new/1, create slides with Podium.Slide.new/1, and add them to the presentation with Podium.add_slide/2.

prs = Podium.new()
slide = Podium.Slide.new()
slide = Podium.add_text_box(slide, "Hello, World!",
  x: {1, :inches}, y: {1, :inches},
  width: {8, :inches}, height: {1, :inches})
prs = Podium.add_slide(prs, slide)
Podium.save(prs, "hello.pptx")

Creating a Presentation

Call Podium.new/1 to create a blank presentation. The default slide dimensions are 16:9 widescreen (13.33" x 7.5").

# Default 16:9 widescreen
prs = Podium.new()

# Standard 4:3
prs = Podium.new(slide_width: {10, :inches}, slide_height: {7.5, :inches})

# Custom dimensions
prs = Podium.new(slide_width: {14, :inches}, slide_height: {8, :inches})

Building on Your Own Template

Podium.from_template/2 starts from a template package of your own instead of the bundled one, so the deck comes out in your brand's masters, layouts, theme and fonts. Pass a path or the bytes of a .pptx or .potx.

prs =
  Podium.from_template("priv/brand/skeleton.pptx", title: "Q3 review")
  |> Podium.add_slide(slide)

Podium.save(prs, "q3.pptx")

What the template needs

A package saved by PowerPoint, Keynote or Google Slides already qualifies. In detail:

• ppt/presentation.xml, ppt/_rels/presentation.xml.rels and [Content_Types].xml must be present.
• The template must contain no slides. Masters, layouts, themes, media and a notes master are what a template is for. An existing slide would collide with the ones Podium writes, so Podium raises rather than deleting your content.
• The template must relate to at least one slide master, or its layouts have nothing for slides to sit on.
• To set core properties, the template's _rels/.rels must already relate to docProps/core.xml, which any PowerPoint-saved package does.

Everything else the template declares survives: masters, layouts, themes, notes master, embedded media, the default text style and the notes page size.

Slide size and scaling

The slide size comes from the template's own p:sldSz, so :slide_width and :slide_height are ignored. Nothing is scaled: the layout and master coordinates your designer set are carried through unscaled. This is different from Podium.new/1, which scales the bundled 4:3 template's coordinates horizontally to whatever slide width you ask for.

Layouts and placeholders

Refer to layouts by their 1-based index in the template's ppt/slideLayouts/ directory:

slide = Podium.Slide.new(2)

Podium.add_slide/2 raises if the template has no such layout.

Placeholder names such as :content and :left_content belong to the bundled template, and the name-based calls raise on a template of your own. Address your template's placeholders instead by the {type, idx} pair that Podium.Template.inspect/1 reports for them:

alias Podium.Chart.ChartData

template = Podium.Template.inspect("priv/brand/skeleton.pptx")
template.layouts[2].placeholders
# => [%{type: "title", idx: 0, name: "Title 1", box: %{...}}, ...]

chart_data =
  ChartData.new()
  |> ChartData.add_categories(["Q1", "Q2", "Q3"])
  |> ChartData.add_series("Volume", [1500, 4600, 5156])

prs = Podium.from_template("priv/brand/skeleton.pptx")

slide =
  Podium.Slide.new(2)
  |> Podium.set_placeholder({"title", 0}, "Volume grew 4.2%")

slide = Podium.set_chart_placeholder(prs, slide, {"obj", 14}, :column_clustered, chart_data)

Charts and tables placed this way take their position and size from the layout placeholder's box, so they need no explicit :x, :y, :width or :height. Podium.add_slide/2 also checks each placeholder on the slide against the layout and raises when the layout has no placeholder at that idx or has one of a different type. See Placeholders and Layouts for the full picture.

Slide Dimensions and Units

Podium uses English Metric Units (EMU) internally. You can pass dimensions as raw EMU integers or as {value, unit} tuples with one of three supported units.

All position and size options throughout Podium accept these unit formats -- :x, :y, :width, :height, :margin_left, column widths, and so on.

Common Slide Sizes

Creating Slides

Create slides with Podium.Slide.new/1. By default it uses the :blank layout.

slide = Podium.Slide.new()

Slide Layouts

Specify a layout by passing a layout atom or index:

slide = Podium.Slide.new(:title_slide)
slide = Podium.set_placeholder(slide, :title, "Annual Report 2025")
slide = Podium.set_placeholder(slide, :subtitle, "Finance & Operations Dashboard")
prs = Podium.add_slide(prs, slide)

Slide Backgrounds

Set a background color, gradient, pattern, or picture when creating a slide.

Slide backgrounds accept solid colors, gradients, patterns, and pictures. On dark backgrounds, use rich text with a light color for readability:

# Solid color
slide = Podium.Slide.new(:blank, background: "E8EDF2")

# Gradient
slide = Podium.Slide.new(:blank,
  background: {:gradient, [{0, "001133"}, {100_000, "004488"}], angle: 5_400_000})

# Pattern
slide = Podium.Slide.new(:blank,
  background: {:pattern, :lt_horz, foreground: "003366", background: "E8EDF2"})

# Picture
image_binary = File.read!("background.jpg")
slide = Podium.Slide.new(:blank, background: {:picture, image_binary})

When no background is set, the slide inherits the background from the slide master.

The Slide Builder Pattern

All content functions take a slide as first argument and return the updated slide. This makes it natural to build slides with the pipe operator.

After building a slide, call Podium.add_slide/2 to add it to the presentation.

prs = Podium.new()

# Build a slide with pipes
slide =
  Podium.Slide.new()
  |> Podium.add_text_box("Hello",
    x: {1, :inches}, y: {1, :inches}, width: {4, :inches}, height: {1, :inches})
  |> Podium.add_chart(:pie, chart_data,
    x: {1, :inches}, y: {2, :inches}, width: {6, :inches}, height: {4, :inches})

# Add the slide to the presentation
prs = Podium.add_slide(prs, slide)

Saving

Save to File

:ok = Podium.save(prs, "report.pptx")

Save to Memory

Use Podium.save_to_memory/1 to get the .pptx as an in-memory binary. This is useful for streaming downloads from a Phoenix controller or uploading to cloud storage.

{:ok, binary} = Podium.save_to_memory(prs)

Core Properties

Set document metadata with Podium.new/1 options or Podium.set_core_properties/2.

prs = Podium.new(
  title: "Q4 Report",
  author: "Analytics Team",
  subject: "Quarterly Review",
  created: ~U[2025-01-15 10:00:00Z],
  modified: DateTime.utc_now(),
  revision: 1
)

All core property options: :title, :author, :subject, :keywords, :category, :comments, :last_modified_by, :created, :modified, :last_printed, :revision, :content_status, :language, :version.

You can also set properties after creation:

prs = Podium.set_core_properties(prs, title: "Updated Title", revision: 2)

Footer, Date, and Slide Numbers

Podium.set_footer/2 adds footer text, a date string, and slide numbers to every slide in the presentation.

prs = Podium.set_footer(prs,
  footer: "Acme Corp Confidential",
  date: "February 2026",
  slide_number: true)

Speaker Notes

Add presenter notes to any slide with Podium.set_notes/2. Notes appear in Presenter View but not on the projected slides.

slide = Podium.set_notes(slide, "Talking points: Revenue grew 35% YoY. Key driver was APAC expansion.")

The next guide covers adding text and rich formatting to your slides. See Text and Formatting.