pptxgo

README

pptxgo

Microsoft PowerPoint .pptx (OOXML / PresentationML) generation in Go.

Status

Early development. The OPC packaging layer and drawingml primitives are in place; pptx.New() builds a presentation's theme, slide master, and slide layout. AddSlide adds slides; AddTextBox/AddParagraph add formatted text; AddImage and its variants embed PNG/JPEG/GIF images (p:pic, with automatic format and size detection); AddChart builds native Bar, Line, Pie, and Doughnut charts; tables, gradients, dashed lines, and multi-level bullets are all supported — all verified against both the Open XML SDK's schema validator and LibreOffice Impress (see Verification below). pptx.Open/OpenFromBytes/OpenFromReader open an existing .pptx for template-style editing — enumerate slides, inspect or Merge/Replace their text — with every untouched part preserved byte-for-byte (see examples/02_read_and_modify).

p := pptx.New()
s := p.AddSlide()

tb := s.AddTextBox(pptx.Inches(1), pptx.Inches(1), pptx.Inches(8), pptx.Inches(2)).
    Fill(pptx.RGB(0xE7, 0xE6, 0xE6)).
    Border(pptx.RGB(0x1F, 0x49, 0x7D), 1.5)
tb.AddParagraph().
    Text("Quarterly Results").Bold().FontSize(32).Font("Calibri").Color(pptx.RGB(0x1F, 0x49, 0x7D)).
    Alignment(pptx.AlignCenter)

// Format and pixel dimensions are auto-detected (96 DPI); use
// AddImageWithSize/AddImageFromBytesWithSize for exact control.
s.AddImage("logo.png", pptx.Inches(1), pptx.Inches(3.5)).
    Border(pptx.RGB(0x44, 0x54, 0x6A), 1.0)

f, _ := os.Create("presentation.pptx")
if err := p.Save(f); err != nil {
    // Save returns the first error accumulated by any builder call, e.g. an
    // out-of-range FontSize or a missing image file — long fluent chains
    // stay usable without an `if err != nil` after every method.
    log.Fatal(err)
}

Design

The core insight driving this project's architecture: PPTX content is DrawingML. Every slide is a p:spTree of shapes, and all text lives in a:txBody / a:p / a:r / a:t. That put a hard constraint on the packaging layer from day one — it had to be part-centric: a package is a map of parts (path → content-type → bytes-or-struct), never a hardcoded sequence of named files. That's what makes "open an existing .pptx template and only replace the parts you touch" the same code path as "generate everything from scratch" — not a bolted-on round-trip mode added later.

Two packages are written to be extraction-ready from the start:

• opc/ — the Open Packaging Conventions layer (parts, relationships, content-types, ZIP serialization). Format-agnostic; knows nothing about slides or paragraphs.
• drawingml/ — the DrawingML primitives shared by DOCX/PPTX/XLSX (a:xfrm, a:off, a:ext, a:blip, a:prstGeom, colors, transforms). It only ever emits the a: namespace — the picture container that wraps a blip fill differs by host format (pic:pic in a Word-embedded graphic, p:pic on a PPTX slide), so that wrapper is deliberately left to the package that needs it, built out of these shared primitives.

If a future sibling project needs the same OPC engine, both are designed to be lifted into a standalone module without a rewrite.

Verification

A file that unzips fine can still be schema-invalid, and Go-level tests alone can't tell you that — they only check what you thought to assert. make check runs three layers:

1. go test ./... — structural regression tests (every relationship target resolves to a part that exists, [Content_Types].xml covers every part, no duplicate relationship IDs within an owner).
2. PptxValidator/ — an OpenXmlValidator (DocumentFormat.OpenXml, the same library Microsoft ships) run against a generated demo file. Wired into CI from the first commit — unlike docxgo, where the equivalent validator existed for nine months before CI ever invoked it.
3. Opening the file in a real consumer. make validate also works as a smoke test if you pipe its output pptx through soffice --headless --convert-to pdf; a manual open in PowerPoint itself remains the authoritative check no automated tool replaces.

make check     # test + build + generate + OpenXML SDK validation

License

MIT