goppt

A Go library for working with PowerPoint presentations. It handles reading, writing, and rendering .pptx files with no external dependencies.

Overview

goppt implements the OOXML specification used by PowerPoint 2007 and later. You can build presentations from scratch, parse existing files, and export slides to PNG images — all from pure Go code.

The slide renderer is designed to produce output that closely matches what PowerPoint itself generates. It handles the tricky parts: text layout, font metrics, CJK line-breaking rules, shape geometry, and chart drawing.

Getting Started

go get github.com/casibase/goppt

Requires Go 1.18 or later.

Building a Presentation

package main

import (
    "log"
    ppt "github.com/casibase/goppt"
)

func main() {
    p := ppt.New()
    p.GetDocumentProperties().Title = "Quarterly Review"
    p.GetDocumentProperties().Creator = "goppt"

    slide := p.GetActiveSlide()

    heading := slide.CreateRichTextShape()
    heading.SetOffsetX(500000).SetOffsetY(300000)
    heading.SetWidth(8000000).SetHeight(1000000)
    run := heading.CreateTextRun("Q3 Results")
    run.GetFont().SetSize(32).SetBold(true).SetColor(ppt.ColorBlue)

    body := slide.CreateRichTextShape()
    body.SetOffsetX(500000).SetOffsetY(1500000)
    body.SetWidth(8000000).SetHeight(600000)
    body.CreateTextRun("Revenue up 18% year over year")

    next := p.CreateSlide()
    chart := next.CreateChartShape()
    chart.BaseShape.SetOffsetX(500000).SetOffsetY(500000)
    chart.BaseShape.SetWidth(7000000).SetHeight(4500000)
    chart.GetTitle().SetText("Revenue by Quarter")

    bars := ppt.NewBarChart()
    bars.AddSeries(ppt.NewChartSeriesOrdered(
        "Revenue",
        []string{"Q1", "Q2", "Q3", "Q4"},
        []float64{120, 180, 150, 210},
    ))
    chart.GetPlotArea().SetType(bars)

    w, _ := ppt.NewWriter(p, ppt.WriterPowerPoint2007)
    if err := w.(*ppt.PPTXWriter).Save("review.pptx"); err != nil {
        log.Fatal(err)
    }
}

Reading an Existing File

reader := &ppt.PPTXReader{}
pres, err := reader.Read("existing.pptx")
if err != nil {
    log.Fatal(err)
}

for i, s := range pres.GetAllSlides() {
    fmt.Printf("slide %d — %d shapes\n", i+1, len(s.GetShapes()))
}

Writing to a Buffer

var buf bytes.Buffer
w, _ := ppt.NewWriter(p, ppt.WriterPowerPoint2007)
w.WriteTo(&buf)

Capabilities

Text and typography

• Rich text runs with font family, size, color, bold, italic, underline, and strikethrough
• Text boxes with auto-fit, auto-shrink, and overflow modes
• Bullet lists (character and numeric)

Shapes

• Auto shapes: rectangles, ellipses, triangles, arrows, stars, callouts, and more
• Line shapes with configurable style and color
• Group shapes and placeholder shapes

Images

• Embed PNG, JPEG, GIF, BMP, or SVG from a file path or raw bytes
• Rotation, flip, and group transform support

Charts

• Bar, Bar3D, Line, Area, Pie, Pie3D, Doughnut, Scatter, Radar

Tables

• Cell-level formatting, fills, and borders

Slide options

• Solid and gradient backgrounds
• Speaker notes
• Comments with author metadata
• Basic animation grouping
• Document and custom properties
• Slide sizes: 4:3, 16:9, 16:10, A4, Letter, or custom

Renderer

The built-in renderer exports slides to PNG. Key behaviors:

• Uses two hinting modes (HintingNone for layout metrics, HintingFull for glyph rendering) to match PowerPoint's DirectWrite measurements
• Implements kinsoku line-breaking rules for CJK text
• Renders shape fills, strokes, drop shadows, and custom geometry paths
• Draws all supported chart types with axes and series colors

Reference

See API.md for the complete API reference.

License

MIT