pptx-generation

name	pptx-generation
description	Generate native PowerPoint .pptx decks programmatically — slides, titles, bullet bodies, tables, charts, and images — with python-pptx (or pptxgenjs in Node). Use when the user wants an editable .pptx file rather than an HTML deck. For browser-based animated decks use frontend-slides instead.
origin	harness
workloads	["writing"]

PPTX Generation

Build editable PowerPoint files. This produces native .pptx (opens in PowerPoint/Keynote/Google Slides); for zero-dependency animated browser decks use frontend-slides.

Tool Selection

• python-pptx — Python-native, the default here. Create/read/update slides, placeholders, tables, charts, images.
• pptxgenjs (Node) — strong alternative when the surrounding toolchain is JS.
• Template editing — for a branded corporate template, unpack the .pptx (it is a zip of XML), edit the XML, repack. Do this when placeholder fidelity matters more than generation speed.

Hello World (python-pptx: title + table)

from pptx import Presentation
from pptx.util import Inches, Pt

prs = Presentation()
slide = prs.slides.add_slide(prs.slide_layouts[5])   # "Title Only"
slide.shapes.title.text = "Quarterly Results"

rows, cols = 3, 2
table = slide.shapes.add_table(rows, cols, Inches(1), Inches(1.6), Inches(6), Inches(2)).table
for r, (a, b) in enumerate([("Name", "Score"), ("Alice", "90"), ("Bob", "85")]):
    table.cell(r, 0).text = a
    table.cell(r, 1).text = b
prs.save("deck.pptx")

Add a bullet body by getting a content placeholder and appending paragraphs:

body = slide.placeholders[1].text_frame
body.word_wrap = True
p = body.add_paragraph(); p.text = "First point"; p.level = 0

Gotchas (encode these)

• No text autofit / reflow. python-pptx cannot measure rendered text, so long strings silently overflow their box. Set text_frame.word_wrap = True, size fonts conservatively, and keep bullet counts low.
• Mandatory visual QA. Assume the first render is wrong. Render each slide to an image (LibreOffice soffice --convert-to pdf → pdftoppm/pdf2image) and inspect for overflow, overlap, and low contrast — delegate the visual check to a subagent for decks beyond a couple of slides.
• Do not hardcode placeholder indices. Enumerate slide.placeholders and map by .placeholder_format.idx; layouts differ.
• No accent line under the title. A thin rule beneath every title is a hallmark of AI-generated slides — avoid it.
• Purge template leftovers. After editing a template, grep for lorem, ipsum, xxxx, and stale sample text.

Design Guidance

• Derive a palette from the content/brand; let one dominant color cover ~60–70% of each slide.
• Left-align body text; give every slide at least one visual element (image, chart, or shape).
• Repeat one motif across slides for cohesion. See brand-guidelines to apply a company's colors, fonts, and logo.