Powerpoint Skill

Create, inspect, and edit PowerPoint (.pptx) presentations using the python-pptx library. Five helper scripts cover deck creation from a JSON spec, structured read-back, in-place edits, template-driven brand decks, and slide rendering — all offline, no PowerPoint installation required.

When to Use

• The user asks to build a slide deck, report presentation, or pitch deck.
• You need to extract text, notes, tables, chart data, or images from a .pptx someone shared.
• You need to update an existing deck: replace text, refresh or patch chart data, swap a logo, duplicate/remove/reorder slides, set backgrounds, footers, hyperlinks, or speaker notes.
• You must produce an on-brand deck from a company .pptx template.
• Do NOT use this for .ppt (legacy binary) files — convert them first with soffice --convert-to pptx old.ppt if LibreOffice is available.

Prerequisites

• Python 3.10+ with python-pptx installed (pip install python-pptx).
• Optional: LibreOffice (soffice) plus poppler (pdftoppm or pdftocairo) for rendering slides to PNGs and for PDF export. pptx_render.py detects both with shutil.which and degrades gracefully (reports {"rendered": false, "missing": [...]}, exit 0) when absent — all create/read/edit operations work without them.
• Check availability via terminal: python -c "import pptx; print(pptx.__version__)" and which soffice pdftoppm.

How to Run

All scripts live in scripts/, take --help, print JSON to stdout, and exit non-zero on failure. Run them with terminal:

python scripts/pptx_create.py deck.json out.pptx
python scripts/pptx_read.py deck.pptx --outline      # full JSON outline
python scripts/pptx_read.py deck.pptx --notes        # speaker notes
python scripts/pptx_read.py deck.pptx --images ./img # export pictures
python scripts/pptx_edit.py deck.pptx --replace-text "Old Corp" "New Corp"
python scripts/pptx_edit.py deck.pptx --chart-data update.json
python scripts/pptx_edit.py deck.pptx --duplicate-slide 2
python scripts/pptx_edit.py deck.pptx --remove-slide 3 --move-slide 2 0
python scripts/pptx_from_template.py brand.pptx out.pptx --values vals.json
python scripts/pptx_render.py deck.pptx --outdir ./render  # slide PNGs

Author JSON specs with write_file; inspect script output and generated JSON with read_file.

Quick Reference

Procedure

1. Create a deck

Write a JSON spec (see pptx_create.py --help for the full format), then run pptx_create.py. Per slide you can set: layout (title, title_content, section, two_content, title_only, blank), title, subtitle, bullets (strings, or dicts with level 0-4, size pt, bold, italic, font, color hex, link URL for a hyperlink), background (solid hex), footer (text; enables the layout's footer placeholder), slide_number (true; enables the layout's slide-number placeholder), images (path + left/top/width/height in inches), tables (rows as list-of-lists), shapes (rectangle, rounded_rectangle, oval, diamond, right_arrow, chevron, with fill hex + optional text), charts (bar, bar_h, line, pie with categories + series), and notes (speaker notes).

2. Read a deck

pptx_read.py deck.pptx --outline returns slide size, layout inventory, and per slide: layout name, all shape texts, table cells, image inventory (filename/ext/bytes), chart categories/series/values, and speaker notes. Use --images DIR to dump embedded pictures to files, then vision_analyze on any exported image if you need to see its content.

3. Edit a deck

pptx_edit.py combines operations in one pass; use --output to keep the original. Text replacement scans slide shapes, table cells, and notes. Image swap retargets the picture's relationship id so position and size are preserved. Slide removal drops the relationship and the <p:sldId> entry; reorder moves the <p:sldId> element within <p:sldIdLst> (python-pptx has no public API for either — the script does the XML-level work). --duplicate-slide N appends an independent deep copy of slide N: shape XML plus image/media/hyperlink relationships are cloned and rIds remapped, so editing the copy never touches the original. Chart slides are refused (see Pitfalls). --set-notes/--append-notes edit speaker notes; --set-background, --hyperlink, --enable-slide-number, and --set-footer handle deck polish.

Chart updates take a JSON spec via --chart-data. Full replace: {"slide": 0, "chart": 0, "categories": [...], "series": {...}}. For surgical edits, pass "ops" instead — a list of {"op": "update_series", "name": ..., "values": [...]}, add_series, remove_series, rename_category (from/to or index), and set_title. python-pptx can only swap a chart's entire dataset (replace_data), so ops are implemented as read-existing → modify → replace; the per-part UX is a wrapper, and any chart data not expressible as categories + numeric series will be normalized by the round-trip.

4. Build from a template

pptx_from_template.py opens a brand .pptx, replaces every {{token}} from a values JSON across slides/tables/notes, and can append new slides that use the template's own layouts (by layout name or index) so they inherit the master's fonts and colors. Tip: to start from a template with zero slides, delete existing ones afterward with pptx_edit.py --remove-slide.

5. Visual verification

pptx_render.py deck.pptx --outdir ./render converts the deck to PDF with soffice --headless and splits it into one PNG per slide with pdftoppm (or pdftocairo). Output JSON lists the PNG paths — review each with vision_analyze. When either tool is missing the script exits 0 with {"rendered": false, "missing": [...]} and guidance; fall back to the JSON outline from pptx_read.py, which verifies content and structure, just not visuals.

Converting to PDF

If LibreOffice is installed, export the finished deck to PDF directly:

soffice --headless --convert-to pdf --outdir ./out deck.pptx

The output lands at ./out/deck.pdf. Fonts not installed on the host are substituted, so render-verify (Procedure step 5) before shipping the PDF. There is no offline pure-Python .pptx→PDF path; if soffice is absent, say so rather than approximating.

Pitfalls

• Run splitting: PowerPoint fragments paragraph text into runs at spell-check and edit boundaries. --replace-text first merges adjacent runs whose formatting is identical, so matches split across such runs are replaced with formatting fully preserved. Only when a match spans genuinely differently-formatted runs is the paragraph rewritten with the first run's formatting — verify those slides after replacement.
• Chart slides cannot be duplicated: each chart relationship embeds a separate XLSX workbook part; cloning that graph reliably is not supported, so --duplicate-slide refuses chart slides cleanly instead of corrupting the deck. Rebuild the chart on a new slide instead. External-hyperlink and image/media rels are carried over; layout and notes rels are recreated fresh.
• Chart ops are a wrapper: python-pptx replaces the whole dataset; "ops" round-trips existing plot data through replace_data, and changing chart type is not possible.
• Reordering is XML-level: python-pptx has no supported reorder API. --move-slide manipulates <p:sldIdLst> directly; safe for ordinary decks but re-read the deck afterward to confirm.
• Copying slides between decks is unsupported — duplication works only within one deck, where layouts and masters are shared.
• Footer/slide-number enablement copies the placeholder from the slide's layout; on layouts without those placeholders, --set-footer fails with a clear message (add a textbox instead).
• Hyperlinks apply to whole runs; --hyperlink links every run containing the given text on that slide.
• The default python-pptx template is 4:3; the create script sets 16:9 unless the spec says otherwise. Custom templates keep their own size.
• Layout indexes vary by template. For brand templates, list layout names first: pptx_read.py template.pptx --outline (layouts_available).
• slide.shapes.title is None on blank layouts — the create script handles this, but remember it when writing ad-hoc python-pptx code.
• Always pass encoding="utf-8" when writing spec files; tokens like {{city}} may be filled with non-ASCII values.

Verification

1. After any create/edit, run pptx_read.py OUT.pptx --outline and check slide count, texts, tables, notes, and chart values match intent.
2. --images DIR then file-size check confirms pictures embedded.
3. Render every slide with pptx_render.py deck.pptx --outdir ./render and review each PNG with vision_analyze — this catches overlapping shapes, truncated text, and color problems the outline cannot. If the render tools are missing, the script says so; rely on the outline.
4. The bundled test suite is the full contract: python -m pytest tests/ -q (requires python-pptx + pytest).