Mermaid diagrams mangled in docx/odt

[reagle]

❯ cat test-diagram.md
---
title: "Test: Diagram with mermaid"
date: 2024-08
diagram:
  cache: true
---

# Introduction

This is a test using
[diagram extension](https://github.com/pandoc-ext/diagram)
The
[results](test-mermaid.html)
of [mermaid-filter](https://github.com/raghur/mermaid-filter).
will be different.

``` mermaid
%%| filename: flowchart
%%| fig-cap: A simple flowchart.
graph TD;
    A-->B;
    A-->C;
    B-->D;
    C-->D;

❯ pandoc -s --lua-filter diagram.lua test-diagram.md -o test-diagram.docx -w docx

<img width="883" alt="SCR-20240813-lihz" src="https://github.com/user-attachments/assets/58526a2d-6ac5-42a0-88ce-8e8b0ca6a230">

[tarleb]

That's a bug: the filter produces a SVG image by default, but it seems that ODT does not support SVG images, and pandoc converts the image with an external program. It would be better if the filter would default to PNG images when targetting ODT.

As a temporary workaround, you can configure the mermaid engine to always produce PNG output:

diagram:
  cache: true
  engine:
    mermaid:
      mime-types: [image/png]

[reagle]

Thanks @tarleb, that does work. (I'll note that mermaid-filter also fails at SVG in docx/odt.)

[tarleb]

It seems that the patch didn't fully fix this, thus reopening.

[tarleb]

Now it's fixed.