Preview area doesn't fill the whole file window

[INeedMySpace]

Hi,
I'm running IntelliJ IDEA 2025.3.4 and plugin version 1.4.1.
In my preview the actual diagram occupies only upper forth or third of file window. So if try to zoom or pan it - it looks like cut from the bottom and the big lower part of the window is just empty.

[Alex9583]

Hi @INeedMySpace

First of all, sorry for the delay!

Could you provide more context along with the diagram so I can try to reproduce the issue? Also, was this happening in the Markdown preview or the mermaid/mmd file preview?
Could you also try reproducing the issue on the official Mermaid editor to see if it persists? Here's the link: https://mermaid.ai/live/

I've been trying to reproduce it on my end with several large diagrams across different screen sizes, but so far the "Fit to Window" button (next to the + button) seems to work as expected. The zoom and pan features also appear to handle any remaining size differences well.

That said, I'll do my best to look into this as soon as I can. Any additional details would be a great help!

[INeedMySpace]

Hi, I tried again. Different computer with IDEA 2025.3.4 and plugin version 1.4.1 - yes it differs for .mmd and .md file with ```mermaid inclusion.

• mmd rendering works well - the diagram of classes is rendered on full window area. Zoom works well, pan (left mouse button pressed with mouse movement) introduces minor artifacts on the render area outside of the main image.
• md with mermaid inclusion is rendered incorrectly. Render area occupies the file window only partly (upper one third or so), if I make Ideas window smaller - render area stays the same.

Attaching generated fake hierarchy (mmd is just the content inside mermaid tag) and screenshot of md/mmd files preview (the same zoom level).

test.md

[Alex9583]

Hi,

Thank you so much for all the details, it helped me tremendously in finding the root cause of the issue, and in particular the Markdown preview part that I needed to look into.

The problem is that I don't have full control over the Markdown preview compared to the mermaid/mmd file preview. IntelliJ integrates its own rules, notably to add text, and I also have to account for that in my rendering. There will be a slight cutoff at the bottom of the preview, but normally 94% of the display area should be used (compared to the initial 60% or less).

That said, I've significantly improved the rendering and it should be much more pleasant to use. I'd still recommend using mermaid/mmd files when you want to work on a diagram on its own.

Let me know if this issue is resolved on your end with plugin version 1.5.2 that should be available in 48h max from now.
If that's the case, I'll let you close the issue, otherwise, feel free to reach out and I'll do my best to address it as soon as possible.

[INeedMySpace]

Hi, thank you very much - it's shows rendered diagram in full window now. Minor glitch that is still present in both md/mmd previews is that when you pan diagram, some parts of previously rendered image are "left behind". Please see attached screenshot. I don't think it's related to the original problem.

[Alex9583]

Hi,

No worries, glad the fix worked on your end.
As for the new issue you're reporting, it's indeed unrelated and I unfortunately can't reproduce it on my side.

I suspect a GPU rendering issue, which can happen on Windows/Linux (depending on the distro being used). I've attempted a quick fix that will request (and it really is a request, not a guarantee, since I don't have control over the built-in browser) to optimize rendering during panning.
Let me know if that's enough, otherwise I'll need a bit more info, such as which platform the issue occurs on and whether resizing the window fixes it or not (since that forces a reload).

The fix will be included in version 1.53, which could land anytime between now and 48 hours from now. I'll let you keep me posted.