Saved Image is Blank When Scaling Factor > 5

[dhollis6]

How to replicate:

1. Visit https://sulcgroup.github.io/oxdna-viewer/ on the latest version of Chrome.
2. Go to the Edit tab and create a 10 bp duplex. Zoom in so the duplex fills the screen.
3. Go to File and under Image Size, increase Scaling Factor to 5. Click camera icon to download image.
4. Set Scaling Factor to 6 and download image again.
5. The first image will show the structure, while the second image will appear fully transparent.

Issue persists in orthographic mode. I'm running Windows 11 on a laptop with a 4k screen, if that matters. Also observed this issue in Edge and DuckDuckGo but did not thoroughly investigate. Odd because I remember downloading super hi-res images not too long ago. Also, I remember having an issue before where the image would appear cropped i.e. taken in a wrong area of the scene. This might be a clue.

[ErikPoppleton]

Reproduction attempts:

MacOS

• Safari - No, able to save 10x scaling with no problem (18 MB file tho)
• Firefox - Throws error saying "Canvas is too large to save"
• Chrome - Reproduced.

Looks like Chrome has the same canvas size limit as Firefox but we're not catching the error correctly (there's nothing in the console either). Will investigate further.

This is the responsible bit of code (from UI.ts):

        new Promise((resolve) => {
            this.scaleCanvas(scaleFactor);
            resolve('success');
        }).then(() => {
            try {
                saveImage();
            } catch (error) {
                notify("Canvas is too large to save, please try a smaller scaling factor", "alert");
            }
            this.scaleCanvas(1/scaleFactor);
        });

So Chrome(ium) isn't throwing an error at all. Will probably have to hardcode whatever the limit is.

[dhollis6]

Thank you for investigating, Erik! Apologies for the delayed reply.

Edit: It's not clear to me if you wanted to leave this issue open and eventually hardcode the limit, or close this issue and have users hardcode it on an individual basis. I'll leave it to you.

Daniel