I don't know the exact difference between what Firefox puts on the clipboard when copying an image versus other browsers. When I was searching, someone mentioned something but I don't recall now.

I also don't know why Electron double-pastes when most other applications seem perfectly fine with what Firefox puts on the clipboard.

One thing comes to mind about PNGs that differs from other image types: when a PNG copied in Firefox contains transparency, in the bitmap data, the transparent pixels are black. Maybe this is somehow related to the problem affecting some or all PNGs?

I know with the PNG on my website it does not have a transparent channel. I checked Irfranview and it's settings for PNG did not have it set by default. I did try it with a .GIF that did have a transparent channel and it pasted fine.

Interesting that regardless of the file type, Discord always says unknown.png.

It seems like the problem lies in how Firefox handles clipboard information or pasting information. Discord allows for multi-picture uploading: you can select multiple files from your drive to upload to a channel. Some interaction between this functionality and Firefox is unique, and possibly relating to the way Firefox handles transparency and .pngs as Mark said.

It could be that it isn't pasting the image the same way as every other browser out there, and is sending in raw data that Electron has to unpack: One layer for transparency, and one layer for the rest of the image, or something. Does anyone here have knowledge of how Firefox does these things?

When I copy an image to the clipboard in Firefox then I see these image flavors:

• image/png, image/jpeg, image/jpg

"image/jpg" does nothing for me, but "image/png" and "image/jpeg" both give a different image.