Unable to read image placed by Spectacle

[chengyuhui]

Environment: Linux with X11, the application is being run as root because it also uses evdev.

For images copied from Chrome, everything works fine, but when I try to read a screenshot produced by Spectacle, this happens:

2023-05-08T12:26:31.282Z TRACE [arboard::platform::linux::x11] Started serve requests thread.
2023-05-08T12:26:31.282Z TRACE [arboard::platform::linux::x11] Trying to get the clipboard data.
2023-05-08T12:26:31.283Z TRACE [arboard::platform::linux::x11] Finished `convert_selection`
2023-05-08T12:26:31.283Z TRACE [arboard::platform::linux::x11] Read SelectionNotify
2023-05-08T12:26:31.283Z TRACE [arboard::platform::linux::x11] Clipboard server window is being destroyed x_x
get_clipboard_content() = Err(
    Unknown { .. } - "Unknown error while interacting with the clipboard: incorrect type received from clipboard",
)

Output of xclip -selection clipboard -t TARGETS -o

Chrome

TIMESTAMP
TARGETS
SAVE_TARGETS
MULTIPLE
image/png
text/html

Spectacle

application/x-qt-image
x-kde-force-image-copy
image/png
image/avif
image/bmp
image/bw
image/cur
image/eps
image/epsf
image/epsi
image/heic
image/heif
image/icns
image/ico
image/jp2
image/jpeg
image/jpg
image/jxl
image/pbm
BITMAP
image/pcx
image/pgm
image/pic
image/ppm
PIXMAP
image/rgb
image/rgba
image/sgi
image/tga
image/tif
image/tiff
image/wbmp
image/webp
image/xbm
image/xpm
TARGETS
MULTIPLE
TIMESTAMP
SAVE_TARGETS

As shown here, both cases do provide image/png, I wonder why this is not working, as the code in this library says that this should never happen.

BTW, since we already uses the image crate, why not provide a function that reads a PNG from the clipboard (this can be behind a feature flag, since we don't need to decode images on Windows)? We might be able to skip some decompression and compression for folks who actually need a PNG or other compressed format to work on.