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highfestiva / finplot

Performant and effortless finance plotting for Python
MIT License
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[BUG] Can't save the line chart to an image file in KDE Wayland #530

Open simprince opened 3 months ago

simprince commented 3 months ago

I have been using finplot to generate a line chart and save to an image file without any problems. Recently I notice that when I use KDE Wayland on Linux, it saves an 0 byte file. When I switch back to X11, it works fine. Any ideas why it doesn't work on Wayland?

highfestiva commented 3 months ago

Sorry about that, and no I do not. If you solve it, please write your solution in here or send me a pull request, as it might help others with the same problem.

simprince commented 1 month ago

I find out the reason but I can't fix it. I appreciate your help. @highfestiva

Root cause: In the screenshot() function, grabWindow() doesn't take the screenshot in wayland because wayland disallows pyqt to capture screen content due to the security reason.

Solution (partial): I google how to capture screenshot on wayland. It turns out that Pillow (PIL) has the ImageGrab to do it. I test below and it works on wayland:

from PIL import ImageGrab .... im = ImageGrab.grab(bbox=win_box)
im.save(file.name)

Need help: I've never done any Qt programming and not familiar with pyqt at all. I can't find a way to get the bbox of the window that displays the chart. I tried 1) using the winx, winy, winh, winw; 2) using geometry(); ... Nothing seems to work. The screen captured is quite off from the chart window. If you could point me to how I can get the absolute coordinate of the (x, y) of the top-left pixel of the chart (excluding the title bar of the app) and the bottom-right (x, y). Both are based on the absolute position on screen, I am pretty that it should work. Once it's confirmed to work, I can share the complete solution here.

highfestiva commented 1 month ago 
print(fplt.windows[0].pos(), fplt.windows[0].size())

prints something like

PyQt6.QtCore.QPoint(406, 197) PyQt6.QtCore.QSize(579, 366)

on my Windows machine. Hope it helps!

simprince commented 4 weeks ago

Unfortunately it doesn't work on wayland either. The x,y,w,h from your codes above is

-3 -30 797 370

Among many who complained the same about wayland, I found this eventually (2nd paragraph): https://wayland-book.com/xdg-shell-in-depth/interactive.html

tl;dr is, wayland intentionally doesn't support positioning/moving of app window programmatically.