Mouse support not working on Windows - potential fix, and interaction with ScrollablePane

[robintw]

I have a prompt_toolkit application which has mouse_support=True in its Application call. The mouse support works fine on OS X and Linux, but nothing happens when clicking on controls when running on Windows.

I've seen various issues on here about this (#1232, #1177 and #1059) and there are various fixes proposed.

The fix in #1177 partially worked for me, but also caused other issues. This fix changes a check from checking for an object being a Win32Output instance, to checking for either a Win32Output or Windows10_Output instance. Altering the code as suggested in that issue led to a few other errors being raised - one of which I think is related to the work in #1347, where the way that mouse handlers are stored is changed, and this bit of code hasn't been updated.

I think I've managed to fix it, with the code looking this in the end:

from prompt_toolkit.output.win32 import Win32Output
from prompt_toolkit.output.windows10 import Windows10_Output

if isinstance(output, Win32Output) or isinstance(output, Windows10_Output):
    screen_buffer_info = output.get_win32_screen_buffer_info()
    rows_above_cursor = (
        screen_buffer_info.dwCursorPosition.Y - event.app.renderer._cursor_pos.y
    )
    y -= rows_above_cursor

    # Call the mouse event handler.
    handler = event.app.renderer.mouse_handlers.mouse_handlers[x, y]
    handler(MouseEvent(position=Point(x=x, y=y), event_type=event_type))

I ran into a few issues where it seemed like the mouse positions weren't being reported quite correctly (possibly due to issues with the ScrollablePane?), but I can't seem to reproduce them properly - so it might not be a problem. I'd be grateful for your experienced eye over the code though.

[jonathanslenders]

Hi @robintw,

Thanks for pointing out this issue! I'll try to look at this in the coming days.

[jonathanslenders]

Thanks Robin,

This makes sense. I just noticed one more issue that some Windows users could experience.
If the ENABLE_PROCESSED_INPUT flag has been set in SetConsoleMode, then there won't be any mouse support in the application. See: https://docs.microsoft.com/en-us/windows/console/setconsolemode and https://github.com/prompt-toolkit/python-prompt-toolkit/pull/1360/files

The required change for the ScrollablePane, I'll do in the ScrollablePane branch. (edit: it was unfortunately that I had to change the API there in the mouse_handlers, but it was required because of the performance, and I assume that nobody depends on this, except here apparently.)

[jonathanslenders]

@robintw : I merged the required changes for the mouse issues on Windows, together with a few other improvements. Further, I rebased the "scrollable-pane" branch on master (and squashed a few commits), so that it includes this changes. (I fixed the mouse_handlers issue on that branch).

[625781186]

@jonathanslenders
Is it possible to add a click event to the scroll bar?
I'll try to add a drag event to the scroll bar.
But don't know how to trigger a scroll bar mouse event

[jonathanslenders]

Hi @625781186 , yes that is possible. It's something I intend to do.