SDL_GetMouseState always returns (0,0) before moving the mouse the first time

[SDLBugzilla]

This bug report was migrated from our old Bugzilla tracker.

These attachments are available in the static archive:

• MWE (attachment.c, text/x-c, 2016-11-11 14:28:47 +0000, 788 bytes)

Reported in version: 2.0.8
Reported for operating system, platform: Linux, x86_64

Comments on the original bug report:

On 2016-11-11 14:28:47 +0000, Andre wrote:

Created attachment 2611
MWE

I have a problem with SDL_GetMouseState: I want to get the initial mouse coordinate before the user moves the mouse the first time, but the function only returns (0,0) regardless of the actual mouse position.

I have attached a MWE that shows my problem. The first line that is printed is always "init: 0, 0". I expected it to give the actual coordinates.

This behavior can be reproduced under Linux 2.28.2 with GNOME shell 3.22.1 and the X window system. It works fine under Windows 7.

How to reproduce:

Run my attached program. Then remember the position of the window. Close the program. Then move the mouse into the position where the window was created last time. Start the program again.

Now you can see that the initial call of SDL_GetMouseState always returns (0,0) although the mouse is somewhere else inside the window.

On 2018-04-10 04:38:40 +0000, Thums wrote:

I have the same problem, SDL_GetMouseState always returns (0,0) until the mouse is moved for the first time since the program was opened.

Tested on Arch Linux, kernel 4.15.14-1 under i3wm.

Calling SDL_PumpEvents before obtaining the mouse state changes nothing.

[Svalorzen]

Hi, it seems I have the same issue; I compiled the example and the same happens on my system (Lubuntu 20.04). I discovered this issue as I was having a problem using the LOVE2d framework, that uses SDL under the hood.

Is this indeed not a bug or is it something else? Note that SDL_GetGlobalMouseState seems to work fine; the issue only happens when the window pops up under the cursor, and the cursor has not moved yet.

[slime73]

Do you know which version of SDL you're using? (if you're using the love AppImage it should be a fairly recent version I think.) There was this other bug report #674 which had at least a partial fix committed in 2019: cf092ec

[Svalorzen]

My local SDL library prints 2.0.10, I installed it using apt:

Package: libsdl2-dev
Version: 2.0.10+dfsg1-3
Priority: optional
Section: universe/libdevel
Source: libsdl2
Origin: Ubuntu

I guess that's before the patch? My LOVE2d is version 11.4, but as I also installed that using a package, it's likely that the SDL version used is the same..

At this point I might try to update my system to 22.04 and see what happens with the updated libsdl.

[slime73]

Yeah it's probably just depending on the existing SDL package you have installed already (2.0.10), I'd try updating to the latest (2.24).