Reverted change for bug 4152 - restrict the win10 mouse bug workaround to win10 v1709 only
authorSam Lantinga <slouken@libsdl.org>
Mon, 07 May 2018 20:10:12 -0700
changeset 119594cc8aad8d434
parent 11958 d7582d7286aa
child 11960 9f61cd1be333
Reverted change for bug 4152 - restrict the win10 mouse bug workaround to win10 v1709 only

Daniel Gibson

Sorry, but it seems like Microsoft didn't fix the issue properly.

I just updated my Win10 machine, it now is Version 1803, Build 17134.1

I tested with SDL2 2.0.7 (my workaround was released with 2.0.8) and still got
lots of events that directly undid the prior "real" events - just like before.
(See simple testcase in attachement)
By default it sets SDL_HINT_MOUSE_RELATIVE_MODE_WARP - which triggered (and on my machine still triggers) the buggy behavior. You can start it with -raw, then it'll not set that hint and the events will be as expected.
The easiest way to see the difference is looking at the window title, which shows accumulated X and Y values: If you just move your mouse to the right, in -raw mode the number just increases. In non-raw mode (using mouse warping) it stays around 0.

I also had a WinAPI-only testcase: https://gist.github.com/DanielGibson/b5b033c67b9137f0280af9fc53352c68
It just calls SetCursorPos(320,240); on each WM_MOUSEMOVE event, and it also
logs all those events to a mouseevents.log textfile.
This log indeed looks a bit different since the latest Win10 update: It seems like all those events with x=320 y=240 do arrive - but only after I stopped moving the mouse - even though the cursor seems to be moved back every frame (or so).
So moving the mouse to the right gives X coordinates like
330, 325, 333, 340, 330, ...
and then when stopping movement I get lots of events with X coordinate 320
src/video/windows/SDL_windowsevents.c
     1.1 --- a/src/video/windows/SDL_windowsevents.c	Mon May 07 19:52:25 2018 -0700
     1.2 +++ b/src/video/windows/SDL_windowsevents.c	Mon May 07 20:10:12 2018 -0700
     1.3 @@ -359,6 +359,11 @@
     1.4      return !SDL_GetHintBoolean(SDL_HINT_WINDOWS_NO_CLOSE_ON_ALT_F4, SDL_FALSE);
     1.5  }
     1.6  
     1.7 +/* Win10 "Fall Creators Update" introduced the bug that SetCursorPos() (as used by SDL_WarpMouseInWindow())
     1.8 +   doesn't reliably generate WM_MOUSEMOVE events anymore (see #3931) which breaks relative mouse mode via warping.
     1.9 +   This is used to implement a workaround.. */
    1.10 +static SDL_bool isWin10FCUorNewer = SDL_FALSE;
    1.11 +
    1.12  LRESULT CALLBACK
    1.13  WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
    1.14  {
    1.15 @@ -481,6 +486,17 @@
    1.16              if (!mouse->relative_mode || mouse->relative_mode_warp) {
    1.17                  SDL_MouseID mouseID = (((GetMessageExtraInfo() & MOUSEEVENTF_FROMTOUCH) == MOUSEEVENTF_FROMTOUCH) ? SDL_TOUCH_MOUSEID : 0);
    1.18                  SDL_SendMouseMotion(data->window, mouseID, 0, GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
    1.19 +                if (isWin10FCUorNewer && mouseID != SDL_TOUCH_MOUSEID && mouse->relative_mode_warp) {
    1.20 +                    /* To work around #3931, Win10 bug introduced in Fall Creators Update, where
    1.21 +                       SetCursorPos() (SDL_WarpMouseInWindow()) doesn't reliably generate mouse events anymore,
    1.22 +                       after each windows mouse event generate a fake event for the middle of the window
    1.23 +                       if relative_mode_warp is used */
    1.24 +                    int center_x = 0, center_y = 0;
    1.25 +                    SDL_GetWindowSize(data->window, &center_x, &center_y);
    1.26 +                    center_x /= 2;
    1.27 +                    center_y /= 2;
    1.28 +                    SDL_SendMouseMotion(data->window, mouseID, 0, center_x, center_y);
    1.29 +                }
    1.30              }
    1.31          }
    1.32          /* don't break here, fall through to check the wParam like the button presses */
    1.33 @@ -1058,6 +1074,43 @@
    1.34      }
    1.35  }
    1.36  
    1.37 +/* to work around #3931, a bug introduced in Win10 Fall Creators Update (build nr. 16299)
    1.38 +   we need to detect the windows version. this struct and the function below does that.
    1.39 +   usually this struct and the corresponding function (RtlGetVersion) are in <Ntddk.h>
    1.40 +   but here we just load it dynamically */
    1.41 +struct SDL_WIN_OSVERSIONINFOW {
    1.42 +    ULONG dwOSVersionInfoSize;
    1.43 +    ULONG dwMajorVersion;
    1.44 +    ULONG dwMinorVersion;
    1.45 +    ULONG dwBuildNumber;
    1.46 +    ULONG dwPlatformId;
    1.47 +    WCHAR szCSDVersion[128];
    1.48 +};
    1.49 +
    1.50 +static SDL_bool
    1.51 +IsWin10FCUorNewer(void)
    1.52 +{
    1.53 +    HMODULE handle = GetModuleHandleW(L"ntdll.dll");
    1.54 +    if (handle) {
    1.55 +        typedef LONG(WINAPI* RtlGetVersionPtr)(struct SDL_WIN_OSVERSIONINFOW*);
    1.56 +        RtlGetVersionPtr getVersionPtr = (RtlGetVersionPtr)GetProcAddress(handle, "RtlGetVersion");
    1.57 +        if (getVersionPtr != NULL) {
    1.58 +            struct SDL_WIN_OSVERSIONINFOW info;
    1.59 +            SDL_zero(info);
    1.60 +            info.dwOSVersionInfoSize = sizeof(info);
    1.61 +            if (getVersionPtr(&info) == 0) { /* STATUS_SUCCESS == 0 */
    1.62 +                if (   (info.dwMajorVersion == 10 && info.dwMinorVersion == 0 && info.dwBuildNumber >= 16299)
    1.63 +                    || (info.dwMajorVersion == 10 && info.dwMinorVersion > 0)
    1.64 +                    || (info.dwMajorVersion > 10) )
    1.65 +                {
    1.66 +                    return SDL_TRUE;
    1.67 +                }
    1.68 +            }
    1.69 +        }
    1.70 +    }
    1.71 +    return SDL_FALSE;
    1.72 +}
    1.73 +
    1.74  static int app_registered = 0;
    1.75  LPTSTR SDL_Appname = NULL;
    1.76  Uint32 SDL_Appstyle = 0;
    1.77 @@ -1122,6 +1175,8 @@
    1.78          return SDL_SetError("Couldn't register application class");
    1.79      }
    1.80  
    1.81 +    isWin10FCUorNewer = IsWin10FCUorNewer();
    1.82 +
    1.83      app_registered = 1;
    1.84      return 0;
    1.85  }