Commit 3a916c6d7b5bc0eb6c244c095ec72a51e33e7af8

Dmitry Rekman 2014-10-29T22:55:40

X11: Fixed SDL_GetGlobalMouseState() to work better with multimonitor configs. Fixes Bugzilla #2770. Thanks to Epic Games for contributing this fix.

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diff --git a/src/video/x11/SDL_x11mouse.c b/src/video/x11/SDL_x11mouse.c
index 02d96da..d3ec619 100644
--- a/src/video/x11/SDL_x11mouse.c
+++ b/src/video/x11/SDL_x11mouse.c
@@ -382,8 +382,14 @@ X11_GetGlobalMouseState(int *x, int *y)
                 retval |= (mask & Button1Mask) ? SDL_BUTTON_LMASK : 0;
                 retval |= (mask & Button2Mask) ? SDL_BUTTON_MMASK : 0;
                 retval |= (mask & Button3Mask) ? SDL_BUTTON_RMASK : 0;
-                *x = data->x + rootx;
-                *y = data->y + rooty;
+                /* SDL_DisplayData->x,y point to screen origin, and adding them to mouse coordinates relative to root window doesn't do the right thing
+                 * (observed on dual monitor setup with primary display being the rightmost one - mouse was offset to the right).
+                 *
+                 * Adding root position to root-relative coordinates seems to be a better way to get absolute position. */
+                XWindowAttributes root_attrs;
+                X11_XGetWindowAttributes(display, root, &root_attrs);
+                *x = root_attrs.x + rootx;
+                *y = root_attrs.y + rooty;
                 return retval;
             }
         }