Commit 27055ea0adcee4642f990b3582ec9fbe3aebb411

Ryan C. Gordon 2015-07-14T23:46:35

X11: center parentless message boxes on the primary display if possible. This relies on a successful SDL_Init(SDL_INIT_VIDEO) to work, since it's silly to reproduce all the Xinerama/XRandR code in the message box parts. If X11 is available but SDL hasn't been initialized, the message box will center in the primary screen, which will be positioned weirdly on multi-head setups, but this should fix the most significant common case.

diff --git a/src/video/x11/SDL_x11messagebox.c b/src/video/x11/SDL_x11messagebox.c
index 7c3aaec..a52d4c9 100644
--- a/src/video/x11/SDL_x11messagebox.c
+++ b/src/video/x11/SDL_x11messagebox.c
@@ -439,8 +439,16 @@ X11_MessageBoxCreateWindow( SDL_MessageBoxDataX11 *data )
         y = attrib.y + ( attrib.height - data->dialog_height ) / 3 ;
         X11_XTranslateCoordinates(display, windowdata->xwindow, RootWindow(display, data->screen), x, y, &x, &y, &dummy);
     } else {
-        x = ( DisplayWidth( display, data->screen ) - data->dialog_width ) / 2;
-        y = ( DisplayHeight( display, data->screen ) - data->dialog_height ) / 3 ;
+        const SDL_VideoDevice *dev = SDL_GetVideoDevice();
+        if ((dev) && (dev->displays) && (dev->num_displays > 0)) {
+            const SDL_VideoDisplay *dpy = &dev->displays[0];
+            const SDL_DisplayData *dpydata = (SDL_DisplayData *) dpy->driverdata;
+            x = dpydata->x + (( dpy->current_mode.w - data->dialog_width ) / 2);
+            y = dpydata->y + (( dpy->current_mode.h - data->dialog_height ) / 3);
+        } else {   /* oh well. This will misposition on a multi-head setup. Init first next time. */
+            x = ( DisplayWidth( display, data->screen ) - data->dialog_width ) / 2;
+            y = ( DisplayHeight( display, data->screen ) - data->dialog_height ) / 3 ;
+        }
     }
     X11_XMoveWindow( display, data->window, x, y );