From d1f7f9e35dce18a2c3e6ee9036a7f938487f2e4d Mon Sep 17 00:00:00 2001
From: Ethan Lee <[EMAIL REDACTED]>
Date: Wed, 6 Apr 2022 11:18:46 -0400
Subject: [PATCH] wayland: Pin the fake window position at (0, 0).
I kind of thought it'd be nice to have it in the center, but this is an issue
for applications that still assume global mouse and window positions are
accessible. For example, this fixes cursor offset issues in UE5.
---
src/video/wayland/SDL_waylandwindow.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/src/video/wayland/SDL_waylandwindow.c b/src/video/wayland/SDL_waylandwindow.c
index 476083b21c5..89b93b7a3e3 100644
--- a/src/video/wayland/SDL_waylandwindow.c
+++ b/src/video/wayland/SDL_waylandwindow.c
@@ -815,12 +815,28 @@ Wayland_move_window(SDL_Window *window,
int i, numdisplays = SDL_GetNumVideoDisplays();
for (i = 0; i < numdisplays; i += 1) {
if (SDL_GetDisplay(i)->driverdata == driverdata) {
- /* Equivalent of SDL_WINDOWPOS_CENTERED_DISPLAY(i) */
+ /* We want to send a very very specific combination here:
+ *
+ * 1. A coordinate that tells the application what display we're on
+ * 2. Exactly (0, 0)
+ *
+ * Part 1 is useful information but is also really important for
+ * ensuring we end up on the right display for fullscreen, while
+ * part 2 is important because numerous applications use a specific
+ * combination of GetWindowPosition and GetGlobalMouseState, and of
+ * course neither are supported by Wayland. Since global mouse will
+ * fall back to just GetMouseState, we need the window position to
+ * be zero so the cursor math works without it going off in some
+ * random direction. See UE5 Editor for a notable example of this!
+ *
+ * This may be an issue some day if we're ever able to implement
+ * SDL_GetDisplayUsableBounds!
+ *
+ * -flibit
+ */
SDL_Rect bounds;
SDL_GetDisplayBounds(i, &bounds);
- SDL_SendWindowEvent(window, SDL_WINDOWEVENT_MOVED,
- bounds.x + (bounds.w - window->w) / 2,
- bounds.y + (bounds.h - window->h) / 2);
+ SDL_SendWindowEvent(window, SDL_WINDOWEVENT_MOVED, bounds.x, bounds.y);
break;
}
}