Backends: SDL: Alternative fix for 5012 (untested)
diff --git a/backends/imgui_impl_sdl.cpp b/backends/imgui_impl_sdl.cpp
index 9384cec..47cb6a1 100644
--- a/backends/imgui_impl_sdl.cpp
+++ b/backends/imgui_impl_sdl.cpp
@@ -96,6 +96,7 @@
Uint32 MouseWindowID;
int MouseButtonsDown;
SDL_Cursor* MouseCursors[ImGuiMouseCursor_COUNT];
+ int PendingMouseLeaveFrame;
char* ClipboardTextData;
bool MouseCanUseGlobalState;
bool UseVulkan;
@@ -315,16 +316,19 @@
}
case SDL_WINDOWEVENT:
{
- // When capturing mouse, SDL will send a bunch of conflicting LEAVE/ENTER event on every mouse move, but the final ENTER tends to be right.
- // However we won't get a correct LEAVE event for a captured window.
+ // - When capturing mouse, SDL will send a bunch of conflicting LEAVE/ENTER event on every mouse move, but the final ENTER tends to be right.
+ // - However we won't get a correct LEAVE event for a captured window.
+ // - In some cases, when detaching a window from main viewport SDL may send SDL_WINDOWEVENT_ENTER one frame too late,
+ // causing SDL_WINDOWEVENT_LEAVE on previous frame to interrupt drag operation by clear mouse position. This is why
+ // we delay process the SDL_WINDOWEVENT_LEAVE events by one frame. See issue #5012 for details.
Uint8 window_event = event->window.event;
if (window_event == SDL_WINDOWEVENT_ENTER)
- bd->MouseWindowID = event->window.windowID;
- if (window_event == SDL_WINDOWEVENT_LEAVE)
{
- bd->MouseWindowID = 0;
- io.AddMousePosEvent(-FLT_MAX, -FLT_MAX);
+ bd->MouseWindowID = event->window.windowID;
+ bd->PendingMouseLeaveFrame = 0;
}
+ if (window_event == SDL_WINDOWEVENT_LEAVE)
+ bd->PendingMouseLeaveFrame = ImGui::GetFrameCount() + 1;
if (window_event == SDL_WINDOWEVENT_FOCUS_GAINED)
io.AddFocusEvent(true);
else if (window_event == SDL_WINDOWEVENT_FOCUS_LOST)
@@ -665,6 +669,12 @@
io.DeltaTime = bd->Time > 0 ? (float)((double)(current_time - bd->Time) / frequency) : (float)(1.0f / 60.0f);
bd->Time = current_time;
+ if (bd->PendingMouseLeaveFrame && bd->PendingMouseLeaveFrame == ImGui::GetFrameCount())
+ {
+ bd->MouseWindowID = 0;
+ io.AddMousePosEvent(-FLT_MAX, -FLT_MAX);
+ }
+
ImGui_ImplSDL2_UpdateMouseData();
ImGui_ImplSDL2_UpdateMouseCursor();
