Backends: Win32: Secondary viewports WndProc handler retrieve/set imgui context from the HWND.
Allowing WndProc dispatch to work in multi-context setups.
diff --git a/backends/imgui_impl_win32.cpp b/backends/imgui_impl_win32.cpp
index 63b57de..0db2900 100644
--- a/backends/imgui_impl_win32.cpp
+++ b/backends/imgui_impl_win32.cpp
@@ -1054,6 +1054,9 @@
vd->HwndOwned = true;
viewport->PlatformRequestResize = false;
viewport->PlatformHandle = viewport->PlatformHandleRaw = vd->Hwnd;
+
+ // Secondary viewports store their imgui context
+ ::SetPropA(vd->Hwnd, "IMGUI_CONTEXT", ImGui::GetCurrentContext());
}
static void ImGui_ImplWin32_DestroyWindow(ImGuiViewport* viewport)
@@ -1256,10 +1259,16 @@
static LRESULT CALLBACK ImGui_ImplWin32_WndProcHandler_PlatformWindow(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
- if (ImGui_ImplWin32_WndProcHandler(hWnd, msg, wParam, lParam))
- return true;
+ // Allow secondary viewport WndProc to be called regardless of current context
+ ImGuiContext* hwnd_ctx = (ImGuiContext*)::GetPropA(hWnd, "IMGUI_CONTEXT");
+ ImGuiContext* prev_ctx = ImGui::GetCurrentContext();
+ if (hwnd_ctx != prev_ctx && hwnd_ctx != NULL)
+ ImGui::SetCurrentContext(hwnd_ctx);
- if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle((void*)hWnd))
+ LRESULT result = 0;
+ if (ImGui_ImplWin32_WndProcHandler(hWnd, msg, wParam, lParam))
+ result = true;
+ else if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle((void*)hWnd))
{
switch (msg)
{
@@ -1274,7 +1283,7 @@
break;
case WM_MOUSEACTIVATE:
if (viewport->Flags & ImGuiViewportFlags_NoFocusOnClick)
- return MA_NOACTIVATE;
+ result = MA_NOACTIVATE;
break;
case WM_NCHITTEST:
// Let mouse pass-through the window. This will allow the backend to call io.AddMouseViewportEvent() correctly. (which is optional).
@@ -1282,12 +1291,15 @@
// If you cannot easily access those viewport flags from your windowing/event code: you may manually synchronize its state e.g. in
// your main loop after calling UpdatePlatformWindows(). Iterate all viewports/platform windows and pass the flag to your windowing system.
if (viewport->Flags & ImGuiViewportFlags_NoInputs)
- return HTTRANSPARENT;
+ result = HTTRANSPARENT;
break;
}
}
-
- return DefWindowProc(hWnd, msg, wParam, lParam);
+ if (result == 0)
+ result = DefWindowProc(hWnd, msg, wParam, lParam);
+ if (hwnd_ctx != prev_ctx && hwnd_ctx != NULL)
+ ImGui::SetCurrentContext(prev_ctx);
+ return result;
}
static void ImGui_ImplWin32_InitPlatformInterface(bool platform_has_own_dc)
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index df91187..fafb8c4 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -68,6 +68,8 @@
- Backends: SDL3: Update for introduction of SDL_GLContext from void*. (#7701, #7702)
[@bcsanches]
+- Backends: Win32: Secondary viewports WndProc handler retrieve/set imgui context from
+ the HWND, allowing WndProc dispatch to work in multi-context setups.
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