From f99fe72c42bd5d578c2443409192b139b1c6623d Mon Sep 17 00:00:00 2001
From: ocornut <omarcornut@gmail.com>
Date: Mon, 2 Aug 2021 17:22:33 +0200
Subject: [PATCH] Backends: Win32: Fixed keyboard modifiers being reported when
 host window doesn't have focus. (#2622)

---
 backends/imgui_impl_win32.cpp | 27 ++++++++++++++-------------
 docs/CHANGELOG.txt            |  1 +
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/backends/imgui_impl_win32.cpp b/backends/imgui_impl_win32.cpp
index 4124b9743..984171a58 100644
--- a/backends/imgui_impl_win32.cpp
+++ b/backends/imgui_impl_win32.cpp
@@ -33,9 +33,10 @@ typedef DWORD (WINAPI *PFN_XInputGetState)(DWORD, XINPUT_STATE*);
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2021-08-02: Inputs: Fixed keyboard modifiers being reported when host window doesn't have focus.
 //  2021-07-29: Inputs: MousePos is correctly reported when the host platform window is hovered but not focused (using TrackMouseEvent() to receive WM_MOUSELEAVE events).
 //  2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX).
-//  2021-06-08: Fix ImGui_ImplWin32_EnableDpiAwareness() and ImGui_ImplWin32_GetDpiScaleForMonitor() to handle Windows 8.1/10 features without a manifest (per-monitor DPI, and properly calls SetProcessDpiAwareness() on 8.1).
+//  2021-06-08: Fixed ImGui_ImplWin32_EnableDpiAwareness() and ImGui_ImplWin32_GetDpiScaleForMonitor() to handle Windows 8.1/10 features without a manifest (per-monitor DPI, and properly calls SetProcessDpiAwareness() on 8.1).
 //  2021-03-23: Inputs: Clearing keyboard down array when losing focus (WM_KILLFOCUS).
 //  2021-02-18: Added ImGui_ImplWin32_EnableAlphaCompositing(). Non Visual Studio users will need to link with dwmapi.lib (MinGW/gcc: use -ldwmapi).
 //  2021-02-17: Fixed ImGui_ImplWin32_EnableDpiAwareness() attempting to get SetProcessDpiAwareness from shcore.dll on Windows 8 whereas it is only supported on Windows 8.1.
@@ -318,13 +319,6 @@ void    ImGui_ImplWin32_NewFrame()
     io.DeltaTime = (float)(current_time - bd->Time) / bd->TicksPerSecond;
     bd->Time = current_time;
 
-    // Read keyboard modifiers inputs
-    io.KeyCtrl = (::GetKeyState(VK_CONTROL) & 0x8000) != 0;
-    io.KeyShift = (::GetKeyState(VK_SHIFT) & 0x8000) != 0;
-    io.KeyAlt = (::GetKeyState(VK_MENU) & 0x8000) != 0;
-    io.KeySuper = false;
-    // io.KeysDown[], io.MousePos, io.MouseDown[], io.MouseWheel: filled by the WndProc handler below.
-
     // Update OS mouse position
     ImGui_ImplWin32_UpdateMousePos();
 
@@ -422,17 +416,24 @@ IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARA
         io.MouseWheelH += (float)GET_WHEEL_DELTA_WPARAM(wParam) / (float)WHEEL_DELTA;
         return 0;
     case WM_KEYDOWN:
-    case WM_SYSKEYDOWN:
-        if (wParam < 256)
-            io.KeysDown[wParam] = 1;
-        return 0;
     case WM_KEYUP:
+    case WM_SYSKEYDOWN:
     case WM_SYSKEYUP:
+    {
+        bool down = (msg == WM_KEYDOWN || msg == WM_SYSKEYDOWN);
         if (wParam < 256)
-            io.KeysDown[wParam] = 0;
+            io.KeysDown[wParam] = down;
+        if (wParam == VK_CONTROL)
+            io.KeyCtrl = down;
+        if (wParam == VK_SHIFT)
+            io.KeyShift = down;
+        if (wParam == VK_MENU)
+            io.KeyAlt = down;
         return 0;
+    }
     case WM_KILLFOCUS:
         memset(io.KeysDown, 0, sizeof(io.KeysDown));
+        io.KeyCtrl = io.KeyShift = io.KeyAlt = io.KeySuper = false;
         return 0;
     case WM_CHAR:
         // You can also use ToAscii()+GetKeyboardState() to retrieve characters.
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index 91d146e42..e20b016b3 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -98,6 +98,7 @@ Other Changes:
 - Backends: Win32: IME functions are disabled by default for non-Visual Studio compilers (MinGW etc.). Enable with
   '#define IMGUI_ENABLE_WIN32_DEFAULT_IME_FUNCTIONS' for those compilers. Undo change from 1.82. (#2590, #738, #4185, #4301)
 - Backends: Win32: Mouse position is correctly reported when the host window is hovered but not focused. (#2445, #2696, #3751, #4377)
+- Backends: Fixed keyboard modifiers being reported when host window doesn't have focus. (#2622)
 - Backends: GLFW: Mouse position is correctly reported when the host window is hovered but not focused. (#3751, #4377, #2445)
   (backend now uses glfwSetCursorEnterCallback(). If you called ImGui_ImplGlfw_InitXXX with install_callbacks=false, you will
   need to install this callback and forward the data to the backend via ImGui_ImplGlfw_CursorEnterCallback).