From 9c3359ef3900ad62e04cd38c847552018fcf23ba Mon Sep 17 00:00:00 2001
From: ocornut <omarcornut@gmail.com>
Date: Thu, 19 Aug 2021 17:35:27 +0200
Subject: [PATCH] IO: modify io.AddFocusEvent() to tolerate in/out for
 multi-viewports. Amend 2f40be6. (#3532)

---
 imgui.cpp | 22 ++++++++++++++++------
 imgui.h   |  4 +++-
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/imgui.cpp b/imgui.cpp
index c05b493d..5dc7a337 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -1214,13 +1214,8 @@ void ImGuiIO::ClearInputCharacters()
     InputQueueCharacters.resize(0);
 }
 
-void ImGuiIO::AddFocusEvent(bool focused)
+void ImGuiIO::ClearInputKeys()
 {
-    if (focused)
-        return;
-
-    // Clear buttons state when focus is lost
-    // (this is useful so e.g. releasing Alt after focus loss on Alt-Tab doesn't trigger the Alt menu toggle)
     memset(KeysDown, 0, sizeof(KeysDown));
     for (int n = 0; n < IM_ARRAYSIZE(KeysDownDuration); n++)
         KeysDownDuration[n] = KeysDownDurationPrev[n] = -1.0f;
@@ -1230,6 +1225,13 @@ void ImGuiIO::AddFocusEvent(bool focused)
         NavInputsDownDuration[n] = NavInputsDownDurationPrev[n] = -1.0f;
 }
 
+void ImGuiIO::AddFocusEvent(bool focused)
+{
+    // We intentionally overwrite this and process in NewFrame(), in order to give a chance
+    // to multi-viewports backends to queue AddFocusEvent(false),AddFocusEvent(true) in same frame.
+    AppFocusLost = !focused;
+}
+
 //-----------------------------------------------------------------------------
 // [SECTION] MISC HELPERS/UTILITIES (Geometry functions)
 //-----------------------------------------------------------------------------
@@ -4187,6 +4189,14 @@ void ImGui::NewFrame()
     g.DragDropWithinTarget = false;
     g.DragDropHoldJustPressedId = 0;
 
+    // Clear buttons state when focus is lost
+    // (this is useful so e.g. releasing Alt after focus loss on Alt-Tab doesn't trigger the Alt menu toggle)
+    if (g.IO.AppFocusLost)
+    {
+        g.IO.ClearInputKeys();
+        g.IO.AppFocusLost = false;
+    }
+
     // Update keyboard input state
     // Synchronize io.KeyMods with individual modifiers io.KeyXXX bools
     g.IO.KeyMods = GetMergedKeyModFlags();
diff --git a/imgui.h b/imgui.h
index 4c0e395d..4d9e8dda 100644
--- a/imgui.h
+++ b/imgui.h
@@ -1950,8 +1950,9 @@ struct ImGuiIO
     IMGUI_API void  AddInputCharacter(unsigned int c);          // Queue new character input
     IMGUI_API void  AddInputCharacterUTF16(ImWchar16 c);        // Queue new character input from an UTF-16 character, it can be a surrogate
     IMGUI_API void  AddInputCharactersUTF8(const char* str);    // Queue new characters input from an UTF-8 string
-    IMGUI_API void  ClearInputCharacters();                     // Clear the text input buffer manually
     IMGUI_API void  AddFocusEvent(bool focused);                // Notifies Dear ImGui when hosting platform windows lose or gain input focus
+    IMGUI_API void  ClearInputCharacters();                     // [Internal] Clear the text input buffer manually
+    IMGUI_API void  ClearInputKeys();                           // [Internal] Release all keys
 
     //------------------------------------------------------------------
     // Output - Updated by NewFrame() or EndFrame()/Render()
@@ -1997,6 +1998,7 @@ struct ImGuiIO
     float       NavInputsDownDuration[ImGuiNavInput_COUNT];
     float       NavInputsDownDurationPrev[ImGuiNavInput_COUNT];
     float       PenPressure;                    // Touch/Pen pressure (0.0f to 1.0f, should be >0.0f only when MouseDown[0] == true). Helper storage currently unused by Dear ImGui.
+    bool        AppFocusLost;
     ImWchar16   InputQueueSurrogate;            // For AddInputCharacterUTF16
     ImVector<ImWchar> InputQueueCharacters;     // Queue of _characters_ input (obtained by platform backend). Fill using AddInputCharacter() helper.