From 85facf6d6e24ebb9c9bdfda4e0c5246fd02392c4 Mon Sep 17 00:00:00 2001
From: reuk <reuk@users.noreply.github.com>
Date: Thu, 7 Jan 2021 18:00:13 +0000
Subject: [PATCH] HWNDComponentPeer:  Dismiss modals more proactively

This change makes heavyweight views listen to window events from higher
in the window hierarchy. If a move or resize event from higher in the
hierarchy is encountered, blocking modal components will be dismissed.

This patch should resolve an issue where the popupmenu for a combobox
could become 'stranded' if the plugin window was moved while the box was
open.
---
 .../native/juce_win32_Windowing.cpp           | 79 +++++++++++++++++--
 1 file changed, 72 insertions(+), 7 deletions(-)

diff --git a/modules/juce_gui_basics/native/juce_win32_Windowing.cpp b/modules/juce_gui_basics/native/juce_win32_Windowing.cpp
index cda94b0ca4..a69619f79e 100644
--- a/modules/juce_gui_basics/native/juce_win32_Windowing.cpp
+++ b/modules/juce_gui_basics/native/juce_win32_Windowing.cpp
@@ -3841,15 +3841,13 @@ private:
 
     bool sendInputAttemptWhenModalMessage()
     {
-        if (component.isCurrentlyBlockedByAnotherModalComponent())
-        {
-            if (Component* const current = Component::getCurrentlyModalComponent())
-                current->inputAttemptWhenModal();
+        if (! component.isCurrentlyBlockedByAnotherModalComponent())
+            return false;
 
-            return true;
-        }
+        if (auto* current = Component::getCurrentlyModalComponent())
+            current->inputAttemptWhenModal();
 
-        return false;
+        return true;
     }
 
     //==============================================================================
@@ -4074,6 +4072,73 @@ private:
         stopTimer();
     }
 
+    static bool isAncestor (HWND outer, HWND inner)
+    {
+        if (outer == nullptr || inner == nullptr)
+            return false;
+
+        if (outer == inner)
+            return true;
+
+        return isAncestor (outer, GetAncestor (inner, GA_PARENT));
+    }
+
+    void windowShouldDismissModals (HWND originator)
+    {
+        if (isAncestor (originator, hwnd))
+            sendInputAttemptWhenModalMessage();
+    }
+
+    // Unfortunately SetWindowsHookEx only allows us to register a static function as a hook.
+    // To get around this, we keep a static list of listeners which are interested in
+    // top-level window events, and notify all of these listeners from the callback.
+    class TopLevelModalDismissBroadcaster
+    {
+    public:
+        TopLevelModalDismissBroadcaster()
+            : hook (SetWindowsHookEx (WH_CALLWNDPROC,
+                                      callWndProc,
+                                      (HINSTANCE) juce::Process::getCurrentModuleInstanceHandle(),
+                                      GetCurrentThreadId()))
+        {}
+
+        ~TopLevelModalDismissBroadcaster() noexcept
+        {
+            UnhookWindowsHookEx (hook);
+        }
+
+    private:
+        static void processMessage (int nCode, const CWPSTRUCT* info)
+        {
+            if (nCode < 0 || info == nullptr)
+                return;
+
+            constexpr UINT events[] { WM_MOVE,
+                                      WM_SIZE,
+                                      WM_WINDOWPOSCHANGED,
+                                      WM_NCPOINTERDOWN,
+                                      WM_NCLBUTTONDOWN,
+                                      WM_NCRBUTTONDOWN,
+                                      WM_NCMBUTTONDOWN };
+
+            if (std::find (std::begin (events), std::end (events), info->message) == std::end (events))
+                return;
+
+            for (auto i = ComponentPeer::getNumPeers(); --i >= 0;)
+                if (auto* hwndPeer = dynamic_cast<HWNDComponentPeer*> (ComponentPeer::getPeer (i)))
+                    hwndPeer->windowShouldDismissModals (info->hwnd);
+        }
+
+        static LRESULT CALLBACK callWndProc (int nCode, WPARAM wParam, LPARAM lParam)
+        {
+            processMessage (nCode, reinterpret_cast<CWPSTRUCT*> (lParam));
+            return CallNextHookEx ({}, nCode, wParam, lParam);
+        }
+
+        HHOOK hook;
+    };
+
+    SharedResourcePointer<TopLevelModalDismissBroadcaster> modalDismissBroadcaster;
     IMEHandler imeHandler;
 
     //==============================================================================