From e2aa1ae24ceaffbe6d40a7c823b6efba9676d35c Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Thu, 25 Dec 2025 19:55:47 +1000
Subject: [PATCH] Qt: Fix handling of mouse double-click events

- Fixes double-click events with mouse binds getting dropped.
- Fixes early release event when toggling fullscreen.
---
 src/duckstation-qt/displaywidget.cpp | 10 ++++++---
 src/duckstation-qt/mainwindow.h      |  6 ++---
 src/util/imgui_manager.cpp           | 33 ++++++++++++++++++++++++++++
 src/util/imgui_manager.h             |  3 +++
 4 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/src/duckstation-qt/displaywidget.cpp b/src/duckstation-qt/displaywidget.cpp
index ea31627f1..ea2a2b18e 100644
--- a/src/duckstation-qt/displaywidget.cpp
+++ b/src/duckstation-qt/displaywidget.cpp
@@ -327,13 +327,11 @@ bool DisplayWidget::event(QEvent* event)
 
     case QEvent::MouseButtonDblClick:
     {
-      // since we don't get press and release events for double-click, we need to send both the down and up
-      // otherwise the second click in a double click won't be registered by the input system
+      // we don't get press events for double-click, the dblclick event is substituted instead
       if (!m_relative_mouse_enabled || !InputManager::IsUsingRawInput())
       {
         const u32 button_index = CountTrailingZeros(static_cast<u32>(static_cast<const QMouseEvent*>(event)->button()));
         emit windowMouseButtonEvent(static_cast<int>(button_index), true);
-        emit windowMouseButtonEvent(static_cast<int>(button_index), false);
       }
 
       // don't toggle fullscreen when we're bound.. that wouldn't end well.
@@ -344,6 +342,12 @@ bool DisplayWidget::event(QEvent* event)
           Core::GetBoolSettingValue("Main", "DoubleClickTogglesFullscreen", true))
       {
         g_core_thread->toggleFullscreen();
+
+        // when swapping fullscreen, the window is going to get recreated, and we won't get the release event.
+        // therefore we need to trigger it here instead, otherwise it gets lost and imgui is confused.
+        // skip this if we're not running on wankland or using render-to-main, since the window is preserved.
+        if (QtHost::IsDisplayWidgetContainerNeeded() || g_main_window->canRenderToMainWindow())
+          Host::RunOnCoreThread(&ImGuiManager::ClearMouseButtonState);
       }
 
       return true;
diff --git a/src/duckstation-qt/mainwindow.h b/src/duckstation-qt/mainwindow.h
index d88b373d4..b95bb2196 100644
--- a/src/duckstation-qt/mainwindow.h
+++ b/src/duckstation-qt/mainwindow.h
@@ -119,6 +119,9 @@ public:
   /// Updates debug menu visibility (hides if disabled).
   void updateDebugMenuVisibility();
 
+  /// Returns true if rendering to the main window should be allowed.
+  bool canRenderToMainWindow() const;
+
   void refreshGameList(bool invalidate_cache);
   void cancelGameListRefresh();
   QIcon getIconForGame(const QString& path);
@@ -183,9 +186,6 @@ private:
   void saveDisplayWindowGeometryToConfig();
   void restoreDisplayWindowGeometryFromConfig();
 
-  /// Returns true if rendering to the main window should be allowed.
-  bool canRenderToMainWindow() const;
-
   /// Returns true if the separate-window display widget should use the main window coordinates.
   bool useMainWindowGeometryForDisplayWindow() const;
 
diff --git a/src/util/imgui_manager.cpp b/src/util/imgui_manager.cpp
index 2010d2ebe..82eedfb3e 100644
--- a/src/util/imgui_manager.cpp
+++ b/src/util/imgui_manager.cpp
@@ -1415,6 +1415,39 @@ bool ImGuiManager::ProcessGenericInputEvent(GenericInputBinding key, float value
   return s_state.imgui_wants_keyboard.load(std::memory_order_acquire);
 }
 
+void ImGuiManager::ClearMouseButtonState()
+{
+  if (!s_state.imgui_context)
+    return;
+
+  GPUThread::RunOnThread([]() {
+    if (!s_state.imgui_context)
+      return;
+
+    ImGuiIO& io = s_state.imgui_context->IO;
+    for (int i = 0; i < ImGuiMouseButton_COUNT; i++)
+    {
+      bool current_state = io.MouseDown[i];
+      for (int n = s_state.imgui_context->InputEventsQueue.Size - 1; n >= 0; n--)
+      {
+        const ImGuiInputEvent& event = s_state.imgui_context->InputEventsQueue[n];
+        if (event.Type == ImGuiInputEventType_MouseButton && event.MouseButton.Button == i)
+        {
+          current_state = event.MouseButton.Down;
+          break;
+        }
+      }
+
+      // not down?
+      if (!current_state)
+        continue;
+
+      // Queue a button up event.
+      s_state.imgui_context->IO.AddMouseButtonEvent(i, false);
+    }
+  });
+}
+
 const char* ImGuiManager::GetClipboardTextImpl(ImGuiContext* ctx)
 {
   const std::string text = Host::GetClipboardText();
diff --git a/src/util/imgui_manager.h b/src/util/imgui_manager.h
index e8c1093e2..e207f1878 100644
--- a/src/util/imgui_manager.h
+++ b/src/util/imgui_manager.h
@@ -174,6 +174,9 @@ bool ProcessHostKeyEvent(InputBindingKey key, float value);
 /// Called on the CPU thread when any input event fires. Allows imgui to take over controller navigation.
 bool ProcessGenericInputEvent(GenericInputBinding key, float value);
 
+/// Resets the state of ImGui mouse buttons, call after the window is changed and events get lost.
+void ClearMouseButtonState();
+
 /// Sets an image and scale for a software cursor. Software cursors can be used for things like crosshairs.
 void SetSoftwareCursor(u32 index, std::string image_path, float image_scale, u32 multiply_color = 0xFFFFFF);
 bool HasSoftwareCursor(u32 index);