From 4881dd63a7c34d12b708494c55e1928c67f92e86 Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Wed, 24 Nov 2021 10:02:54 +0200
Subject: [PATCH] kwineffects: Make OffscreenQuickView generate double click
 events

Currently, MouseArea.doubleClicked doesn't work in QtQuick effects.
Luckily, the overview effect doesn't use it, but it's still worth making
sure that it works as expected regardless of whether it's a kwin effect.

With this change, the OffscreenQuickView will keep track of the last
mouse press event. If the second button press occurs within the mouse
double click interval, the OffscreenQuickView will generate a
QEvent::MouseButtonDblClick event, similar to what QGuiApplication would
normally do when processing window system events.
---
 src/libkwineffects/kwinoffscreenquickview.cpp | 19 ++++++++++++++++++-
 .../kdecorations/aurorae/src/aurorae.cpp      | 11 -----------
 .../kdecorations/aurorae/src/aurorae.h        |  1 -
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/src/libkwineffects/kwinoffscreenquickview.cpp b/src/libkwineffects/kwinoffscreenquickview.cpp
index db084297fb..bea0f3f0e1 100644
--- a/src/libkwineffects/kwinoffscreenquickview.cpp
+++ b/src/libkwineffects/kwinoffscreenquickview.cpp
@@ -12,12 +12,14 @@
 #include "kwinglutils.h"
 #include "logging_p.h"
 
+#include <QGuiApplication>
 #include <QQmlEngine>
 #include <QQuickItem>
 #include <QQmlContext>
 #include <QQmlComponent>
 #include <QQuickView>
 #include <QQuickRenderControl>
+#include <QStyleHints>
 
 #include <QOffscreenSurface>
 #include <QOpenGLContext>
@@ -74,6 +76,9 @@ public:
     Qt::TouchPointStates touchState;
     QTouchDevice *touchDevice;
 
+    ulong lastMousePressTime = 0;
+    Qt::MouseButton lastMousePressButton = Qt::NoButton;
+
     void releaseResources();
 
     void updateTouchState(Qt::TouchPointState state, qint32 id, const QPointF& pos);
@@ -270,13 +275,25 @@ void OffscreenQuickView::forwardMouseEvent(QEvent *e)
     case QEvent::MouseMove:
     case QEvent::MouseButtonPress:
     case QEvent::MouseButtonRelease:
-    case QEvent::MouseButtonDblClick:
     {
         QMouseEvent *me = static_cast<QMouseEvent *>(e);
         const QPoint widgetPos = d->m_view->mapFromGlobal(me->pos());
         QMouseEvent cloneEvent(me->type(), widgetPos, me->pos(), me->button(), me->buttons(), me->modifiers());
         QCoreApplication::sendEvent(d->m_view, &cloneEvent);
         e->setAccepted(cloneEvent.isAccepted());
+
+        if (e->type() == QEvent::MouseButtonPress) {
+            const ulong doubleClickInterval = static_cast<ulong>(QGuiApplication::styleHints()->mouseDoubleClickInterval());
+            const bool doubleClick = (me->timestamp() - d->lastMousePressTime < doubleClickInterval) && me->button() == d->lastMousePressButton;
+            d->lastMousePressTime = me->timestamp();
+            d->lastMousePressButton = me->button();
+            if (doubleClick) {
+                d->lastMousePressButton = Qt::NoButton;
+                QMouseEvent doubleClickEvent(QEvent::MouseButtonDblClick, me->localPos(), me->windowPos(), me->screenPos(), me->button(), me->buttons(), me->modifiers());
+                QCoreApplication::sendEvent(d->m_view, &doubleClickEvent);
+            }
+        }
+
         return;
     }
     case QEvent::HoverEnter:
diff --git a/src/plugins/kdecorations/aurorae/src/aurorae.cpp b/src/plugins/kdecorations/aurorae/src/aurorae.cpp
index 152735608d..23426ae2cb 100644
--- a/src/plugins/kdecorations/aurorae/src/aurorae.cpp
+++ b/src/plugins/kdecorations/aurorae/src/aurorae.cpp
@@ -30,7 +30,6 @@
 #include <QDirIterator>
 #include <QGuiApplication>
 #include <QLabel>
-#include <QStyleHints>
 #include <QOffscreenSurface>
 #include <QOpenGLContext>
 #include <QOpenGLFramebufferObject>
@@ -517,13 +516,6 @@ void Decoration::mousePressEvent(QMouseEvent *event)
 {
     if (m_view) {
         m_view->forwardMouseEvent(event);
-        if (event->button() == Qt::LeftButton) {
-            if (!m_doubleClickTimer.hasExpired(QGuiApplication::styleHints()->mouseDoubleClickInterval())) {
-                QMouseEvent dc(QEvent::MouseButtonDblClick, event->localPos(), event->windowPos(), event->screenPos(), event->button(), event->buttons(), event->modifiers());
-                m_view->forwardMouseEvent(&dc);
-            }
-        }
-        m_doubleClickTimer.invalidate();
     }
     KDecoration2::Decoration::mousePressEvent(event);
 }
@@ -532,9 +524,6 @@ void Decoration::mouseReleaseEvent(QMouseEvent *event)
 {
     if (m_view) {
         m_view->forwardMouseEvent(event);
-        if (event->isAccepted() && event->button() == Qt::LeftButton) {
-            m_doubleClickTimer.start();
-        }
     }
     KDecoration2::Decoration::mouseReleaseEvent(event);
 }
diff --git a/src/plugins/kdecorations/aurorae/src/aurorae.h b/src/plugins/kdecorations/aurorae/src/aurorae.h
index fba4f8614c..5feb7c4aec 100644
--- a/src/plugins/kdecorations/aurorae/src/aurorae.h
+++ b/src/plugins/kdecorations/aurorae/src/aurorae.h
@@ -77,7 +77,6 @@ private:
     QString m_themeName;
 
     KWin::OffscreenQuickView *m_view;
-    QElapsedTimer m_doubleClickTimer;
 };
 
 class ThemeProvider : public KDecoration2::DecorationThemeProvider