From 85e82de916e8799ee1198c63566b7a1f5e47f514 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Mon, 1 Jun 2020 11:54:45 +0200
Subject: [PATCH] QPainter: replace manual memory management [3/5]: engine

Use unique_ptr to indicate ownership, even though it's conditional (on
QPaintEngine::autoDestruct()). That just requires a custom deleter.

Change-Id: Icf8e356c333f9617b2e5172b14f13197e63c9502
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
---
 src/gui/painting/qpainter.cpp | 12 +++++-------
 src/gui/painting/qpainter_p.h | 10 +++++++++-
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index eca80f55f0..eb51e9cc24 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -1545,7 +1545,7 @@ QPaintDevice *QPainter::device() const
 bool QPainter::isActive() const
 {
     Q_D(const QPainter);
-    return d->engine;
+    return d->engine != nullptr;
 }
 
 void QPainterPrivate::initFrom(const QPaintDevice *device)
@@ -1744,7 +1744,7 @@ bool QPainter::begin(QPaintDevice *pd)
     else if (pd->devType() == QInternal::Image)
         static_cast<QImage *>(pd)->detach();
 
-    d->engine = pd->paintEngine();
+    d->engine.reset(pd->paintEngine());
 
     if (!d->engine) {
         qWarning("QPainter::begin: Paint device returned engine == 0, type: %d", pd->devType());
@@ -1753,7 +1753,7 @@ bool QPainter::begin(QPaintDevice *pd)
 
     d->device = pd;
 
-    d->extended = d->engine->isExtended() ? static_cast<QPaintEngineEx *>(d->engine) : nullptr;
+    d->extended = d->engine->isExtended() ? static_cast<QPaintEngineEx *>(d->engine.get()) : nullptr;
     if (d->emulationEngine)
         d->emulationEngine->real_engine = d->extended;
 
@@ -1911,9 +1911,7 @@ bool QPainter::end()
         qWarning("QPainter::end: Painter ended with %d saved states", int(d->savedStates.size()));
     }
 
-    if (d->engine->autoDestruct()) {
-        delete d->engine;
-    }
+    d->engine.reset();
 
     if (d->emulationEngine) {
         delete d->emulationEngine;
@@ -1939,7 +1937,7 @@ bool QPainter::end()
 QPaintEngine *QPainter::paintEngine() const
 {
     Q_D(const QPainter);
-    return d->engine;
+    return d->engine.get();
 }
 
 /*!
diff --git a/src/gui/painting/qpainter_p.h b/src/gui/painting/qpainter_p.h
index 8994bcd3e7..c9caca7901 100644
--- a/src/gui/painting/qpainter_p.h
+++ b/src/gui/painting/qpainter_p.h
@@ -268,7 +268,15 @@ public:
     QPaintDevice *device;
     QPaintDevice *original_device;
     QPaintDevice *helper_device;
-    QPaintEngine *engine;
+    struct QPaintEngineDestructor {
+        void operator()(QPaintEngine *pe) const noexcept
+        {
+            if (pe && pe->autoDestruct())
+                delete pe;
+        }
+    };
+
+    std::unique_ptr<QPaintEngine, QPaintEngineDestructor> engine;
     QEmulationPaintEngine *emulationEngine;
     QPaintEngineEx *extended;
     QBrush colorBrush;          // for fill with solid color