Split QComPtr reset() function into a reset() and an attach() function

The name 'reset' does not specify well how ownership is handled when
reset to a new pointer value. A better name for this is 'attach', which
indicates that AddRef is not called.

'reset' now just resets the pointer to a default constructed state.

This is a step towards replacing QComPtr out with WRL::ComPtr which is used elsewhere in Qt.

Change-Id: Ic72beba8cf212669f5dfa2e01f36754ffb0ad94e
Reviewed-by: Lars Knoll <lars@knoll.priv.no>
Reviewed-by: Pavel Dubsky <pavel.dubsky@qt.io>
(cherry picked from commit b9a3961ff5966af372acad83f9dcee7f082a21c7)

5 files changed, 20 insertions, 6 deletions

diff --git a/src/multimedia/windows/qcomptr_p.h b/src/multimedia/windows/qcomptr_p.h
index 2c7818598..38cae0c17 100644
--- a/src/multimedia/windows/qcomptr_p.h
+++ b/src/multimedia/windows/qcomptr_p.h
@@ -54,7 +54,22 @@ public:
     T *operator->() const { return m_ptr; }
 
     T **address() { Q_ASSERT(m_ptr == nullptr); return &m_ptr; }
-    void reset(T *ptr = nullptr) { if (m_ptr) m_ptr->Release(); m_ptr = ptr; }
+
+    void reset()
+    {
+        if (m_ptr)
+            m_ptr->Release();
+        m_ptr = nullptr;
+    }
+
+    // Takes ownership of interface without calling AddRef
+    void attach(T *ptr)
+    {
+        if (m_ptr)
+            m_ptr->Release();
+        m_ptr = ptr;
+    }
+
     T *release() { T *ptr = m_ptr; m_ptr = nullptr; return ptr; }
     T *get() const { return m_ptr; }
 
diff --git a/src/multimedia/windows/qwindowsmediadevices.cpp b/src/multimedia/windows/qwindowsmediadevices.cpp
index cad49862a..d55b73761 100644
--- a/src/multimedia/windows/qwindowsmediadevices.cpp
+++ b/src/multimedia/windows/qwindowsmediadevices.cpp
@@ -179,7 +179,7 @@ QWindowsMediaDevices::QWindowsMediaDevices()
         }
 
 
-        m_notificationClient.reset(new CMMNotificationClient(this, m_deviceEnumerator, std::move(devState)));
+        m_notificationClient.attach(new CMMNotificationClient(this, m_deviceEnumerator, std::move(devState)));
         m_deviceEnumerator->RegisterEndpointNotificationCallback(m_notificationClient.get());
 
     } else {
diff --git a/src/plugins/multimedia/ffmpeg/qwindowscamera.cpp b/src/plugins/multimedia/ffmpeg/qwindowscamera.cpp
index a6c85dba4..d0d905ab0 100644
--- a/src/plugins/multimedia/ffmpeg/qwindowscamera.cpp
+++ b/src/plugins/multimedia/ffmpeg/qwindowscamera.cpp
@@ -185,7 +185,7 @@ public:
         if (!ac->m_source)
             return {};
 
-        ac->m_readerCallback.reset(new CameraReaderCallback);
+        ac->m_readerCallback.attach(new CameraReaderCallback);
         ac->m_readerCallback->setActiveCamera(ac.get());
         ac->m_reader = createCameraReader(ac->m_source.get(), ac->m_readerCallback);
         if (!ac->m_reader)
diff --git a/src/plugins/multimedia/windows/decoder/mfaudiodecodercontrol.cpp b/src/plugins/multimedia/windows/decoder/mfaudiodecodercontrol.cpp
index 4f25ae5ec..9d9abedb9 100644
--- a/src/plugins/multimedia/windows/decoder/mfaudiodecodercontrol.cpp
+++ b/src/plugins/multimedia/windows/decoder/mfaudiodecodercontrol.cpp
@@ -87,7 +87,7 @@ void MFAudioDecoderControl::startReadingSource(IMFMediaSource *source)
 {
     Q_ASSERT(source);
 
-    m_decoderSourceReader.reset(new MFDecoderSourceReader());
+    m_decoderSourceReader.attach(new MFDecoderSourceReader());
     if (!m_decoderSourceReader) {
         error(QAudioDecoder::ResourceError, tr("Could not instantiate MFDecoderSourceReader"));
         return;
diff --git a/src/plugins/multimedia/windows/evr/evrd3dpresentengine.cpp b/src/plugins/multimedia/windows/evr/evrd3dpresentengine.cpp
index 7fab5b8cd..1c2c2c1aa 100644
--- a/src/plugins/multimedia/windows/evr/evrd3dpresentengine.cpp
+++ b/src/plugins/multimedia/windows/evr/evrd3dpresentengine.cpp
@@ -34,10 +34,9 @@ public:
                           IMFSample *sample, QRhi *rhi, QVideoFrame::HandleType type = QVideoFrame::NoHandle)
         : QAbstractVideoBuffer(type, rhi)
         , m_device(device)
+        , m_sample(sample)
         , m_mapMode(QVideoFrame::NotMapped)
     {
-        sample->AddRef();
-        m_sample.reset(sample);
     }
 
     ~IMFSampleVideoBuffer() override