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winrt: fix camera sample queue thread safety

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Replace sample buffer QVector with C array to avoid reallocations. The
resource needs to be protected, so use atomic indexes to prevent writing
into the same array element that is being read.

Task-number: QTBUG-45667
Change-Id: Ifd30dd128765ea4794fe8614f25ef596bba891ee
Reviewed-by: Andrew Knight <qt@panimo.net>
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@theqtcompany.com>
This commit is contained in:
Peng Wu
2015-04-22 12:42:38 +03:00
committed by PengWu
parent d44f5734bf
commit 61033aa420
1 changed files with 18 additions and 5 deletions
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23
src/plugins/winrt/qwinrtcameravideorenderercontrol.cpp
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@@ -132,11 +132,14 @@ private:
ComPtr<ID3D11VideoProcessorOutputView> m_outputView;
};
#define CAMERA_SAMPLE_QUEUE_SIZE 5
class QWinRTCameraVideoRendererControlPrivate
{
public:
QScopedPointer<D3DVideoBlitter> blitter;
QVector<ComPtr<IMF2DBuffer>> buffers;
ComPtr<IMF2DBuffer> buffers[CAMERA_SAMPLE_QUEUE_SIZE];
QAtomicInteger<quint16> writeIndex;
QAtomicInteger<quint16> readIndex;
};
QWinRTCameraVideoRendererControl::QWinRTCameraVideoRendererControl(const QSize &size, QObject *parent)
@@ -153,13 +156,17 @@ bool QWinRTCameraVideoRendererControl::render(ID3D11Texture2D *target)
{
Q_D(QWinRTCameraVideoRendererControl);
if (d->buffers.isEmpty()) {
const quint16 readIndex = d->readIndex;
if (readIndex == d->writeIndex) {
emit bufferRequested();
return false;
}
HRESULT hr;
ComPtr<IMF2DBuffer> buffer = d->buffers.takeFirst();
ComPtr<IMF2DBuffer> buffer = d->buffers[readIndex];
Q_ASSERT(buffer);
d->buffers[readIndex].Reset();
d->readIndex = (readIndex + 1) % CAMERA_SAMPLE_QUEUE_SIZE;
ComPtr<ID3D11Texture2D> sourceTexture;
ComPtr<IMFDXGIBuffer> dxgiBuffer;
@@ -186,11 +193,17 @@ void QWinRTCameraVideoRendererControl::queueBuffer(IMF2DBuffer *buffer)
{
Q_D(QWinRTCameraVideoRendererControl);
Q_ASSERT(buffer);
d->buffers.append(buffer);
const quint16 writeIndex = (d->writeIndex + 1) % CAMERA_SAMPLE_QUEUE_SIZE;
if (d->readIndex == writeIndex) // Drop new sample if queue is full
return;
d->buffers[d->writeIndex] = buffer;
d->writeIndex = writeIndex;
}
void QWinRTCameraVideoRendererControl::discardBuffers()
{
Q_D(QWinRTCameraVideoRendererControl);
d->buffers.clear();
d->writeIndex = d->readIndex = 0;
for (ComPtr<IMF2DBuffer> &buffer : d->buffers)
buffer.Reset();
}