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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QWINDOWSDIRECT2DDEVICECONTEXT_H
#define QWINDOWSDIRECT2DDEVICECONTEXT_H
#include <QtCore/qscopedpointer.h>
QT_BEGIN_NAMESPACE
/*
* Convenience class for handling device contexts. We have to call BeginDraw
* before anything can happen, and EndDraw once we're done, for every frame and
* pretty much any kind of operation.
*
* Unfortunately, these calls cannot be interleaved, and there is no way to check
* what state a device context is in.
*
* The end result is that the following throws an error if we don't track it:
* QPixmap pmap;
* QPainter painter(&pmap);
* pmap.clear();
*
* Here BeginDraw would first be called through the paint device, then when we clear
* the pixmap we would have to call it again. There is no way to know what state
* the device context is in when performing the clear, and activating the dc is an
* error. Bummer.
*
* Hence we keep a reference count here and only activate/deactivate the device
* if the refcount is zero.
*
* In a nutshell: Do not call BeginDraw/EndDraw yourself on the device pointer, do
* so through the begin/end members below.
*/
class QWindowsDirect2DDeviceContextPrivate;
class QWindowsDirect2DDeviceContext
{
Q_DECLARE_PRIVATE(QWindowsDirect2DDeviceContext)
friend class QWindowsDirect2DDeviceContextSuspender;
public:
QWindowsDirect2DDeviceContext(ID2D1DeviceContext *dc);
~QWindowsDirect2DDeviceContext();
ID2D1DeviceContext *get() const;
void begin();
bool end();
private:
void suspend();
void resume();
QScopedPointer<QWindowsDirect2DDeviceContextPrivate> d_ptr;
};
class QWindowsDirect2DDeviceContextSuspender {
Q_DISABLE_COPY_MOVE(QWindowsDirect2DDeviceContextSuspender)
QWindowsDirect2DDeviceContext *m_dc;
public:
QWindowsDirect2DDeviceContextSuspender(QWindowsDirect2DDeviceContext *dc);
~QWindowsDirect2DDeviceContextSuspender();
void resume();
};
QT_END_NAMESPACE
#endif // QWINDOWSDIRECT2DDEVICECONTEXT_H
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