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#include "qiosbackingstore.h"
#include "qioswindow.h"

#include <QtGui/QOpenGLContext>
#include <QtGui/QOpenGLPaintDevice>
#include <QtGui/QOpenGLFramebufferObject>
#include <QtGui/QOffscreenSurface>
#include <QtGui/qpainter.h>
#include <QtGui/private/qwindow_p.h>

#include <QtDebug>

class QIOSPaintDevice : public QOpenGLPaintDevice
{
public:
    QIOSPaintDevice(QIOSBackingStore *backingStore) : m_backingStore(backingStore) { }
    void ensureActiveTarget() Q_DECL_OVERRIDE;

private:
    QIOSBackingStore *m_backingStore;
};

void QIOSPaintDevice::ensureActiveTarget()
{
    m_backingStore->makeCurrent();
}

QIOSBackingStore::QIOSBackingStore(QWindow *window)
    : QRasterBackingStore(window)
    , m_context(new QOpenGLContext)
    , m_glDevice(nullptr)
{
    QSurfaceFormat fmt = window->requestedFormat();

    // Due to sharing QIOSContext redirects our makeCurrent on window() attempts to
    // the global share context. Hence it is essential to have a compatible format.
    fmt.setDepthBufferSize(QSurfaceFormat::defaultFormat().depthBufferSize());
    fmt.setStencilBufferSize(QSurfaceFormat::defaultFormat().stencilBufferSize());

    if (fmt.depthBufferSize() == 0)
        qWarning("No depth in default format, expect rendering errors");

    // We use the surface both for raster operations and for GL drawing (when
    // we blit the raster image), so the type needs to cover both use cases.
    if (window->surfaceType() == QSurface::RasterSurface)
        window->setSurfaceType(QSurface::RasterGLSurface);

    m_context->setFormat(fmt);
    m_context->setScreen(window->screen());
    Q_ASSERT(QOpenGLContext::globalShareContext());
    m_context->setShareContext(QOpenGLContext::globalShareContext());
    m_context->create();
}

QIOSBackingStore::~QIOSBackingStore()
{
    delete m_context;
    delete m_glDevice;
}

void QIOSBackingStore::makeCurrent()
{
    if (!m_context->makeCurrent(window()))
        qWarning("QIOSBackingStore: makeCurrent() failed");
}

void QIOSBackingStore::beginPaint(const QRegion &region)
{
    makeCurrent();

    if (!m_glDevice)
        m_glDevice = new QIOSPaintDevice(this);

    if (window()->surfaceType() == QSurface::RasterGLSurface)
        QRasterBackingStore::beginPaint(region);
}

void QIOSBackingStore::endPaint()
{
}

QPaintDevice *QIOSBackingStore::paintDevice()
{
    Q_ASSERT(m_glDevice);

    // Keep paint device size and device pixel ratio in sync with window
    qreal devicePixelRatio = window()->devicePixelRatio();
    m_glDevice->setSize(window()->size() * devicePixelRatio);
    m_glDevice->setDevicePixelRatio(devicePixelRatio);

    if (window()->surfaceType() == QSurface::RasterGLSurface)
        return QRasterBackingStore::paintDevice();
    else
        return m_glDevice;
}

void QIOSBackingStore::flush(QWindow *window, const QRegion &region, const QPoint &offset)
{
    Q_ASSERT(!qt_window_private(window)->compositing);

    Q_UNUSED(region);
    Q_UNUSED(offset);

    if (window != this->window()) {
        // We skip flushing raster-based child windows, to avoid the extra cost of copying from the
        // parent FBO into the child FBO. Since the child is already drawn inside the parent FBO, it
        // will become visible when flushing the parent. The only case we end up not supporting is if
        // the child window overlaps a sibling window that's draws using a separate QOpenGLContext.
        return;
    }

    if (window->surfaceType() == QSurface::RasterGLSurface) {
        static QPlatformTextureList emptyTextureList;
        composeAndFlush(window, region, offset, &emptyTextureList, m_context, false);
    } else {
        m_context->makeCurrent(window);
        m_context->swapBuffers(window);
    }
}

void QIOSBackingStore::resize(const QSize &size, const QRegion &staticContents)
{
    Q_UNUSED(staticContents);

    if (window()->surfaceType() == QSurface::OpenGLSurface) {
        // Resizing the backing store would in this case mean resizing the QWindow,
        // as we use an QOpenGLPaintDevice that we target at the window. That's
        // probably not what the user intended, so we ignore resizes of the backing
        // store and always keep the paint device's size in sync with the window
        // size in beginPaint().

        if (size != window()->size() && !window()->inherits("QWidgetWindow"))
            qWarning("QIOSBackingStore needs to have the same size as its window");

        return;
    }

    QRasterBackingStore::resize(size, staticContents);
}

QT_END_NAMESPACE