Source/WebKit/Shared/RemoteLayerTree/CGDisplayListImageBufferBackend.cpp

/*
 * Copyright (C) 2021 Apple Inc. All rights reserved.
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#include "config.h"
#include "CGDisplayListImageBufferBackend.h"

#if ENABLE(CG_DISPLAY_LIST_BACKED_IMAGE_BUFFER)

#include "Logging.h"
#include <WebCore/GraphicsContextCG.h>
#include <WebCore/PixelBuffer.h>
#include <WebKitAdditions/CGDisplayListImageBufferAdditions.h>
#include <wtf/IsoMallocInlines.h>

namespace WebKit {

class GraphicsContextCGDisplayList : public WebCore::GraphicsContextCG {
public:
    GraphicsContextCGDisplayList(CGContextRef cgContext, double immutableBaseScaleFactor)
        : GraphicsContextCG(cgContext)
        , m_scaleTransform(immutableBaseScaleFactor, 0, 0, immutableBaseScaleFactor, 0, 0)
        , m_inverseScaleTransform(1. / immutableBaseScaleFactor, 0, 0, 1. / immutableBaseScaleFactor, 0, 0)
    {
    }

    void setCTM(const WebCore::AffineTransform& transform) final
    {
        GraphicsContextCG::setCTM(m_inverseScaleTransform * transform);
    }

    WebCore::AffineTransform getCTM(IncludeDeviceScale includeDeviceScale) const final
    {
        return m_scaleTransform * GraphicsContextCG::getCTM(includeDeviceScale);
    }

    bool canUseShadowBlur() const final { return false; }

private:
    WebCore::AffineTransform m_scaleTransform;
    WebCore::AffineTransform m_inverseScaleTransform;
};

WTF_MAKE_ISO_ALLOCATED_IMPL(CGDisplayListImageBufferBackend);

size_t CGDisplayListImageBufferBackend::calculateMemoryCost(const Parameters& parameters)
{
    // FIXME: This is fairly meaningless, because we don't actually have a bitmap, and
    // should really be based on the encoded data size.
    auto backendSize = calculateBackendSize(parameters);
    return WebCore::ImageBufferBackend::calculateMemoryCost(backendSize, calculateBytesPerRow(backendSize));
}

std::unique_ptr<CGDisplayListImageBufferBackend> CGDisplayListImageBufferBackend::create(const Parameters& parameters)
{
    auto logicalSize = parameters.logicalSize;
    if (logicalSize.isEmpty())
        return nullptr;

    auto cgContext = adoptCF(WKCGCommandsContextCreate(logicalSize, nullptr));
    if (!cgContext)
        return nullptr;

    auto context = makeUnique<GraphicsContextCGDisplayList>(cgContext.get(), parameters.resolutionScale);
    return std::unique_ptr<CGDisplayListImageBufferBackend>(new CGDisplayListImageBufferBackend(parameters, WTFMove(context)));
}

std::unique_ptr<CGDisplayListImageBufferBackend> CGDisplayListImageBufferBackend::create(const Parameters& parameters, const WebCore::HostWindow*)
{
    return CGDisplayListImageBufferBackend::create(parameters);
}

CGDisplayListImageBufferBackend::CGDisplayListImageBufferBackend(const Parameters& parameters, std::unique_ptr<WebCore::GraphicsContext>&& context)
    : ImageBufferCGBackend { parameters }
    , m_context { WTFMove(context) }
{
}

ImageBufferBackendHandle CGDisplayListImageBufferBackend::createImageBufferBackendHandle() const
{
    auto data = adoptCF(WKCGCommandsContextCopyEncodedData(m_context->platformContext()));
    ASSERT(data);

#if !RELEASE_LOG_DISABLED
    auto size = backendSize();
    RELEASE_LOG(RemoteLayerTree, "CGDisplayListImageBufferBackend of size %dx%d encoded display list of %ld bytes", size.width(), size.height(), CFDataGetLength(data.get()));
#endif

    return ImageBufferBackendHandle { IPC::SharedBufferCopy { WebCore::SharedBuffer::create(data.get()) } };
}

WebCore::GraphicsContext& CGDisplayListImageBufferBackend::context() const
{
    return *m_context;
}

WebCore::IntSize CGDisplayListImageBufferBackend::backendSize() const
{
    return calculateBackendSize(m_parameters);
}

unsigned CGDisplayListImageBufferBackend::bytesPerRow() const
{
    return calculateBytesPerRow(backendSize());
}

RefPtr<WebCore::NativeImage> CGDisplayListImageBufferBackend::copyNativeImage(WebCore::BackingStoreCopy) const
{
    ASSERT_NOT_REACHED();
    return nullptr;
}

std::optional<WebCore::PixelBuffer> CGDisplayListImageBufferBackend::getPixelBuffer(const WebCore::PixelBufferFormat&, const WebCore::IntRect&) const
{
    ASSERT_NOT_REACHED();
    return { };
}

void CGDisplayListImageBufferBackend::putPixelBuffer(const WebCore::PixelBuffer&, const WebCore::IntRect&, const WebCore::IntPoint&, WebCore::AlphaPremultiplication)
{
    ASSERT_NOT_REACHED();
}

}

#endif // ENABLE(CG_DISPLAY_LIST_BACKED_IMAGE_BUFFER)