/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce
{
/*  Resulting pages are arranged in rows from left to right, then top to bottom
*/
static std::vector<Direct2DPixelDataPage> makePages (ComSmartPtr<ID2D1Device1> device,
                                                     ImagePixelData::Ptr backingData,
                                                     bool needsClear)
{
    if (device == nullptr || backingData == nullptr)
    {
        jassertfalse;
        return {};
    }

    // We create a new context rather than reusing an existing one, because we'll run into problems
    // if we call BeginDraw/EndDraw on a context that's already doing its own drawing
    const auto context = Direct2DDeviceContext::create (device);

    if (context == nullptr)
    {
        jassertfalse;
        return {};
    }

    const auto maxDim = (size_t) context->GetMaximumBitmapSize();
    std::vector<Direct2DPixelDataPage> result;

    const auto width = (size_t) backingData->width;
    const auto height = (size_t) backingData->height;
    const auto pixelFormat = backingData->pixelFormat;

    for (size_t h = 0; h < height; h += maxDim)
    {
        const auto tileHeight = (UINT32) jmin (maxDim, height - h);

        for (size_t w = 0; w < width; w += maxDim)
        {
            const auto tileWidth = (UINT32) jmin (maxDim, width - w);

            const auto bitmap = Direct2DBitmap::createBitmap (context,
                                                              pixelFormat,
                                                              D2D1::SizeU (tileWidth, tileHeight),
                                                              D2D1_BITMAP_OPTIONS_TARGET);

            jassert (bitmap != nullptr);

            if (needsClear)
            {
                context->SetTarget (bitmap);
                context->BeginDraw();
                context->Clear();
                context->EndDraw();
            }

            result.push_back (Direct2DPixelDataPage { bitmap, { (int) w, (int) h } });
        }
    }

    return result;
}

/*  Maps the content of the provided bitmap and copies it into target, which should be a software
    bitmap.
*/
static bool readFromDirect2DBitmap (ComSmartPtr<ID2D1DeviceContext1> context,
                                    ComSmartPtr<ID2D1Bitmap1> bitmap,
                                    ImagePixelData::Ptr target)
{
    if (bitmap == nullptr || context == nullptr || target == nullptr)
        return false;

    const auto size = bitmap->GetPixelSize();

    if (std::tuple (target->width, target->height) != std::tuple ((int) size.width, (int) size.height))
    {
        // Mismatched sizes, unable to read D2D image back into software image!
        jassertfalse;
        return false;
    }

    const auto readableBitmap = Direct2DBitmap::createBitmap (context,
                                                              target->pixelFormat,
                                                              size,
                                                              D2D1_BITMAP_OPTIONS_CPU_READ | D2D1_BITMAP_OPTIONS_CANNOT_DRAW);

    const auto dstPoint = D2D1::Point2U();
    const auto srcRect = D2DUtilities::toRECT_U (D2DUtilities::rectFromSize (size));
    readableBitmap->CopyFromBitmap (&dstPoint, bitmap, &srcRect);

    // This is only used to construct a read-only BitmapData backed by a texture for conversion to a
    // software image
    struct TexturePixelData : public ImagePixelData
    {
        TexturePixelData (ComSmartPtr<ID2D1Bitmap1> bitmapIn, Image::PixelFormat format, int w, int h)
            : ImagePixelData (format, w, h),
              bitmap (bitmapIn)
        {
        }

        std::unique_ptr<LowLevelGraphicsContext> createLowLevelContext() override
        {
            jassertfalse; // This should never be called
            return {};
        }

        Ptr clone() override
        {
            jassertfalse; // This should never be called
            return {};
        }

        std::unique_ptr<ImageType> createType() const override
        {
            jassertfalse; // This should never be called
            return {};
        }

        // Unimplemented, should never be called
        void applyGaussianBlurEffectInArea (Rectangle<int>, float) override { jassertfalse; }
        // Unimplemented, should never be called
        void applySingleChannelBoxBlurEffectInArea (Rectangle<int>, int) override { jassertfalse; }
        // Unimplemented, should never be called
        void multiplyAllAlphasInArea (Rectangle<int>, float) override { jassertfalse; }
        // Unimplemented, should never be called
        void desaturateInArea (Rectangle<int>) override { jassertfalse; }

        void initialiseBitmapData (Image::BitmapData& bd, int x, int y, Image::BitmapData::ReadWriteMode mode) override
        {
            if (mode != Image::BitmapData::readOnly)
            {
                // This type only supports read-only access
                jassertfalse;
                return;
            }

            struct Releaser : public Image::BitmapData::BitmapDataReleaser
            {
                explicit Releaser (ComSmartPtr<ID2D1Bitmap1> toUnmapIn) : toUnmap (toUnmapIn) {}
                ~Releaser() override { toUnmap->Unmap(); }
                ComSmartPtr<ID2D1Bitmap1> toUnmap;
            };

            D2D1_MAPPED_RECT mapped{};
            bitmap->Map (D2D1_MAP_OPTIONS_READ, &mapped);
            const auto dataEnd = mapped.bits + bitmap->GetPixelSize().height * mapped.pitch;

            bd.pixelFormat = pixelFormat;
            bd.pixelStride = pixelFormat == Image::SingleChannel ? 1 : 4;
            bd.lineStride = (int) mapped.pitch;
            bd.data = mapped.bits + x * bd.pixelStride + y * (int) mapped.pitch;
            bd.size = (size_t) (dataEnd - bd.data);
            bd.dataReleaser = std::make_unique<Releaser> (bitmap);
        }

        ComSmartPtr<ID2D1Bitmap1> bitmap;
    };

    Image srcImage { new TexturePixelData { readableBitmap,
                                            target->pixelFormat,
                                            (int) size.width,
                                            (int) size.height } };

    Image::BitmapData dstData { Image { target }, Image::BitmapData::writeOnly };
    dstData.convertFrom ({ srcImage, Image::BitmapData::readOnly });

    return true;
}

/*  Returns new software bitmap storage with content matching the provided hardware bitmap. */
static ImagePixelData::Ptr readFromDirect2DBitmap (ComSmartPtr<ID2D1DeviceContext1> context,
                                                   ComSmartPtr<ID2D1Bitmap1> bitmap)
{
    if (bitmap == nullptr)
        return {};

    const auto size = bitmap->GetPixelSize();
    const auto result = SoftwareImageType{}.create (Image::ARGB,
                                                    (int) size.width,
                                                    (int) size.height,
                                                    false);

    if (result == nullptr || ! readFromDirect2DBitmap (context, bitmap, result))
        return {};

    return result;
}

//==============================================================================
Direct2DPixelDataPages::Direct2DPixelDataPages (ImagePixelDataBackupExtensions* parent,
                                                ComSmartPtr<ID2D1Bitmap1> bitmap,
                                                ImagePixelData::Ptr image)
    : parentBackupExtensions (parent),
      backingData (image),
      pages { Page { bitmap, {} } },
      upToDate (true)
{
    // The backup image must be a software image
    jassert (image->createType()->getTypeID() == SoftwareImageType{}.getTypeID());
}

Direct2DPixelDataPages::Direct2DPixelDataPages (ImagePixelDataBackupExtensions* parent,
                                                ComSmartPtr<ID2D1Device1> device,
                                                ImagePixelData::Ptr image,
                                                State initialState)
    : parentBackupExtensions (parent),
      backingData (image),
      pages (makePages (device, backingData, initialState == State::cleared)),
      upToDate (initialState != State::unsuitableToRead)
{
    // The backup image must be a software image
    jassert (image->createType()->getTypeID() == SoftwareImageType{}.getTypeID());
}

auto Direct2DPixelDataPages::getPagesWithoutSync() const -> Span<const Page>
{
    // Accessing page data which is out-of-date!
    jassert (upToDate);
    return pages;
}

auto Direct2DPixelDataPages::getPages() -> Span<const Page>
{
    const ScopeGuard scope { [this] { upToDate = true; } };

    if (upToDate)
        return pages;

    // We need to make sure that the parent image is up-to-date, otherwise we'll end up
    // fetching outdated image data.
    parentBackupExtensions->backupNow();

    auto sourceToUse = backingData->pixelFormat == Image::RGB
                     ? Image { backingData }.convertedToFormat (Image::ARGB)
                     : Image { backingData };

    for (const auto& page : pages)
    {
        const auto pageBounds = page.getBounds();
        const Image::BitmapData bitmapData { sourceToUse,
                                             pageBounds.getX(),
                                             pageBounds.getY(),
                                             pageBounds.getWidth(),
                                             pageBounds.getHeight(),
                                             Image::BitmapData::readOnly };

        const auto target = D2DUtilities::toRECT_U (pageBounds.withZeroOrigin());
        const auto hr = page.bitmap->CopyFromMemory (&target, bitmapData.data, (UINT32) bitmapData.lineStride);
        jassertquiet (SUCCEEDED (hr));
    }

    return pages;
}

std::optional<Direct2DPixelDataPage> Direct2DPixelDataPages::getPageContainingPoint (Point<int> pt) const
{
    if (pages.empty() || backingData == nullptr || backingData->width <= 0)
        return {};

    const auto maxPageBounds = pages.front().getBounds();
    const auto pageX = pt.x / maxPageBounds.getWidth();
    const auto pageY = pt.y / maxPageBounds.getHeight();
    const auto pagesPerRow = 1 + ((backingData->width - 1) / maxPageBounds.getWidth());

    jassert (pages.size() % (size_t) pagesPerRow == 0);

    const auto result = pages[(size_t) (pageX + (pageY * pagesPerRow))];

    jassert (result.getBounds().contains (pt));

    return result;
}

//==============================================================================
Direct2DPixelData::Direct2DPixelData (ImagePixelData::Ptr ptr, State initialState)
    : ImagePixelData { ptr->pixelFormat, ptr->width, ptr->height },
      backingData (ptr),
      state (initialState)
{
    jassert (backingData->createType()->getTypeID() == SoftwareImageType{}.getTypeID());
    directX->adapters.addListener (*this);
}

Direct2DPixelData::Direct2DPixelData (ComSmartPtr<ID2D1Device1> device,
                                      ComSmartPtr<ID2D1Bitmap1> page)
    : Direct2DPixelData (readFromDirect2DBitmap (Direct2DDeviceContext::create (device), page), State::drawn)
{
    pagesForDevice.emplace (device, Direct2DPixelDataPages { this, page, backingData });
}

Direct2DPixelData::Direct2DPixelData (Image::PixelFormat formatToUse, int w, int h, bool clearIn)
    : Direct2DPixelData { SoftwareImageType{}.create (formatToUse, w, h, clearIn),
                          clearIn ? State::initiallyCleared : State::initiallyUndefined }
{
}

Direct2DPixelData::~Direct2DPixelData()
{
    directX->adapters.removeListener (*this);
}

bool Direct2DPixelData::createPersistentBackup (ComSmartPtr<ID2D1Device1> deviceHint)
{
    if (state == State::drawing)
    {
        // Creating a backup while the image is being modified would leave the backup in an invalid state
        jassertfalse;
        return false;
    }

    // If the backup is not outdated, then it must be up-to-date
    if (state != State::outdated)
        return true;

    const auto iter = deviceHint != nullptr
                    ? pagesForDevice.find (deviceHint)
                    : std::find_if (pagesForDevice.begin(),
                                    pagesForDevice.end(),
                                    [] (const auto& pair) { return pair.second.isUpToDate(); });

    if (iter == pagesForDevice.end())
    {
        // There's no up-to-date image in graphics memory, so the graphics device probably got
        // removed, dropping our image data. The image data is irrevocably lost!
        jassertfalse;
        return false;
    }

    auto& [device, pages] = *iter;
    const auto context = Direct2DDeviceContext::create (device);

    if (context == nullptr)
    {
        // Unable to create a device context to read the image data
        jassertfalse;
        return false;
    }

    const auto result = readFromDirect2DBitmap (context, pages.getPagesWithoutSync().front().bitmap, backingData);
    state = result ? State::drawn : State::outdated;
    return result;
}

auto Direct2DPixelData::getIteratorForDevice (ComSmartPtr<ID2D1Device1> device)
{
    mostRecentDevice = device;

    if (device == nullptr)
        return pagesForDevice.end();

    const auto iter = pagesForDevice.find (device);

    if (iter != pagesForDevice.end())
        return iter;

    const auto initialState = [&]
    {
        switch (state)
        {
            // If our image is currently cleared, then the initial state of the page should also
            // be cleared.
            case State::initiallyCleared:
                return Pages::State::cleared;

            // If our image holds junk, then it must be written before first read, which means
            // that the cached pages must also be written before first read. Don't mark the new
            // pages as needing a sync yet - there's a chance that we'll render directly into
            // the new pages, in which case copying the initial state from the software image
            // would be unnecessary and wasteful.
            case State::initiallyUndefined:
                return Pages::State::suitableToRead;

            // If the software image has been written with valid data, then we need to preserve
            // this data when reading or writing (e.g. to a subsection, or with transparency)
            // to the new pages, so mark the new pages as needing a sync before first access.
            case State::drawn:
                return Pages::State::unsuitableToRead;

            // If this is hit, there's already another BitmapData or Graphics context active on this
            // image. Only one BitmapData or Graphics context may be active on an Image at a time.
            case State::drawing:
                jassertfalse;
                return Pages::State::unsuitableToRead;

            // If this is hit, the pages will need to be synced through main memory before they are
            // suitable for reading.
            case State::outdated:
                return Pages::State::unsuitableToRead;
        }

        // Unhandled switch case?
        jassertfalse;
        return Pages::State::unsuitableToRead;
    }();

    const auto pair = pagesForDevice.emplace (device, Pages { this, device, backingData, initialState });
    return pair.first;
}

struct Direct2DPixelData::Context : public Direct2DImageContext
{
    Context (Ptr selfIn,
             ComSmartPtr<ID2D1DeviceContext1> context,
             ComSmartPtr<ID2D1Bitmap1> target)
        : Direct2DImageContext (context, target, D2DUtilities::rectFromSize (target->GetPixelSize())),
          self (selfIn),
          frameStarted (startFrame (1.0f))
    {
        if (frameStarted)
            self->state = State::drawing;
    }

    ~Context() override
    {
        if (! frameStarted)
            return;

        endFrame();

        self->state = State::outdated;

        if (self->sync)
            self->createPersistentBackup (D2DUtilities::getDeviceForContext (getDeviceContext()));
    }

    Ptr self;
    bool frameStarted = false;
};

ComSmartPtr<ID2D1Device1> Direct2DPixelData::getMostRelevantDevice()
{
    if (mostRecentDevice != nullptr)
        return mostRecentDevice;

    const auto adapter = directX->adapters.getDefaultAdapter();

    if (adapter == nullptr)
        return nullptr;

    return adapter->direct2DDevice;
}

auto Direct2DPixelData::createNativeContext() -> std::unique_ptr<Context>
{
    if (state == State::drawing)
        return nullptr;

    sendDataChangeMessage();

    const auto device = getMostRelevantDevice();

    if (device == nullptr)
        return nullptr;

    const auto context = Direct2DDeviceContext::create (device);

    if (context == nullptr)
        return nullptr;

    const auto maxSize = (int) context->GetMaximumBitmapSize();

    if (maxSize < width || maxSize < height)
        return nullptr;

    const auto iter = getIteratorForDevice (device);
    jassert (iter != pagesForDevice.end());

    const auto pages = iter->second.getPages();

    if (pages.empty() || pages.front().bitmap == nullptr)
        return nullptr;

    // Every page *other than the page we're about to render onto* will need to be updated from the
    // software image before it is next read.
    for (auto i = pagesForDevice.begin(); i != pagesForDevice.end(); ++i)
        if (i != iter)
            i->second.markOutdated();

    return std::make_unique<Context> (this, context, pages.front().bitmap);
}

struct ScopedBackupDisabler
{
    explicit ScopedBackupDisabler (Direct2DPixelData& pd)
        : ScopedBackupDisabler (*pd.getBackupExtensions())
    {
        jassert (pd.getBackupExtensions() != nullptr);
    }

    explicit ScopedBackupDisabler (ImagePixelDataBackupExtensions& ext)
        : extensions (ext)
    {
        extensions.setBackupEnabled (false);
    }


    ~ScopedBackupDisabler()
    {
        extensions.setBackupEnabled (initialState);
    }

private:
    ImagePixelDataBackupExtensions& extensions;
    bool initialState = extensions.isBackupEnabled();
};

ImagePixelData::Ptr Direct2DPixelData::clone()
{
    auto device = getMostRelevantDevice();
    auto* exts = getBackupExtensions();

    if (device == nullptr || exts == nullptr || exts->isBackupEnabled())
        return new Direct2DPixelData { backingData->clone(), State::drawn };

    Ptr clonedPixelData = new Direct2DPixelData { pixelFormat, width, height, false };

    const ScopedBackupDisabler scope { *this };
    const ScopedBackupDisabler clonedScope { *clonedPixelData };

    copyPages (device,
               *clonedPixelData,
               *this,
               { 0, 0 },
               { 0, 0, width, height });

    return clonedPixelData;
}

void Direct2DPixelData::moveValidatedImageSection (Point<int> destTopLeft, Rectangle<int> sourceRect)
{
    auto device = getMostRelevantDevice();

    const auto shouldDoSoftwareCopy = std::invoke ([&]
    {
        if (auto exts = getBackupExtensions(); exts != nullptr && ! exts->isBackupEnabled())
            return true;

        if (device == nullptr || getPagesForDevice (device).empty())
            return true;

        return false;
    });

    if (shouldDoSoftwareCopy)
    {
        moveValidatedImageSectionInSoftware (*this, destTopLeft, sourceRect);
        return;
    }

    sendDataChangeMessage();

    Ptr staging = new Direct2DPixelData { pixelFormat,
                                          sourceRect.getWidth(),
                                          sourceRect.getHeight(),
                                          false };

    const ScopedBackupDisabler thisScope { *this };
    const ScopedBackupDisabler stagingScope { *staging };

    copyPages (device, *staging, *this, {}, sourceRect);
    copyPages (device, *this, *staging, destTopLeft, sourceRect.withPosition ({}));
}

template <typename Pages, typename ProcessSubsection>
static void forEachPageInRect (Rectangle<int> rect,
                               Pages&& pages,
                               ProcessSubsection&& processSubsection)
{
    for (auto srcY = rect.getY(); srcY < rect.getBottom();)
    {
        for (auto srcX = rect.getX(); srcX < rect.getRight();)
        {
            const auto srcPage = getPageForPoint (pages, Point { srcX, srcY });

            if (! srcPage.has_value())
            {
                jassertfalse;
                return;
            }

            const auto srcPageBounds = getBounds (*srcPage);
            const auto intersection = srcPageBounds.getIntersection (rect);

            processSubsection (*srcPage, intersection - srcPageBounds.getTopLeft());

            srcX = srcPageBounds.getRight();
        }

        srcY = getBounds (*getPageForPoint (pages, Point { rect.getX(), srcY })).getBottom();
    }
}

template <typename Pages, typename DoCopy>
static void copyAcrossMultiplePages (Pages&& dstPages,
                                     Point<int> dst,
                                     Pages&& srcPages,
                                     Rectangle<int> src,
                                     DoCopy&& doCopy)
{
    const auto globalOffset = dst - src.getTopLeft();

    forEachPageInRect (src, srcPages, [&] (auto& srcPage, Rectangle<int> rectInSrcPage)
    {
        const auto srcPageTopLeft = getBounds (srcPage).getTopLeft();
        const auto srcRectSectionInSrc = rectInSrcPage + srcPageTopLeft;
        const auto srcRectSectionInDst = srcRectSectionInSrc + globalOffset;

        forEachPageInRect (srcRectSectionInDst, dstPages, [&] (auto& dstPage, Rectangle<int> rectInDstPage)
        {
            const auto dstRectSectionInDst = rectInDstPage + getBounds (dstPage).getTopLeft();
            const auto dstRectSectionInSrc = dstRectSectionInDst - globalOffset;
            const auto dstRectSectionInSrcPage = dstRectSectionInSrc - srcPageTopLeft;

            doCopy (dstPage, rectInDstPage.getTopLeft(), srcPage, dstRectSectionInSrcPage);
        });
    });
}

static std::optional<Direct2DPixelDataPage> getPageForPoint (const Direct2DPixelDataPages& pages,
                                                             Point<int> pt)
{
    return pages.getPageContainingPoint (pt);
}

static Rectangle<int> getBounds (const Direct2DPixelDataPage& p)
{
    return p.getBounds();
}

static void copyDstFromSrc (const Direct2DPixelDataPage& dst,
                            Point<int> dstPoint,
                            const Direct2DPixelDataPage& src,
                            Rectangle<int> srcRect)
{
    jassert (! srcRect.isEmpty());
    jassert (dst.bitmap != src.bitmap);

    const auto sourceRect = D2DUtilities::toRECT_U (srcRect);
    const auto destPoint  = D2DUtilities::toPOINT_2U (dstPoint);

    dst.bitmap->CopyFromBitmap (&destPoint, src.bitmap, &sourceRect);
}

void Direct2DPixelData::copyPages (ComSmartPtr<ID2D1Device1> deviceToUse,
                                   Direct2DPixelData& dstData,
                                   Direct2DPixelData& srcData,
                                   Point<int> dstPoint,
                                   Rectangle<int> srcRect)
{
    auto& srcPages = srcData.getPagesStructForDevice (deviceToUse);
    srcPages.getPages();

    copyAcrossMultiplePages (dstData.getPagesStructForDevice (deviceToUse),
                             dstPoint,
                             srcPages,
                             srcRect,
                             copyDstFromSrc);

    dstData.state = State::outdated;
}

std::unique_ptr<LowLevelGraphicsContext> Direct2DPixelData::createLowLevelContext()
{
    if (state == State::drawing)
    {
        // If this is hit, there's already a BitmapData or Graphics context active, drawing to this
        // image. Perhaps you have two Graphics instances drawing into the image, or maybe you
        // called Image::clear while also having a Graphics instance in scope that is targeting this
        // image. A Direct2D Image can only have a single Graphics object active at a time.
        // To fix this issue, check the call stack to see where this assertion is being hit, then
        // modify the program to ensure no other BitmapData or Graphics context is active at this point.
        jassertfalse;

        struct InertContext : public LowLevelGraphicsContext
        {
            bool isVectorDevice() const override { return false; }
            void setOrigin (Point<int>) override {}
            void addTransform (const AffineTransform&) override {}
            float getPhysicalPixelScaleFactor() const override { return 1.0f; }
            bool clipToRectangle (const Rectangle<int>&) override { return false; }
            bool clipToRectangleList (const RectangleList<int>&) override { return false; }
            void excludeClipRectangle (const Rectangle<int>&) override {}
            void clipToPath (const Path&, const AffineTransform&) override {}
            void clipToImageAlpha (const Image&, const AffineTransform&) override {}
            bool clipRegionIntersects (const Rectangle<int>&) override { return false; }
            Rectangle<int> getClipBounds() const override { return {}; }
            bool isClipEmpty() const override { return true; }
            void saveState() override {}
            void restoreState() override {}
            void beginTransparencyLayer (float) override {}
            void endTransparencyLayer() override {}
            void setFill (const FillType&) override {}
            void setOpacity (float) override {}
            void setInterpolationQuality (Graphics::ResamplingQuality) override {}
            void fillRect (const Rectangle<int>&, bool) override {}
            void fillRect (const Rectangle<float>&) override {}
            void fillRectList (const RectangleList<float>&) override {}
            void fillPath (const Path&, const AffineTransform&) override {}
            void drawImage (const Image&, const AffineTransform&) override {}
            void drawLine (const Line<float>&) override {}
            void setFont (const Font& f) override { font = f; }
            const Font& getFont() override { return font; }
            void drawGlyphs (Span<const uint16_t>, Span<const Point<float>>, const AffineTransform&) override {}
            uint64_t getFrameId() const override { return 0; }
            Font font { FontOptions{} };
            std::unique_ptr<ImageType> getPreferredImageTypeForTemporaryImages() const override
            {
                return std::make_unique<NativeImageType>();
            }
        };

        return std::make_unique<InertContext>();
    }

    if (auto ptr = createNativeContext())
        return ptr;

    // If this is hit, something has gone wrong when trying to create a Direct2D renderer,
    // and we're about to fall back to a software renderer instead.
    jassertfalse;

    for (auto& pair : pagesForDevice)
        pair.second.markOutdated();

    return backingData->createLowLevelContext();
}

void Direct2DPixelData::initialiseBitmapData (Image::BitmapData& bitmap,
                                              int x,
                                              int y,
                                              Image::BitmapData::ReadWriteMode mode)
{
    // If this is hit, there's already another BitmapData or Graphics context active on this
    // image. Only one BitmapData or Graphics context may be active on an Image at a time.
    jassert (state != State::drawing);

    // If we're about to read from the image, and the main-memory copy of the image is outdated,
    // then we must force a backup so that we can return up-to-date data
    if (mode != Image::BitmapData::writeOnly
        || Rectangle { x, y, bitmap.width, bitmap.height } != Rectangle { width, height })
    {
        createPersistentBackup (nullptr);
    }

    backingData->initialiseBitmapData (bitmap, x, y, mode);

    // If we're writing, then we'll need to update our textures next time we try to use them, so
    // mark them as outdated.
    if (mode == Image::BitmapData::readOnly)
        return;

    sendDataChangeMessage();

    struct Releaser : public Image::BitmapData::BitmapDataReleaser
    {
        Releaser (std::unique_ptr<BitmapDataReleaser> wrappedIn, Ptr selfIn)
            : wrapped (std::move (wrappedIn)), self (std::move (selfIn))
        {
            self->state = State::drawing;
        }

        ~Releaser() override
        {
            self->state = State::drawn;

            for (auto& pair : self->pagesForDevice)
                pair.second.markOutdated();
        }

        std::unique_ptr<BitmapDataReleaser> wrapped;
        Ptr self;
    };

    bitmap.dataReleaser = std::make_unique<Releaser> (std::move (bitmap.dataReleaser), this);
}

template <typename Fn>
bool Direct2DPixelData::applyEffectInArea (Rectangle<int> area, Fn&& configureEffect)
{
    const auto internalGraphicsContext = createNativeContext();

    if (internalGraphicsContext == nullptr)
    {
        // Something when wrong while trying to create a device context with this image as a target
        jassertfalse;
        return false;
    }

    const auto context = internalGraphicsContext->getDeviceContext();

    if (context == nullptr)
        return false;

    ComSmartPtr<ID2D1Image> target;
    context->GetTarget (target.resetAndGetPointerAddress());

    if (target == nullptr)
        return false;

    const auto size = D2D1::SizeU ((UINT32) area.getWidth(), (UINT32) area.getHeight());

    ComSmartPtr<ID2D1Bitmap> copy;
    context->CreateBitmap (size,
                           D2D1::BitmapProperties (context->GetPixelFormat()),
                           copy.resetAndGetPointerAddress());

    if (copy == nullptr)
        return false;

    const auto rect = D2DUtilities::toRECT_U (area);
    copy->CopyFromRenderTarget (nullptr, context, &rect);

    const auto effect = configureEffect (context, copy);

    if (effect == nullptr)
        return false;

    const auto destPoint = D2D1::Point2F ((float) area.getX(), (float) area.getY());

    context->PushAxisAlignedClip (D2DUtilities::toRECT_F (area), D2D1_ANTIALIAS_MODE_ALIASED);
    context->DrawImage (effect,
                        &destPoint,
                        nullptr,
                        D2D1_INTERPOLATION_MODE_NEAREST_NEIGHBOR,
                        D2D1_COMPOSITE_MODE_SOURCE_COPY);
    context->PopAxisAlignedClip();
    return true;
}

void Direct2DPixelData::applyGaussianBlurEffectInArea (Rectangle<int> b, float radius)
{
    applyEffectInArea (b, [&] (auto dc, auto input) -> ComSmartPtr<ID2D1Effect>
    {
        ComSmartPtr<ID2D1Effect> effect;
        if (const auto hr = dc->CreateEffect (CLSID_D2D1GaussianBlur, effect.resetAndGetPointerAddress());
            FAILED (hr) || effect == nullptr)
        {
            return nullptr;
        }

        effect->SetInput (0, input);
        effect->SetValue (D2D1_GAUSSIANBLUR_PROP_STANDARD_DEVIATION, radius / 3.0f);
        return effect;
    });
}

void Direct2DPixelData::applySingleChannelBoxBlurEffectInArea (Rectangle<int> b, int radius)
{
    applyEffectInArea (b, [&] (auto dc, auto input) -> ComSmartPtr<ID2D1Effect>
    {
        constexpr FLOAT kernel[] { 1.0f / 9.0f, 2.0f / 9.0f, 3.0f / 9.0f, 2.0f / 9.0f, 1.0f / 9.0f };

        ComSmartPtr<ID2D1Effect> begin, end;

        for (auto horizontal : { false, true })
        {
            for (auto i = 0; i < roundToInt (radius); ++i)
            {
                ComSmartPtr<ID2D1Effect> effect;
                if (const auto hr = dc->CreateEffect (CLSID_D2D1ConvolveMatrix, effect.resetAndGetPointerAddress());
                    FAILED (hr) || effect == nullptr)
                {
                    // Unable to create effect!
                    jassertfalse;
                    return nullptr;
                }

                effect->SetValue (D2D1_CONVOLVEMATRIX_PROP_KERNEL_SIZE_X, (UINT32) (horizontal ? std::size (kernel) : 1));
                effect->SetValue (D2D1_CONVOLVEMATRIX_PROP_KERNEL_SIZE_Y, (UINT32) (horizontal ? 1 : std::size (kernel)));
                effect->SetValue (D2D1_CONVOLVEMATRIX_PROP_KERNEL_MATRIX, kernel);

                if (begin == nullptr)
                {
                    begin = effect;
                    end = effect;
                }
                else
                {
                    effect->SetInputEffect (0, end);
                    end = effect;
                }
            }
        }

        begin->SetInput (0, input);
        return end;
    });
}

void Direct2DPixelData::multiplyAllAlphasInArea (Rectangle<int> b, float value)
{
    applyEffectInArea (b, [&] (auto dc, auto input) -> ComSmartPtr<ID2D1Effect>
    {
        ComSmartPtr<ID2D1Effect> effect;
        if (const auto hr = dc->CreateEffect (CLSID_D2D1Opacity, effect.resetAndGetPointerAddress());
            FAILED (hr) || effect == nullptr)
        {
            return nullptr;
        }

        effect->SetInput (0, input);
        effect->SetValue (D2D1_OPACITY_PROP_OPACITY, value);
        return effect;
    });
}

void Direct2DPixelData::desaturateInArea (Rectangle<int> b)
{
    applyEffectInArea (b, [&] (auto dc, auto input) -> ComSmartPtr<ID2D1Effect>
    {
        ComSmartPtr<ID2D1Effect> effect;
        if (const auto hr = dc->CreateEffect (CLSID_D2D1Saturation, effect.resetAndGetPointerAddress());
            FAILED (hr) || effect == nullptr)
        {
            return nullptr;
        }

        effect->SetInput (0, input);
        effect->SetValue (D2D1_SATURATION_PROP_SATURATION, 0.0f);
        return effect;
    });
}

Direct2DPixelDataPages& Direct2DPixelData::getPagesStructForDevice (ComSmartPtr<ID2D1Device1> device)
{
    return getIteratorForDevice (device)->second;
}

auto Direct2DPixelData::getPagesForDevice (ComSmartPtr<ID2D1Device1> device) -> Span<const Page>
{
    return getPagesStructForDevice (device).getPages();
}

void Direct2DPixelData::setBackupEnabled (bool x)
{
    sync = x;
}

bool Direct2DPixelData::isBackupEnabled() const
{
    return sync;
}

bool Direct2DPixelData::backupNow()
{
    return createPersistentBackup (nullptr);
}

bool Direct2DPixelData::needsBackup() const
{
    return state == State::outdated;
}

bool Direct2DPixelData::canBackup() const
{
    return std::any_of (pagesForDevice.begin(), pagesForDevice.end(), [] (const auto& pair)
    {
        return pair.second.isUpToDate();
    });
}

auto Direct2DPixelData::getNativeExtensions() -> NativeExtensions
{
    struct Wrapped
    {
        explicit Wrapped (Ptr s)
            : self (s) {}

        Span<const Direct2DPixelDataPage> getPages (ComSmartPtr<ID2D1Device1> x) const
        {
            return self->getPagesForDevice (x);
        }

        Point<int> getTopLeft() const
        {
            return {};
        }

        Ptr self;
    };

    return NativeExtensions { Wrapped { this } };
}

//==============================================================================
ImagePixelData::Ptr NativeImageType::create (Image::PixelFormat format, int width, int height, bool clearImage) const
{
    SharedResourcePointer<DirectX> directX;

    if (directX->adapters.getFactory() == nullptr)
    {
        // Make sure the DXGI factory exists
        //
        // The caller may be trying to create an Image from a static variable; if this is a DLL, then this is
        // probably called from DllMain. You can't create a DXGI factory from DllMain, so fall back to a
        // software image.
        return new SoftwarePixelData { format, width, height, clearImage };
    }

    return new Direct2DPixelData (format, width, height, clearImage);
}

//==============================================================================
//==============================================================================
#if JUCE_UNIT_TESTS

namespace ImageTestHelperTypes
{
    /*  A stand-in for Direct2DPixelDataPage */
    struct TestPage
    {
        Rectangle<int> bounds;
    };

    /*  A stand-in for Direct2DPixelDataPages */
    struct TestPages
    {
        std::vector<TestPage> pages;
        int width, height;
    };

    /*  Creates an instance of TestPages with arbitrary dimensions */
    static TestPages createTestPages (int totalW, int totalH, int pageW, int pageH)
    {
        TestPages result { {}, totalW, totalH };

        for (auto y = 0; y < totalH; y += pageH)
        {
            for (auto x = 0; x < totalW; x += pageW)
            {
                result.pages.push_back ({ Rectangle { x,
                                                      y,
                                                      jmin (totalW - x, pageW),
                                                      jmin (totalH - y, pageH) } });
            }
        }

        return result;
    }

    /*  Used by forEachPageInRect, copyAcrossMultiplePages. Located using argument-dependent lookup. */
    static Rectangle<int> getBounds (const TestPage& p)
    {
        return p.bounds;
    }

    /*  Used by forEachPageInRect, copyAcrossMultiplePages. Located using argument-dependent lookup. */
    static std::optional<TestPage> getPageForPoint (const TestPages& testPages, Point<int> pt)
    {
        auto& pages = testPages.pages;

        if (pages.empty())
            return {};

        const auto maxPageBounds = getBounds (pages.front());
        const auto pageX = pt.x / maxPageBounds.getWidth();
        const auto pageY = pt.y / maxPageBounds.getHeight();
        const auto pagesPerRow = 1 + ((testPages.width - 1) / maxPageBounds.getWidth());

        jassert (pages.size() % (size_t) pagesPerRow == 0);

        const auto result = pages[(size_t) (pageX + (pageY * pagesPerRow))];

        jassert (getBounds (result).contains (pt));

        return result;
    }
}

class Direct2DImageUnitTest final : public UnitTest
{
public:
    Direct2DImageUnitTest()
        : UnitTest ("Direct2DImageUnitTest", UnitTestCategories::graphics)
    {
        compareFunctions[{ Image::RGB, Image::RGB }] = [] (uint8* rgb1, uint8* rgb2)
        {
            return rgb1[0] == rgb2[0] && rgb1[1] == rgb2[1] && rgb1[2] == rgb2[2];
        };

        compareFunctions[{ Image::RGB, Image::ARGB }] = [] (uint8* rgb, uint8* argb)
        {
            // Compare bytes directly to avoid alpha premultiply issues
            return rgb[0] == argb[0] && // blue
                   rgb[1] == argb[1] && // green
                   rgb[2] == argb[2]; // red
        };

        compareFunctions[{ Image::RGB, Image::SingleChannel }] = [] (uint8*, uint8* singleChannel)
        {
            return *singleChannel == 0xff;
        };

        compareFunctions[{ Image::ARGB, Image::RGB }] = [] (uint8* argb, uint8* rgb)
        {
            // Compare bytes directly to avoid alpha premultiply issues
            return argb[0] == rgb[0] && argb[1] == rgb[1] && argb[2] == rgb[2];
        };

        compareFunctions[{ Image::ARGB, Image::ARGB }] = [] (uint8* argb1, uint8* argb2)
        {
            return *reinterpret_cast<uint32*> (argb1) == *reinterpret_cast<uint32*> (argb2);
        };

        compareFunctions[{ Image::ARGB, Image::SingleChannel }] = [] (uint8* argb, uint8* singleChannel)
        {
            return argb[3] == *singleChannel;
        };

        compareFunctions[{ Image::SingleChannel, Image::RGB }] = [] (uint8* singleChannel, uint8* rgb)
        {
            auto alpha = *singleChannel;
            return rgb[0] == alpha && rgb[1] == alpha && rgb[2] == alpha;
        };

        compareFunctions[{ Image::SingleChannel, Image::ARGB }] = [] (uint8* singleChannel, uint8* argb)
        {
            return *singleChannel == argb[3];
        };

        compareFunctions[{ Image::SingleChannel, Image::SingleChannel }] = [] (uint8* singleChannel1, uint8* singleChannel2)
        {
            return *singleChannel1 == *singleChannel2;
        };
    }

    void runTest() override
    {
        random = getRandom();

        constexpr auto multiPageSize = (1 << 14) + 512 + 3;

        beginTest ("forEachPageInRect");
        {
            const auto pages = ImageTestHelperTypes::createTestPages (1000, 2000, 37, 51);
            const Rectangle innerArea { 100, 100, 500, 500 };

            RectangleList<int> rectangles;

            // Try adding the area of each page to the rectangle list
            forEachPageInRect (innerArea, pages, [&] (auto& page, Rectangle<int> rectInPage)
            {
                const auto rect = rectInPage + getBounds (page).getTopLeft();
                // No area should overlap with any previously-added area
                expect (! rectangles.intersectsRectangle (rect));
                rectangles.add (rect);
            });

            rectangles.consolidate();

            // After the call, we should have covered the entire area of the passed-in rect
            expect (rectangles.getNumRectangles() == 1);
            expect (rectangles.getRectangle (0) == innerArea);
        }

        beginTest ("copyAcrossMultiplePages");
        {
            // Create some test pages with different dimensions
            // These numbers aren't too important, I'm using primes to make sure there are lots of
            // unique intersections
            const auto srcPages = ImageTestHelperTypes::createTestPages (1229, 1231, 73, 79);
            const auto dstPages = ImageTestHelperTypes::createTestPages (1237, 1249, 83, 89);
            const Rectangle srcRect { 192, 199, 383, 389 };
            const Point dstPoint { 599, 601 };

            RectangleList<int> coveredSrcArea, coveredDstArea;

            // For each copied region, keep track of the src and dst areas we've covered
            const auto doCopy = [&] (auto& dst,
                                     Point<int> dstPt, // relative to dst
                                     auto& src,
                                     Rectangle<int> srcRc) // relative to src
            {
                // The destination rectangle, relative to the destination page's bounds
                const auto dstRect = srcRc.withPosition (dstPt);

                // The src and dst rectangles must fall entirely within their respective pages
                expect (getBounds (src).withPosition ({}).contains (srcRc));
                expect (getBounds (dst).withPosition ({}).contains (dstRect));

                // We shouldn't have already visited any part of this srcRc
                const auto globalSrcRect = srcRc + getBounds (src).getTopLeft();
                expect (! coveredSrcArea.intersectsRectangle (globalSrcRect));
                coveredSrcArea.add (globalSrcRect);

                // We shouldn't have already visited any part of this dstRect
                const auto globalDstRect = dstRect + getBounds (dst).getTopLeft();
                expect (! coveredDstArea.intersectsRectangle (globalDstRect));
                coveredDstArea.add (globalDstRect);
            };

            copyAcrossMultiplePages (dstPages, dstPoint, srcPages, srcRect, doCopy);

            coveredSrcArea.consolidate();
            coveredDstArea.consolidate();

            // After copying all subregions, we should have visited the full srcRect and dstRect

            expect (coveredSrcArea.getNumRectangles() == 1);
            expect (coveredSrcArea.getRectangle (0) == srcRect);

            expect (coveredDstArea.getNumRectangles() == 1);
            expect (coveredDstArea.getRectangle (0) == srcRect.withPosition (dstPoint));
        }

        beginTest ("Direct2DImageUnitTest");
        {
            for (const auto size : { 100, multiPageSize })
            {
                for (auto format : formats)
                {
                    compareSameFormat (format, size, 32);
                    compareSameFormat (format, 32, size);
                }

                testFormatConversion (size, 32);
                testFormatConversion (32, size);
            }
        }

        beginTest ("Ensure data parity across mapped page boundaries");
        {
            const auto adapterToUse = directX->adapters.getDefaultAdapter();
            const auto deviceToUse = adapterToUse->direct2DDevice;
            const auto contextToUse = Direct2DDeviceContext::create (deviceToUse);

            for (auto sourceFormat : formats)
            {
                Image softwareImage { SoftwareImageType{}.create (sourceFormat, multiPageSize, 32, true) };

                {
                    const Image::BitmapData bitmap { softwareImage, Image::BitmapData::writeOnly };

                    for (int y = 0; y < bitmap.height; y++)
                    {
                        auto line = bitmap.getLinePointer (y);

                        for (int x = 0; x < bitmap.lineStride; x++)
                            line[x] = (uint8_t) jmap (x, 0, bitmap.lineStride, 0, 256);
                    }
                }

                for (auto destFormat : formats)
                {
                    auto d2dImage = NativeImageType{}.convert (softwareImage)
                                                     .convertedToFormat (destFormat);

                    const auto maxPageBounds = [&]
                    {
                        if (auto* data = dynamic_cast<Direct2DPixelData*> (d2dImage.getPixelData().get()))
                            if (auto pages = data->getPagesForDevice (deviceToUse); ! pages.empty())
                                return pages.front().getBounds();

                        return Rectangle<int>{};
                    }();

                    const auto boundarySize = softwareImage.getHeight();
                    const auto pageBoundary = softwareImage.getBounds().getIntersection ({ maxPageBounds.getWidth() - boundarySize / 2,
                                                                                           0,
                                                                                           boundarySize,
                                                                                           boundarySize });

                    const Image::BitmapData data1 { softwareImage,
                                                    pageBoundary.getX(),
                                                    pageBoundary.getY(),
                                                    pageBoundary.getWidth(),
                                                    pageBoundary.getHeight(),
                                                    Image::BitmapData::ReadWriteMode::readOnly };
                    const Image::BitmapData data2 { d2dImage,
                                                    pageBoundary.getX(),
                                                    pageBoundary.getY(),
                                                    pageBoundary.getWidth(),
                                                    pageBoundary.getHeight(),
                                                    Image::BitmapData::ReadWriteMode::readOnly };

                    auto f = compareFunctions.at ({ data1.pixelFormat, data2.pixelFormat });

                    for (int y = 0; y < data1.height; y++)
                    {
                        for (int x = 0; x < data1.width; x++)
                        {
                            auto p1 = data1.getPixelPointer (x, y);
                            auto p2 = data2.getPixelPointer (x, y);

                            expect (f (p1, p2));
                        }
                    }
                }
            }
        }
    }

    Rectangle<int> randomRectangleWithin (Rectangle<int> container) noexcept
    {
        const auto w = random.nextInt ({ 1, container.getWidth() });
        const auto h = random.nextInt ({ 1, container.getHeight() });
        const auto x = random.nextInt ({ container.getX(), container.getRight() - w });
        const auto y = random.nextInt ({ container.getY(), container.getBottom() - h });

        return { x, y, w, h };
    }

    void compareSameFormat (Image::PixelFormat format, int width, int height)
    {
        auto softwareImage = Image { SoftwareImageType{}.create (format, width, height, true) };
        {
            Graphics g { softwareImage };
            g.fillCheckerBoard (softwareImage.getBounds().toFloat(), 21.0f, 21.0f, makeRandomColor(), makeRandomColor());
        }

        auto direct2DImage = NativeImageType{}.convert (softwareImage);

        compareImages (softwareImage, direct2DImage, compareFunctions[{ softwareImage.getFormat(), direct2DImage.getFormat() }]);
        checkReadWriteModes (softwareImage);
        checkReadWriteModes (direct2DImage);
    }

    void compareImages (Image& image1, Image& image2, std::function<bool (uint8*, uint8*)> compareBytes)
    {
        {
            // BitmapData width & height should match
            Rectangle<int> area = randomRectangleWithin (image1.getBounds());
            Image::BitmapData data1 { image1, area.getX(), area.getY(), area.getWidth(), area.getHeight(), Image::BitmapData::ReadWriteMode::readOnly };
            Image::BitmapData data2 { image2, area.getX(), area.getY(), area.getWidth(), area.getHeight(), Image::BitmapData::ReadWriteMode::readOnly };

            expect (data1.width == data2.width);
            expect (data1.height == data2.height);
        }

        {
            // Bitmap data should match after ImageType::convert
            Image::BitmapData data1 { image1, Image::BitmapData::ReadWriteMode::readOnly };
            Image::BitmapData data2 { image2, Image::BitmapData::ReadWriteMode::readOnly };

            for (int y = 0; y < data1.height; ++y)
            {
                auto line1 = data1.getLinePointer (y);
                auto line2 = data2.getLinePointer (y);

                for (int x = 0; x < data1.width; ++x)
                {
                    expect (compareBytes (line1, line2), "Failed comparing format " + String { image1.getFormat() } + " to " + String { image2.getFormat() });

                    line1 += data1.pixelStride;
                    line2 += data2.pixelStride;
                }
            }
        }

        {
            // Subsection data should match
            // Should be able to have two different BitmapData objects simultaneously for the same source image
            Rectangle<int> area1 = randomRectangleWithin (image1.getBounds());
            Rectangle<int> area2 = randomRectangleWithin (image1.getBounds());
            Image::BitmapData data1 { image1, Image::BitmapData::ReadWriteMode::readOnly };
            Image::BitmapData data2a { image2, area1.getX(), area1.getY(), area1.getWidth(), area1.getHeight(), Image::BitmapData::ReadWriteMode::readOnly };
            Image::BitmapData data2b { image2, area2.getX(), area2.getY(), area2.getWidth(), area2.getHeight(), Image::BitmapData::ReadWriteMode::readOnly };

            auto compareSubsection = [&] (Image::BitmapData& subsection1, Image::BitmapData& subsection2, Rectangle<int> area)
            {
                for (int y = 0; y < area.getHeight(); ++y)
                {
                    auto line1 = subsection1.getLinePointer (y + area.getY());
                    auto line2 = subsection2.getLinePointer (y);

                    for (int x = 0; x < area.getWidth(); ++x)
                    {
                        expect (compareBytes (line1 + (x + area.getX()) * subsection1.pixelStride, line2 + x * subsection2.pixelStride));
                    }
                }
            };

            compareSubsection (data1, data2a, area1);
            compareSubsection (data1, data2b, area2);
        }
    }

    void checkReadWriteModes (Image& image)
    {
        // Check read and write modes
        int x = random.nextInt (image.getWidth());
        auto writeColor = makeRandomColor().withAlpha (1.0f);
        auto expectedColor = writeColor;
        switch (image.getFormat())
        {
            case Image::SingleChannel:
            {
                auto alpha = writeColor.getAlpha();
                expectedColor = Colour { alpha, alpha, alpha, alpha };
                break;
            }

            case Image::RGB:
            case Image::ARGB:
                break;

            case Image::UnknownFormat:
            default:
                jassertfalse;
                break;
        }

        {
            Image::BitmapData data { image, Image::BitmapData::ReadWriteMode::writeOnly };

            for (int y = 0; y < data.height; ++y)
                data.setPixelColour (x, y, writeColor);
        }

        {
            Image::BitmapData data { image, Image::BitmapData::ReadWriteMode::readOnly };

            for (int y = 0; y < data.height; ++y)
            {
                auto color = data.getPixelColour (x, y);
                expect (color == expectedColor);
            }
        }
    }

    void testFormatConversion (int width, int height)
    {
        for (auto sourceFormat : formats)
        {
            for (auto destFormat : formats)
            {
                Image softwareStartImage { SoftwareImageType {}.create (sourceFormat, width, height, true) };
                {
                    Graphics g { softwareStartImage };
                    g.fillCheckerBoard (softwareStartImage.getBounds().toFloat(), 21.0f, 21.0f, makeRandomColor(), makeRandomColor());
                }

                auto convertedSoftwareImage = softwareStartImage.convertedToFormat (destFormat);
                compareImages (softwareStartImage, convertedSoftwareImage, compareFunctions[{ sourceFormat, destFormat }]);

                auto direct2DImage = NativeImageType{}.convert (softwareStartImage);
                compareImages (softwareStartImage, direct2DImage, compareFunctions[{ sourceFormat, sourceFormat }]);

                auto convertedDirect2DImage = direct2DImage.convertedToFormat (destFormat);
                compareImages (softwareStartImage, convertedDirect2DImage, compareFunctions[{ sourceFormat, destFormat }]);
            }
        }
    }

    Colour makeRandomColor()
    {
        uint8 red   = (uint8) random.nextInt (255);
        uint8 green = (uint8) random.nextInt (255);
        uint8 blue  = (uint8) random.nextInt (255);
        uint8 alpha = (uint8) random.nextInt (255);
        return Colour { red, green, blue, alpha };
    }

    SharedResourcePointer<DirectX> directX;
    Random random;
    std::array<Image::PixelFormat, 3> const formats { Image::RGB, Image::ARGB, Image::SingleChannel };
    std::map<std::pair<Image::PixelFormat, Image::PixelFormat>, std::function<bool (uint8*, uint8*)>> compareFunctions;
};

static Direct2DImageUnitTest direct2DImageUnitTest;

#endif

} // namespace juce