JUCE/modules/juce_opengl/opengl/juce_OpenGLImage.cpp

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

   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
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   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

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   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
{

class OpenGLFrameBufferImage final : public ImagePixelData
{
public:
    using Ptr = ReferenceCountedObjectPtr<OpenGLFrameBufferImage>;

    OpenGLFrameBufferImage (OpenGLContext& c, int w, int h)
        : ImagePixelData (Image::ARGB, w, h),
          context (c),
          pixelStride (4)
    {
    }

    bool initialise()
    {
        if (! frameBuffer.initialise (context, width, height))
            return false;

        frameBuffer.clear (Colours::transparentBlack);
        return true;
    }

    std::unique_ptr<LowLevelGraphicsContext> createLowLevelContext() override
    {
        sendDataChangeMessage();
        return createOpenGLGraphicsContext (context, frameBuffer);
    }

    std::unique_ptr<ImageType> createType() const override     { return std::make_unique<OpenGLImageType>(); }

    ImagePixelData::Ptr clone() override
    {
        std::unique_ptr<OpenGLFrameBufferImage> im (new OpenGLFrameBufferImage (context, width, height));

        if (! im->initialise())
            return ImagePixelData::Ptr();

        Image newImage (im.release());
        Graphics g (newImage);
        g.drawImageAt (Image (*this), 0, 0, false);

        return ImagePixelData::Ptr (newImage.getPixelData());
    }

    void initialiseBitmapData (Image::BitmapData& bitmapData, int x, int y, Image::BitmapData::ReadWriteMode mode) override
    {
        bitmapData.pixelFormat = pixelFormat;
        bitmapData.pixelStride = pixelStride;

        auto releaser = std::make_unique<DataReleaser> (this, Rectangle { x, y, bitmapData.width, bitmapData.height }, mode);

        const auto unsignedLineStride = (((size_t) bitmapData.width * (size_t) bitmapData.pixelStride + 3) & ~((size_t) 3));
        bitmapData.lineStride = -((int) unsignedLineStride);
        bitmapData.size = (size_t) bitmapData.height * unsignedLineStride;

        // OpenGL mapped textures are stored in lines from bottom-to-top, but JUCE expects lines to
        // be ordered top-to-bottom.
        // The data pointer points to the beginning of the *last* line, and lineStride steps backwards
        // through the lines.
        bitmapData.data = (uint8*) releaser->data.get() + (ptrdiff_t) bitmapData.size + (ptrdiff_t) bitmapData.lineStride;

        bitmapData.dataReleaser = std::move (releaser);

        if (mode != Image::BitmapData::readOnly)
            sendDataChangeMessage();
    }

    OpenGLContext& context;
    OpenGLFrameBuffer frameBuffer;

private:
    int pixelStride;

    struct DataReleaser final : public Image::BitmapData::BitmapDataReleaser
    {
        DataReleaser (Ptr selfIn, Rectangle<int> areaIn, Image::BitmapData::ReadWriteMode modeIn)
            : self (selfIn),
              data ((size_t) (areaIn.getWidth() * areaIn.getHeight())),
              area (areaIn),
              mode (modeIn)
        {
            if (mode != Image::BitmapData::writeOnly)
                self->frameBuffer.readPixels (data.get(), getArea());
        }

        ~DataReleaser() override
        {
            if (mode != Image::BitmapData::readOnly)
                self->frameBuffer.writePixels (data, getArea());
        }

        Rectangle<int> getArea() const
        {
            return area.withBottomY (self->frameBuffer.getHeight() - area.getY());
        }

        Ptr self;
        HeapBlock<PixelARGB> data;
        Rectangle<int> area;
        Image::BitmapData::ReadWriteMode mode;
    };

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (OpenGLFrameBufferImage)
};

//==============================================================================
OpenGLImageType::OpenGLImageType() {}
OpenGLImageType::~OpenGLImageType() {}

int OpenGLImageType::getTypeID() const
{
    return 3;
}

ImagePixelData::Ptr OpenGLImageType::create (Image::PixelFormat, int width, int height, bool /*shouldClearImage*/) const
{
    OpenGLContext* currentContext = OpenGLContext::getCurrentContext();
    jassert (currentContext != nullptr); // an OpenGL image can only be created when a valid context is active!

    std::unique_ptr<OpenGLFrameBufferImage> im (new OpenGLFrameBufferImage (*currentContext, width, height));

    if (! im->initialise())
        return ImagePixelData::Ptr();

    return *im.release();
}

OpenGLFrameBuffer* OpenGLImageType::getFrameBufferFrom (const Image& image)
{
    if (OpenGLFrameBufferImage* const glImage = dynamic_cast<OpenGLFrameBufferImage*> (image.getPixelData().get()))
        return &(glImage->frameBuffer);

    return nullptr;
}

} // namespace juce