JUCE/modules/juce_gui_basics/detail/juce_ScopedContentSharerInterface.h

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

   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited

   JUCE is an open source library subject to commercial or open-source
   licensing.

   By using JUCE, you agree to the terms of both the JUCE 7 End-User License
   Agreement and JUCE Privacy Policy.

   End User License Agreement: www.juce.com/juce-7-licence
   Privacy Policy: www.juce.com/juce-privacy-policy

   Or: You may also use this code under the terms of the GPL v3 (see
   www.gnu.org/licenses).

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

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

namespace juce::detail
{

/*
    Instances of this type can show and dismiss a content sharer.

    This is an interface rather than a concrete type so that platforms can pick an implementation at
    runtime if necessary.
*/
struct ScopedContentSharerInterface
{
    virtual ~ScopedContentSharerInterface() = default;

    /*  Shows the content sharer.

        When the content sharer exits normally, it should send the result to the passed-in function.
        The passed-in function is safe to call from any thread at any time.
    */
    virtual void runAsync (ContentSharer::Callback callback)
    {
        jassertfalse;
        NullCheckedInvocation::invoke (callback, false, "Content sharing not available on this platform!");
    }

    /*  Forcefully closes the content sharer.

        This will be called when the content sharer handle has fallen out of scope.
        If the content sharer has already been closed by the user, this shouldn't do anything.
    */
    virtual void close() {}

    /*  Implemented differently for each platform. */
    static std::unique_ptr<ScopedContentSharerInterface> shareFiles (const Array<URL>&, Component*);
    static std::unique_ptr<ScopedContentSharerInterface> shareText (const String&, Component*);

    /*  Implemented below. */
    static std::unique_ptr<ScopedContentSharerInterface> shareImages (const Array<Image>&, std::unique_ptr<ImageFileFormat>, Component*);
    static std::unique_ptr<ScopedContentSharerInterface> shareData (MemoryBlock, Component*);
};

class TemporaryFilesDecorator : public ScopedContentSharerInterface,
                                private AsyncUpdater
{
public:
    explicit TemporaryFilesDecorator (Component* parentIn)
        : parent (parentIn) {}

    void runAsync (ContentSharer::Callback cb) override
    {
        callback = std::move (cb);

        task = std::async (std::launch::async, [this]
        {
            std::tie (temporaryFiles, error) = prepareTemporaryFiles();
            triggerAsyncUpdate();
        });
    }

    void close() override
    {
        if (inner != nullptr)
            inner->close();
    }

private:
    virtual std::tuple<Array<URL>, String> prepareTemporaryFiles() const = 0;

    void handleAsyncUpdate() override
    {
        if (error.isNotEmpty())
        {
            NullCheckedInvocation::invoke (callback, false, error);
            return;
        }

        inner = shareFiles (temporaryFiles, parent);

        if (inner == nullptr)
        {
            NullCheckedInvocation::invoke (callback, false, TRANS ("Failed to create file sharer"));
            return;
        }

        inner->runAsync (callback);
    }

    Array<URL> temporaryFiles;
    String error;
    std::unique_ptr<ScopedContentSharerInterface> inner;
    ContentSharer::Callback callback;
    std::future<void> task;
    Component* parent = nullptr;
};

std::unique_ptr<ScopedContentSharerInterface> ScopedContentSharerInterface::shareImages (const Array<Image>& images,
                                                                                         std::unique_ptr<ImageFileFormat> format,
                                                                                         Component* parent)
{
    class Decorator : public TemporaryFilesDecorator
    {
    public:
        Decorator (Array<Image> imagesIn, std::unique_ptr<ImageFileFormat> formatIn, Component* parentIn)
            : TemporaryFilesDecorator (parentIn), images (std::move (imagesIn)), format (std::move (formatIn)) {}

    private:
        std::tuple<Array<URL>, String> prepareTemporaryFiles() const override
        {
            const auto extension = format->getFormatName().toLowerCase();

            Array<URL> result;

            for (const auto& image : images)
            {
                File tempFile = File::createTempFile (extension);

                if (! tempFile.create().wasOk())
                    return { Array<URL>{}, TRANS ("Failed to create temporary file") };

                std::unique_ptr<FileOutputStream> outputStream (tempFile.createOutputStream());

                if (outputStream == nullptr)
                    return { Array<URL>{}, TRANS ("Failed to open temporary file for writing") };

                if (format->writeImageToStream (image, *outputStream))
                    result.add (URL (tempFile));
            }

            jassert (std::all_of (result.begin(),
                                  result.end(),
                                  [] (const auto& url)
                                  {
                                      return url.isLocalFile() && url.getLocalFile().existsAsFile();
                                  }));

            return { std::move (result), String{} };
        }

        Array<Image> images;
        std::unique_ptr<ImageFileFormat> format;
    };

    return std::make_unique<Decorator> (images,
                                        format == nullptr ? std::make_unique<PNGImageFormat>() : std::move (format),
                                        parent);
}

std::unique_ptr<ScopedContentSharerInterface> ScopedContentSharerInterface::shareData (MemoryBlock mb, Component* parent)
{
    class Decorator : public TemporaryFilesDecorator
    {
    public:
        Decorator (MemoryBlock mbIn, Component* parentIn)
            : TemporaryFilesDecorator (parentIn), mb (std::move (mbIn)) {}

    private:
        std::tuple<Array<URL>, String> prepareTemporaryFiles() const override
        {
            File tempFile = File::createTempFile ("data");

            if (! tempFile.create().wasOk())
                return { Array<URL>{}, TRANS ("Failed to create temporary file") };

            std::unique_ptr<FileOutputStream> outputStream (tempFile.createOutputStream());

            if (outputStream == nullptr)
                return { Array<URL>{}, TRANS ("Failed to open temporary file for writing") };

            size_t pos = 0;
            size_t totalSize = mb.getSize();

            while (pos < totalSize)
            {
                size_t numToWrite = std::min ((size_t) 8192, totalSize - pos);

                if (! outputStream->write (mb.begin() + pos, numToWrite))
                    return { Array<URL>{}, TRANS ("Failed to write to temporary file") };

                pos += numToWrite;
            }

            return { Array<URL> { URL (tempFile) }, String{} };
        }

        MemoryBlock mb;
    };

    return std::make_unique<Decorator> (std::move (mb), parent);
}

} // namespace juce::detail