cairo_images_cache.h

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#ifndef LITEHTML_CAIRO_IMAGES_CACHE_H
#define LITEHTML_CAIRO_IMAGES_CACHE_H
 
#include <mutex>
#include <map>
#include <string>
#include <cairo.h>
 
class cairo_surface_wrapper
{
    cairo_surface_t* surface;
public:
    cairo_surface_wrapper() : surface(nullptr) {}
    cairo_surface_wrapper(const cairo_surface_wrapper& v) : surface(v.surface)
    {
        if(v.surface)
        {
            surface = cairo_surface_reference(v.surface);
        }
    }
    explicit cairo_surface_wrapper(cairo_surface_t* v) : surface(v) {}
    cairo_surface_wrapper(cairo_surface_wrapper&& v) noexcept
    {
        surface = v.surface;
        v.surface = nullptr;
    }
    cairo_surface_wrapper& operator=(const cairo_surface_wrapper& v)
    {
        if(surface != v.surface)
        {
            if(surface)
            {
                cairo_surface_destroy(surface);
            }
            surface = cairo_surface_reference(v.surface);
        }
        return *this;
    }
    ~cairo_surface_wrapper()
    {
        if(surface)
        {
            cairo_surface_destroy(surface);
        }
    }
    cairo_surface_t* get() { return cairo_surface_reference(surface); }
};
 
class cairo_images_cache
{
    std::mutex m_mutex;
    std::map<std::string, cairo_surface_wrapper> m_images;
public:
    void add_image(const std::string& url, cairo_surface_t* image)
    {
        std::unique_lock<std::mutex> lock(m_mutex);
        m_images[url] = cairo_surface_wrapper(image);
    }
 
    cairo_surface_t* get_image(const std::string& url)
    {
        std::unique_lock<std::mutex> lock(m_mutex);
        auto iter = m_images.find(url);
        if(iter != m_images.end())
        {
            return iter->second.get();
        }
        return nullptr;
    }
 
    bool reserve(const std::string& url)
    {
        std::unique_lock<std::mutex> lock(m_mutex);
        auto iter = m_images.find(url);
        if (iter == m_images.end())
        {
            m_images[url] = cairo_surface_wrapper();
            return true;
        }
        return false;
    }
 
    bool exists(const std::string& url)
    {
        std::unique_lock<std::mutex> lock(m_mutex);
        auto iter = m_images.find(url);
        return iter != m_images.end();
    }
};
 
#endif //LITEHTML_CAIRO_IMAGES_CACHE_H