Backend.hpp

//
// TGUI - Texus' Graphical User Interface
// Copyright (C) 2012-2025 Bruno Van de Velde (vdv_b@tgui.eu)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
//    you must not claim that you wrote the original software.
//    If you use this software in a product, an acknowledgment
//    in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
//    and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
 
#ifndef TGUI_BACKEND_HPP
#define TGUI_BACKEND_HPP
 
#include <TGUI/Font.hpp>
#include <TGUI/Event.hpp>
#include <TGUI/Cursor.hpp>
#include <TGUI/Backend/Font/BackendFont.hpp>
#include <TGUI/Backend/Font/BackendFontFactory.hpp>
#include <TGUI/Backend/Renderer/BackendText.hpp>
#include <TGUI/Backend/Renderer/BackendTexture.hpp>
#include <TGUI/Backend/Renderer/BackendRenderer.hpp>
 
#if !TGUI_EXPERIMENTAL_USE_STD_MODULE
    #include <cstdint>
    #include <memory>
    #include <set>
#endif

 
TGUI_MODULE_EXPORT namespace tgui
{
    class Sprite;
    class Backend;
    class BackendGui;
    class BackendRenderer;
    class BackendFontFactory;

    TGUI_API bool isBackendSet();

    TGUI_API void setBackend(std::shared_ptr<Backend> backend);

    TGUI_API std::shared_ptr<Backend> getBackend();
 

    class TGUI_API Backend
    {
    public:

        Backend() = default;

        // The object cannot be copied
        Backend(const Backend&) = delete;

        // The object cannot be copied
        Backend& operator=(const Backend&) = delete;

        virtual ~Backend() = default;

        void setDestroyOnLastGuiDetatch(bool destroyOnDetatch);

        virtual void attachGui(BackendGui* gui);

        virtual void detatchGui(BackendGui* gui);

        TGUI_NODISCARD virtual Font createDefaultFont();

        TGUI_NODISCARD std::shared_ptr<BackendFont> createFont();

        TGUI_NODISCARD std::shared_ptr<BackendText> createText();

        TGUI_NODISCARD std::shared_ptr<BackendTexture> createTexture();

        void setFontScale(float scale);

        float getFontScale() const;

        virtual void setMouseCursorStyle(Cursor::Type type, const std::uint8_t* pixels, Vector2u size, Vector2u hotspot) = 0;

        virtual void resetMouseCursorStyle(Cursor::Type type) = 0;

        virtual void setMouseCursor(BackendGui* gui, Cursor::Type type) = 0;
 
#ifndef TGUI_REMOVE_DEPRECATED_CODE
        TGUI_DEPRECATED("Use BackendGui::startTextInput instead") virtual void openVirtualKeyboard(const FloatRect& inputRect);

        TGUI_DEPRECATED("Use BackendGui::stopTextInput instead") virtual void closeVirtualKeyboard();
#endif

        TGUI_DEPRECATED("Use gui.isKeyboardModifierPressed(modifierKey) instead") TGUI_NODISCARD virtual bool isKeyboardModifierPressed(Event::KeyModifier modifierKey);

        virtual void setClipboard(const String& contents);

        TGUI_NODISCARD virtual String getClipboard() const;

        TGUI_NODISCARD virtual std::unique_ptr<std::uint8_t[]> readFileFromAndroidAssets(const String& filename, std::size_t& fileSize) const;

        TGUI_NODISCARD bool hasRenderer() const;

        TGUI_NODISCARD std::shared_ptr<BackendRenderer> getRenderer() const;

        virtual void setRenderer(std::shared_ptr<BackendRenderer> renderer);

        TGUI_NODISCARD bool hasFontBackend() const;

        TGUI_NODISCARD std::shared_ptr<BackendFontFactory> getFontBackend() const;

        virtual void setFontBackend(std::shared_ptr<BackendFontFactory> fontBackend);

        void registerFont(BackendFont* font);

        void unregisterFont(BackendFont* font);

        void registerSvgSprite(Sprite* sprite);

        void unregisterSvgSprite(Sprite* sprite);

    protected:
 
        bool m_destroyOnLastGuiDetatch = false;
        String m_clipboardContents;
        float m_fontScale = 1;
 
        std::shared_ptr<BackendRenderer> m_renderer;
        std::shared_ptr<BackendFontFactory> m_fontBackend;
 
        std::set<BackendGui*> m_guis;
        std::set<BackendFont*> m_registeredFonts;
        std::set<Sprite*> m_registeredSvgSprites;
    };

}

 
#endif // TGUI_BACKEND_HPP