MRCommandLoop.h

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#pragma once
#include "exports.h"
#include <queue>
#include <functional>
#include <condition_variable>
#include <mutex>
#include <thread>
 
namespace MR
{
 
 
class CommandLoop
{
public:
    using CommandFunc = std::function<void()>;
 
    enum class StartPosition
    {
        AfterWindowInit,    
        AfterSplashAppear,  
        AfterPluginInit,    
        BeforeWindowAppear, 
        AfterWindowAppear   
    };
 
    MRVIEWER_API static void setMainThreadId( const std::thread::id& id );
    MRVIEWER_API static std::thread::id getMainThreadId();
    MRVIEWER_API static void setState( StartPosition state );
 
    MRVIEWER_API static void appendCommand( CommandFunc func, StartPosition state = StartPosition::BeforeWindowAppear );
 
    MRVIEWER_API static void runCommandFromGUIThread( CommandFunc func );
 
    MRVIEWER_API static void processCommands();
 
    MRVIEWER_API static bool empty();
 
    MRVIEWER_API static void removeCommands( bool closeLoop );
 
private:
    CommandLoop() = default;
    ~CommandLoop();
 
    static CommandLoop& instance_();
 
    static void addCommand_( CommandFunc func, bool blockThread, StartPosition state );
 
    struct Command
    {
        CommandFunc func;
        StartPosition state{ StartPosition::BeforeWindowAppear };
        std::condition_variable callerThreadCV;
        std::thread::id threadId;
    };
 
    StartPosition state_{ StartPosition::AfterWindowInit };
 
    bool queueClosed_{ false }; 
    std::thread::id mainThreadId_;
    std::queue<std::shared_ptr<Command>> commands_;
    std::mutex mutex_;
};
 
}