有沒有辦法清除Curse的事件隊列？

Question

我想從PDCurses獲取鼠標位置數據，它通常工作。問題是，如果在事件檢查發生之前按下鼠標按鈕兩次，則只有一個事件會從隊列中彈出。這意味着第二次按下的事件仍然在隊列中，並且下次按下鼠標時，舊位置將彈出而不是最近的位置。如果這種情況持續發生，則隊列開始備份，並且報告的鼠標按下變得越來越近。因爲我使用getch的唯一的事情是鼠標事件（我使用Window的GetAsyncKeyState和我自己的鍵盤事件管理器），我認爲一個簡單的修復就是在閱讀完後清除事件隊列一個鼠標事件。

不幸的是，它似乎並不那麼容易，因爲我找不到任何允許清除隊列的方法。

我能想到的唯一方法是使用nodelay將getch設置爲非阻塞，然後重複使用getch，保留彈出的最後一個事件。這似乎效率低下，但不準確。

因爲這是一個潛在的問題XY，這裏是有問題的功能：

void EventHandler::getMousePos(int& x, int& y) { 
    MEVENT event; 
    if (nc_getmouse(&event) == OK) { 
     x = event.x, y = event.y; 
    } 
} 

EventHandler.h：

#ifndef EVENT_HANDLER_H 
#define EVENT_HANDLER_H 

#include <vector> 
#include <atomic> 
#include <thread> 
#include <functional> 
#include <windows.h> 
#include <WinUser.h> 
#include "curses.h" 

#define LEFT_MOUSE VK_LBUTTON 
#define RIGHT_MOUSE VK_RBUTTON 
#define MIDDLE_MOUSE VK_MBUTTON 

typedef std::function<void(char)> KeyHandler; 
typedef std::function<void(char,long,long)> MouseHandler; 

class EventHandler { 

    std::thread listeningThread; 

    std::atomic<bool> listening = false; 

    std::vector<char> keysToCheck; 
    std::vector<char> mButtonsToCheck; 

    KeyHandler keyHandler = KeyHandler(); 
    MouseHandler mouseHandler = MouseHandler(); 

    void actOnPressedKeys(); 

public: 
    EventHandler(); 

    ~EventHandler(); 

    void setKeyHandler(KeyHandler); 
    void setMouseHandler(MouseHandler); 

    void setKeysToListenOn(std::vector<char>); 
    void setButtonsToListenOn(std::vector<char>); 

    void listenForPresses(int loopMSDelay = 100); 
    void stopListening(); 

    static void getMousePos(int& x, int& y); 

}; 

#endif 

EventHandler.cpp：

#include "EventHandler.h" 

#include <thread> 
#include <stdexcept> 
#include <cctype> 

EventHandler::EventHandler() { 

} 

EventHandler::~EventHandler() { 
    stopListening(); 
    if (listeningThread.joinable()) { 
     //May need to fix this. May cause the EventHandler to freeze 
     // on destruction if listeningThread can't join; 
     listeningThread.join(); 
    } 
} 

void EventHandler::actOnPressedKeys() { 
    for (char key : keysToCheck) { 
     if (GetAsyncKeyState(key)) { 
      //pressedKeys.insert(key); 
      keyHandler(key); 
     } 
    } 

    for (char button : mButtonsToCheck) { 
     if (GetAsyncKeyState(button)) { 

      int x = 0, y = 0; 
      getMousePos(x, y); 
      mvprintw(y, x, "Button Press Detected"); 
      mouseHandler(button, x, y); 
     } 
    } 
} 

/*void EventHandler::actOnPressedKeys() { 
    pressedKeys.forEach([](char key){ 
     keyHandler(key); 
    }); 
}*/ 

void EventHandler::setKeyHandler(KeyHandler handler) { 
    keyHandler = handler; 
} 

void EventHandler::setMouseHandler(MouseHandler handler) { 
    mouseHandler = handler; 
} 

void EventHandler::setKeysToListenOn(std::vector<char> newListenKeys) { 
    if (listening) { 
     throw std::runtime_error::runtime_error(
      "Cannot change the listened-on keys while listening" 
     ); 
     //This could be changed to killing the thread by setting 
     // listening to false, changing the keys, then restarting 
     // the listening thread. I can't see that being necessary though. 
    } 

    //Untested 
    for (char& key : newListenKeys) { 
     if (key >= 'a' && key <= 'z') { 
      key += 32; 
     } 
    } 

    keysToCheck = newListenKeys; 

} 

void EventHandler::setButtonsToListenOn(std::vector<char> newListenButtons) { 
    if (listening) { 
     throw std::runtime_error::runtime_error(
      "Cannot change the listened-on buttons while listening" 
     ); 
    } 

    mButtonsToCheck = newListenButtons; 
} 

void EventHandler::listenForPresses(int loopMSDelay) { 
    listening = true; 
    listeningThread = std::thread ([=]{ 
     do { 
      actOnPressedKeys(); 
      std::this_thread::sleep_for(std::chrono::milliseconds(loopMSDelay)); 
     } while (listening); 

    }); 
} 

void EventHandler::stopListening() { 
    listening = false; 
} 

void EventHandler::getMousePos(int& x, int& y) { 
    MEVENT event; 
    if (nc_getmouse(&event) == OK) { 
     x = event.x, y = event.y; 
    } 
} 

Answer 1

PDCurses實現flushinp ，這是應該做的要求。註釋和功能（適用於Win32，例如）

/* discard any pending keyboard or mouse input -- this is the core 
    routine for flushinp() */ 

void PDC_flushinp(void) 
{ 
    PDC_LOG(("PDC_flushinp() - called\n")); 

    FlushConsoleInputBuffer(pdc_con_in); 
} 

此功能通過沿途設置在最詛咒實現的狀態。這裏是ncurses中的manual page的鏈接，這可能會有所幫助。