C++ GetAsyncKeyState() with private overridden attributes - c++

Question

I am trying to figure out how to use GetAsyncKeyState with private attributes forward and backwards from a base class. I need to be able to reset GetAsyncKeyState to other keypresses. Any idea?
Maybe overriding forward and backwards with other keypresses?
#include <iostream>
#include <windows.h>
#include <string>
#include<conio.h>
using namespace std;
bool reset_defaults = false;
class Base {
protected: // OR private
int forward = VK_UP, backwards = VK_DOWN;
public: //...
}
////////////
class Move : public Base {
public:
Base def;
int move() {
while (true) {
if (GetAsyncKeyState(forward) < 0){
cout << ("forward >>>\n");
if (GetAsyncKeyState(forward) == 0){
cout << ("Stopped\n");
}
}
if (GetAsyncKeyState(VK_SPACE) < 0){break;}
}
}
int main() {
Move move;
move.move();
}
Sorry, but I don't think I understand the whole logic of this yet.
PS UPDATE:
How can I override baseKeys values:
class MovementKeys {
protected:
int baseKeys(int default_key_forward, int default_key_backward, int default_key_left, int default_key_right){
default_key_forward = VK_UP;
default_key_backward = VK_DOWN;
default_key_left = VK_LEFT;
default_key_right = VK_RIGHT;
}
public:
int definedCommand(int default_key_forward, int default_key_backward, int default_key_left, int default_key_right) {
while (reset_defaults == false)
{
cout << ("HERE 1 \n");
if (GetAsyncKeyState(default_key_forward) < 0)
{
cout << ("forward\n");
}
if (GetAsyncKeyState(default_key_backward) < 0)
{
court << ("backwards\n");
}
if (GetAsyncKeyState(default_key_left) < 0)
{
cout << ("left\n");
}
if (GetAsyncKeyState(default_key_right) < 0)
{
cout << ("right\n");
}
if (GetAsyncKeyState(VK_SPACE) < 0) { break; }
}
return 0;
}
int derived_newKeys(int default_key_forward, int default_key_backward, int default_key_left, int default_key_right) {
return baseKeys(default_key_forward, default_key_backward, default_key_left, default_key_right);
}

Answer 1

You probably want to use member variables to store the keys. Instead of deriving the class with new keys, you set the variables in constructors (to default or to changed values) and can also change the key assignment later on.
You probably want to create a separate class, which reacts on the events.
#include <iostream>
#include <windows.h>
#include <conio.h>
using namespace std;
class World {
public:
void forward() { y--; };
void backward() { y++; };
void left() { x--; };
void right() { x++; };
private:
int x = 0;
int y = 0;
};
class MovementKeys {
// member variables
private:
// keep reference to world instead of copy; main() has to make sure World object outlives MovementKeys object
World& world;
int key_forward;
int key_backward;
int key_left;
int key_right;
public:
// constructor, which only sets world, but keeps the keys at their default settings
//
// world has to be initialized before the constructor function body
// as references have no default value
// put initialization in member initialization list
MovementKeys(World& w) : world(w)
{
key_forward = VK_UP;
key_backward = VK_DOWN;
key_left = VK_LEFT;
key_right = VK_RIGHT;
}
// constructor which modifies keys
MovementKeys(World& w, int change_key_forward, int change_key_backward, int change_key_left, int change_key_right) : world(w)
{
changeKeys(change_key_forward, change_key_backward, change_key_left, change_key_right);
}
// command loop controlled by keys
int definedCommand()
{
while (true)
{
cout << ("HERE 1 \n");
if (GetAsyncKeyState(key_forward) < 0)
{
cout << ("forward\n");
world.forward();
}
if (GetAsyncKeyState(key_backward) < 0)
{
cout << ("backwards\n");
world.backward();
}
if (GetAsyncKeyState(key_left) < 0)
{
cout << ("left\n");
world.left();
}
if (GetAsyncKeyState(key_right) < 0)
{
cout << ("right\n");
world.right();
}
// optionally change keys from within while loop
if (GetAsyncKeyState(VK_BACK) < 0)
{
key_forward = VK_RETURN;
}
if (GetAsyncKeyState(VK_SPACE) < 0)
{
break;
}
}
return 0;
}
// function for changing the keys stored in the member variables
// can be called by constructor or externally
void changeKeys(int change_key_forward, int change_key_backward, int change_key_left, int change_key_right)
{
key_forward = change_key_forward;
key_backward = change_key_backward;
key_left = change_key_left;
key_right = change_key_right;
}
};
int main()
{
World earth;
// use default keys, declares local variable and constructs MovementKeys object called move
MovementKeys move(earth);
move.definedCommand();
// use custom keys, share same world, declares local variable and constructs MovementKeys object called move2
// static_cast<int>() with a letter in a literal char parameter works, because the VK_ values of letter keys are the actual ASCII values (on purpose by Microsoft, I would assume)
MovementKeys move2(earth, static_cast<int>('W'), static_cast<int>('S'), static_cast<int>('A'), static_cast<int>('D'));
move2.definedCommand();
// change keys in move2
move2.changeKeys(VK_LBUTTON, VK_RBUTTON, VK_CONTROL, VK_SHIFT);
move2.definedCommand();
// run first one again for the fun of it
move.definedCommand();
}
Alternatively passing World& only, where it is used in definedCommand (and at the same time be able to use several worlds):
class World {
// ...
};
class MovementKeys {
// member variables without world, we can also put default value here
private:
int key_forward = VK_UP;
int key_backward = VK_DOWN;
int key_left = VK_LEFT;
int key_right = VK_RIGHT;
public:
// default constructor with no parameters, delegate to other constructor
// delegating not necessary, as the default values are set above anyway; just demonstrating various techniques for initializing member variables
MovementKeys() : MovementKeys(VK_UP, VK_DOWN, VK_LEFT, VK_RIGHT) {};
// constructor which modifies keys, put everything in member initialization list
MovementKeys(int change_key_forward, int change_key_backward, int change_key_left, int change_key_right) : key_forward(change_key_forward), key_backward(change_key_backward), key_left(change_key_left), key_right(change_key_right) {};
// command loop controlled by keys, pass World& here as parameter
int definedCommand(World& world)
{
while (true)
{
// ...
}
return 0;
}
void changeKeys(int change_key_forward, int change_key_backward, int change_key_left, int change_key_right)
{
// ...
}
};
int main()
{
// use default keys, declares local variable and constructs MovementKeys object called move
MovementKeys move;
// use custom keys, declares local variable and constructs MovementKeys object called move2
MovementKeys move2(static_cast<int>('W'), static_cast<int>('S'), static_cast<int>('A'), static_cast<int>('D'));
MovementKeys defaultMenuKeys;
World earth;
World moon;
World menu; // between moving in worlds, we want to control some settings in a menu
move.definedCommand(earth);
move2.definedCommand(earth);
move2.definedCommand(moon);
// change keys in move2
move2.changeKeys(VK_LBUTTON, VK_RBUTTON, VK_CONTROL, VK_SHIFT);
move2.definedCommand(earth);
defaultMenuKeys.definedCommand(menu);
// run first one again for the fun of it
move.definedCommand(moon);
}
You can introduce a (class) enum with a list of the states, why definedCommand() returns:
// outside or can be put into MovementKeys and henceforth used as MovementKeys::ReturnReason
class enum ReturnReason { EXIT, NEWKEYS, SHOWMENU, SWITCHWORLD };
// in class MovementKeys
ReturnReason definedCommand() {
// ...
return NEWKEYS;
// ...
return EXIT;
// ...
return SHOWMENU;
// ...
}
// in main()
ReturnReason r = definedCommand();
if (r == NEWKEYS)
move2.changeKeys(...);
else if (r == EXIT)
return 0;
If you use that 'trick' to also control the menu, it could make sense to use virtual inheritance now for World. As the normal World and the menu World probably react quite differently. (The base class (ancestor) would be World, which is recognized by MovementKeys. Your actual Worlds are objects of derived (children) classes, with more specific behaviour.
definedCommand then can be called and run with any derived class of the base class World.