因为示例代码有效，所以程序中的其他东西会导致错误。尝试将下面的代码部分移动到你自己的代码中，直到它起作用，然后你就会知道哪一部分代码是罪魁祸首。
示例代码
好吧，巨大的代码块来了。这段代码对我来说是正确的。（Escape，以及所有其他键成功激活和停用）。它很大，有评论，并且很好地解释了事情。试试这个，如果它有效，我们将检查你程序的其他部分，如果没有，我只能给你“祝你好运”，然后拿你想要的：
// DirectInput
#define DIRECTINPUT_VERSION 0x0800
#include<dinput.h>
// Standard stuff
#include <iostream>
#include <stdexcept>
#include <sstream>
#include <string>
// Link from code, MSVC specific, could be done in project settings
#pragma comment(lib, "dinput8.lib")
#pragma comment(lib, "dxguid.lib")
// Utility lexical_cast, use Boost if possible.
// Simple replacement, converts a stream-able `T`
// to a string
template <typename T>
const std::string lexical_cast(const T& pValue)
{
std::stringstream ss;
ss << pValue;
return ss.str();
}
// Utility function + macro to execute DirectX code with exceptions.
// Kinda ugly, but helpful for us.
void check_error(HRESULT pResult, const std::string& pFuncName)
{
// DI_OK == S_OK, but S_OK is more general, so we'll use that
if (pResult != S_OK)
{
throw std::runtime_error("Error executing: " + pFuncName +
"! Returned: " + lexical_cast(pResult));
}
}
// Macro, makes calling the function easier. It is wrapped in
// an `if` statement for reasons outlined in:
// http://www.parashift.com/c++-faq-lite/misc-technical-issues.html#faq-39.5
#define CHECK_ERROR(x) if (true) { check_error(x, #x); } else (void)0
// The above gives the warning:
// "warning C4127: conditional expression is constant", disable below:
#pragma warning(disable: 4127)
// Manages input
class input_manager
{
public:
// Constants
static const int NumberKeys = 256;
// Creation
input_manager(void)
{
// Create input and keyboard (like I said, ugly macro, but helpful :] )
CHECK_ERROR(DirectInput8Create(GetModuleHandle(NULL), DIRECTINPUT_VERSION,
IID_IDirectInput8, reinterpret_cast<void**>(&_input), 0));
CHECK_ERROR(_input->CreateDevice(GUID_SysKeyboard, &_keyboard, 0));
CHECK_ERROR(_keyboard->SetDataFormat(&c_dfDIKeyboard));
CHECK_ERROR(_keyboard->Acquire());
}
~input_manager(void)
{
// Free resources. Note: Many programmers
// unnecessarily wrap this stuff in
// `if (_keyboard !=0)`, and then
// `_keyboard = 0`. This is completely unnecessary,
// because destructors are only run one time.
// Also, I can assume they are valid, because if they
// weren't, we wouldn't be here (an exception would have
// been thrown)
_keyboard->Unacquire();
_keyboard->Release();
_input->Release();
// Also, if we wrapped this into a nice RAII class, we wouldn't
// be forced to write a destructor, but this is outside the scope.
// Feel free to ask how; additionally, since we're on the topic, if you'd
// like more tips handling input (I've written PLENTY of input managers)
// I'm free for asking about things like testing for triggers rather than pressed
// ("was it pressed, regardless if it's being held now" versus
// "is it being pressed"), etc.
}
// Operations
void update(void)
{
CHECK_ERROR(_keyboard->GetDeviceState(NumberKeys, reinterpret_cast<void*>(&_keys)));
}
// Query
bool key_pressed(int pKey) const
{
return test_key(pKey);
}
// Might wrap into an operator[] for convenience.
private:
// Constants
static const int PressMask = 0x80;
// Sorry for the confusion, but indeed, with
// `char`s the mask is simply 0x80.
// Utility
bool test_key(int pKey) const
{
return (_keys[pKey] & PressMask) != 0;
}
// Members
LPDIRECTINPUT8 _input;
LPDIRECTINPUTDEVICE8 _keyboard;
char _keys[NumberKeys];
};
void test_keys(const input_manager& input)
{
bool anyPressed = false;
for (unsigned i = 0; i < input_manager::NumberKeys; ++i)
{
if (input.key_pressed(i))
{
std::cout << "Pressing: " << i << std::endl;
anyPressed = true;
}
}
if (!anyPressed)
{
std::cout << "No keys pressed." << std::endl;
}
}
void execute(void)
{
input_manager input;
std::cout << "Press Q to quit." << std::endl;
bool running = true;
while (running)
{
input.update();
if (input.key_pressed(DIK_Q))
{
running = false;
}
test_keys(input);
Sleep(0); // give some processor time
}
}
int main(void)
{
// Place real code in an execute function, so main
// is clean and ready to catch exceptions:
try
{
execute();
}
catch (const std::exception& e)
{
// Error!
std::cerr << "Unhandled exception:" << e.what() << std::endl;
}
}
老建议：
尝试从 GetDeviceState 中获取返回值：
HRESULT result = // v Prefer C++-style casts
di_keyboard->GetDeviceState(sizeof(keys), reinterpret_cast<void*>(&keys);
if (result != DI_OK)
{
// uh-oh
std::cout << result << std::endl;
}
将其与此处的表格进行比较。
老半答案：
在 Extra Stuff 部分中编辑代码后不久，我意识到了错误，抱歉我没有早点发现它。您正在测试错误的位:)
观察：
// v HERE! Should be 0x8000, not 0x80.
return (GetAsyncKeyState(pKeyCode) & 0x8000) != 0;
试试看：
int KeyDown(int key)
{
return (keys[key] & 0x8000);
}
此外，这应该被移动到一个常数以避免幻数：
// somewhere, probably in the private section of the class or in a detail namespace:
static const int PushedMask = 0x8000;
// code reads better:
int KeyDown(int key)
{
return (keys[key] & PushedMask);
}
最后，在 C++ 中你有一个bool类型，所以好好利用它！
// v here
bool KeyDown(int key)
{
return (keys[key] & PushedMask);
}
我知道 Visual Studio 会警告这种从intto 的转换bool，所以你可以摆脱它，同时也让你的意图更清晰：
bool KeyDown(int key)
{
return (keys[key] & PushedMask) != 0; // or == 1, your choice
}
额外的东西：
试试下面的代码：
#include <iostream>
#include <windows.h>
bool key_pressed(int pKeyCode)
{
return (GetAsyncKeyState(pKeyCode) & 0x8000) != 0;
}
void test_keys(void)
{
for (unsigned i = 0; i < 255; ++i)
{
if (key_pressed(i))
{
std::cout << "Pressing: " << i << std::endl;
}
}
}
int main(void)
{
bool running = true;
while (running)
{
if (key_pressed(VK_ESCAPE))
{
running = false;
}
test_keys();
Sleep(0);
}
}
这对我有用（响应所有键，退出时退出）。的最小测试用例GetAsyncKeyState。如果这不起作用，请在您的评论中添加操作系统、键盘等。