关于 c：各种输入 API 的问题(RAWINPUT、WINAPI)

Trouble with various input API’s (RAWINPUT, WINAPI)

背景：

在我使用 Windows API 进行开发的大部分时间里，我一直在分别使用 WM_MOUSEMOVE 和 WM_KEYDOWN/WM_KEYUP 消息进行鼠标和键盘输入。然而，我最近开始实现一个输入类，它使用 RAWINPUT 和 WM_INPUT 消息来处理输入。

感谢这个网站，键盘实现完美无缺

但是，我现在将注意力转向实现鼠标移动。据我了解，WM_INPUT 在处理鼠标时会生成鼠标移动增量，而不是客户端空间坐标。

问题是我还想在类中存储鼠标指针的客户端和屏幕空间坐标，理想情况下我想这样做而不需要同时捕获 WM_MOUSEMOVE 消息或使用 GetCursorPos() /ScreenToClient() 尽可能使用函数，因为我(可能是没有根据的)担心性能问题。

我对 RAWINPUT 的研究将我带到了这里，它说明了鼠标的详细信息：

Note that the values returned are not screen space values like you get from the WM_MOUSEMOVE message. This is raw data we are getting so the values need interpreting.

这让我相信可以通过使用初始调用 GetCursorPos() 计算鼠标光标的初始位置来解释数据，然后对于 WM_INPUT 消息检测到的每个鼠标移动事件，添加检索到的增量从 WM_INPUT 消息到初始光标位置，采取措施确保该位置保持在屏幕边界内。例如像这样的东西(注意这不会编译，因为它包含我的课程的摘录，但它应该足以概述我目前正在做的事情)

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// Somewhere in class header

RECT m_screenMouseBounds;
POINT m_mouseDelta;
POINT m_mouseScreenPosition;
POINT m_mouseScreenPositionGETCURSOR;
RAWMOUSE m_rawMouse;

// …

// Somewhere during class initialisation

GetCursorPos(&m_mouseScreenPosition); // Get initial mouse cursor position

// Determine maximum and minimum boundaires of current display
m_screenMouseBounds.right = GetSystemMetrics(SM_CXSCREEN);
m_screenMouseBounds.bottom = GetSystemMetrics(SM_CYSCREEN);
m_screenMouseBounds.top = 0;
m_screenMouseBounds.left = 0;

// Prepare the devices for registering
RAWINPUTDEVICE theInputDevices[2];

// 0 = keyboard
theInputDevices[0].usUsagePage = 0x01;
theInputDevices[0].usUsage = 0x06;
theInputDevices[0].dwFlags = RIDEV_NOLEGACY;
theInputDevices[0].hwndTarget = theWindowToHandle;

// 1 = mouse
theInputDevices[1].usUsagePage = 0x01;
theInputDevices[1].usUsage = 0x02;
theInputDevices[1].dwFlags = 0; // RIDEV_NOLEGACY
theInputDevices[1].hwndTarget = theWindowToHandle;

// Register each device with raw input
if(RegisterRawInputDevices(theInputDevices,2,sizeof(RAWINPUTDEVICE))==FALSE)
{
// throw exception
return false;
}

// …

// In the WM_INPUT processing function with parameters : (WPARAM wParam, LPARAM lParam)

char inputBuffer[sizeof(RAWINPUT)] = {};
UINT inputBufferSize = sizeof(RAWINPUT);
GetRawInputData(reinterpret_cast<HRAWINPUT>(lParam), RID_INPUT, inputBuffer, &inputBufferSize, sizeof(RAWINPUTHEADER));
RAWINPUT* rawData = reinterpret_cast<RAWINPUT*>(inputBuffer);

if(rawData–>header.dwType == RIM_TYPEMOUSE)
{
m_rawMouse = rawData–>data.mouse;

// Add the movement deltas acquired from the WM_INPUT message
m_mouseDelta.x = m_rawMouse.lLastX;
m_mouseDelta.y = m_rawMouse.lLastY;

// Update the screen position using the delta values (Does not work as expected!)
m_mouseScreenPosition.x += m_mouseDelta.x;
m_mouseScreenPosition.y += m_mouseDelta.y;

// Ensure mouse coords are within the screens boundaries
if (m_mouseScreenPosition.x < m_screenMouseBounds.left)
{
m_mouseScreenPosition.x = m_screenMouseBounds.left;
}
if (m_mouseScreenPosition.x > m_screenMouseBounds.right)
{
m_mouseScreenPosition.x = m_screenMouseBounds.right;
}
if (m_mouseScreenPosition.y < m_screenMouseBounds.top)
{
m_mouseScreenPosition.y = m_screenMouseBounds.top;
}
if (m_mouseScreenPosition.y > m_screenMouseBounds.bottom)
{
m_mouseScreenPosition.y = m_screenMouseBounds.bottom;
}

// Double check to make sure that the screen position coordinates calculated
// above match the screen coordinates as determined by Windows
// using GetCursorPos() (Hint: They don’t! :( )
GetCursorPos(&m_mouseScreenPositionGETCURSOR);

TCHAR s[256];
swprintf(s, L“MouseDX: %ld MouseDY: %ld\
“, m_mouseDelta.x, m_mouseDelta.y);
OutputDebugString(s);

swprintf(s, L“MouseX(Screen(WM_INPUT)): %ld MouseY(Screen(WM_INPUT)): %ld\
“, m_mouseScreenPosition.x, m_mouseScreenPosition.y);
OutputDebugString(s);

swprintf(s, L“MouseX(Screen(GetCursorPos)): %ld MouseY(Screen(GetCursorPos)): %ld\
“, m_mouseScreenPositionGETCURSOR.x, m_mouseScreenPositionGETCURSOR.y);
OutputDebugString(s);
}

问题是通过这种方法为m_mouseScreenPosition获取的值与通过WINAPI函数GetCursorPos()获取的m_mouseScreenPositionGETCURSOR的值不同。

总结

我想我的全部问题是：

RAWMOUSE 结构的lLastX 和lLastY 的值是什么关系？它们是否与屏幕坐标/客户端坐标相关，即返回的值与屏幕上的像素成 1:1 关系，或者它们是否与显示器完全无关，而是与鼠标的细节(灵敏度等)相关，因此不是与像素的 1:1 关系？

如果1的答案与鼠标有关而不是显示坐标：是否可以仅使用WM_INPUT确定鼠标指针的实际屏幕坐标？还是我必须捕获 WM_MOUSEMOVE 消息和/或使用 GetCursorPos() 以确定客户端空间和屏幕空间中的光标坐标？

如果 2 的答案是，我将需要使用 WM_MOUSEMOVE/GetCursorPos()：如果我最终使用 RAWINPUT 以及 WM_MOUSEMOVE/GetCursorPos()，我应该注意哪些性能问题?还是我对性能的担忧毫无根据？

如果你已经做到了这一点，我非常感谢你，我很感激你能给我的任何帮助或信息。谢谢！

Trouble with various input API’s (RAWINPUT, WINAPI)

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