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RGFW 底层：原始鼠标输入和鼠标锁定

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2024-08-14 0 875

解释如何锁定光标并为 x11、winAPI、cocoa 和 emscrIPten 启用原始鼠标输入的教程。

介绍

rgfw 是一个轻量级单头窗口库，其源代码可以在这里找到。
本教程基于其源代码。

当您创建锁定光标的应用程序时，例如带有第一人称相机的游戏，能够禁用光标非常重要。
这意味着将光标锁定在屏幕中间并获取原始输入。

此方法的唯一替代方法是在鼠标移动时将鼠标拉回到窗口的中心。然而，这是一个 hack，所以它可能有错误
并且不适用于所有操作系统。因此，使用原始输入正确锁定鼠标非常重要。

本教程解释了 rgfw 如何处理原始鼠标输入，以便您可以了解如何自己实现它。

概述

所需步骤的快速概述

锁定光标
将光标居中
启用原始输入
处理原始输入
禁用原始输入
解锁光标

当用户要求 rgfw 保持光标时，rgfw 启用一个表示光标已保持的位标志。

1	`win->_winargs \|= rgfw_hold_mouse;`

第 1 步（锁定光标）

在 x11 上，可以通过 xgrabpointer 抓取光标来锁定光标

1	`xgrabpointer(display, window, true, pointermotionmask, grabmodeasync, grabmodeasync, none, none, currenttime);`

这使窗口可以完全控制指针。

在 windows 上，clipcursor 将光标锁定到屏幕上的特定矩形。
这意味着我们必须在屏幕上找到窗口矩形，然后将鼠标夹到该矩形上。

还使用：geTCLientrect) 和 clienttoscreen

//first get the window size (the rgfw_window struct also includes this infORMation, but using this ensures it's correct)
rect cliprect;
getclientrect(window, &amp;cliprect);

// clipcursor needs screen coordinates, not coordinates relative to the window
clienttoscreen(window, (point*) &amp;cliprect.left);
clienttoscreen(window, (point*) &amp;cliprect.right);

// now we can lock the cursor
clipcursor(&amp;cliprect);

在 macos 和 emscripten 上，启用原始输入的功能也会锁定光标。所以我将在步骤 4 中了解它的功能。

步骤2（将光标置于中心）

光标锁定后，应居中于屏幕中间。
这可确保光标锁定在正确的位置，不会干扰其他任何内容。

rgfw 使用名为 rgfw_window_movemouse 的 rgfw 函数将鼠标移动到窗口中间。

在x11上，xwarppointer可用于将光标移动到窗口中心

1	`xwarppointer(display, none, window, 0, 0, 0, 0, window_width / 2, window_height / 2);`

在windows上，使用setcursorpos

1	`setcursorpos(window_x + (window_width / 2), window_y + (window_height / 2));`

在 macos 上，使用 cgwarpmousecursorposition

1	`cgwarpmousecursorposition(window_x + (window_width / 2), window_y + (window_height / 2));`

在 emscripten 上，rgfw 不移动鼠标。

步骤 3（启用原始输入）

对于 x11，xi 用于启用原始输入

// mask for xi and set mouse for raw mouse input ("rawmotion")
unsigned char mask[ximasklen(xi_rawmotion)] = { 0 };
xisetmask(mask, xi_rawmotion);

// set up x1 struct
xieventmask em;
em.deviceid = xiallmasterdevices;
em.mask_len = sizeof(mask);
em.mask = mask;

//enable raw input using the structure
xiselectevents(display, xdefaultrootwindow(display), &amp;em, 1);

在 windows 上，您需要设置 rawinputdevice 结构并使用 registerrawinputdevices 启用它

1 2	`const` `rawinputdevice id = { 0x01, 0x02, 0, window };` `registerrawinputdevices(&id, 1, sizeof(id));`

在 macos 上你只需要运行 cgassociatemouseandmousecursorposition
这还通过解除鼠标光标和鼠标移动的关联来锁定光标

1	`cgassociatemouseandmousecursorposition(0);`

在 emscripten 上你只需要请求用户锁定指针

1	`emscripten_request_pointerlock("#canvas", 1);`

步骤 4（处理原始输入事件）

这些都发生在事件循环期间。

对于x11，您必须处理普通的motionnotify，手动将输入转换为原始输入。
要检查原始鼠标输入事件，您需要使用 genericevent。

switch (e.type) {
    (...)
    case motionnotify:
        /* check if mouse hold is enabled */
        if ((win-&gt;_winargs &amp; rgfw_hold_mouse)) {
            /* convert e.xmotion to raw input by subtracting the previous point */
            win-&gt;event.point.x = win-&gt;_lastmousepoint.x - e.xmotion.x;
            win-&gt;event.point.y = win-&gt;_lastmousepoint.y - e.xmotion.y;

            //the mouse must be moved back to the center when it moves
            xwarppointer(display, none, window, 0, 0, 0, 0, window_width / 2, window_height / 2);
        }

        break;

    case genericevent: {
        /* motionnotify is used for mouse events if the mouse isn't held */
        if (!(win-&gt;_winargs &amp; rgfw_hold_mouse)) {
            xfreeeventdata(display, &amp;e.xcookie);
            break;
        }

        xgeteventdata(display, &amp;e.xcookie);
        if (e.xcookie.evtype == xi_rawmotion) {
            xirawevent *raw = (xirawevent *)e.xcookie.data;
            if (raw-&gt;valuators.mask_len == 0) {
                xfreeeventdata(display, &amp;e.xcookie);
                break;
            }

            double deltax = 0.0f; 
            double deltay = 0.0f;

            /* check if relative motion data exists Where we think it does */
            if (ximaskisset(raw-&gt;valuators.mask, 0) != 0)
                deltax += raw-&gt;raw_values[0];
            if (ximaskisset(raw-&gt;valuators.mask, 1) != 0)
                deltay += raw-&gt;raw_values[1];

            //the mouse must be moved back to the center when it moves
            xwarppointer(display, none, window, 0, 0, 0, 0, window_width / 2, window_height / 2);
            win-&gt;event.point = rgfw_point((u32)-deltax, (u32)-deltay);
        }

        xfreeeventdata(display, &amp;e.xcookie);
        break;
    }

在 windows 上，您只需要处理 wm_input 事件并检查原始运动输入

switch (msg.message) {
    (...)
    case wm_input: {
        /* check if the mouse is being held */
        if (!(win-&gt;_winargs &amp; rgfw_hold_mouse))
            break;

        /* get raw data as an array */
        unsigned size = sizeof(rawinput);
        static rawinput raw[sizeof(rawinput)];
        getrawinputdata((hrawinput)msg.lparam, rid_input, raw, &amp;size, sizeof(rawinputHEADer));

        //make sure raw data is valid 
        if (raw-&gt;header.dwtype != rim_typemouse || (raw-&gt;data.mouse.llastx == 0 &amp;&amp; raw-&gt;data.mouse.llasty == 0) )
            break;

        //the data is flipped  
        win-&gt;event.point.x = -raw-&gt;data.mouse.llastx;
        win-&gt;event.point.y = -raw-&gt;data.mouse.llasty;
        break;
    }

在 macos 上，您可以正常检查鼠标输入，同时使用 deltax 和 deltay 获取和翻转鼠标点

switch (objc_msgsend_uint(e, sel_registername("type"))) {
    case nseventtypeleftmousedragged:
    case nseventtypeothermousedragged:
    case nseventtyperightmousedragged:
    case nseventtypemousemoved:
        if ((win-&gt;_winargs &amp; rgfw_hold_mouse) == 0) // if the mouse is not held
                    break;

                nspoint p;
        p.x = ((cgfloat(*)(id, sel))abi_objc_msgsend_fpret)(e, sel_registername("deltax"));
        p.y = ((cgfloat(*)(id, sel))abi_objc_msgsend_fpret)(e, sel_registername("deltay"));

                //the raw input must be flipped for macos as well, and cast for rgfw's event data
        win-&gt;event.point = rgfw_point((u32) -p.x, (u32) -p.y));

在 emscripten 上，可以像平常一样检查鼠标事件，除了我们要使用和翻转 e->movementx/y

em_bool emscripten_on_mousemove(int eventtype, const emscriptenmouseevent* e, void* userdata) {
    if ((rgfw_root-&gt;_winargs &amp; rgfw_hold_mouse) == 0) // if the mouse is not held
            return

    //the raw input must be flipped for emscripten as well
        rgfw_point p = rgfw_point(-e-&gt;movementx, -e-&gt;movementy);
}

步骤 5（禁用原始输入）

最后，rgfw 允许禁用原始输入并解锁光标以恢复正常的鼠标输入。

首先，rgfw 禁用位标志。

1	`win->_winargs ^= rgfw_hold_mouse;`

在x11中，首先，你必须创建一个带有空白掩码的结构。
这将禁用原始输入。

unsigned char mask[] = { 0 };
xieventmask em;
em.deviceid = xiallmasterdevices;

em.mask_len = sizeof(mask);
em.mask = mask;
xiselectevents(display, xdefaultrootwindow(display), &amp;em, 1);

对于 windows，您可以使用 ridev_remove 传递原始输入设备结构来禁用原始输入。

1 2	`const` `rawinputdevice id = { 0x01, 0x02, ridev_remove, null };` `registerrawinputdevices(&id, 1, sizeof(id));`

在 macos 和 emscripten 上，解锁光标也会禁用原始输入。

第6步（解锁光标）

在x11上，xungrabpoint用于解锁光标。

1	`xungrabpointer(display, currenttime);`

在 windows 上，将 null 矩形指针传递给 clipcursor 以指向光标。

1	`clipcursor(null);`

在 macos 上，关联鼠标光标和鼠标移动将禁用原始输入并解锁光标

1	`cgassociatemouseandmousecursorposition(1);`

在 emscripten 上，退出指针锁定将解锁光标并禁用原始输入。

1	`emscripten_exit_pointerlock();`

完整代码示例

x11

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// this can be compiled with 
// gcc x11.c -lx11 -lxi

#include <x11>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <x11>

int main(void) {
    unsigned int window_width = 200;
    unsigned int window_height = 200;

    display* display = xopendisplay(null);  
    window window = xcreatesimplewindow(display, rootwindow(display, defaultscreen(display)), 400, 400, window_width, window_height, 1, blackpixel(display, defaultscreen(display)), whitepixel(display, defaultscreen(display)));

    xselectinput(display, window, exposuremask | keypressmask);
    xmapwindow(display, window);

    xgrabpointer(display, window, true, pointermotionmask, grabmodeasync, grabmodeasync, none, none, currenttime);

    xwarppointer(display, none, window, 0, 0, 0, 0, window_width / 2, window_height / 2);

    // mask for xi and set mouse for raw mouse input ("rawmotion")
    unsigned char mask[ximasklen(xi_rawmotion)] = { 0 };
    xisetmask(mask, xi_rawmotion);

    // set up x1 struct
    xieventmask em;
    em.deviceid = xiallmasterdevices;
    em.mask_len = sizeof(mask);
    em.mask = mask;

    // enable raw input using the structure
    xiselectevents(display, xdefaultrootwindow(display), &amp;em, 1);

    bool rawinput = true;
    xpoint point;
    xpoint _lastmousepoint;

    xevent event;

    for (;;) {
        xnextevent(display, &amp;event);
        switch (event.type) {
            case motionnotify:
                /* check if mouse hold is enabled */
                if (rawinput) {
                    /* convert e.xmotion to rawinput by substracting the previous point */
                    point.x = _lastmousepoint.x - event.xmotion.x;
                    point.y = _lastmousepoint.y - event.xmotion.y;
                    printf("rawinput %i %i\n", point.x, point.y);
                    xwarppointer(display, none, window, 0, 0, 0, 0, window_width / 2, window_height / 2);
                }

                break;

            case genericevent: {
                /* motionnotify is used for mouse events if the mouse isn't held */
                if (rawinput == false) {
                    xfreeeventdata(display, &amp;event.xcookie);
                    break;
                }

                xgeteventdata(display, &amp;event.xcookie);
                if (event.xcookie.evtype == xi_rawmotion) {
                    xirawevent *raw = (xirawevent *)event.xcookie.data;
                    if (raw-&gt;valuators.mask_len == 0) {
                        xfreeeventdata(display, &amp;event.xcookie);
                        break;
                    }

                    double deltax = 0.0f; 
                    double deltay = 0.0f;

                    /* check if relative motion data exists where we think it does */
                    if (ximaskisset(raw-&gt;valuators.mask, 0) != 0)
                        deltax += raw-&gt;raw_values[0];
                    if (ximaskisset(raw-&gt;valuators.mask, 1) != 0)
                        deltay += raw-&gt;raw_values[1];

                    point = (xpoint){-deltax, -deltay};
                    xwarppointer(display, none, window, 0, 0, 0, 0, window_width / 2, window_height / 2);

                    printf("rawinput %i %i\n", point.x, point.y);
                }   

                xfreeeventdata(display, &amp;event.xcookie);
                break;
            }
            case keypress:
                if (rawinput == false)
                    break;

                unsigned char mask[] = { 0 };
                xieventmask em;
                em.deviceid = xiallmasterdevices;

                em.mask_len = sizeof(mask);
                em.mask = mask;
                xiselectevents(display, xdefaultrootwindow(display), &amp;em, 1);
                xungrabpointer(display, currenttime);

                printf("raw input disabled\n");
                break;
            default: break;
        }
    }

    xclosedisplay(display);
 }
</x11></string.h></stdlib.h></stdio.h></x11>

维纳皮

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// compile with gcc winapi.c

#include <windows.h>

#include <stdio.h>
#include <stdint.h>
#include <assert.h>

int main() {
    WNDCLASS wc = {0};
    wc.lpfnWndProc   = DefWindowproc; // Default window procedure
    wc.hInstance     = GetModuleHandle(NULL);
    wc.lPSzClassName = "SampleWindowClass";

    RegisterClass(&amp;wc);

    int window_width = 300;
    int window_height = 300;
    int window_x = 400;
    int window_y = 400;

    HWND hwnd = CreateWindowA(wc.lpszClassName, "Sample Window", 0,
            window_x, window_y, window_width, window_height,
            NULL, NULL, wc.hInstance, NULL);

    ShowWindow(hwnd, SW_SHOW);
    UpdateWindow(hwnd);

    // first get the window size (the RGFW_window struct also includes this informaton, but using this ensures it's correct)
    RECT clipRect;
    GetClientRect(hwnd, &amp;clipRect);

    // ClipCursor needs screen coords, not coords relative to the window
    ClientToScreen(hwnd, (POINT*) &amp;clipRect.left);
    ClientToScreen(hwnd, (POINT*) &amp;clipRect.right);

    // now we can lock the cursor
    ClipCursor(&amp;clipRect);

    SetCursorPos(window_x + (window_width / 2), window_y + (window_height / 2));    
    const RAWINPUTDEVICE id = { 0x01, 0x02, 0, hwnd };
    RegisterRawInputDevices(&amp;id, 1, sizeof(id));

    MSG msg;

    BOOL holdMouse = TRUE;

    BOOL running = TRUE;

    POINT point;

    while (running) {
        if (PeekMessageA(&amp;msg, hwnd, 0u, 0u, PM_REMOVE)) {
            switch (msg.message) {
                case WM_CLOSE:
                case WM_QuiT:
                    running = FALSE;
                    break;
                case WM_INPUT: {
                    /* check if the mouse is being held */
                    if (holdMouse == FALSE)
                        break;

                    /* get raw data as an array */
                    unsigned size = sizeof(RAWINPUT);
                    static RAWINPUT raw[sizeof(RAWINPUT)];
                    GetRawInputData((HRAWINPUT)msg.lParam, RID_INPUT, raw, &amp;size, sizeof(RAWINPUTHEADER));

                    // make sure raw data is valid 
                    if (raw-&gt;header.dwType != RIM_TYPEMOUSE || (raw-&gt;data.mouse.lLastX == 0 &amp;&amp; raw-&gt;data.mouse.lLastY == 0) )
                        break;

                    // the data is flipped  
                    point.x = -raw-&gt;data.mouse.lLastX;
                    point.y = -raw-&gt;data.mouse.lLastY;
                    printf("raw input: %i %i\n", point.x, point.y);
                    break;
                }
                case WM_KEYDOWN:
                    if (holdMouse == FALSE)
                        break;

                    const RAWINPUTDEVICE id = { 0x01, 0x02, RIDEV_REMOVE, NULL };
                    RegisterRawInputDevices(&amp;id, 1, sizeof(id));
                    ClipCursor(NULL);

                    printf("rawinput disabled\n");
                    holdMouse = FALSE;
                    break;

                default: break;
            }
            TranslateMessage(&amp;msg);
            DispatchMessage(&amp;msg);
        }

        running = IsWindow(hwnd);
    }

    DestroyWindow(hwnd);
    return 0;
}
</assert.h></stdint.h></stdio.h></windows.h>

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