立刻关闭显示器并锁屏，一个 Rust 调用 Windows API 的小工具。

main.rs

//! ```toml
//! # cargo.toml
//! [package]
//! name = "screenoff"
//! version = "0.1.0"
//! edition = "2021"
//! description = "通过 Windows API 关闭电脑显示屏"
//! # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
//!
//! [dependencies]
//! windows = { version = "0.48.0", features = [
//!     "Win32_Foundation",
//!     "Win32_System_Diagnostics_Debug",
//!     "Win32_System_Shutdown",
//!     "Win32_UI_WindowsAndMessaging",
//! ] }
//! ```
//!
//! 参考链接：
//! + <https://learn.microsoft.com/en-us/windows/win32/menurc/wm-syscommand>
//! + <https://microsoft.github.io/windows-docs-rs/doc/windows/Win32/index.html>

use windows::core::PWSTR;
use windows::Win32::Foundation::{GetLastError, HWND, LPARAM, WPARAM};
use windows::Win32::System::Diagnostics::Debug::{FormatMessageW, FORMAT_MESSAGE_FROM_SYSTEM};
use windows::Win32::System::Shutdown::LockWorkStation;
use windows::Win32::UI::WindowsAndMessaging::{PostMessageA, SC_MONITORPOWER, WM_SYSCOMMAND};

const HWND_BROADCAST: HWND = HWND(0xffff);

#[allow(dead_code)]
enum MonitorPower {
    On = -1isize,
    LowPower = 1isize,
    Off = 2isize,
}

fn main() {
    unsafe {
        let ok = PostMessageA(
            HWND_BROADCAST,
            WM_SYSCOMMAND,
            WPARAM(SC_MONITORPOWER as usize),
            LPARAM(MonitorPower::Off as isize),
        );
        if !ok.as_bool() {
            panic_last_error();
        }
        let ok = LockWorkStation();
        if !ok.as_bool() {
            panic_last_error();
        }
    }
}

unsafe fn panic_last_error() -> ! {
    let errorcode = GetLastError();
    let mut errmsg = [0u16; 1024];
    FormatMessageW(
        FORMAT_MESSAGE_FROM_SYSTEM,
        None,
        errorcode.0,
        0, // 当前用户使用的语言
        PWSTR(&mut errmsg as *mut u16),
        1024,
        None,
    );
    let errmsg = String::from_utf16_lossy(&errmsg);
    panic!("错误(0x{:x}): {}", errorcode.0, &errmsg);
}