go语言 FindWindow

Go 语言中的 FindWindow 函数是用于查找窗口句柄的函数。它是由 Windows API 提供的，在 Go 中通过 syscall 包来调用。

用法示例：

package main

import (
	"fmt"
	"syscall"
	"unsafe"
)

var (
	user32               = syscall.NewLazyDLL("user32.dll")
	findWindow           = user32.NewProc("FindWindowW")
	getWindowTextLength  = user32.NewProc("GetWindowTextLengthW")
	getWindowText        = user32.NewProc("GetWindowTextW")
	getWindowRect        = user32.NewProc("GetWindowRect")
	getClientRect        = user32.NewProc("GetClientRect")
	getWindowThreadProcessId = user32.NewProc("GetWindowThreadProcessId")
	isWindowVisible      = user32.NewProc("IsWindowVisible")
)

func FindWindow(className, windowName string) (hwnd syscall.Handle, err error) {
	var cname, wname *uint16
	if className != "" {
		cname, err = syscall.UTF16PtrFromString(className)
		if err != nil {
			return 0, err
		}
	}
	if windowName != "" {
		wname, err = syscall.UTF16PtrFromString(windowName)
		if err != nil {
			return 0, err
		}
	}
	r1, _, e1 := syscall.Syscall(findWindow.Addr(), 2, uintptr(unsafe.Pointer(cname)), uintptr(unsafe.Pointer(wname)), 0)
	if r1 == 0 {
		if e1 != 0 {
			err = error(e1)
		} else {
			err = syscall.EINVAL
		}
	}
	hwnd = syscall.Handle(r1)
	return
}

func main() {
	hwnd, err := FindWindow("", "Calculator")
	if err != nil {
		fmt.Println("error:", err)
		return
	}
	fmt.Println("window handle:", hwnd)
}

在这个例子中，FindWindow 函数被用来查找一个没有类名（className 参数为空），名称为 "Calculator" 的窗口的句柄。如果找到了，就输出窗口句柄的值。