cursor-monitor_windows.go

// taken from https://claude.ai/chat/c1e10885-ed75-4106-96d3-7db09b64fd09
package main

import (
	"fmt"
	"log"
	"log/slog"
	"syscall"
	"unsafe"

	"github.com/gek64/displayController"
	rl "github.com/gen2brain/raylib-go/raylib"
)

var (
	user32                  = syscall.NewLazyDLL("user32.dll")
	procGetCursorPos        = user32.NewProc("GetCursorPos")
	procEnumDisplayMonitors = user32.NewProc("EnumDisplayMonitors")
	procGetMonitorInfoW     = user32.NewProc("GetMonitorInfoW")
)

type (
	HMONITOR syscall.Handle

	POINT         struct{ X, Y int32 }
	RECT          struct{ Left, Top, Right, Bottom int32 }
	MONITORINFOEX struct {
		CbSize    uint32
		RcMonitor RECT
		RcWork    RECT
		DwFlags   uint32
		SzDevice  [32]uint16
	}
)

func cursorOnMonitor() (*HMONITOR, string, rl.Vector2, error) {
	var cursorPos POINT
	ret, _, err := procGetCursorPos.Call(uintptr(unsafe.Pointer(&cursorPos)))
	if ret == 0 {
		return nil, "", rl.Vector2{}, fmt.Errorf("GetCursorPos failed: %v", err)
	}

	// fmt.Printf("Cursor position: (%d, %d)\n", cursorPos.X, cursorPos.Y)

	var monitors []HMONITOR
	callback := syscall.NewCallback(func(hMonitor HMONITOR, hdcMonitor uintptr, lprcMonitor *RECT, dwData uintptr) uintptr {
		monitors = append(monitors, hMonitor)
		return 1 // continue enumeration
	})

	ret, _, err = procEnumDisplayMonitors.Call(0, 0, callback, 0)
	if ret == 0 {
		return nil, "", rl.Vector2{}, fmt.Errorf("EnumDisplayMonitors failed: %v", err)
	}

	for i, hMonitor := range monitors {
		var info MONITORINFOEX
		info.CbSize = uint32(unsafe.Sizeof(info))
		ret, _, err = procGetMonitorInfoW.Call(
			uintptr(hMonitor),
			uintptr(unsafe.Pointer(&info)),
		)
		if ret == 0 {
			slog.Warn(fmt.Sprintf("GetMonitorInfoW failed for monitor %d: %v\n", i, err))
			continue
		}

		deviceName := syscall.UTF16ToString(info.SzDevice[:])
		//fmt.Printf("Monitor %d: %s\n", i, deviceName)

		if cursorPos.X >= info.RcMonitor.Left && cursorPos.X < info.RcMonitor.Right &&
			cursorPos.Y >= info.RcMonitor.Top && cursorPos.Y < info.RcMonitor.Bottom {
			return &hMonitor, deviceName, rl.Vector2{X: float32(info.RcMonitor.Left), Y: float32(info.RcMonitor.Top)}, nil
		}
	}

	return nil, "", rl.Vector2{}, fmt.Errorf("failed to find the monitor with the cursor")
}

type DDCMonitor struct {
	name            string
	physicalMonitor *displayController.PhysicalMonitorInfo
	pos             rl.Vector2
} // usually external displays

func (m DDCMonitor) getInstanceName() string {
	return m.name
}

func (m DDCMonitor) getPosition() rl.Vector2 {
	return m.pos
}

func (m DDCMonitor) setBrightness(value int) {
	err := displayController.SetMonitorBrightness(m.physicalMonitor.Handle, value)
	if err != nil {
		log.Fatal(err)
	}
}

func (m DDCMonitor) getBrightness() (int, error) {
	b, _, _, err := displayController.GetMonitorBrightness(m.physicalMonitor.Handle)
	if err != nil {
		return 0, err
	}
	return b, nil
}