


In the current computer operating system, the top layer of the screen refers to the window or application currently being displayed. In Windows systems, top-level windows can be obtained and managed through the Win32 API. In this article, we will introduce how to use golang to implement a program that can obtain and display the top-level window of the screen.
- Get the top-level window list
In golang, use the syscall package to call system-level functions. We can use the FindWindowEx function to obtain the handle list of the top-level window. For example:
hwnd := uintptr(0) var list []uintptr for { hwnd = uintptr(C.FindWindowEx( 0, hwnd, nil, nil, )) if hwnd == 0 { break } list = append(list, hwnd) }
Among them, the meaning of the parameters of the FindWindowEx function is as follows:
- The first parameter is the parent window handle where the search starts. If it is 0, the search starts from the desktop.
- The second parameter is the handle of the previous window. If it is 0, the search starts from the first window.
- The third parameter is the window class name, nil means that the window class name is not restricted.
- The fourth parameter is the window title, nil means not to limit the window title.
The return value is the found window handle. If not found, 0 is returned.
- Get top-level window information
After obtaining the window handle, we can call the GetWindowRect function to obtain the position and size information of the window. For example:
var rect syscall.Rect C.GetWindowRect( C.HWND(hwnd), (*C.RECT)(unsafe.Pointer(&rect)), )
Among them, the parameters of the GetWindowRect function have the following meanings:
- The first parameter is the window handle.
- The second parameter is a pointer to the window position and size information.
- Display top-level window information
By obtaining the window position and size information, we can use golang's graphics library to display the thumbnail of the window. For example:
thumb, err := goscreenshot.CaptureWindowRect(rect) if err != nil { log.Println(err) continue } screen, err := png.Decode(bytes.NewReader(thumb)) if err != nil { log.Println(err) continue } win := Window{ Title: title, X: rect.Left, Y: rect.Top, Width: rect.Right - rect.Left, Height: rect.Bottom - rect.Top, Picture: screen, } viewer.Show(win)
Among them, the CaptureWindowRect function implements the window screenshot function through golang's screenshot package. Then use golang's image/png package to read the image data and display it in the window. Finally, the Window structure is defined and the viewer.Show method is used to display window information.
- Complete code
The complete code is as follows:
package main import ( "bytes" "image/png" "log" "unsafe" "github.com/lxn/walk" . "github.com/lxn/walk/declarative" "golang.org/x/sys/windows" ) var ( C = windows.NewLazySystemDLL("user32.dll") ) // 窗口信息结构 type Window struct { Title string // 窗口标题 X int32 // 窗口左上角X坐标 Y int32 // 窗口左上角Y坐标 Width int32 // 窗口宽度 Height int32 // 窗口高度 Picture image.Image // 窗口截图 } func main() { // 创建窗口 var mw *walk.MainWindow var tv *walk.TableView var viewer *walk.ImageView MainWindow{ Title: "Screen Viewer", MinSize: Size{640, 480}, Layout: VBox{}, Children: []Widget{ TableView{ AssignTo: &tv, AlternatingRowBG: true, Columns: []TableViewColumn{ {Title: "Title"}, {Title: "X"}, {Title: "Y"}, {Title: "Width"}, {Title: "Height"}, }, }, ImageView{ AssignTo: &viewer, }, }, }.Create(&mw) // 获取顶层窗口列表 hwnd := uintptr(0) var list []uintptr for { hwnd = uintptr(C.FindWindowEx( 0, hwnd, nil, nil, )) if hwnd == 0 { break } list = append(list, hwnd) } // 遍历窗口列表并显示窗口信息 var data []Window for _, hwnd := range list { var rect syscall.Rect C.GetWindowRect( C.HWND(hwnd), (*C.RECT)(unsafe.Pointer(&rect)), ) title := getWindowText(hwnd) if title == "" { continue } thumb, err := goscreenshot.CaptureWindowRect(rect) if err != nil { log.Println(err) continue } screen, err := png.Decode(bytes.NewReader(thumb)) if err != nil { log.Println(err) continue } win := Window{ Title: title, X: rect.Left, Y: rect.Top, Width: rect.Right - rect.Left, Height: rect.Bottom - rect.Top, Picture: screen, } data = append(data, win) tv.PublishRowsReset() } // 设置模型 model, _ := NewWindowModel(data) tv.SetModel(model) // 开始消息循环 mw.Run() } // 获取窗口标题 func getWindowText(hwnd uintptr) string { var buf [256]uint16 C.GetWindowText( C.HWND(hwnd), (*C.CHAR)(unsafe.Pointer(&buf)), 256, ) return syscall.UTF16ToString(buf[:]) } // 窗口模型 type WindowModel struct { walk.TableModelBase items []Window } func NewWindowModel(items []Window) (*WindowModel, error) { m := new(WindowModel) m.items = items return m, nil } func (m *WindowModel) RowCount() int { return len(m.items) } func (m *WindowModel) Value(row, col int) interface{} { item := m.items[row] switch col { case 0: return item.Title case 1: return item.X case 2: return item.Y case 3: return item.Width case 4: return item.Height } panic("unexpected col") }
- Summary
This article introduces how to use Golang implements a program to obtain and display the top-level window of the screen. By calling Windows API functions and implementing operations such as window screenshots and image display, we can easily write a simple screenshot tool. At the same time, with the cooperation of golang's graphics library and Windows API, we can write cross-platform applications.
The above is the detailed content of How to implement a program in golang that can obtain and display the top-level window of the screen. For more information, please follow other related articles on the PHP Chinese website!

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