Golang : Qt get screen resolution and display on center example

Problem:

You need to start your Qt desktop application main window on the screen center and also need to detect the screen's resolution in order to compute the X and Y co-ordinates for moving your application to the screen center. How to do that?

Solution:

In order to detect the screen resolution, use the QApplication.Desktop() function and its ScreenGeometry() method. It will return the default screen's (if specified to 0) width and height.

To calculate the screen center's X and Y co-ordinates, you can divide the width and height by 2 or use second method which is the Center() function.

Below are two small programs that demonstrate the first and second ways.

Here you go!

 package main

 import (
 "fmt"
 "github.com/therecipe/qt/core"
 "github.com/therecipe/qt/widgets"
 "os"
 )

 var (
 mainApp *widgets.QApplication
 mainLayout *widgets.QWidget
 )

 func populate() *widgets.QWidget {

 mainLayout = widgets.NewQWidget(nil, 0)
 button := widgets.NewQPushButton2("Bye!", nil)
 button.ConnectClicked(func(flag bool) {
 mainApp.Quit()
 })

 layout := widgets.NewQVBoxLayout()
 layout.AddWidget(button, 0, core.Qt__AlignCenter)
 mainLayout.SetLayout(layout)
 return mainLayout
 }

 func main() {

 mainApp = widgets.NewQApplication(len(os.Args), os.Args)

 // get screen resolution(heights and width)
 // 0 for default screen
 screenRect := mainApp.Desktop().ScreenGeometry(0)
 fmt.Println("Detected screen Height : ", screenRect.Height())
 fmt.Println("Detected screen Width : ", screenRect.Width())

 p := populate()

 // first way to display on screen center
 screenWidthCenter := screenRect.Width() / 2
 screenHeightCenter := screenRect.Height() / 2

 p.Move2(screenWidthCenter, screenHeightCenter)
 p.Show()

 mainApp.Exec()
 }

and second way with slight modification. Both programs will show the same result.

 package main

 import (
 "fmt"
 "github.com/therecipe/qt/core"
 "github.com/therecipe/qt/widgets"
 "os"
 )

 var (
 mainApp *widgets.QApplication
 mainLayout *widgets.QWidget
 )

 func populate() *widgets.QWidget {

 mainLayout = widgets.NewQWidget(nil, 0)
 button := widgets.NewQPushButton2("Bye!", nil)
 button.ConnectClicked(func(flag bool) {
 mainApp.Quit()
 })

 layout := widgets.NewQVBoxLayout()
 layout.AddWidget(button, 0, core.Qt__AlignCenter)
 mainLayout.SetLayout(layout)
 return mainLayout
 }

 func main() {

 mainApp = widgets.NewQApplication(len(os.Args), os.Args)

 // get screen resolution(heights and width)
 // 0 for default screen
 screenRect := mainApp.Desktop().ScreenGeometry(0)
 fmt.Println("Detected screen Height : ", screenRect.Height())
 fmt.Println("Detected screen Width : ", screenRect.Width())

 p := populate()

 // second way to display on screen center
 centerPoint := screenRect.Center()
 p.Move2(centerPoint.X(), centerPoint.Y())
 p.Show()

 mainApp.Exec()
 }

Please follow up the setup instruction at https://github.com/therecipe/qt to setup Qt if you haven't done so.

Build and run both programs above and it will show the main application window starting in the middle of your screen.

Happy Qt-ing!

References:

http://www.qtcentre.org/threads/43158-How-to-center-main-window-on-screen