Golang : Qt image viewer example

This is the Qt version of the previous tutorial on how to create a simple image viewer with Go-GTK. To create this Qt image viewer program, we will use the Go-Qt binding package

Please follow up the setup instruction at https://github.com/therecipe/qt to setup Qt.

What this program does is to load the given image file and display it. It will be able to detect animated GIF file and use the proper Qt functions such as QLabel and QMovie to display the animated GIF. There is also a button to quit the image viewer application properly.

Here you go!

 package main

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

 var (
  displayArea *widgets.QWidget
  scene *widgets.QGraphicsScene
  view *widgets.QGraphicsView
  item *widgets.QGraphicsPixmapItem
  mainApp *widgets.QApplication
  imageFileName string
 )

 func imageViewer() *widgets.QWidget {
  displayArea = widgets.NewQWidget(nil, 0)
  scene = widgets.NewQGraphicsScene(nil)
  view = widgets.NewQGraphicsView(nil)

  var imageReader = gui.NewQImageReader3(imageFileName, "")
  // test to see if we are dealing with animated GIF
  fmt.Println("Animated GIF : ", imageReader.SupportsAnimation())

  if imageReader.SupportsAnimation() {
 // instead of reading from file(disk) again, we take from memory
 // HOWEVER, this will cause segmentation violation error ! :(
 //var movie = gui.NewQMovieFromPointer(imageReader.Pointer())
 var movie = gui.NewQMovie3(imageFileName, "", nil)

 // see http://stackoverflow.com/questions/5769766/qt-how-to-show-gifanimated-image-in-qgraphicspixmapitem
 var movieLabel = widgets.NewQLabel(nil, core.Qt__Widget)
 movieLabel.SetMovie(movie)
 movie.Start()
 scene.AddWidget(movieLabel, core.Qt__Widget)
  } else {

 var pixmap = gui.NewQPixmap5(imageFileName, "", core.Qt__AutoColor)
 item = widgets.NewQGraphicsPixmapItem2(pixmap, nil)

 scene.AddItem(item)
  }

  view.SetScene(scene)

  //create a button and connect the clicked signal
  var button = widgets.NewQPushButton2("Quit", nil)
  button.ConnectClicked(func(flag bool) {

 //os.Exit(0)

 widgets.QApplication_Beep()
 widgets.QMessageBox_Information(nil, "OK", "You clicked quit button!", widgets.QMessageBox__Ok, widgets.QMessageBox__Ok)

 // errmm... proper way to quit Qt application
 // https://godoc.org/github.com/therecipe/qt/widgets#QApplication.Quit
 mainApp.Quit()
  })

  var layout = widgets.NewQVBoxLayout()

  layout.AddWidget(view, 0, core.Qt__AlignCenter)
  layout.AddWidget(button, 0, core.Qt__AlignCenter)

  displayArea.SetLayout(layout)

  return displayArea
 }

 func main() {

  if len(os.Args) != 2 {
 fmt.Printf("Usage : %s <image file>\n", os.Args[0])
 os.Exit(0)
  }

  imageFileName = os.Args[1]

  fmt.Println("Loading image : ", imageFileName)

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

  imageViewer().Show()

  widgets.QApplication_Exec()
 }

To test this program, build and run this program from the command line. Supply it with animated and non-animated images.

Happy coding!

References:

https://godoc.org/github.com/therecipe/qt/widgets

https://godoc.org/github.com/therecipe/qt/core

https://godoc.org/github.com/therecipe/qt/gui

https://godoc.org/github.com/therecipe/qt/widgets#QApplication.Quit

https://socketloop.com/tutorials/golang-simple-image-viewer-with-go-gtk