This document discusses using QLineEdit events and displaying message boxes in Qt. It provides an example Qt application that: - Creates a window with a label, two buttons, and a line edit widget - Configures event handlers for the line edit and buttons - Displays a message box when the user presses enter in the line edit The example demonstrates how to use QLineEdit text change and return pressed events, and the QMessageBox class to display a popup message. It also briefly discusses other widget events like state changed for QCheckBox.

1. Ring Documentation, Release 1.2
47.27 QLineEdit Events and QMessageBox
In this example we will learn about using QLineEdit Events and displaying a Messagebox
Load "guilib.ring"
MyApp = New qApp {
win1 = new qWidget() {
setwindowtitle("Welcome")
setGeometry(100,100,400,300)
label1 = new qLabel(win1) {
settext("What is your name ?")
setGeometry(10,20,350,30)
setalignment(Qt_AlignHCenter)
}
btn1 = new qpushbutton(win1) {
setGeometry(10,200,100,30)
settext("Say Hello")
setclickevent("pHello()")
}
btn1 = new qpushbutton(win1) {
setGeometry(150,200,100,30)
settext("Close")
setclickevent("pClose()")
}
lineedit1 = new qlineedit(win1) {
setGeometry(10,100,350,30)
settextchangedevent("pChange()")
setreturnpressedevent("penter()")
}
47.27. QLineEdit Events and QMessageBox 420

2. Ring Documentation, Release 1.2
show()
}
exec()
}
Func pHello
lineedit1.settext( "Hello " + lineedit1.text())
Func pClose
MyApp.quit()
Func pChange
win1 { setwindowtitle( lineedit1.text() ) }
Func pEnter
new qmessagebox(win1) {
setwindowtitle("Thanks")
settext("Hi " + lineedit1.text() )
setstylesheet("background-color : white")
show()
}
The application during the runtime
47.27. QLineEdit Events and QMessageBox 421

3. Ring Documentation, Release 1.2
47.28 Other Widgets Events
Each Qt signal can be used in RingQt, just add Set before the signal name and add event after the signal name to get
the method that can be used to determine the event code.
For example the QProgressBar class contains a signal named valueChanged() To use it just use the function setVal-
ueChangedEvent()
Example:
Load "guilib.ring"
New qApp {
win1 = new qMainWindow() {
setwindowtitle("QProgressBar valueChanged Event")
progress1 = new qprogressbar(win1) {
setGeometry(100,100,350,30)
setvalue(10)
setvaluechangedevent("pChange()")
}
new qpushbutton(win1) {
setGeometry(10,10,100,30)
settext("increase")
setclickevent("pIncrease()")
}
showMaximized()
}
47.28. Other Widgets Events 422

4. Ring Documentation, Release 1.2
exec()
}
func pIncrease
progress1 { setvalue(value()+1) }
func pchange
win1.setwindowtitle("value : " + progress1.value() )
The application during the runtime
Another example for the stateChanged event of the QCheckBox class
Load "guilib.ring"
New qApp {
win1 = new qMainWindow() {
setwindowtitle("QCheckBox")
new qcheckbox(win1) {
setGeometry(100,100,100,30)
settext("New Customer!")
setstatechangedevent("pchange()")
}
showMaximized()
}
exec()
}
Func pChange
new qMessageBox(Win1) {
setWindowTitle("Checkbox")
settext("State Changed!")
show()
}
The application during the runtime
47.28. Other Widgets Events 423

5. Ring Documentation, Release 1.2
47.29 Using the QTimer Class
In this example we will learn about using the QTimer class
Load "guilib.ring"
new qApp {
win1 = new qwidget() {
setgeometry(100,100,200,70)
setwindowtitle("Timer")
label1 = new qlabel(win1) {
setgeometry(10,10,200,30)
settext(thetime())
}
new qtimer(win1) {
setinterval(1000)
settimeoutevent("pTime()")
start()
}
show()
}
exec()
}
func ptime
label1.settext(thetime())
Func thetime
return "Time : " + Time()
The application during the runtime
47.29. Using the QTimer Class 424

6. Ring Documentation, Release 1.2
47.30 Using QProgressBar and Timer
In this example we will learn about using the “animated” QProgressBar class and Timer
###------------------------------------
### ProgressBar and Timer Example
Load "guilib.ring"
new qApp
{
win1 = new qwidget()
{
setgeometry(100,100,400,100)
setwindowtitle("Timer and ProgressBar")
LabelMan = new qlabel(win1)
{
setgeometry(10,10,200,30)
settext(theTime()) ### ==>> func
}
TimerMan = new qtimer(win1)
{
setinterval(1000)
settimeoutevent("pTime()") ### ==>> func
start()
}
BarMan = new qprogressbar(win1)
{
setGeometry(100,50,300,10) ### Position X y, Length, Thickness
setvalue(0) ### Percent filled
}
show()
}
exec()
}
func pTime
LabelMan.settext(theTime()) ### ==>> func
Increment = 10
if BarMan.value() >= 100 ### ProgressBar start over.
BarMan.setvalue(0)
ok
BarMan{ setvalue(value() + Increment) }
47.30. Using QProgressBar and Timer 425

7. Ring Documentation, Release 1.2
Func theTime
return "Time : " + Time()
47.31 Display Scaled Image using QLabel
In this example we will learn about displaying and scaling an image so that it looks “animated” using the QLabel
widget
Load "guilib.ring"
#----------------------------------------------------
# REQUIRES: image = "C:RINGbinstock.jpg"
# imageStock: start dimensions for growing image
imageW = 200 ; imageH = 200 ; GrowBy = 4
###----------------------------------------------------
### Window and Box Size dimensions
WinWidth = 1280 ; WinHeight = 960
BoxWidth = WinWidth -80 ; BoxHeight = WinHeight -80
###----------------------------------------------------
New qapp {
win1 = new qwidget() {
setgeometry(50,50, WinWidth,WinHeight)
setwindowtitle("Animated Image - Display Image Scaled and Resized")
imageStock = new qlabel(win1) {
image = new qpixmap("C:RINGbinstock.jpg")
AspectRatio = image.width() / image.height()
imageW = 200
imageH = imageH / AspectRatio
### Size-H, Size-V, Aspect, Transform
setpixmap(image.scaled(imageW , imageH ,0,0))
PosLeft = (BoxWidth - imageW ) / 2
PosTop = (BoxHeight - imageH ) / 2
47.31. Display Scaled Image using QLabel 426

8. Ring Documentation, Release 1.2
setGeometry(PosLeft,PosTop,imageW,imageH)
}
TimerMan = new qtimer(win1) {
setinterval(100) ### interval 100 millisecs.
settimeoutevent("pTime()") ### ==>> func
start()
}
show()
}
exec()
}
###------------------------------------------------------
### Fuction TimerMan: calling interval 100 milliseconds
func pTime
### Stop Timer when image is size of Window area
if imageW > BoxWidth
TimerMan.stop()
imageStock.clear() ### Will clear the image
ok
### Grow image
imageW += GrowBy
imageH = imageW / AspectRatio
### Scaled Image: Size-H, Size-V, Aspect, Transform
imageStock.setpixmap(image.scaled(imageW , imageH ,0,0))
### Center the image
PosLeft = (WinWidth - imageW ) / 2
PosTop = (WinHeight - imageH ) / 2
imageStock.setGeometry(PosLeft,PosTop,imageW,imageH)
47.32 Using the QFileDialog Class
Example
Load "guilib.ring"
New qapp {
win1 = new qwidget() {
setwindowtitle("open file")
setgeometry(100,100,400,400)
new qpushbutton(win1) {
setgeometry(10,10,200,30)
settext("open file")
setclickevent("pOpen()")
}
show()
}
47.32. Using the QFileDialog Class 427

9. Ring Documentation, Release 1.2
exec()
}
Func pOpen
new qfiledialog(win1) {
cName = getopenfilename(win1,"open file","c:","source files(*.ring)")
win1.setwindowtitle(cName)
}
The application during the runtime
47.33 Drawing using QPainter
In this example we will learn about drawing using the QPainter class
Load "guilib.ring"
New qapp {
win1 = new qwidget() {
setwindowtitle("Drawing using QPainter")
setgeometry(100,100,500,500)
label1 = new qlabel(win1) {
setgeometry(10,10,400,400)
settext("")
}
new qpushbutton(win1) {
setgeometry(200,400,100,30)
settext("draw")
setclickevent("draw()")
}
show()
}
47.33. Drawing using QPainter 428

10. Ring Documentation, Release 1.2
exec()
}
Func draw
p1 = new qpicture()
color = new qcolor() {
setrgb(0,0,255,255)
}
pen = new qpen() {
setcolor(color)
setwidth(10)
}
new qpainter() {
begin(p1)
setpen(pen)
drawline(500,150,950,450)
drawline(950,550,500,150)
endpaint()
}
label1 { setpicture(p1) show() }
The application during the runtime
47.33. Drawing using QPainter 429