The Ring programming language version 1.3 book - Part 49 of 88
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The document describes how to use events filters in Qt to handle key press and mouse events in a GUI application. It shows code to detect key presses and mouse clicks, movements and button presses, and update the window title or show messages based on the detected events. It then shows how to make a label movable by tracking mouse movements and presses.
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The Ring programming language version 1.3 book - Part 49 of 88
- 1. Ring Documentation, Release 1.3 49.42 KeyPress and Mouse Move Events In this example we will learn how to use the Events Filter to know about KeyPress and Mouse Move Events Load "guilib.ring" new qApp { win1 = new qWidget() { setWindowTitle("Test using Event Filter!") setGeometry(100,100,400,400) setmousetracking(true) myfilter = new qallevents(win1) myfilter.setKeyPressEvent("pWork()") myfilter.setMouseButtonPressevent("pClick()") myfilter.setmousemoveevent("pMove()") installeventfilter(myfilter) show() } exec() } 49.42. KeyPress and Mouse Move Events 458
- 2. Ring Documentation, Release 1.3 func pWork win1.setwindowtitle('KeyPress! : ' + myfilter.getkeycode()) func pClick new qmessagebox(win1) { setgeometry(100,100,400,100) setwindowtitle("click event!") settext("x : " + myfilter.getx() + " y : " + myfilter.gety() + " button : " + myfilter.getbutton() ) show() } func pMove win1.setwindowtitle("Mouse Move , X : " + myfilter.getx() + " Y : " + myfilter.gety() ) The application during the runtime 49.43 Moving Objects using the Mouse In the next example we will learn how to program movable objects where the user can move a label Load "guilib.ring" lPress = false 49.43. Moving Objects using the Mouse 459
- 3. Ring Documentation, Release 1.3 nX = 0 nY = 0 new qApp { win1 = new qWidget() { setWindowTitle("Move this label!") setGeometry(100,100,400,400) setstylesheet("background-color:white;") Label1 = new qLabel(Win1){ setGeometry(100,100,200,50) setText("Welcome") setstylesheet("font-size: 30pt") myfilter = new qallevents(label1) myfilter.setEnterevent("pEnter()") myfilter.setLeaveevent("pLeave()") myfilter.setMouseButtonPressEvent("pPress()") myfilter.setMouseButtonReleaseEvent("pRelease()") myfilter.setMouseMoveEvent("pMove()") installeventfilter(myfilter) } show() } exec() } Func pEnter Label1.setStyleSheet("background-color: purple; color:white;font-size: 30pt;") Func pLeave Label1.setStyleSheet("background-color: white; color:black;font-size: 30pt;") Func pPress lPress = True nX = myfilter.getglobalx() ny = myfilter.getglobaly() Func pRelease lPress = False pEnter() Func pMove nX2 = myfilter.getglobalx() ny2 = myfilter.getglobaly() ndiffx = nX2 - nX ndiffy = nY2 - nY if lPress Label1 { move(x()+ndiffx,y()+ndiffy) setStyleSheet("background-color: Green; color:white;font-size: 30pt;") nX = nX2 ny = nY2 49.43. Moving Objects using the Mouse 460
- 4. Ring Documentation, Release 1.3 } ok The application during the runtime 49.43. Moving Objects using the Mouse 461
- 5. Ring Documentation, Release 1.3 49.43. Moving Objects using the Mouse 462
- 6. Ring Documentation, Release 1.3 49.44 Inheritance from GUI Classes Example : Load "guilib.ring" New MyWindow() new qApp { exec() } class mywindow from qwidget Func init super.init() setwindowtitle("First Window") setgeometry(100,100,400,400) setstylesheet("background-color: purple;") settooltip("my first window!") show() The application during the runtime 49.44. Inheritance from GUI Classes 463
- 7. Ring Documentation, Release 1.3 49.45 Using QDesktopWidget Class In the next example we will learn about using the QDesktopWidget class Load "guilib.ring" New qApp { win1 = New qWidget() { resize(400,400) btn1 = new qPushbutton(win1) { setText("Center") move(100,100) resize(100,30) setClickEvent("pCenter()") } Show() } exec() } Func pCenter oDesktop = new qDesktopWidget() 49.45. Using QDesktopWidget Class 464
- 8. Ring Documentation, Release 1.3 oRect = oDesktop.screenGeometry( oDesktop.primaryScreen() ) win1.move((oRect.width()-win1.width()) /2 , (oRect.Height()-win1.Height())/2 ) win1.show() The application during the runtime 49.46 Rotate Text The next example rotate text using a Timer. Load "guilib.ring" nAngle = 0 New qapp { win1 = new qwidget() { setwindowtitle("Rotate Text") resize(800,600) label1 = new qlabel(win1) { settext("") myfilter = new qallevents(win1) myfilter.setMouseButtonPressevent("pClick()") installeventfilter(myfilter) } new qtimer(win1) { setinterval(50) 49.46. Rotate Text 465
- 9. Ring Documentation, Release 1.3 settimeoutevent("pTime()") start() } pDraw() L1 = new qVBoxLayout() { AddWidget(Label1) } SetLayout(L1) showMaximized() } exec() } Func pDraw p1 = new qpicture() color = new qcolor() { setrgb(0,0,255,255) } pen = new qpen() { setcolor(color) setwidth(50) } painter = new qpainter() { begin(p1) setpen(pen) myfont = font() myfont.setpointsize(50) setfont(myfont) rotate(nAngle) drawtext(350,0*nAngle,"welcome") drawtext(0,0*nAngle,"welcome") endpaint() } label1 { setpicture(p1) show() } Func pClick win1 { setwindowtitle("Click Event") } Func pTime nAngle++ if nAngle = 90 nAngle = 10 ok pDraw() The application during the runtime 49.46. Rotate Text 466
- 10. Ring Documentation, Release 1.3 49.47 Change Focus The next example change the focus using the ENTER key. load "guilib.ring" new qApp { win = new qWidget() { resize(600,600) SetWindowTitle("Change Focus") text1 = new qLineEdit(win) text2 = new qLineEdit(win) text3 = new qLineEdit(win) text4 = new qLineEdit(win) layout1 = new qVBoxLayout() { AddWidget(text1) AddWidget(text2) AddWidget(text3) AddWidget(text4) } setLayout(Layout1) 49.47. Change Focus 467