Category: wxpython

wxPython Tutorial PDF Version Quick Guide Resources Job Search Discussion wxPython is a blend of wxWidgets and Python programming library. This introductory tutorial provides the basics of GUI programming and helps you create desktop GUI applications. Audience This tutorial is designed for software programmers who are keen on learning how to develop GUI applications for the desktop. Prerequisites You should have a basic understanding of computer programming terminologies. A basic understanding of Python and any of the programming languages is a plus. Print Page Previous Next Advertisements ”;

wxPython – GUI Builder Tools ”; Previous Next Creating a good looking GUI by manual coding can be tedious. A visual GUI designer tool is always handy. Many GUI development IDEs targeted at wxPython are available. Following are some of them − wxFormBuilder wxDesigner wxGlade BoaConstructor gui2py wxFormBuilder is an open source, cross-platform WYSIWYG GUI builder that can translate the wxWidget GUI design into C++, Python, PHP or XML format. A brief introduction to usage of wxFormBuilder is given here. First of all the latest version of wxFormBuilder needs to be downloaded and installed from http://sourceforge.net/projects/wxformbuilder/. On opening the application, a new project with blank grey area at the center appears. Give a suitable name to the project and choose Python as code generation language. This is done in the Object properties window as shown in the following image − Then from ‘Forms’ tab of components palette, choose Frame. Add a vertical wxBoxSizer from ‘Layouts’ tab. Add necessary controls in the Box with suitable captions. Here, a StaticText (label), two TextCtrl objects (text boxes) and a wxButton object are added. The frame looks like the following image − Enable Expand and Stretch on these three controls. In the object properties for wxButton object, assign a function findsquare() to OnButtonClick event. Save the project and press F8 to generate Python code for developed GUI. Let the generated file be named as Demo.py In the executable Python script, import demo.py and define FindSquare() function. Declare Application object and start a main event loop. Following is the executable code − import wx #import the newly created GUI file import demo class CalcFrame(demo.MyFrame1): def __init__(self,parent): demo.MyFrame1.__init__(self,parent) def FindSquare(self,event): num = int(self.m_textCtrl1.GetValue()) self.m_textCtrl2.SetValue (str(num*num)) app = wx.App(False) frame = CalcFrame(None) frame.Show(True) #start the applications app.MainLoop() The above code produces the following output − Print Page Previous Next Advertisements ”;

wxPython – Buttons ”; Previous Next Button widget is most widely used in any GUI interface. It captures the click event generated by the user. Its most obvious use is to trigger a handler function bound to it. wxPython class library provides different types of buttons. There is a simple, traditional button, wx.Button class object, which carries some text as its caption. A two-state button is also available, which is named as wx.ToggleButton. Its pressed or depressed state can be identified by eventhandler function. Another type of button, wx.BitmapButton displays a bitmap (image) as icon on its face. Constructor for wx.Button class and wx.ToggleButton class takes the following arguments − Wx.Button(parent, id, label, pos, size, style) These are some important methods of wx.Button class − S.N. Methods & Description 1 SetLabel() Sets the button’s caption programmatically 2 GetLabel() Returns the button’s caption 3 SetDefault() Button is set to default for the top level window. Emulates the click event on pressing Enter key Two important methods of wx.ToggleButton class are − S.N. Methods & Description 1 GetValue() Returns the state of toggle button (on/off) 2 SetValue() Sets the state of button programmatically In order to create a bitmap button, firstly, a bitmap object needs to be constructed out of an image file. The following variation of wx.Bitmap class constructor is most commonly used − Wx.Bitmap(fiiename, wx.BITMAP_TYPE) Some of the predefined bitmap type constants are − wx.BITMAP_TYPE_BMP wx.BITMAP_TYPE_ICO wx.BITMAP_TYPE_CUR wx.BITMAP_TYPE_TIFF wx.BITMAP_TYPE_TIF wx.BITMAP_TYPE_GIF wx.BITMAP_TYPE_PNG wx.BITMAP_TYPE_JPEG wx.BITMAP_TYPE_PCX wx.BITMAP_TYPE_ICON wx.BITMAP_TYPE_ANY This bitmap object is used as one of the parameters for wx.BitmapButton class constructor. Wx.BitmapButton(parent, id, bitmap, pos, size, style) On some OS platforms, the bitmap button can display both bitmap and label. SetLabel() methods assign the caption. On other platforms, it serves as an internal label. The normal button as well bitmap button emits a wx.CommandEvent. EVT_BUTTON binder associates a handler function to it. The toggle button on the other hand uses wx.TOGGLEBUTTON binder for event handling. In the following example, buttons of all three types are placed in a vertical box sizer of a panel. Simple button object is created using the statement − self.btn = wx.Button(panel, -1, “click Me”) Toggle button is constructed by following statement − self.tbtn = wx.ToggleButton(panel , -1, “click to on”) These buttons are added into vertical sizer using the following statements − vbox.Add(self.btn,0,wx.ALIGN_CENTER) vbox.Add(self.tbtn,0,wx.EXPAND|wx.ALIGN_CENTER) Note − Because of wx.EXPAND flag, the toggle button occupies the entire width of the frame. Using EVT_BUTTON and EVT_TOGGLEBUTTON binders they are associated with the respective handlers. self.btn.Bind(wx.EVT_BUTTON,self.OnClicked) self.tbtn.Bind(wx.EVT_TOGGLEBUTTON,self.OnToggle) Three bitmap buttons are added into a horizontal box sizer. These buttons display an image as icon as their caption. bmp = wx.Bitmap(“NEW.BMP”, wx.BITMAP_TYPE_BMP) self.bmpbtn = wx.BitmapButton(panel, id = wx.ID_ANY, bitmap = bmp, size = (bmp.GetWidth()+10, bmp.GetHeight()+10)) bmp1 = wx.Bitmap(“OPEN.BMP”, wx.BITMAP_TYPE_BMP) self.bmpbtn1 = wx.BitmapButton(panel, id = wx.ID_ANY, bitmap = bmp1, size = (bmp.GetWidth()+10, bmp.GetHeight()+10)) bmp2 = wx.Bitmap(“SAVE.BMP”, wx.BITMAP_TYPE_BMP) self.bmpbtn2 = wx.BitmapButton(panel, id = wx.ID_ANY, bitmap = bmp2, size = (bmp.GetWidth()+10, bmp.GetHeight()+10)) Click event of these three buttons is directed to OnClicked() method. self.bmpbtn.Bind(wx.EVT_BUTTON, self.OnClicked) self.bmpbtn1.Bind(wx.EVT_BUTTON, self.OnClicked) self.bmpbtn2.Bind(wx.EVT_BUTTON, self.OnClicked) Internal labels of these buttons are set to NEW, OPEN and SAVE respectively. OnClicked() event handler function retrieves the label of source button, which caused the click event. That label is printed on the console. def OnClicked(self, event): btn = event.GetEventObject().GetLabel() print “Label of pressed button = “,btn OnToggle() event handler is triggered when the toggle button is clicked. Its state is read by GetValue() method and accordingly, the button’s caption is set. def OnToggle(self,event): state = event.GetEventObject().GetValue() if state == True: print “off” event.GetEventObject().SetLabel(“click to off”) else: print “on” event.GetEventObject().SetLabel(“click to on”) The complete code listing is as follows − import wx class Mywin(wx.Frame): def __init__(self, parent, title): super(Mywin, self).__init__(parent, title = title,size = (200,150)) panel = wx.Panel(self) vbox = wx.BoxSizer(wx.VERTICAL) self.btn = wx.Button(panel,-1,”click Me”) vbox.Add(self.btn,0,wx.ALIGN_CENTER) self.btn.Bind(wx.EVT_BUTTON,self.OnClicked) self.tbtn = wx.ToggleButton(panel , -1, “click to on”) vbox.Add(self.tbtn,0,wx.EXPAND|wx.ALIGN_CENTER) self.tbtn.Bind(wx.EVT_TOGGLEBUTTON,self.OnToggle) hbox = wx.BoxSizer(wx.HORIZONTAL) bmp = wx.Bitmap(“NEW.BMP”, wx.BITMAP_TYPE_BMP) self.bmpbtn = wx.BitmapButton(panel, id = wx.ID_ANY, bitmap = bmp, size = (bmp.GetWidth()+10, bmp.GetHeight()+10)) hbox.Add(self.bmpbtn,0,wx.ALIGN_CENTER) self.bmpbtn.Bind(wx.EVT_BUTTON,self.OnClicked) self.bmpbtn.SetLabel(“NEW”) bmp1 = wx.Bitmap(“OPEN.BMP”, wx.BITMAP_TYPE_BMP) self.bmpbtn1 = wx.BitmapButton(panel, id = wx.ID_ANY, bitmap = bmp1, size = (bmp.GetWidth()+10, bmp.GetHeight()+10)) hbox.Add(self.bmpbtn1,0,wx.ALIGN_CENTER) self.bmpbtn1.Bind(wx.EVT_BUTTON,self.OnClicked) self.bmpbtn1.SetLabel(“OPEN”) bmp2 = wx.Bitmap(“SAVE.BMP”, wx.BITMAP_TYPE_BMP) self.bmpbtn2 = wx.BitmapButton(panel, id = wx.ID_ANY, bitmap = bmp2, size = (bmp.GetWidth()+10, bmp.GetHeight()+10)) hbox.Add(self.bmpbtn2,0,wx.ALIGN_CENTER) self.bmpbtn2.Bind(wx.EVT_BUTTON,self.OnClicked) self.bmpbtn2.SetLabel(“SAVE”) vbox.Add(hbox,1,wx.ALIGN_CENTER) panel.SetSizer(vbox) self.Centre() self.Show() self.Fit() def OnClicked(self, event): btn = event.GetEventObject().GetLabel() print “Label of pressed button = “,btn def OnToggle(self,event): state = event.GetEventObject().GetValue() if state == True: print “Toggle button state off” event.GetEventObject().SetLabel(“click to off”) else: print ” Toggle button state on” event.GetEventObject().SetLabel(“click to on”) app = wx.App() Mywin(None, ”Button demo”) app.MainLoop() The above code produces the following output − Label of pressed button = click Me Toggle button state off Toggle button state on Label of pressed button = NEW Label of pressed button = OPEN Label of pressed button = SAVE Print Page Previous Next Advertisements ”;

wxPython – Drag & Drop ”; Previous Next Provision of drag and drop is very intuitive for the user. It is found in many desktop applications where the user can copy or move objects from one window to another just by dragging it with the mouse and dropping on another window. Drag and drop operation involves the following steps − Declare a drop target Create data object Create wx.DropSource Execute drag operation Cancel or accept drop In wxPython, there are two predefined drop targets − wx.TextDropTarget wx.FileDropTarget Many wxPython widgets support drag and drop activity. Source control must have dragging enabled, whereas target control must be in a position to accept (or reject) drag. Source Data that the user is dragging is placed on the the target object. OnDropText() of target object consumes the data. If so desired, data from the source object can be deleted. Example In the following example, two ListCrl objects are placed horizontally in a Box Sizer. List on the left is populated with a languages[] data. It is designated as the source of drag. One on the right is the target. languages = [”C”, ”C++”, ”Java”, ”Python”, ”Perl”, ”JavaScript”, ”PHP”, ”VB.NET”,”C#”] self.lst1 = wx.ListCtrl(panel, -1, style = wx.LC_LIST) self.lst2 = wx.ListCtrl(panel, -1, style = wx.LC_LIST) for lang in languages: self.lst1.InsertStringItem(0,lang) The second list control is empty and is an argument for object of TextDropTarget class. class MyTextDropTarget(wx.TextDropTarget): def __init__(self, object): wx.TextDropTarget.__init__(self) self.object = object def OnDropText(self, x, y, data): self.object.InsertStringItem(0, data) OnDropText() method adds source data in the target list control. Drag operation is initialized by the event binder. wx.EVT_LIST_BEGIN_DRAG(self, self.lst1.GetId(), self.OnDragInit) OnDragInit() function puts drag data on the target and deletes from the source. def OnDragInit(self, event): text = self.lst1.GetItemText(event.GetIndex()) tobj = wx.PyTextDataObject(text) src = wx.DropSource(self.lst1) src.SetData(tobj) src.DoDragDrop(True) self.lst1.DeleteItem(event.GetIndex()) The complete code is as follows − import wx class MyTarget(wx.TextDropTarget): def __init__(self, object): wx.TextDropTarget.__init__(self) self.object = object def OnDropText(self, x, y, data): self.object.InsertStringItem(0, data) class Mywin(wx.Frame): def __init__(self, parent, title): super(Mywin, self).__init__(parent, title = title,size = (-1,300)) panel = wx.Panel(self) box = wx.BoxSizer(wx.HORIZONTAL) languages = [”C”, ”C++”, ”Java”, ”Python”, ”Perl”, ”JavaScript”, ”PHP”, ”VB.NET”,”C#”] self.lst1 = wx.ListCtrl(panel, -1, style = wx.LC_LIST) self.lst2 = wx.ListCtrl(panel, -1, style = wx.LC_LIST) for lang in languages: self.lst1.InsertStringItem(0,lang) dt = MyTarget(self.lst2) self.lst2.SetDropTarget(dt) wx.EVT_LIST_BEGIN_DRAG(self, self.lst1.GetId(), self.OnDragInit) box.Add(self.lst1,0,wx.EXPAND) box.Add(self.lst2, 1, wx.EXPAND) panel.SetSizer(box) panel.Fit() self.Centre() self.Show(True) def OnDragInit(self, event): text = self.lst1.GetItemText(event.GetIndex()) tobj = wx.PyTextDataObject(text) src = wx.DropSource(self.lst1) src.SetData(tobj) src.DoDragDrop(True) self.lst1.DeleteItem(event.GetIndex()) ex = wx.App() Mywin(None,”Drag&Drop Demo”) ex.MainLoop() The above code produces the following output − Print Page Previous Next Advertisements ”;

wxPython – Dockable Windows ”; Previous Next wxAui is an Advanced User Interface library incorporated in wxWidgets API. Wx.aui.AuiManager the central class in AUI framework. AuiManager manages the panes associated with a particular frame using each panel’s information in wx.aui.AuiPanelInfo object. Let us learn about various properties of PanelInfo object control docking and floating behavior. Putting dockable windows in the top level frame involves the following steps − First, create an AuiManager object. self.mgr = wx.aui.AuiManager(self) Then, a panel with required controls is designed. pnl = wx.Panel(self) pbox = wx.BoxSizer(wx.HORIZONTAL) text1 = wx.TextCtrl(pnl, -1, “Dockable”, style = wx.NO_BORDER | wx.TE_MULTILINE) pbox.Add(text1, 1, flag = wx.EXPAND) pnl.SetSizer(pbox) The following parameters of AuiPanelInfo are set. Direction − Top, Bottom, Left, Right, or Center Position − More than one pane can be placed inside a dockable region. Each is given a position number. Row − More than one pane appears in one row. Just like more than one toolbar appearing in the same row. Layer − Panes can be placed in layers. Using this PanelInfo, the designed panel is added into the manager object. info1 = wx.aui.AuiPaneInfo().Bottom() self.mgr.AddPane(pnl,info1) Rest of the top level window may have other controls as usual. The complete code is as follows − import wx import wx.aui class Mywin(wx.Frame): def __init__(self, parent, title): super(Mywin, self).__init__(parent, title = title, size = (300,300)) self.mgr = wx.aui.AuiManager(self) pnl = wx.Panel(self) pbox = wx.BoxSizer(wx.HORIZONTAL) text1 = wx.TextCtrl(pnl, -1, “Dockable”, style = wx.NO_BORDER | wx.TE_MULTILINE) pbox.Add(text1, 1, flag = wx.EXPAND) pnl.SetSizer(pbox) info1 = wx.aui.AuiPaneInfo().Bottom() self.mgr.AddPane(pnl, info1) panel = wx.Panel(self) text2 = wx.TextCtrl(panel, size = (300,200), style = wx.NO_BORDER | wx.TE_MULTILINE) box = wx.BoxSizer(wx.HORIZONTAL) box.Add(text2, 1, flag = wx.EXPAND) panel.SetSizerAndFit(box) self.mgr.Update() self.Bind(wx.EVT_CLOSE, self.OnClose) self.Centre() self.Show(True) def OnClose(self, event): self.mgr.UnInit() self.Destroy() app = wx.App() Mywin(None,”Dock Demo”) app.MainLoop() The above code produces the following output − Print Page Previous Next Advertisements ”;

wxPython – Event Handling ”; Previous Next Unlike a console mode application, which is executed in a sequential manner, a GUI based application is event driven. Functions or methods are executed in response to user’s actions like clicking a button, selecting an item from collection or mouse click, etc., called events. Data pertaining to an event which takes place during the application’s runtime is stored as object of a subclass derived from wx.Event. A display control (such as Button) is the source of event of a particular type and produces an object of Event class associated to it. For instance, click of a button emits a wx.CommandEvent. This event data is dispatched to event handler method in the program. wxPython has many predefined event binders. An Event binder encapsulates relationship between a specific widget (control), its associated event type and the event handler method. For example, to call OnClick() method of the program on a button’s click event, the following statement is required − self.b1.Bind(EVT_BUTTON, OnClick) Bind() method is inherited by all display objects from wx.EvtHandler class. EVT_.BUTTON here is the binder, which associates button click event to OnClick() method. Example In the following example, the MoveEvent, caused by dragging the top level window – a wx.Frame object in this case – is connected to OnMove() method using wx.EVT_MOVE binder. The code displays a window. If it is moved using mouse, its instantaneous coordinates are displayed on the console. import wx class Example(wx.Frame): def __init__(self, *args, **kw): super(Example, self).__init__(*args, **kw) self.InitUI() def InitUI(self): self.Bind(wx.EVT_MOVE, self.OnMove) self.SetSize((250, 180)) self.SetTitle(”Move event”) self.Centre() self.Show(True) def OnMove(self, e): x, y = e.GetPosition() print “current window position x = “,x,” y= “,y ex = wx.App() Example(None) ex.MainLoop() The above code produces the following output − current window position x = 562 y = 309 current window position x = 562 y = 309 current window position x = 326 y = 304 current window position x = 384 y = 240 current window position x = 173 y = 408 current window position x = 226 y = 30 current window position x = 481 y = 80 Some of the subclasses inherited from wx.Event are listed in the following table − Given below are the most commonly used events of wx.Event S.N. Events & Description 1 wxKeyEvent Occurs when a key is presses or released 2 wxPaintEvent Is generated whenever contents of the window needs to be redrawn 3 wxMouseEvent Contains data about any event due to mouse activity like mouse button pressed or dragged 4 wxScrollEvent Associated with scrollable controls like wxScrollbar and wxSlider 5 wxCommandEvent Contains event data originating from many widgets such as button, dialogs, clipboard, etc. 6 wxMenuEvent Different menu-related events excluding menu command button click 7 wxColourPickerEvent wxColourPickerCtrl generated events 8 wxDirFilePickerEvent Events generated by FileDialog and DirDialog Events in wxPython are of two types. Basic events and Command events. A basic event stays local to the window in which it originates. Most of the wxWidgets generate command events. A command event can be propagated to window or windows, which are above the source window in class hierarchy. Example Following is a simple example of event propagation. The complete code is − import wx class MyPanel(wx.Panel): def __init__(self, parent): super(MyPanel, self).__init__(parent) b = wx.Button(self, label = ”Btn”, pos = (100,100)) b.Bind(wx.EVT_BUTTON, self.btnclk) self.Bind(wx.EVT_BUTTON, self.OnButtonClicked) def OnButtonClicked(self, e): print ”Panel received click event. propagated to Frame class” e.Skip() def btnclk(self,e): print “Button received click event. propagated to Panel class” e.Skip() class Example(wx.Frame): def __init__(self,parent): super(Example, self).__init__(parent) self.InitUI() def InitUI(self): mpnl = MyPanel(self) self.Bind(wx.EVT_BUTTON, self.OnButtonClicked) self.SetTitle(”Event propagation demo”) self.Centre() self.Show(True) def OnButtonClicked(self, e): print ”click event received by frame class” e.Skip() ex = wx.App() Example(None) ex.MainLoop() In the above code, there are two classes. MyPanel, a wx.Panel subclass and Example, a wx.Frame subclass which is the top level window for the program. A button is placed in the panel. This Button object is bound to an event handler btnclk() which propagates it to parent class (MyPanel in this case). Button click generates a CommandEvent which can be propagated to its parent by Skip() method. MyPanel class object also binds the received event to another handler OnButtonClicked(). This function in turn transmits to its parent, the Example class. The above code produces the following output − Button received click event. Propagated to Panel class. Panel received click event. Propagated to Frame class. Click event received by frame class. Print Page Previous Next Advertisements ”;