Category: pygtk

PyGTK – ScrolledWindow Class ”; Previous Next Scrolled window is created to access other widget of area larger than parent window. Some widgets like TreeView and TextView of native support for scrolling. For others such as Label or Table, a Viewport should be provided. The following syntax is used for the constructor of the gtk.ScrolledWindow class − sw = gtk.ScrolledWindow(hadj, vadj) The following are the methods of the gtk.ScrolledWindow class − ScrolledWindow.set_hadjustment() − This sets the horizontal adjustment to a gtk.Adjustment object ScrolledWindow.set_vadjustment() − This sets the vertical adjustment to a gtk.Adjustment object ScrolledWindow.set_Policy (hpolicy, vpolicy) − This sets the “hscrollbar_policy” and “vscrollbar_policy” properties. One of the following predefined constants are used − gtk.POLICY_ALWAYS − The scrollbar is always present gtk.POLICY_AUTOMATIC − The scrollbar is present only if needed i.e. the contents are larget than the window gtk.POLICY_NEVER − The scrollbar is never present ScrolledWindow.add_with_viewport(child) − This method is used to add a widget (specified by child) without native scrolling capabilities to the scrolled window. This is a convenience function that is equivalent to adding child to a gtk.Viewport, then adding the viewport to the scrolled window. The following code adds a scrolled window around a gtk.Table object with 10 by 10 dimensions. Since a Table object doesn”t support adjustments automatically, it is added in a Viewport. sw = gtk.ScrolledWindow() table = gtk.Table(10,10) Two nested loops are used to add 10 rows of 10 columns each. A gtk.Button widget is placed in each cell. for i in range(1,11): for j in range(1,11): caption = “Btn”+str(j)+str(i) btn = gtk.Button(caption) table.attach(btn, i, i+1, j, j+1) This large enough table is now added in the scrolled window along with a viewport. sw.add_with_viewport(table) Example Observe the following code − import gtk class PyApp(gtk.Window): def __init__(self): super(PyApp, self).__init__() self.set_title(“ScrolledWindow and Viewport”) self.set_size_request(400,300) self.set_position(gtk.WIN_POS_CENTER) sw = gtk.ScrolledWindow() table = gtk.Table(10,10) table.set_row_spacings(10) table.set_col_spacings(10) for i in range(1,11): for j in range(1,11): caption = “Btn”+str(j)+str(i) btn = gtk.Button(caption) table.attach(btn, i, i+1, j, j+1) sw.add_with_viewport(table) self.add(sw) self.connect(“destroy”, gtk.main_quit) self.show_all() PyApp() gtk.main() The above code will generate the following output − Print Page Previous Next Advertisements ”;

PyGTK – AspectFrame Class ”; Previous Next gtk.AspectFrame class is a subclass of the Frame class. The child widget in this frame always retains its aspect ratio (of width and height) even if the main window is resized. The ratio property of gtk.AspectFrame widget determines the widget width:height ratio. An aspect ratio of 0.5 means the width is one half the height; an aspect ratio of 2.0 means the width is twice the height. The default value for the “ratio” property is 1.0. The following syntax is used for the constructor of gtk.AspectFrame class − gtk.AspectFrame (label = None, xalign = 0.5, yalign = 0.5, ratio = 1.0, obey_child = True) The xalign property determines the fraction of horizontal free space to the left of the child. 0.0 means no free space to the left, 1.0 means all free space to the left. The yalign property determines the fraction of vertical free space above the child. 0.0 means no free space above, 1.0 means all free space above. Ratio of width to height of frame is maintained if obey_child property is False. The obey_child property determines if the ratio is to be ignored. The default is True. The following code is similar to the one used for the Frame class. The only difference is that the ButonBox is placed in an AspectFrame widget. frm = gtk.AspectFrame(label = None, xalign = 0.5, yalign = 0.5, ratio = 5.0, obey_child = False) Note − The obey_child property is set to False because it is desired to retain the aspect ratio even if the window is resized. Example Observe the following code − import gtk class PyApp(gtk.Window): def __init__(self): super(PyApp, self).__init__() self.set_title(“Aspect Frame Demo”) self.set_default_size(250, 200) self.set_border_width(5) frm = gtk.AspectFrame(label = None, xalign = 0.5, yalign = 0.5, ratio = 5.0, obey_child = False) hb = gtk.HButtonBox() btn1 = gtk.RadioButton(None,”Degree”) hb.add(btn1) btn2 = gtk.RadioButton(btn1,”P.G.”) hb.add(btn2) btn3 = gtk.RadioButton(btn1,”Doctorate”) hb.add(btn3) frm.add(hb) frm.set_label(“Qualifications”) self.add(frm) self.connect(“destroy”, gtk.main_quit) self.show_all() if __name__ == ”__main__”: PyApp() gtk.main() The above code will produce the following original and resized windows − Original Window Resized Window Print Page Previous Next Advertisements ”;

PyGTK – Drag and Drop ”; Previous Next Widgets having associated X Window are capable of drag and drop. In the program, a widget as a source and/or destination for drag-and-drop must first be designated. The widget defined as source can send out the dragged data. The destination widget accepts it when dragged data is dropped on it. The following steps are involved in setting up a drag-and-drop enabled application − Step 1 − Setting up a source widget. Step 2 − The drag_source_set() method specifies the target types for a drag operation − widget.drag_source_set(start_button_mask, targets, info) Step 3 − The start_button_mask argument specifies a bitmask of buttons that starts the drag operation. Step 4 − The target argument is a list of tuples of this structure − (target, flags, info) The target argument is a string representing drag type, for example, text/plain or image/x-xpixmap. Step 6 − The following flags are predefined − gtk.TARGET_SAME_APP gtk.TARGET_SAME_WIDGET Step 7 − There will be no limitation as the flag is set to 0. If the widget is not required to act as source, it can be unset − widget.drag_source_unset() The source signal emits signals. The following table lists the signals and their callbacks. drag_begin def drag_begin_cb(widget, drag_context, data): drag_data_get def drag_data_get_cb(widget, drag_context, selection_data, info, time, data): drag_data_delete def drag_data_delete_cb(widget, drag_context, data): drag_end def drag_end_cb(widget, drag_context, data): Setting up a Destination Widget The drag_dest_set() method specifies which widget can receive dragged data. widget.drag_dest_set(flags, targets, action) The flags parameter can take one of the following constants − gtk.DEST_DEFAULT_MOTION This checks if the drag matches this widget”s list of possible targets and actions, then calls the drag_status() as appropriate. gtk.DEST_DEFAULT_HIGHLIGHT This draws a highlight on this widget as long as a drag is over this widget gtk.DEST_DEFAULT_DROP When a drop occurs, if the drag matches this widget”s list of possible targets and actions call drag_get_data() on behalf of the widget. Whether or not the drop is successful, call drag_finish(). If the action was a move and the drag was successful, then TRUE will be passed for the delete parameter to drag_finish(). gtk.DEST_DEFAULT_ALL If set, specifies that all default actions should be taken. The target is a list of tuples containing target information. The actions argument is a bitmask of or a combination of one or more of the following values − gtk.gdk.ACTION_DEFAULT gtk.gdk.ACTION_COPY gtk.gdk.ACTION_MOVE gtk.gdk.ACTION_LINK gtk.gdk.ACTION_PRIVATE gtk.gdk.ACTION_ASK The “drag-motion” handler must determine if the drag data is appropriate by matching the destination targets with the gtk.gdk.DragContext targets and optionally by examining the drag data by calling the drag_get_data() method. The gtk.gdk.DragContext. drag_status() method must be called to update the drag_context status. The “drag-drop” handler must determine the matching target using the drag_dest_find_target() method and then ask for the drag data using the drag_get_data() method. The data will be available in the “drag-data-received” handler. Print Page Previous Next Advertisements ”;

PyGTK – File Chooser Dialog ”; Previous Next This dialog is useful to let the user select the location and the name of file that needs to be opened or saved. It embeds FileChooserWidget and provides OK and CANCEL buttons in the action_area. The following is a constructor of the gtk.FileChooserDialog class − Dlg=gtk.FileChooserDialog (title = None, parent = None, action = gtk.FILE_CHOOSER_ACTION_OPEN, buttons = None, backend = None) The parameters are − title This is the title of the dialog parent The transient parent of the dialog, or None action The open or save mode for the dialog buttons This is a tuple containing button label-response id pairs or None backend The name of the specific filesystem backend to use. The following are the action modes − gtk.FILE_CHOOSER_ACTION_OPEN gtk.FILE_CHOOSER_ACTION_SAVE gtk.FILE_CHOOSER_ACTION_SELECT_FOLDER gtk.FILE_CHOOSER_ACTION_CREATE_FOLDER If it is desired to restrict the types of files to be available for display, an object of the gtk.FileFilter can be applied by using the add_filter() method. If the FileChooserDialog menu button is clicked, the following callback function is run. def on_file(self, widget): dlg = gtk.FileChooserDialog(“Open..”, None, gtk.FILE_CHOOSER_ACTION_OPEN, (gtk.STOCK_CANCEL, gtk.RESPONSE_CANCEL, gtk.STOCK_OPEN, gtk.RESPONSE_OK)) response = dlg.run() self.text.set_text(dlg.get_filename()) dlg.destroy() The file is selected from the dialog − The selected file is displayed on the label on the toplevel gtk.Window − Print Page Previous Next Advertisements ”;

PyGTK – Quick Guide ”; Previous Next PyGTK – Introduction PyGTK is a set of wrappers written in Python and C for GTK + GUI library. It is part of the GNOME project. It offers comprehensive tools for building desktop applications in Python. Python bindings for other popular GUI libraries are also available. PyQt is a Python port of QT library. Our PyQt tutorial can be found here. Similarly, wxPython toolkit is Python binding for wxWidgets, another popular cross-platform GUI library. Our wxPython tutorial is available here. GTK+, or the GIMP Toolkit, is a multi-platform toolkit for creating graphical user interfaces. Offering a complete set of widgets, GTK+ is suitable for projects ranging from small one-off tools to complete application suites. GTK+ has been designed from the ground up to support a wide range of languages. PyGTK is a Python wrapper for GTK+. GTK+ is built around the following four libraries − Glib − A low-level core library that forms the basis of GTK+. It provides data structure handling for C. Pango − A library for layout and rendering of text with an emphasis on internationalization. Cairo − A library for 2D graphics with support for multiple output devices (including the X Window System, Win32) ATK − A library for a set of interfaces providing accessibility tools such as screen readers, magnifiers, and alternative input devices. PyGTK eases the process and helps you create programs with a graphical user interface using the Python programming language. The underlying GTK+ library provides all kinds of visual elements and utilities for it to develop full-featured applications for the GNOME Desktop. PyGTK is a cross-platform library. It is a free software distributed under the LGPL license. PyGTK is built around GTK + 2.x. In order to build applications for GTK +3, PyGObject bindings are also available. PyGTK – Environment PyGTK for Microsoft Windows The installation of PyGTK for Microsoft Windows involves the following steps − Step 1 − Install a 32-bit Python interpreter (latest Python 2.7 distribution) Step 2 − Download and install GTK+ runtime. Step 3 − Download and install GTK+ runtime −https://ftp.gnome.org Step 4 − It is also recommended that you download PyCairo and PyGobject modules from the following URLs − https://ftp.gnome.org https://ftp.gnome.org/pub Step 5 − For convenience, all-in-one installer which handles all of the PyGTK dependencies is also available. Download and install the latest all-in-one installer for Windows from the following URL − https://ftp.gnome.org/pub/GNOME PyGTK for Linux PyGTK is included in most Linux distributions (including Debian, Fedora, Ubuntu,RedHat etc); the source code can also be downloaded and compiled from the following URL https://ftp.gnome.org/pub/GNOME/sources/pygtk/2.24/ PyGTK – Hello World Creating a window using PyGTK is very simple. To proceed, we first need to import the gtk module in our code. import gtk The gtk module contains the gtk.Window class. Its object constructs a toplevel window. We derive a class from gtk.Window. class PyApp(gtk.Window): Define the constructor and call the show_all() method of the gtk.window class. def __init__(self): super(PyApp, self).__init__() self.show_all() We now have to declare the object of this class and start an event loop by calling its main() method. PyApp() gtk.main() It is recommended we add a label “Hello World” in the parent window. label = gtk.Label(“Hello World”) self.add(label) The following is a complete code to display “Hello World”− import gtk class PyApp(gtk.Window): def __init__(self): super(PyApp, self).__init__() self.set_default_size(300,200) self.set_title(“Hello World in PyGTK”) label = gtk.Label(“Hello World”) self.add(label) self.show_all() PyApp() gtk.main() The implementation of the above code will yield the following output − PyGTK – Important Classes The PyGTK module contains various widgets. gtk.Object class acts as the base class for most of the widgets as well as for some non-widget classes. The toplevel window for desktop applications using PyGTK is provided by gtk.Window class. The following table lists the important widgets and their functions − S.NO Classes and Description 1 gtk.Widget This is a gtk.base class for all PyGTK widgets. gtk.Widget provides a common set of methods and signals for the widgets. 2 gtk.Window This is a toplevel window that holds one child widget. gtk.Window is a display area decorated with a title bar, and items to allow the user to close, resize and move the window. 3 gtk.Button This is a pushbutton widget that issues a signal when clicked. gtk.Button is usually displayed as a pushbutton with a text label and is generally used to attach a callback function. 4 gtk.Entry This is a single line text entry widget. 5 gtk.Label This widget displays a limited amount of read-only text. 6 gtk.ButtonBox This is a base class for widgets that contains multiple buttons. 7 gtk.HBox This is a container that organizes its child widgets into a single horizontal row. 8 gtk.VBox This is a container that organizes its child widgets into a single column. 9 gtk.Fixed This is a container that can place child widgets at fixed positions and with fixed sizes, given in pixels. 10 gtk.Layout This provides infinite scrollable area containing child widgets and custom drawing. 11 gtk.MenuItem This widget implements the appearance and behavior of menu items. The derived widget subclasses of the gtk.MenuItem are the only valid children of menus. When selected by a user, they can display a popup menu or invoke an associated function or method 12 gtk.Menu This is a dropdown menu consisting of a list of MenuItem objects which can be navigated and activated by the user to perform application functions. 13 gtk.MenuBar This displays the menu items horizontally in an application window or dialog. 14 gtk.ComboBox This widget is used to choose from a list of items. 15 gtk.Scale This is a horizontal or vertical slider control to select a numeric value. 16 gtk.Scrollbar This displays a horizontal or vertical scrollbar. 17 gtk.ProgressBar This is used to display the progress of a long running operation. 18 gtk.Dialog This displays a popup window for user information and action. 19 gtk.Notebook This widget is a container whose children are overlapping pages that can be switched between using tab labels. 20

PyGTK – Useful Resources ”; Previous Next The following resources contain additional information on PyGTK. Please use them to get more in-depth knowledge on this. Python Programming Certification 2024 Most Popular  9 Courses     1 eBooks Tutorialspoint More Detail Artificial Intelligence and Machine Learning Certification 2024 Most Popular  7 Courses     1 eBooks Tutorialspoint More Detail Java Certification 2024 Best Seller  7 Courses     1 eBooks Tutorialspoint More Detail Print Page Previous Next Advertisements ”;

PyGTK – ProgressBar Class ”; Previous Next Progress bars are used to give user the visual indication of a long running process. The gtk.ProgressBar widget can be used in two modes — percentage mode and activity mode. When it is possible to accurately estimate how much of work is pending to be completed, the progress bar can be used in percentage mode, and the user sees an incremental bar showing percentage of completed job. If on the other hand, the amount of work to be completed can be accurately determined, the progress bar is used in activity mode in which, the bar shows the activity by displaying a block moving back and forth. The following constructor initializes the widget of the gtk.ProgressBar class − pb = gtk.ProgressBar() gtk.ProgressBar uses the following methods to manage functionality − ProgressBar.pulse() − This nudges the progressbar to indicate that some progress has been made, but you don”t know how much. This method also changes the progress bar mode to “activity mode,” where a block bounces back and forth. ProgressBar.set_fraction(fraction) − This causes the progress bar to “fill in” the portion of the bar specified by fraction. The value of fraction should be between 0.0 and 1.0. ProgressBar.set_pulse_setup() − This sets the portion (specified by fraction) of the total progress bar length to move the bouncing block for each call to the pulse() method. ProgressBar.set_orientation() − This sets the orientation of the progress bar. It may be set to one of the following constants: gtk.PROGRESS_LEFT_TO_RIGHT gtk.PROGRESS_RIGHT_TO_LEFT gtk.PROGRESS_BOTTOM_TO_TOP gtk.PROGRESS_TOP_TO_BOTTOM In the following program, the gtk.ProgressBar widget is used in activity mode. Hence, the initial position of progress is set to 0.0 by the set_fraction() method. self.pb = gtk.ProgressBar() self.pb.set_text(“Progress”) self.pb.set_fraction(0.0) In order to increment the progress by 1 percent after 100 milliseconds, a timer object is declared and a callback function is set up to be invoked after every 100 ms so that the progress bar is updated. self.timer = gobject.timeout_add (100, progress_timeout, self) Here, progress_timeout() is the callback function. It increments the parameter of the set_fraction() method by 1 percent and updates the text in progress bar to show the percentage of completion. def progress_timeout(pbobj): new_val = pbobj.pb.get_fraction() + 0.01 pbobj.pb.set_fraction(new_val) pbobj.pb.set_text(str(new_val*100)+” % completed”) return True Example Observe the following code − import gtk, gobject def progress_timeout(pbobj): new_val = pbobj.pb.get_fraction() + 0.01 pbobj.pb.set_fraction(new_val) pbobj.pb.set_text(str(new_val*100)+” % completed”) return True class PyApp(gtk.Window): def __init__(self): super(PyApp, self).__init__() self.set_title(“Progressbar demo”) self.set_size_request(300,200) self.set_position(gtk.WIN_POS_CENTER) fix = gtk.Fixed() self.pb = gtk.ProgressBar() self.pb.set_text(“Progress”) self.pb.set_fraction(0.0) fix.put(self.pb,80,100) self.add(fix) self.timer = gobject.timeout_add (100, progress_timeout, self) self.connect(“destroy”, gtk.main_quit) self.show_all() PyApp() gtk.main() The above code will generate the following output − To use the progress bar in activity mode, change callback function to the following and run − def progress_timeout(pbobj): pbobj.pb.pulse() return True The back and forth movement of a block inside the Progress bar will show the progress of the activity. Print Page Previous Next Advertisements ”;

PyGTK – Environment ”; Previous Next PyGTK for Microsoft Windows The installation of PyGTK for Microsoft Windows involves the following steps − Step 1 − Install a 32-bit Python interpreter (latest Python 2.7 distribution) Step 2 − Download and install GTK+ runtime. Step 3 − Download and install GTK+ runtime −https://ftp.gnome.org Step 4 − It is also recommended that you download PyCairo and PyGobject modules from the following URLs − https://ftp.gnome.org https://ftp.gnome.org/pub Step 5 − For convenience, all-in-one installer which handles all of the PyGTK dependencies is also available. Download and install the latest all-in-one installer for Windows from the following URL − https://ftp.gnome.org/pub/GNOME PyGTK for Linux PyGTK is included in most Linux distributions (including Debian, Fedora, Ubuntu,RedHat etc); the source code can also be downloaded and compiled from the following URL https://ftp.gnome.org/pub/GNOME/sources/pygtk/2.24/ Print Page Previous Next Advertisements ”;

PyGTK – ToggleButton Class ”; Previous Next ToggleButton widget is a gtk.Button with two states — a pressed or active (or on) state and a normal or inactive (or off) state. Every time the button is pressed, the state alternates. The state of the ToggleButton can also be changed programmatically by set_active() method. To switch the state of the button, the toggled() method is also available. The gtk.ToggleButton class has the following constructor − gtk.ToggleButton(label = None, use_underline = True) Here, label is the test to be displayed on button. The use_underline property , if True, an underscore in the text indicates the next character should be underlined and used for the mnemonic accelerator. Some of the important methods of the gtk.ToggleButton class are given in the following table − set_active() This sets the active property to the value to True (active or pressed or on) or False (inactive or normal or off) get_active() This retrieves the state of button toggled() This emits the “toggled” signal on the togglebutton. The ToggleButton widget emits the following signal − Toggled This is emitted when the togglebutton state changes either programmatically or by the user action. The code given below demonstrates the use of ToggleButton widgets. Two ToggleButtons and Label widgets are placed in a VBox container. The toggled signal emitted by Button1 is connected to a callback function on_toggled(). In this function, the state of Button2 is set to True if that of Button1 is False and vice versa. if self.btn1.get_active() == True: self.btn2.set_active(False) else: self.btn2.set_active(True) It displays the instantaneous states of buttons on the Label. Example Observe the following code − import gtk PyApp(gtk.Window): def __init__(self): super(PyApp, self).__init__() self.set_title(“Toggle Button”) self.set_default_size(250, 200) self.set_position(gtk.WIN_POS_CENTER) vbox = gtk.VBox() self.btn1 = gtk.ToggleButton(“Button 1”) self.btn1.connect(“toggled”, self.on_toggled) self.btn2 = gtk.ToggleButton(“Button 2”) self.lbl = gtk.Label() vbox.add(self.btn1) vbox.add(self.btn2) vbox.add(self.lbl) self.add(vbox) self.connect(“destroy”, gtk.main_quit) self.show_all() def on_toggled(self, widget, data = None): if self.btn1.get_active() == True: self.btn2.set_active(False) else: self.btn2.set_active(True) state = “Button1 : “+str(self.btn1.get_active())+” Button2 : “+str(self.btn2.get_active()) self.lbl.set_text(state) if __name__ == ”__main__”: PyApp() gtk.main() The above code generates the following output − Print Page Previous Next Advertisements ”;

PyGTK – Important Classes ”; Previous Next The PyGTK module contains various widgets. gtk.Object class acts as the base class for most of the widgets as well as for some non-widget classes. The toplevel window for desktop applications using PyGTK is provided by gtk.Window class. The following table lists the important widgets and their functions − S.NO Classes and Description 1 gtk.Widget This is a gtk.base class for all PyGTK widgets. gtk.Widget provides a common set of methods and signals for the widgets. 2 gtk.Window This is a toplevel window that holds one child widget. gtk.Window is a display area decorated with a title bar, and items to allow the user to close, resize and move the window. 3 gtk.Button This is a pushbutton widget that issues a signal when clicked. gtk.Button is usually displayed as a pushbutton with a text label and is generally used to attach a callback function. 4 gtk.Entry This is a single line text entry widget. 5 gtk.Label This widget displays a limited amount of read-only text. 6 gtk.ButtonBox This is a base class for widgets that contains multiple buttons. 7 gtk.HBox This is a container that organizes its child widgets into a single horizontal row. 8 gtk.VBox This is a container that organizes its child widgets into a single column. 9 gtk.Fixed This is a container that can place child widgets at fixed positions and with fixed sizes, given in pixels. 10 gtk.Layout This provides infinite scrollable area containing child widgets and custom drawing. 11 gtk.MenuItem This widget implements the appearance and behavior of menu items. The derived widget subclasses of the gtk.MenuItem are the only valid children of menus. When selected by a user, they can display a popup menu or invoke an associated function or method 12 gtk.Menu This is a dropdown menu consisting of a list of MenuItem objects which can be navigated and activated by the user to perform application functions. 13 gtk.MenuBar This displays the menu items horizontally in an application window or dialog. 14 gtk.ComboBox This widget is used to choose from a list of items. 15 gtk.Scale This is a horizontal or vertical slider control to select a numeric value. 16 gtk.Scrollbar This displays a horizontal or vertical scrollbar. 17 gtk.ProgressBar This is used to display the progress of a long running operation. 18 gtk.Dialog This displays a popup window for user information and action. 19 gtk.Notebook This widget is a container whose children are overlapping pages that can be switched between using tab labels. 20 gtk.Paned This is a base class for widgets with two panes, arranged either horizontally or vertically. Child widgets are added to the panes of the widget. The division between the two children can be adjusted by the user. 21 gtk.TextView This widget displays the contents of a TextBuffer object. 22 gtk.Toolbar This container holds and manages a set of buttons and widgets in a horizontal or vertical bar. 23 gtk.TreeView This widget displays the contents of standard TreeModel (ListStore, TreeStore, TreeModelSort) 24 gtk.DrawingArea This widget helps in creating custom user interface elements. gtk.DrawingArea is essentially a blank widget containing a window that you can draw on. 25 gtk.Calendar This widget displays a calendar and allows the user to select a date. 26 gtk.Viewport This widget displays a portion of a larger widget. Print Page Previous Next Advertisements ”;