Marble/MarblePythonSignalsSlots

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    Basic interaction with MarbleWidget
    Tutorial Series   Marble Python Tutorial
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    Creating a window with controls

    Note
    the documentation for the Marble Python bindings are currently not available online. They can instead be found in the source code at the location: src/bindings/python/html/marble/Marble.html.


    We'd like to add other widgets to our Marble window: A zoom slider and a label that shows the current zoom level of the map.

    In order to achieve this we need to create a vertical layout. The layout must be added as the central widget to the application, and have the map, slider and label added to it. Also we zoom the globe to the slider's default value using the marble.zoomView(int) method.

    We want to center our globe onto South America. So we create a new GeoDataCoordinates object that takes the longitude and the latitude as a parameter and we call marble.centerOn(location).

    As you might have realized already GeoDataCoordinates is the geodetic "sister" of QPoint. They share a very similar API. Additionally GeoDataCoordinates features a nice set of string conversion methods (GeoDataCoordinates.fromString(), GeoDataCoordinates.lonToString() and GeoDataCoordinates.latToString()). They are used in various places inside Marble such as the signal MarbleWidget.mouseMoveGeoPosition(string) .

    Finally we connect the signals and slots that MarbleWidget offers to the signals and slots of the slider and the label (and the label, through a custom method that prefixes the string 'Zoom Level:'):

    #!/usr/bin/env python
    from PyQt4.QtCore import *
    from PyQt4.QtGui import *
    from PyKDE4.marble import *
    import sys
    
    
    class MainWindow():
        def __init__(self):
            # create the app
            app = QApplication(sys.argv)
    
            # create the main window and set it's title
            window = QWidget()
            window.setWindowTitle("Marble Map with Controls")
    
            # create the marble widget
            marble = Marble.MarbleWidget()
    
            # Load the OpenStreetMap map
            marble.setMapThemeId("earth/plain/plain.dgml")
    
            # Enable the cloud cover and enable the country borders
            marble.setShowClouds(True)
            marble.setShowBorders(True)
    
            # Hide the FloatItems: Compass and StatusBar
            marble.setShowOverviewMap(False)
            marble.setShowScaleBar(False)
            marble.setShowCompass(False)
    
            # Change the map to center on Australia
            home = Marble.GeoDataCoordinates(135.0, -25.0, 0.0, Marble.GeoDataCoordinates.Degree)
            marble.centerOn(home)
    
            # create the slider
            zoomSlider = QSlider(Qt.Horizontal)
            # set the limits of the slider
            zoomSlider.setMinimum(1000)
            zoomSlider.setMaximum(2400)
            # set a default zoom value
            zoomSlider.setValue(1200)
    
            # zoom the map
            marble.zoomView(zoomSlider.value())
    
            # create the position label
            self.zoomLabel = QLabel()
            # show the current zoom level
            self.setZoomLabel(zoomSlider.value())
    
            # make elements size correctly
            self.zoomLabel.setSizePolicy(QSizePolicy.Preferred, QSizePolicy.Fixed)
    
            # create the layout
            layout = QVBoxLayout()
    
            # add all the components
            layout.addWidget(marble)
            layout.addWidget(zoomSlider)
            layout.addWidget(self.zoomLabel)
    
            # make the layout placeholder the central widget
            window.setLayout(layout)
    
            # connect slider value to map zoom via signal slots
            app.connect(zoomSlider, SIGNAL('valueChanged(int)'), marble.zoomView)
    
            # display the zoom level on the label, but pass it though the
            # custom self.setZoomLabel function to add prefix text
            app.connect(marble, SIGNAL('zoomChanged(int)'), self.setZoomLabel)
    
            # resize the window
            window.resize(600, 400)
    
            # display the app
            window.show()
    
            app.exec_()
    
        def setZoomLabel(self, value):
            self.zoomLabel.setText("Zoom Level: " + str(value))
    
    MainWindow()
    

    Save the code above as marble_controls.py and run it:

    python marble_controls.py
    

    If things go fine, you end up with a map application along with a slider and label below it. The map should be centered on Australia and have a zoom level of 1200 to start with: