The Pan Tool

To let the user move around the map, we'll make use of the PanTool class we implemented in an earlier chapter. Add the following class definition to the mapTools.py module:

class PanTool(QgsMapTool):
    def __init__(self, mapCanvas):
        QgsMapTool.__init__(self, mapCanvas)
        self.setCursor(Qt.OpenHandCursor)
        self.dragging = False

    def canvasMoveEvent(self, event):
        if event.buttons() == Qt.LeftButton:
            self.dragging = True
            self.canvas().panAction(event)

    def canvasReleaseEvent(self, event):
        if event.button() == Qt.LeftButton and self.dragging:
            self.canvas().panActionEnd(event.pos())
            self.dragging = False

Back in our forestTrails.py module, add the following new method:

    def setupMapTools(self):
        self.panTool = PanTool(self.mapCanvas)
        self.panTool.setAction(self.actionPan)

This method will initialize the various map tools that our application will use; we'll add to this method...