class MeasureAreaTool(QgsMapTool):
finished = pyqtSignal()
def __init__(self, canvas, msglog):
super().__init__(canvas)
self.canvas = canvas
self.msglog = msglog
self.start_point = self.middle_point = self.end_point = None
self.rubber_band = QgsRubberBand(self.canvas,
QgsWkbTypes.PolygonGeometry)
self.rubber_band.setColor(QColor(255, 0, 0, 100))
self.rubber_band.setWidth(3)
self.rubber_band_points = QgsRubberBand(self.canvas,
QgsWkbTypes.PointGeometry)
self.rubber_band_points.setIcon(QgsRubberBand.ICON_CIRCLE)
self.rubber_band_points.setIconSize(10)
self.rubber_band_points.setColor(QColor(255, 0, 0, 150))
crs = self.canvas.mapSettings().destinationCrs()
self.area_calc = QgsDistanceArea()
self.area_calc.setSourceCrs(crs,
QgsProject.instance().transformContext())
self.area_calc.setEllipsoid(crs.ellipsoidAcronym())
self.reset()
def reset(self):
""" Reset log message and rubber band"""
self.msglog.logMessage("")
self.start_point = self.end_point = None
self.rubber_band.reset(QgsWkbTypes.PolygonGeometry)
self.rubber_band_points.reset(QgsWkbTypes.PointGeometry)
def canvasPressEvent(self, event):
pass
def canvasReleaseEvent(self, event):
transform = self.canvas.getCoordinateTransform()
point = transform.toMapCoordinates(event.pos().x(), event.pos().y())
if self.start_point and event.button() == Qt.RightButton:
multipoint = self.rubber_band.asGeometry()
area = self.area_calc.measureArea(multipoint)
anglemsg = QMessageBox(self.parent())
anglemsg.finished.connect(self.deactivate)
anglemsg.setWindowTitle("Measure area tool")
anglemsg.setText("Area: {} ".format(
self.area_calc.formatArea(area, 3,
QgsUnitTypes.AreaSquareMeters,
True)))
anglemsg.exec()
self.finish()
elif self.start_point:
self.rubber_band.addPoint(point)
self.rubber_band_points.addPoint(point)
else:
self.start_point = point
self.rubber_band.addPoint(self.start_point)
self.rubber_band_points.addPoint(self.start_point)
def canvasMoveEvent(self, e):
if self.start_point and not self.end_point:
transform = self.canvas.getCoordinateTransform()
point = transform.toMapCoordinates(e.pos().x(), e.pos().y())
self.rubber_band.movePoint(point)
multipoint = self.rubber_band.asGeometry()
area = self.area_calc.measureArea(multipoint)
self.msglog.logMessage("")
self.msglog.logMessage(
"Current area: {} ".format(
self.area_calc.formatArea(area, 3,
QgsUnitTypes.AreaSquareMeters,
True)), "Measure Area:", 0)
def keyPressEvent(self, event):
"""
When escape key is pressed, line is restarted
"""
if event.key() == Qt.Key_Escape:
self.reset()
def finish(self):
self.reset()
self.finished.emit()