def paint(self, painter, xxx, xxx2):
"""Paint scalebar on painter."""
mymajorticksize = 8
mypreferredsize = 1
mytextoffsetx = 3
myscalebarunit = "m"
mymapunits = QgsUnitTypes.DistanceMeters
# get height and width
canvasheight = painter.device().height()
canvaswidth = painter.device().width()
# set origins
myoriginx = canvaswidth - 40
myoriginy = canvasheight - 20
# save previous painter
painter.save()
# set rotation
painter.rotate(-self.canvas.rotation())
# set translation
painter.translate(myoriginx, myoriginy)
# calculate size of scale bar for preferred number of map units
myscalebarwidth = mypreferredsize
# if scale bar is very small reset to 1/4 of the canvs wide
if myscalebarwidth < 30:
# pixels
myscalebarwidth = canvaswidth / 4.0
# if scale bar is more than half the cnavs wide keep halving until not
while myscalebarwidth > canvaswidth / 3.0:
myscalebarwidth = myscalebarwidth / 3.0
# get the distance between 2 points
transform = self.canvas.getCoordinateTransform()
start_point = transform.toMapCoordinates(0 - myscalebarwidth, 0)
end_point = transform.toMapCoordinates(0, 0)
distance = self.distance_calc.measureLine([start_point, end_point])
# change scale (km,m,cm,mm)
if mymapunits == QgsUnitTypes.DistanceMeters:
if distance > 1000.0:
myscalebarunit = "km"
distance = distance / 1000
rounddist = round(distance, 1)
elif distance < 0.01:
myscalebarunit = "mm"
distance = distance * 1000
rounddist = round(distance, 4)
elif distance < 0.1:
myscalebarunit = "cm"
distance = distance * 100
rounddist = round(distance, 2)
else:
myscalebarunit = "m"
rounddist = round(distance, 1)
# set new scalebarwidth
myroundscalebarwidth = (rounddist * myscalebarwidth / distance)
# set qpen
mybackgroundpen = QPen(Qt.black, 4)
# create bar
mybararray = QPolygon(2)
mybararray.putPoints(0, 0 - myroundscalebarwidth,
0 + mymajorticksize / 2, 0,
0 + mymajorticksize / 2)
painter.setPen(mybackgroundpen)
# draw line
painter.drawPolyline(mybararray)
# draw 0
painter.drawText(
0 - myroundscalebarwidth - (self.myfontmetrics.width("0") / 2),
0 - (self.myfontmetrics.height() / 4), "0")
# draw max
painter.drawText(0 - (self.myfontmetrics.width(str(rounddist)) / 2),
0 - (self.myfontmetrics.height() / 4), str(rounddist))
# draw unit label
painter.drawText((0 + mytextoffsetx), (0 + mymajorticksize),
str(myscalebarunit))
# restore painter
painter.restore()
