About Layer tree embedded widgets and have your WM(T)S always crispy sharp

Bij gebruik van bovenstaande code liep ik tegen wat problemen op. Uiteindelijk gebruik ik nu deze code die vooralsnog probleemloos loopt:

def __init__(self, layer):
# layout the widget itself: a label, slider and checkbox
QWidget.__init__(self)
label = QLabel("Zoomniveau")
self.slider = QSlider(Qt.Horizontal)
self.ckbox = QCheckBox()
self.ckbox.setToolTip("Zoom alleen naar beschikbare niveau's")
layout = QHBoxLayout()
layout.addWidget(label)
layout.addWidget(self.slider)
layout.addWidget(self.ckbox)
self.setLayout(layout)
self.layer = layer
self.resolutions = layer.dataProvider().property('resolutions')
self.mapCanvas = iface.mapCanvas()
self.slider.setRange(0, len(self.resolutions)-1)
self.slider.setTickInterval(1)
self.slider.setTickPosition(QSlider.TicksBothSides)
# invert because 'highest' value == most zoomed out == 0
self.slider.setInvertedAppearance(True)
self.slider.setPageStep(1)
self.slider.setTracking(False)
self.slider.setEnabled(True)
# set the right value of the slider now
self.on_scale_changed(self.mapCanvas.scale())
# connect signals
self.mapCanvas.scaleChanged.connect(self.on_scale_changed)
self.slider.valueChanged.connect(self.on_value_changed)
self.ckbox.stateChanged.connect(self.on_chkbox_change)
def on_chkbox_change(self, state):
# force a rescaling OR not
self.on_scale_changed(self.mapCanvas.scale())
def on_scale_changed(self, scale):
if len(self.resolutions)==0:
return
try:
# enable or disabe the 'fixed zooms' checkbox
self.ckbox.setVisible(self.layer.crs().srsid() == \
iface.mapCanvas().mapSettings().destinationCrs().srsid())
mupp = self.mapCanvas.mapUnitsPerPixel()
r = 0
for i in range(0, len(self.resolutions)):
r = i
if self.resolutions[i] > mupp:
if i > 0 \
and (self.resolutions[i]-mupp > mupp-self.resolutions[i-1]):
r = i-1
break
# only do fixed zooms if the chkbox is checked AND visible
if self.ckbox.isVisible() and self.ckbox.isChecked() \
and not math.isclose(self.resolutions[r], mupp, rel_tol=1e-5):
self.mapCanvas.zoomByFactor(self.resolutions[r] / \
self.mapCanvas.mapUnitsPerPixel())
return
self.slider.blockSignals(True)
self.slider.setValue(r)
self.slider.setToolTip('Z: {:.3f}\nResolution: {:.3f}'.\
format(self.slider.maximum() - r, self.resolutions[r]))
self.slider.blockSignals(False)
except:
pass
def on_value_changed(self, value):
if len(self.resolutions)==0:
return
self.mapCanvas.zoomByFactor(self.resolutions[value] / \
self.mapCanvas.mapUnitsPerPixel())