def loadLabelImage(imagepath, labeldescriptor = None):
"""
Load a labeled single band raster in the canvas
Keyword arguments:
imagepath -- the path to the image
labeldescriptor -- a dictionnary for label (int) to tuple (QColor, QString) conversion
"""
if imagepath is None:
return
name = os.path.splitext( os.path.basename(imagepath) )[0]
qgslayer = QgsRasterLayer(imagepath, name)
if not qgslayer.isValid():
QtGui.QMessageBox.critical(None,
u"Erreur",
u"Impossible de charger la couche %s" % unicode(imagepath))
QgsMapLayerRegistry.instance().addMapLayer(qgslayer)
qgslayer.setDrawingStyle('SingleBandPseudoColor')
colorlist = []
max_label = 0
for label in sorted(labeldescriptor.keys()):
color = labeldescriptor[label][0]
labeltxt = labeldescriptor[label][1]
colorlist.append(QgsColorRampShader.ColorRampItem(label, color, labeltxt))
if labeltxt > max_label:
max_label = labeltxt
s = QgsRasterShader()
c = QgsColorRampShader()
c.setColorRampType(QgsColorRampShader.INTERPOLATED)
c.setColorRampItemList(colorlist)
s.setRasterShaderFunction(c)
ps = QgsSingleBandPseudoColorRenderer(qgslayer.dataProvider(), 1, s)
qgslayer.setRenderer(ps)
for bandNo in range(1,qgslayer.dataProvider().bandCount()+1):
qgslayer.dataProvider().setUseSrcNoDataValue( bandNo, False )
QGisLayers.iface.legendInterface().refreshLayerSymbology(qgslayer)
if hasattr(qgslayer, "setCacheImage"):
qgslayer.setCacheImage(None)
qgslayer.triggerRepaint()
