class CartogramWorkOrchestratorMixIn:
"""Manage the tasks of the plugin’s workers."""
def __init__(self):
"""Manage the tasks of the plugin’s workers."""
super(CartogramWorkOrchestratorMixIn, self).__init__()
self.add_processing_provider()
def add_processing_provider(self):
self.provider = CartogramProcessingProvider()
QgsApplication.processingRegistry().addProvider(self.provider)
def cancel_task(self):
self.disable_cancel_button()
self.task.cancel()
def is_task_running(self):
try:
return self.task.isActive()
except (AttributeError, RuntimeError): # (no self.task)
return False
def remove_processing_provider(self):
QgsApplication.processingRegistry().removeProvider(self.provider)
def sample_layer(self):
source_layer = QgsVectorLayer(
os.path.join(self.plugin_dir, "data", "Austria_PopulationByNUTS2.gml"),
""
)
# (empty) memory layer
sample_layer = QgsVectorLayer(
QgsWkbTypes.geometryDisplayString(source_layer.geometryType())
+ "?crs=" + source_layer.crs().authid()
+ "&index=yes",
"Austria_Population_NUTS2_20170101",
"memory"
)
sample_layer_data_provider = sample_layer.dataProvider()
sample_layer_data_provider.addAttributes(source_layer.fields().toList())
sample_layer.updateFields()
sample_layer_data_provider.addFeatures(list(source_layer.getFeatures()))
sample_layer.loadNamedStyle(
os.path.join(self.plugin_dir, "data", "Austria_PopulationByNUTS2.qml")
)
sample_layer.setTitle("Austria: Population by NUTS2 regions, 1 Jan 2017")
sample_layer.setShortName("Austria_Population_NUTS2_20170101")
sample_layer.setAbstract(
"Austria’s population by NUTS2 region, as of 1 Jan 2017 \n"
+ "\n"
+ "Data sources: \n"
+ " http://ec.europa.eu/eurostat/web/gisco/geodata/"
+ "reference-data/administrative-units-statistical-units/"
+ "nuts#nuts13 \n"
+ " http://www.statistik.at/web_de/statistiken/"
+ "menschen_und_gesellschaft/bevoelkerung/"
+ "bevoelkerungsstand_und_veraenderung/"
+ "bevoelkerung_zu_jahres-_quartalsanfang/index.html"
)
return sample_layer
def start_task(self, input_layer, field, max_iterations, max_average_error):
self.context = QgsProcessingContext()
self.feedback = QgsProcessingFeedback()
self.task = QgsProcessingAlgRunnerTask(
QgsApplication.processingRegistry().algorithmById("cartogram3:compute_cartogram"),
{
"INPUT": input_layer,
"FIELD": field,
"MAX_ITERATIONS": max_iterations,
"MAX_AVERAGE_ERROR": max_average_error,
"OUTPUT": "memory:"
},
self.context,
self.feedback
)
self.task.executed.connect(self.task_finished)
self.feedback.progressChanged.connect(self.update_progress)
QgsApplication.taskManager().addTask(self.task)
def task_finished(self, successful, results={}):
if successful:
output_layer = self.context.getMapLayer(results["OUTPUT"])
if output_layer and output_layer.isValid():
layer = self.context.takeResultLayer(output_layer.id())
self.add_result_layer_to_map_canvas(layer, results["FIELD"])
self.feedback.pushInfo(
(
"Finished computing cartogram for layer {:s} on field {:s} "
+ "after {:d} iterations with {:.2n}% residual error."
).format(
self.input_layer.name(),
results["FIELD"],
results["ITERATIONS"],
results["RESIDUAL_AVERAGE_ERROR"]
)
)
else:
if self.feedback.isCanceled():
self.feedback.pushWarning("User canceled cartogram computation")
self.feedback.reportError("Failed to compute cartogram")
self.clean_up_ui() # remove progress bar
def update_progress(self, progress):
self.update_progress_bar(progress)
