Svarbu

Vertimas yra bendruomenės pastangos, prie kurių jūs galite prisijungti. Šis puslapis šiuo metu išverstas 25.00%.

17. Apdorojimo priedo rašymas

Priklausomai nuo to, kokį ruošiatės kurti priedą, gali būti geresnis variantas pridėti jo funkcionalumą kaip Apdorojimo algoritmą (arba jų aibę). Tai suteiktų geresnę integraciją QGIS viduje, papildomą funkcionalumą (kadangi jį galima būtų paleisti Apdorojimo komponentuose, tokiuose kaip modelyje arba paketinio apdorojimo sąsajoje). Tai taipogi leistų greitesnį kūrimą (kadangi Apdorojimas užims didžiąją darbo dalį).

Norėdami platinti tokius algoritmus, jūs turite sukurti priedą kuris prideda juos į Apdorojimo įrankinę. Priedas turi turėti algoritmo tiekėją, kuris turi būti registruotas kai sukuriama priedo kopija.

17.1. Updating a plugin

If you want to add your existing plugin to Processing, you need to add some code.

1. In your metadata.txt file, you need to add a variable:

   hasProcessingProvider=yes
   

2. In the Python file where your plugin is setup with the initGui method, you need to adapt some lines like this:

   from qgis.core import QgsApplication
   from .processing_provider.provider import Provider
   
   class YourPluginName:
   
       def __init__(self):
           self.provider = None
   
       def initProcessing(self):
           self.provider = Provider()
           QgsApplication.processingRegistry().addProvider(self.provider)
   
       def initGui(self):
           self.initProcessing()
   
       def unload(self):
           QgsApplication.processingRegistry().removeProvider(self.provider)
   

3. You can create a folder processing_provider with three files in it:

   • __init__.py with nothing in it. This is necessary to make a valid Python package.

   • provider.py which will create the Processing provider and expose your algorithms.

     from qgis.core import QgsProcessingProvider
     from qgis.PyQt.QtGui import QIcon
     
     from .example_processing_algorithm import ExampleProcessingAlgorithm
     
     class Provider(QgsProcessingProvider):
     
         """ The provider of our plugin. """
     
         def loadAlgorithms(self):
             """ Load each algorithm into the current provider. """
             self.addAlgorithm(ExampleProcessingAlgorithm())
             # add additional algorithms here
             # self.addAlgorithm(MyOtherAlgorithm())
     
         def id(self) -> str:
             """The ID of your plugin, used for identifying the provider.
     
             This string should be a unique, short, character only string,
             eg "qgis" or "gdal". This string should not be localised.
             """
             return 'yourplugin'
     
         def name(self) -> str:
             """The human friendly name of your plugin in Processing.
     
             This string should be as short as possible (e.g. "Lastools", not
             "Lastools version 1.0.1 64-bit") and localised.
             """
             return self.tr('Your plugin')
     
         def icon(self) -> QIcon:
             """Should return a QIcon which is used for your provider inside
             the Processing toolbox.
             """
             return QgsProcessingProvider.icon(self)
     

   • example_processing_algorithm.py which contains the example algorithm file. Copy/paste the content of the script template file and update it according to your needs.

   You should have a tree similar to this:

   └── your_plugin_root_folder
      ├── __init__.py
      ├── LICENSE
      ├── metadata.txt
      └── processing_provider
            ├── example_processing_algorithm.py
            ├── __init__.py
            └── provider.py
   

4. Now you can reload your plugin in QGIS and you should see your example script in the Processing toolbox and modeler.

17.1.1. Creating a custom algorithm

Here’s a simple example of a custom buffer algorithm:

from qgis.core import (
    QgsProcessingAlgorithm,
    QgsProcessingParameterFeatureSource,
    QgsProcessingParameterNumber,
    QgsProcessingParameterFeatureSink,
    QgsFeatureSink,
)

class BufferAlgorithm(QgsProcessingAlgorithm):

    INPUT = 'INPUT'
    DISTANCE = 'DISTANCE'
    OUTPUT = 'OUTPUT'

    def initAlgorithm(self, config=None):
        self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT, 'Input layer'))
        self.addParameter(QgsProcessingParameterNumber(self.DISTANCE, 'Buffer distance', defaultValue=100.0))
        self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, 'Output layer'))

    def processAlgorithm(self, parameters, context, feedback):
        source = self.parameterAsSource(parameters, self.INPUT, context)
        distance = self.parameterAsDouble(parameters, self.DISTANCE, context)
        (sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
                                               source.fields(), source.wkbType(), source.sourceCrs())

        for f in source.getFeatures():
            f.setGeometry(f.geometry().buffer(distance, 5))
            sink.addFeature(f, QgsFeatureSink.FastInsert)

        return {self.OUTPUT: dest_id}

    def name(self):
        return 'buffer'

    def displayName(self):
        return 'Buffer Features'

    def group(self):
        return 'Examples'

    def groupId(self):
        return 'examples'

    def createInstance(self):
        return BufferAlgorithm()