Set widget context for widget wrappers

python/gui/auto_generated/processing/qgsprocessingmodelerparameterwidget.sip.in

@@ -57,6 +57,15 @@ last for the lifetime of the widget.
 
     ~QgsProcessingModelerParameterWidget();
 
+    void setWidgetContext( const QgsProcessingParameterWidgetContext &context );
+%Docstring
+Sets the ``context`` in which the modeler parameter widget is shown, e.g., the
+parent model algorithm and other relevant information which allows the widget
+to fine-tune its behavior.
+
+.. seealso:: :py:func:`widgetContext`
+%End
+
     void populateSources( const QStringList &compatibleParameterTypes,
                           const QStringList &compatibleOutputTypes,
                           const QList< int > &compatibleDataTypes );

python/plugins/processing/gui/BatchPanel.py

@@ -36,6 +36,8 @@ from qgis.core import (Qgis,
                        QgsApplication,
                        QgsSettings,
                        QgsProcessingParameterDefinition)
+from qgis.gui import QgsProcessingParameterWidgetContext
+from qgis.utils import iface
 
 from processing.gui.wrappers import WidgetWrapperFactory, WidgetWrapper
 from processing.gui.BatchOutputSelectionPanel import BatchOutputSelectionPanel
@@ -253,6 +255,9 @@ class BatchPanel(BASE, WIDGET):
         # TODO QGIS 4.0 - remove
         is_cpp_wrapper = not issubclass(wrapper.__class__, WidgetWrapper)
         if is_cpp_wrapper:
+            widget_context = QgsProcessingParameterWidgetContext()
+            widget_context.setMapCanvas(iface.mapCanvas())
+            wrapper.setWidgetContext(widget_context)
             widget = wrapper.createWrappedWidget(context)
         else:
             widget = wrapper.widget

python/plugins/processing/gui/ParametersPanel.py

@@ -42,7 +42,9 @@ from qgis.core import (QgsProcessingParameterDefinition,
                        QgsProcessingParameterFeatureSink,
                        QgsProcessingParameterVectorDestination,
                        QgsProject)
-from qgis.gui import QgsProcessingContextGenerator
+from qgis.gui import (QgsProcessingContextGenerator,
+                      QgsProcessingParameterWidgetContext)
+from qgis.utils import iface
 
 from qgis.PyQt import uic
 from qgis.PyQt.QtCore import QCoreApplication, Qt
@@ -122,6 +124,10 @@ class ParametersPanel(BASE, WIDGET):
             if param.flags() & QgsProcessingParameterDefinition.FlagAdvanced:
                 self.grpAdvanced.show()
                 break
+
+        widget_context = QgsProcessingParameterWidgetContext()
+        widget_context.setMapCanvas(iface.mapCanvas())
+
         # Create widgets and put them in layouts
         for param in self.alg.parameterDefinitions():
             if param.flags() & QgsProcessingParameterDefinition.FlagHidden:
@@ -142,6 +148,7 @@ class ParametersPanel(BASE, WIDGET):
                 # TODO QGIS 4.0 - remove
                 is_python_wrapper = issubclass(wrapper.__class__, WidgetWrapper)
                 if not is_python_wrapper:
+                    wrapper.setWidgetContext(widget_context)
                     widget = wrapper.createWrappedWidget(self.processing_context)
                     wrapper.registerProcessingContextGenerator(self.context_generator)
                 else:

python/plugins/processing/modeler/ModelerParametersDialog.py

@@ -58,7 +58,9 @@ from qgis.gui import (QgsGui,
                       QgsScrollArea,
                       QgsFilterLineEdit,
                       QgsHelp,
-                      QgsProcessingModelerParameterWidget)
+                      QgsProcessingModelerParameterWidget,
+                      QgsProcessingParameterWidgetContext)
+from qgis.utils import iface
 
 from processing.gui.wrappers import WidgetWrapperFactory
 from processing.gui.wrappers import InvalidParameterValue
@@ -131,6 +133,9 @@ class ModelerParametersDialog(QDialog):
             self.algorithmItem.setConfiguration(self.configuration)
         self.verticalLayout.addWidget(self.algorithmItem)
 
+        widget_context = QgsProcessingParameterWidgetContext()
+        widget_context.setMapCanvas(iface.mapCanvas())
+
         for param in self._alg.parameterDefinitions():
             if param.flags() & QgsProcessingParameterDefinition.FlagAdvanced:
                 self.advancedButton = QPushButton()
@@ -150,6 +155,7 @@ class ModelerParametersDialog(QDialog):
             self.wrappers[param.name()] = wrapper
 
             if issubclass(wrapper.__class__, QgsProcessingModelerParameterWidget):
+                wrapper.setWidgetContext(widget_context)
                 widget = wrapper
             else:
                 widget = wrapper.widget

src/gui/processing/qgsprocessingmodelerparameterwidget.cpp

@@ -113,6 +113,12 @@ QgsProcessingModelerParameterWidget::QgsProcessingModelerParameterWidget( QgsPro
 
 QgsProcessingModelerParameterWidget::~QgsProcessingModelerParameterWidget() = default;
 
+void QgsProcessingModelerParameterWidget::setWidgetContext( const QgsProcessingParameterWidgetContext &context )
+{
+  if ( mStaticWidgetWrapper )
+    mStaticWidgetWrapper->setWidgetContext( context );
+}
+
 const QgsProcessingParameterDefinition *QgsProcessingModelerParameterWidget::parameterDefinition() const
 {
   return mParameterDefinition;

src/gui/processing/qgsprocessingmodelerparameterwidget.h

@@ -30,6 +30,7 @@ class QgsProcessingParameterDefinition;
 class QgsAbstractProcessingParameterWidgetWrapper;
 class QgsExpressionLineEdit;
 class QgsProcessingModelAlgorithm;
+class QgsProcessingParameterWidgetContext;
 
 class QLabel;
 class QToolButton;
@@ -82,6 +83,15 @@ class GUI_EXPORT QgsProcessingModelerParameterWidget : public QWidget
 
     ~QgsProcessingModelerParameterWidget() override;
 
+    /**
+     * Sets the \a context in which the modeler parameter widget is shown, e.g., the
+     * parent model algorithm and other relevant information which allows the widget
+     * to fine-tune its behavior.
+     *
+     * \see widgetContext()
+     */
+    void setWidgetContext( const QgsProcessingParameterWidgetContext &context );
+
     /**
      * Populates the widget with available sources for the parameter's value, e.g.
      * adding the available child algorithm outputs and model input parameter

tests/src/gui/testprocessinggui.cpp

@@ -40,6 +40,8 @@
 #include "qgsprojectionselectionwidget.h"
 #include "qgsdoublespinbox.h"
 #include "qgsspinbox.h"
+#include "qgsmapcanvas.h"
+#include "models/qgsprocessingmodelalgorithm.h"
 
 class TestParamType : public QgsProcessingParameterDefinition
 {
@@ -306,6 +308,21 @@ void TestProcessingGui::testWrapperGeneral()
   w = falseDefault.createWrappedWidget( context );
   QVERIFY( !falseDefault.widgetValue().toBool() );
   delete w;
+
+  std::unique_ptr< QgsMapCanvas > mc = qgis::make_unique< QgsMapCanvas >();
+  QgsProcessingParameterWidgetContext widgetContext;
+  widgetContext.setMapCanvas( mc.get() );
+  QCOMPARE( widgetContext.mapCanvas(), mc.get() );
+  std::unique_ptr< QgsProcessingModelAlgorithm > model = qgis::make_unique< QgsProcessingModelAlgorithm >();
+  widgetContext.setModel( model.get() );
+  QCOMPARE( widgetContext.model(), model.get() );
+  widgetContext.setModelChildAlgorithmId( QStringLiteral( "xx" ) );
+  QCOMPARE( widgetContext.modelChildAlgorithmId(), QStringLiteral( "xx" ) );
+
+  wrapper.setWidgetContext( widgetContext );
+  QCOMPARE( wrapper.widgetContext().mapCanvas(), mc.get() );
+  QCOMPARE( wrapper.widgetContext().model(), model.get() );
+  QCOMPARE( wrapper.widgetContext().modelChildAlgorithmId(), QStringLiteral( "xx" ) );
 }
 
 class TestProcessingContextGenerator : public QgsProcessingContextGenerator