[processing] Add API to set contexts for QgsProcessingAlgorithmConfigurationWidgets

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

@@ -12,7 +12,8 @@
 
 
 
-class QgsProcessingAlgorithmConfigurationWidget : QWidget
+
+class QgsProcessingAlgorithmConfigurationWidget : QWidget, QgsExpressionContextGenerator
 {
 %Docstring
 A configuration widget for processing algorithms allows providing additional
@@ -41,6 +42,47 @@ Read the current configuration from this widget.
 %Docstring
 Set the configuration which this widget should represent.
 %End
+
+    virtual void setWidgetContext( const QgsProcessingParameterWidgetContext &context );
+%Docstring
+Sets the ``context`` in which the Processing algorithm widget is shown, e.g., the
+parent model algorithm, a linked map canvas, and other relevant information which allows the widget
+to fine-tune its behavior.
+
+Subclasses should take care to call the base class method when reimplementing this method.
+
+.. seealso:: :py:func:`widgetContext`
+%End
+
+    void setAlgorithm( const QgsProcessingAlgorithm *algorithm );
+%Docstring
+Sets the algorithm instance associated with the widget.
+
+.. seealso:: :py:func:`algorithm`
+
+.. versionadded:: 3.6
+%End
+
+    const QgsProcessingAlgorithm *algorithm() const;
+%Docstring
+Returns the algorithm instance associated with this widget.
+
+.. seealso:: :py:func:`setAlgorithm`
+
+.. versionadded:: 3.6
+%End
+
+    void registerProcessingContextGenerator( QgsProcessingContextGenerator *generator );
+%Docstring
+Registers a Processing context ``generator`` class that will be used to retrieve
+a Processing context for the widget when required.
+
+.. versionadded:: 3.6
+%End
+
+    virtual QgsExpressionContext createExpressionContext() const;
+
+
 };
 
 

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

@@ -109,6 +109,7 @@ Sets the child algorithm ``id`` within the model which the parameter widget is a
 
 };
 
+
 class QgsAbstractProcessingParameterWidgetWrapper : QObject, QgsExpressionContextGenerator
 {
 %Docstring

src/gui/processing/qgsprocessingalgorithmconfigurationwidget.cpp

@@ -21,3 +21,23 @@ QgsProcessingAlgorithmConfigurationWidget::QgsProcessingAlgorithmConfigurationWi
   : QWidget( parent )
 {
 }
+
+void QgsProcessingAlgorithmConfigurationWidget::setWidgetContext( const QgsProcessingParameterWidgetContext &context )
+{
+  mWidgetContext = context;
+}
+
+void QgsProcessingAlgorithmConfigurationWidget::setAlgorithm( const QgsProcessingAlgorithm *algorithm )
+{
+  mAlgorithm = algorithm;
+}
+
+void QgsProcessingAlgorithmConfigurationWidget::registerProcessingContextGenerator( QgsProcessingContextGenerator *generator )
+{
+  mContextGenerator = generator;
+}
+
+QgsExpressionContext QgsProcessingAlgorithmConfigurationWidget::createExpressionContext() const
+{
+  return QgsProcessingGuiUtils::createExpressionContext( mContextGenerator, mWidgetContext, mAlgorithm, nullptr );
+}

src/gui/processing/qgsprocessingalgorithmconfigurationwidget.h

@@ -24,10 +24,12 @@
 
 #include "qgis_gui.h"
 #include "qgis_sip.h"
+#include "qgsprocessingwidgetwrapper.h"
 
 class QgsProcessingAlgorithm;
 class QgsProcessingAlgorithmConfigurationWidget;
 
+
 /**
  * A configuration widget for processing algorithms allows providing additional
  * configuration options directly on algorithm level, in addition to parameters.
@@ -35,7 +37,7 @@ class QgsProcessingAlgorithmConfigurationWidget;
  * \ingroup gui
  * \since QGIS 3.2
  */
-class GUI_EXPORT QgsProcessingAlgorithmConfigurationWidget : public QWidget
+class GUI_EXPORT QgsProcessingAlgorithmConfigurationWidget : public QWidget, public QgsExpressionContextGenerator
 {
     Q_OBJECT
 
@@ -56,6 +58,49 @@ class GUI_EXPORT QgsProcessingAlgorithmConfigurationWidget : public QWidget
      * Set the configuration which this widget should represent.
      */
     virtual void setConfiguration( const QVariantMap &configuration ) = 0;
+
+    /**
+     * Sets the \a context in which the Processing algorithm widget is shown, e.g., the
+     * parent model algorithm, a linked map canvas, and other relevant information which allows the widget
+     * to fine-tune its behavior.
+     *
+     * Subclasses should take care to call the base class method when reimplementing this method.
+     *
+     * \see widgetContext()
+     */
+    virtual void setWidgetContext( const QgsProcessingParameterWidgetContext &context );
+
+    /**
+     * Sets the algorithm instance associated with the widget.
+     *
+     * \see algorithm()
+     * \since QGIS 3.6
+     */
+    void setAlgorithm( const QgsProcessingAlgorithm *algorithm );
+
+    /**
+     * Returns the algorithm instance associated with this widget.
+     *
+     * \see setAlgorithm()
+     * \since QGIS 3.6
+     */
+    const QgsProcessingAlgorithm *algorithm() const { return mAlgorithm; }
+
+    /**
+     * Registers a Processing context \a generator class that will be used to retrieve
+     * a Processing context for the widget when required.
+     *
+     * \since QGIS 3.6
+     */
+    void registerProcessingContextGenerator( QgsProcessingContextGenerator *generator );
+
+    QgsExpressionContext createExpressionContext() const override;
+
+  private:
+
+    QgsProcessingContextGenerator *mContextGenerator = nullptr;
+    const QgsProcessingAlgorithm *mAlgorithm = nullptr;
+    QgsProcessingParameterWidgetContext mWidgetContext;
 };