Allow setting the context for widget wrappers

The context contains settings which reflect the context ini which a Processing parameter 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.
qgis · Sep 21, 2018 · 55e22b9 · 55e22b9
1 parent 33eb295
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diff --git a/python/gui/auto_generated/processing/qgsprocessingwidgetwrapper.sip.in b/python/gui/auto_generated/processing/qgsprocessingwidgetwrapper.sip.in
@@ -36,6 +36,79 @@ return a pointer to a context which they have already created and own.
     virtual ~QgsProcessingContextGenerator();
 };
 
+class QgsProcessingParameterWidgetContext
+{
+%Docstring
+Contains settings which reflect the context in which a Processing parameter 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.
+
+.. versionadded:: 3.4
+%End
+
+%TypeHeaderCode
+#include "qgsprocessingwidgetwrapper.h"
+%End
+  public:
+
+    QgsProcessingParameterWidgetContext();
+%Docstring
+Constructor for QgsProcessingParameterWidgetContext.
+%End
+
+    void setMapCanvas( QgsMapCanvas *canvas );
+%Docstring
+Sets the map ``canvas`` associated with the widget. This allows the widget to retrieve the current
+map scale and other properties from the canvas.
+
+.. seealso:: :py:func:`mapCanvas`
+%End
+
+    QgsMapCanvas *mapCanvas() const;
+%Docstring
+Returns the map canvas associated with the widget.
+
+.. seealso:: :py:func:`setMapCanvas`
+%End
+
+    QgsProcessingModelAlgorithm *model() const;
+%Docstring
+Returns the model which the parameter widget is associated with.
+
+.. seealso:: :py:func:`setModel`
+
+.. seealso:: :py:func:`modelChildAlgorithmId`
+%End
+
+    void setModel( QgsProcessingModelAlgorithm *model );
+%Docstring
+Sets the ``model`` which the parameter widget is associated with.
+
+.. seealso:: :py:func:`model`
+
+.. seealso:: :py:func:`setModelChildAlgorithmId`
+%End
+
+    QString modelChildAlgorithmId() const;
+%Docstring
+Returns the child algorithm ID within the model which the parameter widget is associated with.
+
+.. seealso:: :py:func:`setModelChildAlgorithmId`
+
+.. seealso:: :py:func:`model`
+%End
+
+    void setModelChildAlgorithmId( const QString &id );
+%Docstring
+Sets the child algorithm ``id`` within the model which the parameter widget is associated with.
+
+.. seealso:: :py:func:`modelChildAlgorithmId`
+
+.. seealso:: :py:func:`setModel`
+%End
+
+};
+
 class QgsAbstractProcessingParameterWidgetWrapper : QObject
 {
 %Docstring
@@ -71,6 +144,26 @@ Constructor for QgsAbstractProcessingParameterWidgetWrapper, for the specified
     QgsProcessingGui::WidgetType type() const;
 %Docstring
 Returns the dialog type for which widgets and labels will be created by this wrapper.
+%End
+
+    virtual void setWidgetContext( const QgsProcessingParameterWidgetContext &context );
+%Docstring
+Sets the ``context`` in which the Processing parameter 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
+
+    const QgsProcessingParameterWidgetContext &widgetContext() const;
+%Docstring
+Returns the context in which the Processing parameter 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.
+
+.. seealso:: :py:func:`setWidgetContext`
 %End
 
     QWidget *createWrappedWidget( QgsProcessingContext &context ) /Factory/;

diff --git a/src/gui/processing/qgsprocessingwidgetwrapper.cpp b/src/gui/processing/qgsprocessingwidgetwrapper.cpp
@@ -23,6 +23,45 @@
 #include <QLabel>
 #include <QHBoxLayout>
 
+//
+// QgsProcessingParameterWidgetContext
+//
+
+void QgsProcessingParameterWidgetContext::setMapCanvas( QgsMapCanvas *canvas )
+{
+  mMapCanvas = canvas;
+}
+
+QgsMapCanvas *QgsProcessingParameterWidgetContext::mapCanvas() const
+{
+  return mMapCanvas;
+}
+
+QString QgsProcessingParameterWidgetContext::modelChildAlgorithmId() const
+{
+  return mModelChildAlgorithmId;
+}
+
+void QgsProcessingParameterWidgetContext::setModelChildAlgorithmId( const QString &modelChildAlgorithmId )
+{
+  mModelChildAlgorithmId = modelChildAlgorithmId;
+}
+
+QgsProcessingModelAlgorithm *QgsProcessingParameterWidgetContext::model() const
+{
+  return mModel;
+}
+
+void QgsProcessingParameterWidgetContext::setModel( QgsProcessingModelAlgorithm *model )
+{
+  mModel = model;
+}
+
+
+//
+// QgsAbstractProcessingParameterWidgetWrapper
+//
+
 QgsAbstractProcessingParameterWidgetWrapper::QgsAbstractProcessingParameterWidgetWrapper( const QgsProcessingParameterDefinition *parameter, QgsProcessingGui::WidgetType type, QObject *parent )
   : QObject( parent )
   , mType( type )
@@ -35,6 +74,16 @@ QgsProcessingGui::WidgetType QgsAbstractProcessingParameterWidgetWrapper::type()
   return mType;
 }
 
+void QgsAbstractProcessingParameterWidgetWrapper::setWidgetContext( const QgsProcessingParameterWidgetContext &context )
+{
+  mWidgetContext = context;
+}
+
+const QgsProcessingParameterWidgetContext &QgsAbstractProcessingParameterWidgetWrapper::widgetContext() const
+{
+  return mWidgetContext;
+}
+
 QWidget *QgsAbstractProcessingParameterWidgetWrapper::createWrappedWidget( QgsProcessingContext &context )
 {
   if ( mWidget )
@@ -222,3 +271,4 @@ QString QgsProcessingParameterWidgetFactoryInterface::modelerExpressionFormatStr
 {
   return QString();
 }
+
diff --git a/src/gui/processing/qgsprocessingwidgetwrapper.h b/src/gui/processing/qgsprocessingwidgetwrapper.h
@@ -34,6 +34,8 @@ class QgsProcessingModelAlgorithm;
 class QLabel;
 class QgsPropertyOverrideButton;
 class QgsVectorLayer;
+class QgsProcessingModelAlgorithm;
+class QgsMapCanvas;
 
 /**
  * \class QgsProcessingContextGenerator
@@ -59,6 +61,79 @@ class GUI_EXPORT QgsProcessingContextGenerator
     virtual ~QgsProcessingContextGenerator() = default;
 };
 
+/**
+ * \ingroup gui
+ * \class QgsProcessingParameterWidgetContext
+ * Contains settings which reflect the context in which a Processing parameter 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.
+ *
+ * \since QGIS 3.4
+ */
+class GUI_EXPORT QgsProcessingParameterWidgetContext
+{
+  public:
+
+    /**
+     * Constructor for QgsProcessingParameterWidgetContext.
+     */
+    QgsProcessingParameterWidgetContext() = default;
+
+    /**
+     * Sets the map \a canvas associated with the widget. This allows the widget to retrieve the current
+     * map scale and other properties from the canvas.
+     * \see mapCanvas()
+     */
+    void setMapCanvas( QgsMapCanvas *canvas );
+
+    /**
+     * Returns the map canvas associated with the widget.
+     * \see setMapCanvas()
+     */
+    QgsMapCanvas *mapCanvas() const;
+
+    /**
+     * Returns the model which the parameter widget is associated with.
+     *
+     * \see setModel()
+     * \see modelChildAlgorithmId()
+     */
+    QgsProcessingModelAlgorithm *model() const;
+
+    /**
+     * Sets the \a model which the parameter widget is associated with.
+     *
+     * \see model()
+     * \see setModelChildAlgorithmId()
+     */
+    void setModel( QgsProcessingModelAlgorithm *model );
+
+    /**
+     * Returns the child algorithm ID within the model which the parameter widget is associated with.
+     *
+     * \see setModelChildAlgorithmId()
+     * \see model()
+     */
+    QString modelChildAlgorithmId() const;
+
+    /**
+     * Sets the child algorithm \a id within the model which the parameter widget is associated with.
+     *
+     * \see modelChildAlgorithmId()
+     * \see setModel()
+     */
+    void setModelChildAlgorithmId( const QString &id );
+
+  private:
+
+    QgsProcessingModelAlgorithm *mModel = nullptr;
+
+    QString mModelChildAlgorithmId;
+
+    QgsMapCanvas *mMapCanvas = nullptr;
+
+};
+
 /**
  * \class QgsAbstractProcessingParameterWidgetWrapper
  *
@@ -96,6 +171,26 @@ class GUI_EXPORT QgsAbstractProcessingParameterWidgetWrapper : public QObject
      */
     QgsProcessingGui::WidgetType type() const;
 
+    /**
+     * Sets the \a context in which the Processing parameter 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 );
+
+    /**
+     * Returns the context in which the Processing parameter 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.
+     *
+     * \see setWidgetContext()
+     */
+    const QgsProcessingParameterWidgetContext &widgetContext() const;
+
     /**
      * Creates and return a new wrapped widget which allows customization of the parameter's value.
      *
@@ -226,6 +321,7 @@ class GUI_EXPORT QgsAbstractProcessingParameterWidgetWrapper : public QObject
   protected:
 
     QgsProcessingContextGenerator *mProcessingContextGenerator = nullptr;
+    QgsProcessingParameterWidgetContext mWidgetContext;
 
   private slots: