Class: QgsModelGraphicsScene

QGraphicsScene subclass representing the model designer.

Warning

Not stable API

Added in version 3.14.

Class Hierarchy

Base classes

QGraphicsScene
QObject

Methods

childAlgorithmItem	Returns the graphic item corresponding to the specified child algorithm
componentItemAt	Returns the topmost component item at a specified position.
createGroupBoxGraphicItem	Creates a new graphic item for a model group box.
createItems	Populates the scene by creating items representing the specified model.
deselectAll	Clears any selected items in the scene.
flags	Returns the current combination of flags set for the scene.
groupBoxItem	Returns the graphic item corresponding to the specified group box uuid.
messageBar	Returns the message bar associated with the scene.
model
parameterItem	Returns the QgsModelComponentGraphicItem corresponding to the specified child algorithm
requestRebuildRequired	Requests a complete rebuild of a model by emitting the according signal
selectAll	Selects all the components in the scene.
selectedComponentItems	Returns list of selected component items.
setFlag	Enables or disables a particular flag for the scene.
setFlags	Sets the combination of flags controlling how the scene is rendered and behaves.
setLastRunResult	Sets the result of the last run of the model through the designer window.
setMessageBar	Sets the message bar associated with the scene.
setModel
setSelectedItem	Clears any selected items and sets item as the current selection.
showWarning	Shows a warning message, allowing users to click a button to see the full details (longMessage).
updateBounds	Updates the scene rect based on the bounds of the model.

Virtual Methods

In PyQGIS, only methods marked as virtual can be safely overridden in a Python subclass of QgsModelGraphicsScene. See the FAQ for more details.

createChildAlgGraphicItem	Creates a new graphic item for a model child algorithm.
createCommentGraphicItem	Creates a new graphic item for a model comment.
createOutputGraphicItem	Creates a new graphic item for a model output.
createParameterGraphicItem	Creates a new graphic item for a model parameter.

Signals

componentAboutToChange	Emitted whenever a component of the model is about to be changed.
componentChanged	Emitted whenever a component of the model is changed.
rebuildRequired	Emitted when a change in the model requires a full rebuild of the scene.
runFromChild	Emitted when the user opts to run the part of the model starting from the specified child algorithm.
runSelected	Emitted when the user opts to run selected steps from the model.
selectedItemChanged	Emitted whenever the selected item changes.
showChildAlgorithmLog	Emitted when the user opts to view the previous log from the child algorithm with matching ID.
showChildAlgorithmOutputs	Emitted when the user opts to view previous results from the child algorithm with matching ID.

Attributes

ArrowLink
FlagHideComments
FlagHideControls
GroupBox
ModelComponent
MouseHandles
RubberBand
ZSnapIndicator

class qgis.gui.QgsModelGraphicsScene

Bases: QGraphicsScene

__init__(parent: QObject | None = None)

Constructor for QgsModelGraphicsScene with the specified parent object.

Parameters:

parent (Optional[QObject] = None)

ArrowLink = 1

class Flag

Bases: int

FlagHideComments = 4

FlagHideControls = 2

class Flags

class Flags(f: QgsModelGraphicsScene.Flags | QgsModelGraphicsScene.Flag)

class Flags(a0: QgsModelGraphicsScene.Flags)

Bases: object

GroupBox = 0

ModelComponent = 2

MouseHandles = 99

RubberBand = 100

ZSnapIndicator = 101

class ZValues

Bases: int

childAlgorithmItem(self, childId: str | None) → QgsModelChildAlgorithmGraphicItem | None

Returns the graphic item corresponding to the specified child algorithm

Added in version 3.44.

Parameters:

childId (Optional[str])

Return type:

Optional[QgsModelChildAlgorithmGraphicItem]

signal componentAboutToChange(text: str, id: int = 0)

Emitted whenever a component of the model is about to be changed.

The text argument gives the translated text describing the change about to occur, and the optional id can be used to group the associated undo commands.

Parameters:

• text (str)

• id (int = 0)

signal componentChanged

Emitted whenever a component of the model is changed.

componentItemAt(self, position: QPointF | QPoint) → QgsModelComponentGraphicItem | None

Returns the topmost component item at a specified position.

Parameters:

position (Union[QPointF, QPoint])

Return type:

Optional[QgsModelComponentGraphicItem]

virtual createChildAlgGraphicItem(self, model: QgsProcessingModelAlgorithm | None, child: QgsProcessingModelChildAlgorithm | None) → QgsModelChildAlgorithmGraphicItem | None

Creates a new graphic item for a model child algorithm.

Parameters:

• model (Optional[QgsProcessingModelAlgorithm])

• child (Optional[QgsProcessingModelChildAlgorithm])

Return type:

Optional[QgsModelChildAlgorithmGraphicItem]

virtual createCommentGraphicItem(self, model: QgsProcessingModelAlgorithm | None, comment: QgsProcessingModelComment | None, parentItem: QgsModelComponentGraphicItem | None) → QgsModelComponentGraphicItem | None

Creates a new graphic item for a model comment.

Parameters:

• model (Optional[QgsProcessingModelAlgorithm])

• comment (Optional[QgsProcessingModelComment])

• parentItem (Optional[QgsModelComponentGraphicItem])

Return type:

Optional[QgsModelComponentGraphicItem]

createGroupBoxGraphicItem(self, model: QgsProcessingModelAlgorithm | None, box: QgsProcessingModelGroupBox | None) → QgsModelComponentGraphicItem | None

Creates a new graphic item for a model group box.

Parameters:

• model (Optional[QgsProcessingModelAlgorithm])

• box (Optional[QgsProcessingModelGroupBox])

Return type:

Optional[QgsModelComponentGraphicItem]

createItems(self, model: QgsProcessingModelAlgorithm | None, context: QgsProcessingContext)

Populates the scene by creating items representing the specified model.

Parameters:

• model (Optional[QgsProcessingModelAlgorithm])

• context (QgsProcessingContext)

virtual createOutputGraphicItem(self, model: QgsProcessingModelAlgorithm | None, output: QgsProcessingModelOutput | None) → QgsModelComponentGraphicItem | None

Creates a new graphic item for a model output.

Parameters:

• model (Optional[QgsProcessingModelAlgorithm])

• output (Optional[QgsProcessingModelOutput])

Return type:

Optional[QgsModelComponentGraphicItem]

virtual createParameterGraphicItem(self, model: QgsProcessingModelAlgorithm | None, param: QgsProcessingModelParameter | None) → QgsModelComponentGraphicItem | None

Creates a new graphic item for a model parameter.

Parameters:

• model (Optional[QgsProcessingModelAlgorithm])

• param (Optional[QgsProcessingModelParameter])

Return type:

Optional[QgsModelComponentGraphicItem]

deselectAll(self)

Clears any selected items in the scene.

Call this method rather than QGraphicsScene.clearSelection, as the latter does not correctly emit signals to allow the scene’s model to update.

flags(self) → QgsModelGraphicsScene.Flags

Returns the current combination of flags set for the scene.

See also

setFlags()

See also

setFlag()

Return type:

QgsModelGraphicsScene.Flags

groupBoxItem(self, uuid: str | None) → QgsModelComponentGraphicItem | None

Returns the graphic item corresponding to the specified group box uuid.

Parameters:

uuid (Optional[str])

Return type:

Optional[QgsModelComponentGraphicItem]

messageBar(self) → QgsMessageBar | None

Returns the message bar associated with the scene.

See also

setMessageBar()

Return type:

Optional[QgsMessageBar]

model(self) → QgsProcessingModelAlgorithm | None

Return type:

Optional[QgsProcessingModelAlgorithm]

parameterItem(self, name: str | None) → QgsModelComponentGraphicItem | None

Returns the QgsModelComponentGraphicItem corresponding to the specified child algorithm

Added in version 3.44.

Parameters:

name (Optional[str])

Return type:

Optional[QgsModelComponentGraphicItem]

signal rebuildRequired

Emitted when a change in the model requires a full rebuild of the scene.

requestRebuildRequired(self)

Requests a complete rebuild of a model by emitting the according signal

Added in version 3.44.

signal runFromChild(childId: str)

Emitted when the user opts to run the part of the model starting from the specified child algorithm.

Added in version 3.38.

Parameters:

childId (str)

signal runSelected

Emitted when the user opts to run selected steps from the model.

Added in version 3.38.

selectAll(self)

Selects all the components in the scene.

selectedComponentItems(self) → List[QgsModelComponentGraphicItem]

Returns list of selected component items.

Return type:

List[QgsModelComponentGraphicItem]

signal selectedItemChanged(selected: QgsModelComponentGraphicItem)

Emitted whenever the selected item changes. If None, no item is selected.

Parameters:

selected (QgsModelComponentGraphicItem)

setFlag(self, flag: QgsModelGraphicsScene.Flag, on: bool = True)

Enables or disables a particular flag for the scene. Other existing flags are not affected.

See also

setFlags()

See also

flags()

Parameters:

• flag (QgsModelGraphicsScene.Flag)

• on (bool = True)

setFlags(self, flags: QgsModelGraphicsScene.Flags | QgsModelGraphicsScene.Flag)

Sets the combination of flags controlling how the scene is rendered and behaves.

See also

setFlag()

See also

flags()

Parameters:

flags (Union[QgsModelGraphicsScene.Flags, QgsModelGraphicsScene.Flag])

setLastRunResult(self, result: QgsProcessingModelResult)

Sets the result of the last run of the model through the designer window.

Parameters:

result (QgsProcessingModelResult)

setMessageBar(self, bar: QgsMessageBar | None)

Sets the message bar associated with the scene.

See also

messageBar()

Parameters:

bar (Optional[QgsMessageBar])

setModel(self, model: QgsProcessingModelAlgorithm | None)

Parameters:

model (Optional[QgsProcessingModelAlgorithm])

setSelectedItem(self, item: QgsModelComponentGraphicItem | None)

Clears any selected items and sets item as the current selection.

Parameters:

item (Optional[QgsModelComponentGraphicItem])

signal showChildAlgorithmLog(childId: str)

Emitted when the user opts to view the previous log from the child algorithm with matching ID.

Added in version 3.38.

Parameters:

childId (str)

signal showChildAlgorithmOutputs(childId: str)

Emitted when the user opts to view previous results from the child algorithm with matching ID.

Added in version 3.38.

Parameters:

childId (str)

showWarning(self, shortMessage: str | None, title: str | None, longMessage: str | None, level: Qgis.MessageLevel = Qgis.MessageLevel.Warning)

Shows a warning message, allowing users to click a button to see the full details (longMessage).

Parameters:

• shortMessage (Optional[str])

• title (Optional[str])

• longMessage (Optional[str])

• level (Qgis.MessageLevel = Qgis.MessageLevel.Warning)

updateBounds(self)

Updates the scene rect based on the bounds of the model.

The bounding rectangle of the model is calculated off all components of the model, with an additional margin arounds items.

Added in version 4.0.