Class: QgsMeshLayer

Represents a mesh layer supporting display of data on structured or unstructured meshes.

The QgsMeshLayer is instantiated by specifying the name of a data provider, such as mdal, and url defining the specific data set to connect to. The vector layer constructor in turn instantiates a QgsMeshDataProvider subclass corresponding to the provider type, and passes it the url. The data provider connects to the data source.

The QgsMeshLayer provides a common interface to the different data types. It does not yet support editing transactions.

The main data providers supported by QGIS are listed below.

Mesh data providers

Memory data providerType (mesh_memory)

The memory data provider is used to construct in memory data, for example scratch data. There is no inherent persistent storage of the data. The data source uri is constructed where vertices and faces are comma separated coordinates and connections for the mesh. E.g. to create a mesh with one quad and one triangle

uri = "1.0, 2.0 \n" \
    "2.0, 2.0 \n" \
    "3.0, 2.0 \n" \
    "2.0, 3.0 \n" \
    "1.0, 3.0 \n" \
    "---" \
    "0, 1, 3, 4 \n" \
    "1, 2, 3 \n"

scratchLayer = QgsMeshLayer(uri, "My Scratch layer", "mesh_memory")

MDAL data provider (mdal)

Accesses data using the MDAL drivers (https://github.com/lutraconsulting/MDAL). The url is the MDAL connection string. QGIS must be built with MDAL support to allow this provider.

uri = "test/land.2dm"
scratchLayer = QgsMeshLayer(uri, "My Scratch Layer",  "mdal")

Note

The API is considered EXPERIMENTAL and can be changed without a notice

Added in version 3.2.

Class Hierarchy

Base classes

QgsMapLayer	Base class for all map layer types.
QObject
QgsAbstractProfileSource	Interface for classes which can generate elevation profiles.

Abstract Methods

setTransformContext

Sets the coordinate transform context to transformContext.

Methods

activeScalarDatasetAtTime	Returns dataset index from active scalar group depending on the time range.
activeScalarDatasetIndex	Returns current active scalar dataset index for current renderer context.
activeVectorDatasetAtTime	Returns dataset index from active vector group depending on the time range If the temporal properties is not active, return the static dataset
addDatasets	Adds datasets to the mesh from file with path.
areFacesActive	Returns whether the faces are active for particular dataset
closestElement	Returns the index of the snapped point on the mesh element closest to point intersecting with the searching area defined by point and searchRadius The position of the snapped point on the closest element is stored in projectedPoint
commitFrameEditing	Commits editing of the mesh frame, Rebuilds the triangular mesh and its spatial index with transform, Continue editing with the same mesh editor if continueEditing is True
contains	Returns whether the mesh contains at mesh elements of given type
dataset1dValue	Returns the value of 1D mesh dataset defined on edge that are in the search area defined by point ans searchRadius
dataset3dValue	Returns the 3d values of stacked 3d mesh defined by the given point
dataset3dValues	Returns N vector/scalar values from the face index from the dataset for 3d stacked meshes
datasetCount	Returns the dataset count in the dataset groups
datasetGroupCount	Returns the dataset groups count handle by the layer
datasetGroupMetadata	Returns the dataset groups metadata
datasetGroupTreeRootItem	Returns the root items of the dataset group tree item
datasetGroupsIndexes	Returns the list of indexes of dataset groups handled by the layer
datasetIndexAtRelativeTime	Returns dataset index from datasets group depending on the relative time from the layer reference time.
datasetIndexAtTime	Returns dataset index from datasets group depending on the time range.
datasetIndexInRelativeTimeInterval	Returns a list of dataset indexes from datasets group that are in a interval time from the layer reference time.
datasetMetadata	Returns the dataset metadata
datasetRelativeTime	Returns the relative time of the dataset from the reference time of its group
datasetRelativeTimeInMilliseconds	Returns the relative time (in milliseconds) of the dataset from the reference time of its group
datasetValue	Returns vector/scalar value associated with the index from the dataset To read multiple continuous values, use datasetValues()
datasetValues	Returns N vector/scalar values from the index from the dataset
datasetsPathUnique	Checks whether that datasets path is already added to this mesh layer.
enabledDatasetGroupsIndexes	Returns the list of indexes of enables dataset groups handled by the layer
extraDatasetGroupCount	Returns the extra dataset groups count handle by the layer
firstValidTimeStep	Returns the first valid time step of the dataset groups, invalid QgInterval if no time step is present
formatTime	Returns (date) time in hours formatted to human readable form
isFaceActive	Returns N vector/scalar values from the face index from the dataset for 3d stacked meshes
labeling	Access to labeling configuration.
labelsEnabled	Returns whether the layer contains labels which are enabled and should be drawn.
meshEdgeCount	Returns the edges count of the mesh frame
meshEditor	Returns a pointer to the mesh editor own by the mesh layer
meshFaceCount	Returns the faces count of the mesh frame
meshVertexCount	Returns the vertices count of the mesh frame
minimumMaximumActiveScalarDataset	Extracts minimum and maximum value for active scalar dataset on mesh faces.
reindex	Re-indexes the faces and vertices, and renumber the indexes if renumber is True.
removeDatasets	Removes datasets from the mesh with given name.
rendererSettings	Returns renderer settings
resetDatasetGroupTreeItem	Reset the dataset group tree item to default from provider
rollBackFrameEditing	Rolls Back editing of the mesh frame.
saveDataset	Saves datasets group on file with the specified driver
selectFacesByExpression	Returns a list of faces indexes that meet the condition defined by expression with the context expressionContext
selectVerticesByExpression	Returns a list of vertex indexes that meet the condition defined by expression with the context expressionContext
setDatasetGroupTreeRootItem	Sets the root items of the dataset group tree item.
setLabeling	Sets labeling configuration.
setLabelsEnabled	Sets whether labels should be enabled for the layer.
setReferenceTime	Sets the reference time of the layer
setRendererSettings	Sets new renderer settings
setTemporalMatchingMethod	Sets the method used to match the temporal dataset from a requested time, see activeVectorDatasetAtTime()
setTimeSettings	Sets time format settings
snapOnElement	Returns the position of the snapped point on the mesh element closest to point intersecting with the searching area defined by point and searchRadius
startFrameEditing	Starts editing of the mesh frame.
staticScalarDatasetIndex	Returns the static scalar dataset index that is rendered if the temporal properties is not active.
staticVectorDatasetIndex	Returns the static vector dataset index that is rendered if the temporal properties is not active.
stopFrameEditing	Stops editing of the mesh, re-indexes the faces and vertices, rebuilds the triangular mesh and its spatial index with transform, clean the undostack
timeSettings	Returns time format settings
updateTriangularMesh	Gets native mesh and updates (creates if it doesn't exist) the base triangular mesh

Virtual Methods

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

isModified

Returns whether the mesh frame has been modified since the last save

Signals

activeScalarDatasetGroupChanged	Emitted when active scalar group dataset is changed
activeVectorDatasetGroupChanged	Emitted when active vector group dataset is changed
reloaded	Emitted when the mesh layer is reloaded, see reload()
timeSettingsChanged	Emitted when time format is changed

class qgis.core.QgsMeshLayer

Bases: QgsMapLayer, QgsAbstractProfileSource

__init__(path: str | None = '', baseName: str | None = '', providerLib: str | None = '', options: QgsMeshLayer.LayerOptions = QgsMeshLayer.LayerOptions())

Constructor - creates a mesh layer

The QgsMeshLayer is constructed by instantiating a data provider. The provider interprets the supplied path (url) of the data source to connect to and access the data.

Parameters:

• path (Optional[str] = '') – The path or url of the parameter. Typically this encodes parameters used by the data provider as url query items.

• baseName (Optional[str] = '') – The name used to represent the layer in the legend

• providerLib (Optional[str] = '') – The name of the data provider, e.g., “mesh_memory”, “mdal”

• options (QgsMeshLayer.LayerOptions = QgsMeshLayer.LayerOptions()) – general mesh layer options

class LayerOptions

Bases: object

Setting options for loading mesh layers.

skipCrsValidation: bool

Controls whether the layer is allowed to have an invalid/unknown CRS.

If True, then no validation will be performed on the layer’s CRS and the layer layer’s crs() may be invalid() (i.e. the layer will have no georeferencing available and will be treated as having purely numerical coordinates).

If False (the default), the layer’s CRS will be validated using QgsCoordinateReferenceSystem.validate(), which may cause a blocking, user-facing dialog asking users to manually select the correct CRS for the layer.

Added in version 3.10.

activeScalarDatasetAtTime(self, timeRange: QgsDateTimeRange, group: int = -1) → QgsMeshDatasetIndex

Returns dataset index from active scalar group depending on the time range. If the temporal properties is not active, return the static dataset

Since QGIS 3.38, the group argument can be used to specify a fixed group to use. If this is not specified, then the active group from the layer’s renderer will be used.

Note

the returned dataset index depends on the matching method, see setTemporalMatchingMethod()

Added in version 3.14.

Parameters:

• timeRange (QgsDateTimeRange)

• group (int = -1)

Return type:

QgsMeshDatasetIndex

signal activeScalarDatasetGroupChanged(index: int)

Emitted when active scalar group dataset is changed

Added in version 3.14.

Parameters:

index (int)

activeScalarDatasetIndex(self, rendererContext: QgsRenderContext) → QgsMeshDatasetIndex

Returns current active scalar dataset index for current renderer context.

Added in version 3.42.

Parameters:

rendererContext (QgsRenderContext)

Return type:

QgsMeshDatasetIndex

activeVectorDatasetAtTime(self, timeRange: QgsDateTimeRange, group: int = -1) → QgsMeshDatasetIndex

Returns dataset index from active vector group depending on the time range If the temporal properties is not active, return the static dataset

Since QGIS 3.38, the group argument can be used to specify a fixed group to use. If this is not specified, then the active group from the layer’s renderer will be used.

Note

the returned dataset index depends on the matching method, see setTemporalMatchingMethod()

Added in version 3.14.

Parameters:

• timeRange (QgsDateTimeRange)

• group (int = -1)

Return type:

QgsMeshDatasetIndex

signal activeVectorDatasetGroupChanged(index: int)

Emitted when active vector group dataset is changed

Added in version 3.14.

Parameters:

index (int)

addDatasets(self, path: str | None, defaultReferenceTime: QDateTime | datetime.datetime = QDateTime()) → bool

Adds datasets to the mesh from file with path. Use the the time defaultReferenceTime as reference time is not provided in the file

Parameters:

• path (Optional[str]) – the path to the datasets file

• defaultReferenceTime (Union[QDateTime, datetime.datetime] = QDateTime()) – reference time used if not provided in the file

Return type:

bool

Returns:

whether the dataset is added

Added in version 3.14.

addDatasets(self, datasetGroup: QgsMeshDatasetGroup | None) → bool

Adds extra datasets to the mesh. Take ownership.

Parameters:

datasetGroup (Optional[QgsMeshDatasetGroup]) – the extra dataset group

Return type:

bool

Returns:

whether the dataset is effectively added

Added in version 3.16.

areFacesActive(self, index: QgsMeshDatasetIndex, faceIndex: int, count: int) → QgsMeshDataBlock

Returns whether the faces are active for particular dataset

Parameters:

• index (QgsMeshDatasetIndex) – index of the dataset

• faceIndex (int) – index of the face

• count (int) – number of values to return

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes are different from the data provider indexes.

Added in version 3.16.

Return type:

QgsMeshDataBlock

closestElement(self, elementType: QgsMesh.ElementType, point: QgsPointXY, searchRadius: float)

Returns the index of the snapped point on the mesh element closest to point intersecting with the searching area defined by point and searchRadius The position of the snapped point on the closest element is stored in projectedPoint

For vertex, the snapped position is the vertex position For edge, the snapped position is the projected point on the edge, extremity of edge if outside the edge For face, the snapped position is the centroid of the face The snapped position is in map coordinates.

Note

It uses previously cached and indexed triangular mesh and so if the layer has not been rendered previously (e.g. when used in a script) it returns empty QgsPointXY

See also

updateTriangularMesh()

Note

This is similar to the snapOnElement() method, except it also returns the index of the snapped point

See also

snapOnElement()

Parameters:

• elementType (QgsMesh.ElementType) – the type of element to snap

• point (QgsPointXY) – the center of the search area in map coordinates

• searchRadius (float) -> (int) – the radius of the search area in map units

Returns:

• index of the snapped point on the closest element, -1 if no element of type elementType

• projectedPoint: the position of the snapped point on the closest element, empty QgsPointXY if no element of type elementType

Added in version 3.44.

commitFrameEditing(self, transform: QgsCoordinateTransform, continueEditing: bool = True) → bool

Commits editing of the mesh frame, Rebuilds the triangular mesh and its spatial index with transform, Continue editing with the same mesh editor if continueEditing is True

Return type:

bool

Returns:

True if the commit succeeds

Added in version 3.22.

Parameters:

• transform (QgsCoordinateTransform)

• continueEditing (bool = True)

contains(self, type: QgsMesh.ElementType) → bool

Returns whether the mesh contains at mesh elements of given type

Added in version 3.22.

Parameters:

type (QgsMesh.ElementType)

Return type:

bool

dataset1dValue(self, index: QgsMeshDatasetIndex, point: QgsPointXY, searchRadius: float) → QgsMeshDatasetValue

Returns the value of 1D mesh dataset defined on edge that are in the search area defined by point ans searchRadius

Note

It uses previously cached and indexed triangular mesh and so if the layer has not been rendered previously (e.g. when used in a script) it returns NaN value

See also

updateTriangularMesh()

Parameters:

• index (QgsMeshDatasetIndex) – dataset index specifying group and dataset to extract value from

• point (QgsPointXY) – the center point of the search area

• searchRadius (float) – the radius of the searc area in map unit

Return type:

QgsMeshDatasetValue

Returns:

interpolated value at the projected point. Returns NaN values for values outside the mesh layer and in case triangular mesh was not previously used for rendering

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes are different from the data provider indexes.

Added in version 3.14.

dataset3dValue(self, index: QgsMeshDatasetIndex, point: QgsPointXY) → QgsMesh3DDataBlock

Returns the 3d values of stacked 3d mesh defined by the given point

Note

It uses previously cached and indexed triangular mesh and so if the layer has not been rendered previously (e.g. when used in a script) it returns NaN value

See also

updateTriangularMesh()

Parameters:

• index (QgsMeshDatasetIndex) – dataset index specifying group and dataset to extract value from

• point (QgsPointXY) – point to query in map coordinates

Return type:

QgsMesh3DDataBlock

Returns:

all 3d stacked values that belong to face defined by given point. Returns invalid block for point outside the mesh layer or in case triangular mesh was not previously used for rendering or for datasets that do not have type DataOnVolumes

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes are different from the data provider indexes.

Added in version 3.12.

dataset3dValues(self, index: QgsMeshDatasetIndex, faceIndex: int, count: int) → QgsMesh3DDataBlock

Returns N vector/scalar values from the face index from the dataset for 3d stacked meshes

See QgsMeshDatasetMetadata.isVector() to check if the returned value is vector or scalar

returns invalid block for DataOnFaces and DataOnVertices.

Parameters:

• index (QgsMeshDatasetIndex) – index of the dataset

• faceIndex (int) – index of the face

• count (int) – number of values to return

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes can be different from the data provider indexes.

Added in version 3.16.

Return type:

QgsMesh3DDataBlock

datasetCount(self, index: QgsMeshDatasetIndex) → int

Returns the dataset count in the dataset groups

Parameters:

index (QgsMeshDatasetIndex) – index of the dataset in the group

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes can be different from the data provider indexes.

Added in version 3.16.

Return type:

int

datasetGroupCount(self) → int

Returns the dataset groups count handle by the layer

Added in version 3.16.

Return type:

int

datasetGroupMetadata(self, index: QgsMeshDatasetIndex) → QgsMeshDatasetGroupMetadata

Returns the dataset groups metadata

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes can be different from the data provider indexes.

Added in version 3.16.

Parameters:

index (QgsMeshDatasetIndex)

Return type:

QgsMeshDatasetGroupMetadata

datasetGroupTreeRootItem(self) → QgsMeshDatasetGroupTreeItem | None

Returns the root items of the dataset group tree item

Return type:

Optional[QgsMeshDatasetGroupTreeItem]

Returns:

the root item

Added in version 3.14.

datasetGroupsIndexes(self) → List[int]

Returns the list of indexes of dataset groups handled by the layer

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes can be different from the data provider indexes.

Added in version 3.16.

Return type:

List[int]

datasetIndexAtRelativeTime(self, relativeTime: QgsInterval, datasetGroupIndex: int) → QgsMeshDatasetIndex

Returns dataset index from datasets group depending on the relative time from the layer reference time. Dataset index is valid even the temporal properties is inactive. This method is used for calculation on mesh layer.

Parameters:

• relativeTime (QgsInterval) – the relative from the mesh layer reference time

• datasetGroupIndex (int) – the index of the dataset group

Return type:

QgsMeshDatasetIndex

Returns:

dataset index

Note

the returned dataset index depends on the matching method, see setTemporalMatchingMethod()

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes are different from the data provider indexes.

Added in version 3.16.

datasetIndexAtTime(self, timeRange: QgsDateTimeRange, datasetGroupIndex: int) → QgsMeshDatasetIndex

Returns dataset index from datasets group depending on the time range. If the temporal properties is not active, returns invalid dataset index. This method is used for rendering mesh layer.

Parameters:

• timeRange (QgsDateTimeRange) – the time range

• datasetGroupIndex (int) – the index of the dataset group

Return type:

QgsMeshDatasetIndex

Returns:

dataset index

Note

the returned dataset index depends on the matching method, see setTemporalMatchingMethod()

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes are different from the data provider indexes.

Added in version 3.14.

datasetIndexInRelativeTimeInterval(self, startRelativeTime: QgsInterval, endRelativeTime: QgsInterval, datasetGroupIndex: int) → List[QgsMeshDatasetIndex]

Returns a list of dataset indexes from datasets group that are in a interval time from the layer reference time. Dataset index is valid even the temporal properties is inactive. This method is used for calculation on mesh layer.

Parameters:

• startRelativeTime (QgsInterval) – the start time of the relative interval from the reference time.

• endRelativeTime (QgsInterval) – the end time of the relative interval from the reference time.

• datasetGroupIndex (int) – the index of the dataset group

Return type:

List[QgsMeshDatasetIndex]

Returns:

dataset index

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes are different from the data provider indexes.

Added in version 3.22.

datasetMetadata(self, index: QgsMeshDatasetIndex) → QgsMeshDatasetMetadata

Returns the dataset metadata

Parameters:

index (QgsMeshDatasetIndex) – index of the dataset

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes can be different from the data provider indexes.

Added in version 3.16.

Return type:

QgsMeshDatasetMetadata

datasetRelativeTime(self, index: QgsMeshDatasetIndex) → QgsInterval

Returns the relative time of the dataset from the reference time of its group

Added in version 3.16.

Parameters:

index (QgsMeshDatasetIndex)

Return type:

QgsInterval

datasetRelativeTimeInMilliseconds(self, index: QgsMeshDatasetIndex) → int

Returns the relative time (in milliseconds) of the dataset from the reference time of its group

Added in version 3.16.

Parameters:

index (QgsMeshDatasetIndex)

Return type:

int

datasetValue(self, index: QgsMeshDatasetIndex, valueIndex: int) → QgsMeshDatasetValue

Returns vector/scalar value associated with the index from the dataset To read multiple continuous values, use datasetValues()

See QgsMeshDatasetMetadata.isVector() or QgsMeshDataBlock.type() to check if the returned value is vector or scalar

Returns invalid value for DataOnVolumes

Parameters:

• index (QgsMeshDatasetIndex) – index of the dataset

• valueIndex (int) – index of the value

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes can be different from the data provider indexes.

Added in version 3.16.

Return type:

QgsMeshDatasetValue

datasetValue(self, index: QgsMeshDatasetIndex, point: QgsPointXY, searchRadius: float = 0) → QgsMeshDatasetValue

Interpolates the value on the given point from given dataset. For 3D datasets, it uses dataset3dValue(), n For 1D datasets, it uses dataset1dValue() with searchRadius

Note

It uses previously cached and indexed triangular mesh and so if the layer has not been rendered previously (e.g. when used in a script) it returns NaN value

See also

updateTriangularMesh()

Parameters:

• index (QgsMeshDatasetIndex) – dataset index specifying group and dataset to extract value from

• point (QgsPointXY) – point to query in map coordinates

• searchRadius (float = 0) – the radius of the search area in map unit

Return type:

QgsMeshDatasetValue

Returns:

interpolated value at the point. Returns NaN values for values outside the mesh layer, nodata values and in case triangular mesh was not previously used for rendering

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes are different from the data provider indexes.

Added in version 3.4.

datasetValues(self, index: QgsMeshDatasetIndex, valueIndex: int, count: int) → QgsMeshDataBlock

Returns N vector/scalar values from the index from the dataset

See QgsMeshDatasetMetadata.isVector() or QgsMeshDataBlock.type() to check if the returned value is vector or scalar

Returns invalid block for DataOnVolumes. Use QgsMeshLayerUtils.datasetValues() if you need block for any type of data type

Parameters:

• index (QgsMeshDatasetIndex) – index of the dataset

• valueIndex (int) – index of the value

• count (int) – number of values to return

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes can be different from the data provider indexes.

Added in version 3.16.

Return type:

QgsMeshDataBlock

datasetsPathUnique(self, path: str | None) → bool

Checks whether that datasets path is already added to this mesh layer. Return True if the dataset path is not already added.

Parameters:

path (Optional[str]) – the path to the datasets file

Return type:

bool

Returns:

whether the datasets path is unique

Added in version 3.42.

enabledDatasetGroupsIndexes(self) → List[int]

Returns the list of indexes of enables dataset groups handled by the layer

Note

indexes are used to distinguish all the dataset groups handled by the layer (from dataprovider, extra dataset group,…) In the layer scope, those indexes can be different from the data provider indexes.

Added in version 3.16.3.

Return type:

List[int]

extraDatasetGroupCount(self) → int

Returns the extra dataset groups count handle by the layer

Added in version 3.16.

Return type:

int

firstValidTimeStep(self) → QgsInterval

Returns the first valid time step of the dataset groups, invalid QgInterval if no time step is present

Added in version 3.14.

Return type:

QgsInterval

formatTime(self, hours: float) → str

Returns (date) time in hours formatted to human readable form

Parameters:

hours (float) – time in double in hours

Return type:

str

Returns:

formatted time string

Added in version 3.8.

isFaceActive(self, index: QgsMeshDatasetIndex, faceIndex: int) → bool

Returns N vector/scalar values from the face index from the dataset for 3d stacked meshes

See QgsMeshDatasetMetadata.isVector() to check if the returned value is vector or scalar

returns invalid block for DataOnFaces and DataOnVertices.

Parameters:

• index (QgsMeshDatasetIndex)

• faceIndex (int)

Return type:

bool

virtual isModified(self) → bool

Returns whether the mesh frame has been modified since the last save

Added in version 3.22.

Return type:

bool

labeling(self) → QgsAbstractMeshLayerLabeling | None

Access to labeling configuration. May be None if labeling is not used.

Note

Labels will only be rendered if labelsEnabled() returns True.

See also

labelsEnabled()

Added in version 3.36.

Return type:

Optional[QgsAbstractMeshLayerLabeling]

labelsEnabled(self) → bool

Returns whether the layer contains labels which are enabled and should be drawn.

Return type:

bool

Returns:

True if layer contains enabled labels

See also

setLabelsEnabled()

See also

labeling()

Added in version 3.36.

meshEdgeCount(self) → int

Returns the edges count of the mesh frame

Added in version 3.22.

Return type:

int

meshEditor(self) → QgsMeshEditor | None

Returns a pointer to the mesh editor own by the mesh layer

Added in version 3.22.

Return type:

Optional[QgsMeshEditor]

meshFaceCount(self) → int

Returns the faces count of the mesh frame

Note

during mesh editing, some faces can be void and are not included in this returned value

Added in version 3.22.

Return type:

int

meshVertexCount(self) → int

Returns the vertices count of the mesh frame

Note

during mesh editing, some vertices can be void and are not included in this returned value

Added in version 3.22.

Return type:

int

minimumMaximumActiveScalarDataset(self, extent: QgsRectangle, datasetIndex: QgsMeshDatasetIndex)

Extracts minimum and maximum value for active scalar dataset on mesh faces.

Parameters:

• extent (QgsRectangle) – extent in which intersecting faces are searched for

• datasetIndex (QgsMeshDatasetIndex) -> (bool) – index for which dataset the values should be extracted

Returns:

• True if values were extracted

• min: minimal value

• max: maximal value

Added in version 3.42.

reindex(self, transform: QgsCoordinateTransform, renumber: bool) → bool

Re-indexes the faces and vertices, and renumber the indexes if renumber is True. rebuilds the triangular mesh and its spatial index with transform, clean the undostack

Returns False if the operation fails

Added in version 3.22.

Parameters:

• transform (QgsCoordinateTransform)

• renumber (bool)

Return type:

bool

signal reloaded

Emitted when the mesh layer is reloaded, see reload()

Added in version 3.28.

removeDatasets(self, name: str | None) → bool

Removes datasets from the mesh with given name.

Parameters:

name (Optional[str]) – name of dataset group to remove

Return type:

bool

Returns:

whether the dataset is removed

Added in version 3.42.

rendererSettings(self) → QgsMeshRendererSettings

Returns renderer settings

Return type:

QgsMeshRendererSettings

resetDatasetGroupTreeItem(self)

Reset the dataset group tree item to default from provider

Added in version 3.14.

rollBackFrameEditing(self, transform: QgsCoordinateTransform, continueEditing: bool = True) → bool

Rolls Back editing of the mesh frame. Reload mesh from file, rebuilds the triangular mesh and its spatial index with transform, Continue editing with the same mesh editor if continueEditing is True

Return type:

bool

Returns:

True if the rollback succeeds

Added in version 3.22.

Parameters:

• transform (QgsCoordinateTransform)

• continueEditing (bool = True)

saveDataset(self, path: str | None, datasetGroupIndex: int, driver: str | None) → bool

Saves datasets group on file with the specified driver

Parameters:

• path (Optional[str]) – the path of the file

• datasetGroupIndex (int) – the index of the dataset group

• driver (Optional[str]) – the driver to used for saving

Return type:

bool

Returns:

false if succeeds

Added in version 3.16.

selectFacesByExpression(self, expression: QgsExpression) → List[int]

Returns a list of faces indexes that meet the condition defined by expression with the context expressionContext

To express the relation with a face, the expression can be defined with function returning value linked to the current face, like “ $face_area “

Added in version 3.22.

Parameters:

expression (QgsExpression)

Return type:

List[int]

selectVerticesByExpression(self, expression: QgsExpression) → List[int]

Returns a list of vertex indexes that meet the condition defined by expression with the context expressionContext

To express the relation with a vertex, the expression can be defined with function returning value linked to the current vertex, like ” $vertex_z “, “$vertex_as_point”

Added in version 3.22.

Parameters:

expression (QgsExpression)

Return type:

List[int]

setDatasetGroupTreeRootItem(self, rootItem: QgsMeshDatasetGroupTreeItem | None)

Sets the root items of the dataset group tree item. Changes active dataset groups if those one are not enabled anymore :

• new active scalar dataset group is the first root item enabled child

• new active vector dataset group is none

Doesn’t take ownership of the pointed item, the root item is cloned.

Parameters:

rootItem (Optional[QgsMeshDatasetGroupTreeItem]) – the new root item

Added in version 3.14.

setLabeling(self, labeling: QgsAbstractMeshLayerLabeling | None)

Sets labeling configuration. Takes ownership of the object.

Added in version 3.36.

Parameters:

labeling (Optional[QgsAbstractMeshLayerLabeling])

setLabelsEnabled(self, enabled: bool)

Sets whether labels should be enabled for the layer.

Note

Labels will only be rendered if labelsEnabled() is True and a labeling object is returned by labeling().

See also

labelsEnabled()

See also

labeling()

Added in version 3.36.

Parameters:

enabled (bool)

setReferenceTime(self, referenceTime: QDateTime | datetime.datetime)

Sets the reference time of the layer

Parameters:

referenceTime (Union[QDateTime, datetime.datetime]) – the reference time

Added in version 3.14.

setRendererSettings(self, settings: QgsMeshRendererSettings, repaint: bool = True)

Sets new renderer settings

Parameters:

• settings (QgsMeshRendererSettings)

• repaint (bool = True) – should the update of renderer settings trigger repaint and emit rendererChanged signal

setTemporalMatchingMethod(self, matchingMethod: QgsMeshDataProviderTemporalCapabilities.MatchingTemporalDatasetMethod)

Sets the method used to match the temporal dataset from a requested time, see activeVectorDatasetAtTime()

Parameters:

matchingMethod (QgsMeshDataProviderTemporalCapabilities.MatchingTemporalDatasetMethod) – the matching method

Added in version 3.14.

setTimeSettings(self, settings: QgsMeshTimeSettings)

Sets time format settings

Added in version 3.8.

Parameters:

settings (QgsMeshTimeSettings)

abstract setTransformContext(self, transformContext: QgsCoordinateTransformContext)

Sets the coordinate transform context to transformContext.

Added in version 3.8.

Parameters:

transformContext (QgsCoordinateTransformContext)

snapOnElement(self, elementType: QgsMesh.ElementType, point: QgsPointXY, searchRadius: float) → QgsPointXY

Returns the position of the snapped point on the mesh element closest to point intersecting with the searching area defined by point and searchRadius

For vertex, the snapped position is the vertex position For edge, the snapped position is the projected point on the edge, extremity of edge if outside the edge For face, the snapped position is the centroid of the face The returned position is in map coordinates.

Note

It uses previously cached and indexed triangular mesh and so if the layer has not been rendered previously (e.g. when used in a script) it returns empty QgsPointXY

See also

updateTriangularMesh()

Parameters:

• elementType (QgsMesh.ElementType) – the type of element to snap

• point (QgsPointXY) – the center of the search area in map coordinates

• searchRadius (float) – the radius of the search area in map units

Return type:

QgsPointXY

Returns:

the position of the snapped point on the closest element, empty QgsPointXY if no element of type elementType

Added in version 3.14.

startFrameEditing(self, transform: QgsCoordinateTransform) → bool

Starts editing of the mesh frame. Coordinate transform used to initialize the triangular mesh if needed. This operation will disconnect the mesh layer from the data provider and removes all existing dataset group

Added in version 3.22.

Deprecated since version 3.28: Use the version with QgsMeshEditingError instead.

Parameters:

transform (QgsCoordinateTransform)

Return type:

bool

startFrameEditing(self, transform: QgsCoordinateTransform, fixErrors: bool)

Starts editing of the mesh frame. Coordinate transform used to initialize the triangular mesh if needed. This operation will disconnect the mesh layer from the data provider and removes all existing dataset group. Returns False if starting fails and the error that is the reason (No error, if the mesh is not editable or already in edit mode).

If fixErrors is set to True, errors will be attempted to be fixed. In that case returns False if there is an error that could not be fixed and the remaining error.

Added in version 3.28.

Parameters:

• transform (QgsCoordinateTransform)

• fixErrors (bool) -> (bool)

staticScalarDatasetIndex(self, group: int = -1) → QgsMeshDatasetIndex

Returns the static scalar dataset index that is rendered if the temporal properties is not active.

Since QGIS 3.38, the group argument can be used to specify a fixed group to use. If this is not specified, then the active group from the layer’s renderer will be used.

Added in version 3.14.

Parameters:

group (int = -1)

Return type:

QgsMeshDatasetIndex

staticVectorDatasetIndex(self, group: int = -1) → QgsMeshDatasetIndex

Returns the static vector dataset index that is rendered if the temporal properties is not active.

Since QGIS 3.38, the group argument can be used to specify a fixed group to use. If this is not specified, then the active group from the layer’s renderer will be used.

Added in version 3.14.

Parameters:

group (int = -1)

Return type:

QgsMeshDatasetIndex

stopFrameEditing(self, transform: QgsCoordinateTransform)

Stops editing of the mesh, re-indexes the faces and vertices, rebuilds the triangular mesh and its spatial index with transform, clean the undostack

Added in version 3.22.

Parameters:

transform (QgsCoordinateTransform)

timeSettings(self) → QgsMeshTimeSettings

Returns time format settings

Added in version 3.8.

Return type:

QgsMeshTimeSettings

signal timeSettingsChanged

Emitted when time format is changed

Added in version 3.8.

updateTriangularMesh(self, transform: QgsCoordinateTransform = QgsCoordinateTransform())

Gets native mesh and updates (creates if it doesn’t exist) the base triangular mesh

Parameters:

transform (QgsCoordinateTransform = QgsCoordinateTransform()) – Transformation from layer CRS to destination (e.g. map) CRS. With invalid transform, it keeps the native mesh CRS

Added in version 3.14.