Class: QgsMeshLayer¶

class qgis.core.QgsMeshLayer(path: str = '', baseName: str = '', providerLib: str = '', options: QgsMeshLayer.LayerOptions = QgsMeshLayer.LayerOptions())¶

Bases: qgis._core.QgsMapLayer

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 – The path or url of the parameter. Typically this encodes parameters used by the data provider as url query items.
baseName – The name used to represent the layer in the legend
providerLib – The name of the data provider, e.g., “mesh_memory”, “mdal”
options – general mesh layer options

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.

section mesh_providers Mesh data providers

subsection mesh_memory 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. Data can be populated by setMesh(const QString &vertices, const QString &faces), where vertices and faces is comma separated coordinates and connections for mesh. E.g. to create mesh with one quad and one triangle

QString 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"
  );
  QgsMeshLayer *scratchLayer = new QgsMeshLayer(uri, "My Scratch layer", "memory_mesh");

subsection mdal 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.

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

Note

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

New in version 3.2: Enums

Methods

`appendError`
`childEvent`
`clone`
`connectNotify`
`createMapRenderer`
`customEvent`
`dataProvider`	QgsMeshLayer cannot be copied.
`datasetValue`	Interpolates the value on the given point from given dataset.
`decodedSource`
`disconnectNotify`
`encodedSource`
`extent`
`formatTime`	Returns (date) time in hours formatted to human readable form
`hasDependencyCycle`
`isSignalConnected`
`providerType`	Returns the provider type for this layer
`readCommonStyle`
`readCustomProperties`
`readStyleManager`
`readSymbology`
`readXml`
`receivers`
`reload`
`rendererSettings`	Returns renderer settings
`sender`
`senderSignalIndex`
`setError`
`setExtent`
`setProviderType`
`setRendererSettings`	Sets new renderer settings
`setTimeSettings`	Sets time format settings
`setTransformContext`	Sets the coordinate transform context to `transformContext`.
`setValid`
`timeSettings`	Returns time format settings
`timerEvent`
`writeCommonStyle`
`writeCustomProperties`
`writeStyleManager`
`writeSymbology`
`writeXml`

Signals

`activeScalarDatasetChanged`	Emitted when active scalar dataset is changed
`activeVectorDatasetChanged`	Emitted when active vector dataset is changed
`timeSettingsChanged`	Emitted when time format is changed

Attributes

class LayerOptions(transformContext: QgsCoordinateTransformContext = QgsCoordinateTransformContext())¶

Bases: sip.wrapper

Constructor for LayerOptions with optional transformContext.

Note

transformContext argument was added in QGIS 3.8

QgsMeshLayer.LayerOptions(QgsMeshLayer.LayerOptions)

transformContext¶

activeScalarDatasetChanged¶: Emitted when active scalar dataset is changed

New in version 3.4: [signal]

activeVectorDatasetChanged¶: Emitted when active vector dataset is changed

New in version 3.4: [signal]

appendError()¶

childEvent()¶

clone(self) → QgsMeshLayer¶

connectNotify()¶

createMapRenderer(self, rendererContext: QgsRenderContext) → QgsMapLayerRenderer¶

customEvent()¶

dataProvider(self) → QgsMeshDataProvider¶: QgsMeshLayer cannot be copied.

datasetValue(self, index: QgsMeshDatasetIndex, point: QgsPointXY) → QgsMeshDatasetValue¶

Interpolates the value on the given point from given dataset.

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

Parameters

index – dataset index specifying group and dataset to extract value from
point – point to query in map coordinates

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

New in version 3.4.

decodedSource(self, source: str, provider: str, context: QgsReadWriteContext) → str¶

disconnectNotify()¶

encodedSource(self, source: str, context: QgsReadWriteContext) → str¶

extent(self) → QgsRectangle¶

formatTime(self, hours: float) → str¶

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

Parameters: hours – time in double in hours
Returns: formatted time string

New in version 3.8.

hasDependencyCycle()¶

isSignalConnected()¶

providerType(self) → str¶: Returns the provider type for this layer

readCommonStyle()¶

readCustomProperties()¶

readStyleManager()¶

readSymbology(self, node: QDomNode, errorMessage: str, context: QgsReadWriteContext, categories: Union[QgsMapLayer.StyleCategories, QgsMapLayer.StyleCategory] = QgsMapLayer.AllStyleCategories) → bool¶

readXml(self, layer_node: QDomNode, context: QgsReadWriteContext) → bool¶

receivers()¶

reload(self)¶

rendererSettings(self) → QgsMeshRendererSettings¶: Returns renderer settings

sender()¶

senderSignalIndex()¶

setError()¶

setExtent()¶

setProviderType()¶

setRendererSettings(self, settings: QgsMeshRendererSettings)¶: Sets new renderer settings

setTimeSettings(self, settings: QgsMeshTimeSettings)¶: Sets time format settings

New in version 3.8.

setTransformContext(self, transformContext: QgsCoordinateTransformContext)¶: Sets the coordinate transform context to transformContext.

New in version 3.8.

setValid()¶

timeSettings(self) → QgsMeshTimeSettings¶: Returns time format settings

New in version 3.8.

timeSettingsChanged¶: Emitted when time format is changed

New in version 3.8: [signal]

timerEvent()¶

writeCommonStyle()¶

writeCustomProperties()¶

writeStyleManager()¶

writeSymbology(self, node: QDomNode, doc: QDomDocument, errorMessage: str, context: QgsReadWriteContext, categories: Union[QgsMapLayer.StyleCategories, QgsMapLayer.StyleCategory] = QgsMapLayer.AllStyleCategories) → bool¶

writeXml(self, layer_node: QDomNode, doc: QDomDocument, context: QgsReadWriteContext) → bool¶