QgsInterpolator class
Interface class for interpolations.
Contents
Interpolators take the vertices of a vector layer as base data. The z-Value can be an attribute or the z-coordinates in case of 3D types.
Derived classes
- class QgsIDWInterpolator
- Inverse distance weight interpolator.
- class QgsTinInterpolator
- Interpolation in a triangular irregular network.
Public types
- struct LayerData
- A source together with the information about interpolation attribute / z-coordinate interpolation and the type (point, structure line, breakline)
- enum Result { Success = 0, Canceled, InvalidSource, FeatureGeometryError }
- Result of an interpolation operation.
- enum SourceType { SourcePoints, SourceStructureLines, SourceBreakLines }
- Describes the type of input data.
- enum ValueSource { ValueAttribute, ValueZ, ValueM }
- Source for interpolated values from features.
Public functions
- auto interpolatePoint(double x, double y, double& result, QgsFeedback* feedback = nullptr) -> int pure virtual
- Calculates interpolation value for map coordinates x, y.
- auto layerData() const -> QList<LayerData>
Protected functions
- auto cacheBaseData(QgsFeedback* feedback = nullptr) -> Result
- Caches the vertex and value data from the provider.
Protected variables
- QVector<QgsInterpolatorVertexData> mCachedBaseData
- Cached vertex data for input sources.
- bool mDataIsCached
- Flag that tells if the cache already has been filled.
- QList<LayerData> mLayerData
- Information about the input vector layers and the attributes (or z-values) that are used for interpolation.
Enum documentation
enum QgsInterpolator::
Result of an interpolation operation.
| Enumerators | |
|---|---|
| Success |
Operation was successful. |
| Canceled |
Operation was manually canceled. |
| InvalidSource |
Operation failed due to invalid source. |
| FeatureGeometryError |
Operation failed due to invalid feature geometry. |
enum QgsInterpolator::
Describes the type of input data.
| Enumerators | |
|---|---|
| SourcePoints |
Point source. |
| SourceStructureLines |
Structure lines. |
| SourceBreakLines |
Break lines. |
enum QgsInterpolator::
Source for interpolated values from features.
| Enumerators | |
|---|---|
| ValueAttribute |
Take value from feature's attribute. |
| ValueZ |
Use feature's geometry Z values for interpolation. |
| ValueM |
Use feature's geometry M values for interpolation. |
Function documentation
int QgsInterpolator::
Calculates interpolation value for map coordinates x, y.
| Parameters | |
|---|---|
| x | x-coordinate (in map units) |
| y | y-coordinate (in map units) |
| result | interpolation result |
| feedback | optional feedback object for progress and cancelation support |
| Returns | 0 in case of success |
Result QgsInterpolator::
Caches the vertex and value data from the provider.
| Returns | Success in case of success |
|---|
All the vertex data will be held in virtual memory.
An optional feedback argument may be specified to allow cancelation and progress reports from the cache operation.