gsdview.gdalbackend.ogrqt4

Helper tools and custom components for binding OGR and Qt4.

Functions

geometryToGraphicsItem(geom[, transform])	Convert an OGR geometry into a Qt4 graphics item.
layerToGraphicsItem(layer[, srs, transform])	Convert an OGR layer into a Qt4 graphics item.
singleGeometryToGraphicsItem(geom[, transform])	Convert a single OGR geometry into a Qt4 graphics item.
transformGeometry(geom, transform)	Apply an OSR transform to an OGR geometry.

gsdview.gdalbackend.ogrqt4.MAX_FEATURE_COUNT = 600

the max number of features that are converted whan the graphics item for a layer is generated

gsdview.gdalbackend.ogrqt4.geometryToGraphicsItem(geom, transform=None)

Convert an OGR geometry into a Qt4 graphics item.

If the transform callable is provided then each point in the geometry is converted using the transform(x, y, z) call before genereting the graphics item path.

Parameters:

• geom – an OGR geometry
• transform – callable object for arbitrary coordinate conversion

Returns:

a Qt4 graphics item representing the geometry

See also

singleGeometryToGraphicsItem()

gsdview.gdalbackend.ogrqt4.layerToGraphicsItem(layer, srs=None, transform=None)

Convert an OGR layer into a Qt4 graphics item.

If the srs parameter is provided each feature is converted into the target spatial reference system before generating the graphics item.

If the transform callable is provided then each point in the geometry is converted using the transform(x, y, z) call before genereting the graphics item path.

Parameters:

• layer – ane OGR layer
• srs – the target OSR spatial reference system
• transform – callable object for arbitrary coordinate conversion

Returns:

a Qt4 graphics item (QGraphicsItemGroup) representing the layer

See also

singleGeometryToGraphicsItem(), geometryToGraphicsItem() and MAX_FEATURE_COUNT

gsdview.gdalbackend.ogrqt4.singleGeometryToGraphicsItem(geom, transform=None)

Convert a single OGR geometry into a Qt4 graphics item.

A “single geometry” is an OGR gemetry that don’t include other geometries (GetGeometryCount() == 0).

If the transform callable is provided then each point in the geometry is converted using the transform(x, y, z) call before genereting the graphics item path.

Parameters:

• geom – a single OGR geometry
• transform – callable object for arbitrary coordinate conversion

Returns:

a Qt4 graphics item representing the geometry

See also

geometryToGraphicsItem()

gsdview.gdalbackend.ogrqt4.transformGeometry(geom, transform)

Apply an OSR transform to an OGR geometry.

This function is almost equal to the ogr.Geometry.Transform method but raises an exception if the conversion fails and clone the geometry before performing the transformation in order to leave the original geometry unmodified.

Parameters:

• geom – OGR geometry
• transform – OSR transformer

Returns:

a new geometry instance with transforation applied