Arcobjects- IAnnotateLayerPropertiesCollection2.QueryItem in Python

Question

Anyone tried access label properties trough ArcObjects with Python?

I try to obtain reference to label object with IAnnotateLayerPropertiesCollection2.QueryItem, but when I do:

pA = pGLyr.AnnotationProperties
new = NewObj(esriCarto.LabelEngineLayerProperties,esriCarto.IAnnotateLayerProperties)
pA.QueryItem(0,new)

I get: Runtime error : call takes exactly 2 arguments (3 given)

I'm not sure where is the error comming from.

Any ideas?

Answer 1

In comtypes, out arguments are returned as a tuple, they do not need to be passed in to the function. From the comtypes home page:

Calling methods

Calling COM methods is straightforward just like with other Python objects. They can be called with positional and named arguments.

Arguments marked [out] or [out, retval] in the IDL are returned from a sucessful method call, in a tuple if there is more than one. If no [out] or [out, retval] arguments are present, the HRESULT returned by the method call is returned. When [out] or [out, retval] arguments are returned from a sucessful call, the HRESULT value is lost.

If the COM method call fails, a COMError exception is raised, containing the HRESULT value.

This works for me:

def enumerate_anno_properties(layer):
 gfl = CType(layer, esriCarto.IGeoFeatureLayer)
 if gfl:
 annoProps = gfl.AnnotationProperties
 for i in range(annoProps.Count):
 yield (CType(annoProps, esriCarto.IAnnotateLayerPropertiesCollection2)
 .QueryItem(i))[0]

• Tomek: Cool, works great. I would not think of generator use.