[python-win32] COM illegal argument puzzler

[Roger Upole]

Adam Pletcher wrote:
> A co-worker of mine is writing a tool to automate tasks in Photoshop, and
> found a win32 error we can't explain.  And possibly a bug.
>
> The following script generates an error about how Select() can only take
> one-dimensional arrays:
>
> import win32com.client
> ps_app = win32com.client.Dispatch('Photoshop.Application')
> ps_app.Documents.Add(128, 128, 72)
>
> # select a 10x10 square in the upper left corner of the document
> sel_area = ((0, 0), (10, 0), (10, 10), (0, 10), (0, 0))
> ps_app.ActiveDocument.Selection.Select(sel_area)
>
> The error:
>
> com_error: (-2147352567, 'Exception occurred.', (0, 'Adobe Photoshop',
> 'Illegal argument - argument 1\n- Only arrays with dimension 1 are
> supported', None, 0, -2147220262), None)
> File "c:\Python_Scripts\COM\Photoshop\selectionTest.py", line 7, in
> <module>
>  ps_app.ActiveDocument.Selection.Select(sel_area)
> File
> "C:\Python25\Lib\site-packages\win32com\gen_py\E891EE9A-D0AE-4CB4-8871-F92C0109F18Ex0x9x0.py",
> line 2606, in Select
>  , Type, Feather, AntiAlias)
>
> The problem is that that method is documented as taking two dimensional
> arrays. Here's an exerpt from the Photoshop CS3 VBScript Ref doc:
>
> docH = appRef.ActiveDocument.Width / 2
> docV = appRef.ActiveDocument.Height / 2
> selRegion = Array( Array( topLeftH * docH, topLeftV * docV), _
> Array( topLeftH * docH + docH, topLeftV * docV), _
> Array( topLeftH * docH + docH, topLeftV * docV + docV), _
> Array( topLeftH * docH, topLeftV * docV + docV), _
> Array( topLeftH * docH, topLeftV * docV))
> appRef.ActiveDocument.Selection.Select(selRegion)
>
> It makes sense that it has to take a sequence of two-element sequences,
> right?  Oddly enough, if you run the above code using the comtypes
> extensions instead of win32com, it works perfectly.  The > first two lines
> then become:
>
> import comtypes.client
> ps_app = comtypes.client.CreateObject('Photoshop.Application')
>
> Any ideas why this throws an exception with win32com.client/Dispatch?  Is
> this a bug?
>
> Thanks in advance.
>
> - Adam

I think the difference here is whether to interpret the tuple as a 2-dim 
array or
a 1 dim array of 1 dim arrays.  Comtypes apparently does it in the way that
this particular API expects, although other applications may have different
requirements.

There's a patch (#1195096) for giving finer grained control over how arrays
are passed to and from COM calls.

            Roger