[Shapelib] Shapelib.dll PInvoke error

David.Gancarz at ci.orlando.fl.us David.Gancarz at ci.orlando.fl.us
Mon Feb 26 10:31:09 PST 2007


It's been a while since I did anything with PocketPC, so I don't remember 
all the differences between .NET on it versus full Windows.  But ... 
regarding the shapelib.dll -- it dos not need to be included in your 
Visual Studio project; it just needs to reside in a place the your 
assembly can find it (typically, the same directory -- which is exactly 
where the post build event puts it).  Copying it there manually, as you 
did, accomplishes the same thing.  Shapelib.dll gets called at runtime. It 
does not become part of the .net assembly, so your Visual Studio solution 
ReadArcShape needs no reference to it at all.  It only needs shapelib.dll 
at runtime. 

Secondly, the version of shapelib.dll on MapTools.org is compiled for 
windows, so you will need to recompile it for Windows CE.  The C/C++ 
source and VS projects should be out on the Shapelib site.  That should be 
possible since there is nothing exotic or windows-specific about the 
shapelib c code. 

Finally, I wouldn't  think you will need to revisit the PInvoke calls in 
the .net wrapper.  As I recall the Compact Framework supports PInvoke -- 
although you might want to check the details on that. 

I hope some of this helps, and good luck.

David Gancarz

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"Constanze Tschritter" <Conny3 at gmx.de> 
Sent by: shapelib-bounces at lists.maptools.org
02/26/2007 01:02 PM
Please respond to
Shapelib Development <shapelib at lists.maptools.org>

shapelib at lists.maptools.org

[Shapelib] Shapelib.dll PInvoke error

Dear List,

When I tried to compile my Pocket PC 2003 project, the result was a 
MissingMethodException saying the entry point SHPopen within the PInvoke 
DLL shapelib.dll was not found (I¡¦ve got the german version of Visual 
studio 8, but this is more or less what it said). 

Here is the offending code snippet:

Const STRSHAPEPATH As String = "xxx\\xxx\\strassen.shp"

Private Sub ReadArcShape()
        Dim myShapeType As ShapeLib.ShapeType = 
        Dim hShape As IntPtr = New IntPtr()
        Dim intNum As Integer = 0
        Dim dblMinBounds As Double() = New Double(1) {0, 0}
        Dim dblMaxBounds As Double() = New Double(1) {0, 0}

'At this point I get the MissingMethodException
hShape = ShapeLib.SHPOpen(STRSHAPEPATH, "rb")
End Sub

Looking up that error message at the internet I found some possible causes 
for the error but until now, nothing I tried changed anything: 

„³ 1) Platform:  I downloaded the Shapelib .Net Wrapper by David Gancarz 
and recompiled the shapelib for Pocket-PC 2003. However I got an error 
message, when I tried to use the same shapelib files he did. Thus I used a 
windows ce shapelib package which had been assembled by Mateusz Loskot and 
was able to compile those without problems. The only difference I noticed 
was, that this package contained more files than David Gancarz had used. 

A test with

¡§Dumpbin /header shapefile.dll |find ¡§machine¡¨¡¨ resulted in 
                 ¡§1C0 machine(ARM)¡¨ so I must have done something right. 

Afterwards I tried to recompile the Maptools-Project (which is said 
wrapper project), now with the new shapelib.dll. The only error message I 
got was that the post build event copy $(ProjectDir)shapelib.dll 
$(TargetDir) had failed, so I copied it manually into my project folder. 
I¡¦m not sure if that was the right thing to do, because I don¡¦t know the 
background behind this.

I added the maptools.dll reference to my project, but got an error, when I 
tried the same with the shapelib (¡§Unable to add reference to 
Shapelib.dll¡¨). Do I even have to add that, too, or is sufficient to only 
add the maptools.dll? Well everything seemed to be ok, though, Visual 
studio recognized the Shapelib functions. 

„³ 2) Build Action: I set the build action of the shapelib.dll in my 
project to content, but nothing changed.

„³ 3) PInvoke: I thought with the .Net wrapper I won¡¦t have to worry about 

I don¡¦t know what else to do. I must have missed something, but I don¡¦t 
know what. Maybe someone here can give me a hint what I¡¦m doing wrong. 
Thank you very much in advance!

Constanze Tschritter

PS: Sorry for the long mail. I didn't know how to describe it in a shorter 

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