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Array in StructureI've got a some structures defined as ////// <StructLayout(LayoutKind.Sequential)> Public Structure GM_LayerInfo_t Public mDescription As String Public mNativeRect As GM_Rectangle_t Public mGlobalRect As GM_Rectangle_t Public mPixelWidth As Int32 Public mPixelHeight As Int32 Public mNativeProj As GM_Projection_t Public mControlPoints As IntPtr Public mNumGCPs As Int32 Public mMinElevation As Single Public mMaxElevation As Single Public mNumAreas As Int32 Public mNumLines As Int32 Public mNumPoints As Int32 Public mPixelSizeX As Double Public mPixelSizeY As Double Public mHasRasterData As Byte Public mEnabled As Byte Public mHasVectorData As Byte Public mUsedDefaultPos As Byte Public mFilename As String Public mArchiveFilename As String Public mTypeName As String End Structure <StructLayout(LayoutKind.Sequential)> Public Structure GM_ProjAttrValue_t Public mAttr As PROJATTR Public mValue As Double End Structure <StructLayout(LayoutKind.Sequential)> Public Structure GM_Projection_t Public mProjSys As PROJSYS Public mDatum As DATUM Public mUnit As UNIT Public mNumAttrs As Int32 <VBFixedArray(15)> Public mAttrList() As GM_ProjAttrValue_t End Structure /////// The Types PROJATTR, PROJSYS, DATUM, and UNIT are defined enums while GM_Rectangle_t is another structure but these are not part of the problem (at lease I'm farily positive they're not). It's the array in the GM_Projection_t structure that seems to be the problem. Here it's fixed, but I've also attempted just leaving it dynamic and the same problem occurs. The array *should* almost always contains at least 1 element in it after fill the structure (but it could be empty or it could contain up to 16 at max). Anyway, mAttrList is always NOTHING when ever I fill the structure as it's coded above. (the code to fill it at the botom of this message). Every other member of the structure is filled in fine. However, if I don't make mAttrList an array - just defined within the structure as ///// Public mAttrList As GM_ProjAttrValue_t ///// then mAttrList is properly filled with the mAttr and mValue members of the GM_ProjAttrValue_t structure (remember, there's *almost always* at least one attribute to fill the mAttrList). Here is the code making the call to fill the strucure ///// ' Convert the pointer to our structure Dim theLayerInfo As GM_LayerInfo_t theLayerInfo = CType(Marshal.PtrToStructure(theLayerInfoPtr, GetType(GM_LayerInfo_t)), GM_LayerInfo_t) /////
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"Lance" <nu***@business.com> ha scritto nel messaggio First of all I think you need a read to namimng guidelines for types and news:%23fyk5qgvGHA.560@TK2MSFTNGP05.phx.gbl... > > Here is the code making the call to fill the strucure > > ///// > ' Convert the pointer to our structure > Dim theLayerInfo As GM_LayerInfo_t > theLayerInfo = CType(Marshal.PtrToStructure(theLayerInfoPtr, > GetType(GM_LayerInfo_t)), GM_LayerInfo_t) > ///// variables. Regarding your problem I wonder why you are passing by marshalling and I don't understand if your array is or not a fixed array. Remember also that if you don't have a really need you should use a class instead of an large structure. just about all of this code was cut and pasted from an SDK, so the variable names wouldn't
be my first choice either. the SDK example also passes by marshalling. the only thing i've changed from the SDK is the structure. it was originally ///// <StructLayout(LayoutKind.Sequential)> Public Structure GM_Projection_t Public mProjSys As PROJSYS ' Projection system Public mDatum As DATUM ' Horizontal datum Public mUnit As UNIT ' Ground units Public mNumAttrs As Int32 ' Number of attributes in attribute list Public mAttrVal1 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal2 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal3 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal4 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal5 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal6 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal7 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal8 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal9 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal10 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal11 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal12 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal13 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal14 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal15 As GM_ProjAttrValue_t ' First attribute value Public mAttrVal16 As GM_ProjAttrValue_t ' First attribute value End Structure ///// I was trying to change the structure to better reflect and behave more like the original C Header file definition of ///// typedef struct { PROJSYS mProjSys; // Projection system DATUM mDatum; // Horizontal datum UNIT mUnit; // Ground units uint32 mNumAttrs; // Number of attributes in attribute list GM_ProjAttrValue_t mAttrList[ 16 ]; // Attribute list } GM_Projection_t; ///// Show quoteHide quote "Fabio" <znt.fa***@virgilio.it> wrote in message news:%23lQW$DhvGHA.3552@TK2MSFTNGP03.phx.gbl... > "Lance" <nu***@business.com> ha scritto nel messaggio > news:%23fyk5qgvGHA.560@TK2MSFTNGP05.phx.gbl... > > >> >> Here is the code making the call to fill the strucure >> >> ///// >> ' Convert the pointer to our structure >> Dim theLayerInfo As GM_LayerInfo_t >> theLayerInfo = CType(Marshal.PtrToStructure(theLayerInfoPtr, GetType(GM_LayerInfo_t)), >> GM_LayerInfo_t) >> ///// > > > First of all I think you need a read to namimng guidelines for types and variables. > > Regarding your problem I wonder why you are passing by marshalling and I don't > understand if your array is or not a fixed array. > > Remember also that if you don't have a really need you should use a class instead of an > large structure. > > -- > > Free .Net Reporting Tool - http://www.neodatatype.net > "Lance" <nu***@business.com> ha scritto nel messaggio Ok, but why?news:Oa0deMhvGHA.3552@TK2MSFTNGP03.phx.gbl... > the SDK example also passes by marshalling. You need it? If you don't use PInvoke the use of marshalling is masochist. Also the use of StructLayout and VBFixedArray is not good if you don't need it. to tell you the truth, i hadn't really thought about whether or not marshaling is needed;
it's just a cut and paste from the SDK. the only thing i've changed from the SDK is the structure so as to more accurately behave like the C Header file version as mentioned previously (obviously failing at that...). I've removed <StructLayout(LayoutKind.Sequential)> from the structure. Do you think marshaling is the issue? Show quoteHide quote "Fabio" <znt.fa***@virgilio.it> wrote in message news:%23FR90QhvGHA.3552@TK2MSFTNGP03.phx.gbl... > "Lance" <nu***@business.com> ha scritto nel messaggio > news:Oa0deMhvGHA.3552@TK2MSFTNGP03.phx.gbl... > > >> the SDK example also passes by marshalling. > > Ok, but why? > You need it? > If you don't use PInvoke the use of marshalling is masochist. > Also the use of StructLayout and VBFixedArray is not good if you don't need it. > > > -- > > Free .Net Reporting Tool - http://www.neodatatype.net > "Lance" <nu***@business.com> ha scritto nel messaggio Listen to me: if you don't use this structure for PInvoke remove all the news:OAl55WhvGHA.1956@TK2MSFTNGP02.phx.gbl... > to tell you the truth, i hadn't really thought about whether or not > marshaling is needed; it's just a cut and paste from the SDK. the only > thing i've changed from the SDK is the structure so as to more accurately > behave like the C Header file version as mentioned previously (obviously > failing at that...). > > I've removed <StructLayout(LayoutKind.Sequential)> from the structure. Do > you think marshaling is the issue? attributes and use it in the .Net way (remove also all the Marshal references). Marshalling is used to comunicate from managed (.net) and unmanaged (native win32) world, if you don't need this avoid to use it and you'll live more happy. If you copy an example from an SDK it is presumed to be used as the SDK says, so if you change the structure this is no more the structure of the SDK, so you cannot apply the same logic to it (I hope the SDK explain why it was using the marshalling and the structure itself, and I hope you read it). Tom's solution worked. I am indeed making calls to an unmanaged DLL, so to the best of my
knowledge (newly aquired knowledge ;-) ) marshaling is needed. As far as the SDK goes, the VB Example was written for .NET 1.1. The author suggested I try and update the original translated-to-VB structures, enum, etc to take advantage of ..NET 2.0. The author of the SDK has explained to me himself that it's supplied VB Example is - and i'm quoting here, "In general the VB definitions are not kept up to date with the source C++ declarations for the functions and types. The VB code is just there to serve as a reference and not a complete sample of how to use the SDK from VB." Lance Show quoteHide quote "Fabio" <znt.fa***@virgilio.it> wrote in message news:OpCdxMivGHA.2260@TK2MSFTNGP03.phx.gbl... > > "Lance" <nu***@business.com> ha scritto nel messaggio > news:OAl55WhvGHA.1956@TK2MSFTNGP02.phx.gbl... > >> to tell you the truth, i hadn't really thought about whether or not marshaling is >> needed; it's just a cut and paste from the SDK. the only thing i've changed from the >> SDK is the structure so as to more accurately behave like the C Header file version as >> mentioned previously (obviously failing at that...). >> >> I've removed <StructLayout(LayoutKind.Sequential)> from the structure. Do you think >> marshaling is the issue? > > Listen to me: if you don't use this structure for PInvoke remove all the attributes and > use it in the .Net way (remove also all the Marshal references). > > Marshalling is used to comunicate from managed (.net) and unmanaged (native win32) > world, if you don't need this avoid to use it and you'll live more happy. > > If you copy an example from an SDK it is presumed to be used as the SDK says, so if you > change the structure this is no more the structure of the SDK, so you cannot apply the > same logic to it (I hope the SDK explain why it was using the marshalling and the > structure itself, and I hope you read it). > > > -- > > Free .Net Reporting Tool - http://www.neodatatype.net > Lance wrote:
Show quoteHide quote > just about all of this code was cut and pasted from an SDK, so the variable names wouldn't Lance, if you are passing this to an unmanged function via P/Invoke (a> be my first choice either. the SDK example also passes by marshalling. > > the only thing i've changed from the SDK is the structure. it was originally > > ///// <StructLayout(LayoutKind.Sequential)> Public Structure GM_Projection_t > Public mProjSys As PROJSYS ' Projection system > Public mDatum As DATUM ' Horizontal datum > Public mUnit As UNIT ' Ground units > Public mNumAttrs As Int32 ' Number of attributes in attribute list > Public mAttrVal1 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal2 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal3 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal4 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal5 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal6 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal7 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal8 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal9 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal10 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal11 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal12 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal13 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal14 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal15 As GM_ProjAttrValue_t ' First attribute value > Public mAttrVal16 As GM_ProjAttrValue_t ' First attribute value > End Structure > ///// > > I was trying to change the structure to better reflect and behave more like the original C > Header file definition of > ///// > typedef struct > { > PROJSYS mProjSys; // Projection system > DATUM mDatum; // Horizontal datum > UNIT mUnit; // Ground units > uint32 mNumAttrs; // Number of attributes in attribute list > GM_ProjAttrValue_t mAttrList[ 16 ]; // Attribute list > } GM_Projection_t; > ///// > declare statement) then you should leave it like the original. The marshaller in .NET 1.1 does not support arrays of structures in structures.... -- Tom Shelton [MVP] i am indeed passing it to a declare statement (i'm utilizing an unmanaged DLL). however,
I'm using .NET 2.0. It occurs to me that the SDK uses examples written for Pre .Net 2.0 (1.1, I think) so that may be causing some confusion. Show quoteHide quote "Tom Shelton" <t**@mtogden.com> wrote in message news:1155391588.808727.81840@74g2000cwt.googlegroups.com... > > Lance wrote: >> just about all of this code was cut and pasted from an SDK, so the variable names >> wouldn't >> be my first choice either. the SDK example also passes by marshalling. >> >> the only thing i've changed from the SDK is the structure. it was originally >> >> ///// <StructLayout(LayoutKind.Sequential)> Public Structure GM_Projection_t >> Public mProjSys As PROJSYS ' Projection system >> Public mDatum As DATUM ' Horizontal datum >> Public mUnit As UNIT ' Ground units >> Public mNumAttrs As Int32 ' Number of attributes in attribute >> list >> Public mAttrVal1 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal2 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal3 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal4 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal5 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal6 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal7 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal8 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal9 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal10 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal11 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal12 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal13 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal14 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal15 As GM_ProjAttrValue_t ' First attribute value >> Public mAttrVal16 As GM_ProjAttrValue_t ' First attribute value >> End Structure >> ///// >> >> I was trying to change the structure to better reflect and behave more like the >> original C >> Header file definition of >> ///// >> typedef struct >> { >> PROJSYS mProjSys; // Projection system >> DATUM mDatum; // Horizontal datum >> UNIT mUnit; // Ground units >> uint32 mNumAttrs; // Number of attributes in attribute list >> GM_ProjAttrValue_t mAttrList[ 16 ]; // Attribute list >> } GM_Projection_t; >> ///// >> > > Lance, if you are passing this to an unmanged function via P/Invoke (a > declare statement) then you should leave it like the original. The > marshaller in .NET 1.1 does not support arrays of structures in > structures.... > > -- > Tom Shelton [MVP] > by the way, Dim'ing the array as 15 is a typo in the snippet below. it should be 16.
Show quoteHide quote "Lance" <nu***@business.com> wrote in message news:%23fyk5qgvGHA.560@TK2MSFTNGP05.phx.gbl... > Hi all, > > I've got a some structures defined as > > ////// > <StructLayout(LayoutKind.Sequential)> Public Structure GM_LayerInfo_t > Public mDescription As String > Public mNativeRect As GM_Rectangle_t > Public mGlobalRect As GM_Rectangle_t > Public mPixelWidth As Int32 > Public mPixelHeight As Int32 > Public mNativeProj As GM_Projection_t > Public mControlPoints As IntPtr > Public mNumGCPs As Int32 > Public mMinElevation As Single > Public mMaxElevation As Single > Public mNumAreas As Int32 > Public mNumLines As Int32 > Public mNumPoints As Int32 > Public mPixelSizeX As Double > Public mPixelSizeY As Double > Public mHasRasterData As Byte > Public mEnabled As Byte > Public mHasVectorData As Byte > Public mUsedDefaultPos As Byte > Public mFilename As String > Public mArchiveFilename As String > Public mTypeName As String > End Structure > > <StructLayout(LayoutKind.Sequential)> Public Structure GM_ProjAttrValue_t > Public mAttr As PROJATTR > Public mValue As Double > End Structure > > <StructLayout(LayoutKind.Sequential)> Public Structure GM_Projection_t > Public mProjSys As PROJSYS > Public mDatum As DATUM > Public mUnit As UNIT > Public mNumAttrs As Int32 > <VBFixedArray(15)> Public mAttrList() As GM_ProjAttrValue_t > End Structure > /////// > > The Types PROJATTR, PROJSYS, DATUM, and UNIT are defined enums while GM_Rectangle_t is > another structure but these are not part of the problem (at lease I'm farily positive > they're not). It's the array in the GM_Projection_t structure that seems to be the > problem. Here it's fixed, but I've also attempted just leaving it dynamic and the same > problem occurs. > > The array *should* almost always contains at least 1 element in it after fill the > structure (but it could be empty or it could contain up to 16 at max). Anyway, > mAttrList is always NOTHING when ever I fill the structure as it's coded above. (the > code to fill it at the botom of this message). Every other member of the structure is > filled in fine. However, if I don't make mAttrList an array - just defined within the > structure as > > ///// > Public mAttrList As GM_ProjAttrValue_t > ///// > > then mAttrList is properly filled with the mAttr and mValue members of the > GM_ProjAttrValue_t structure (remember, there's *almost always* at least one attribute > to fill the mAttrList). > > > Here is the code making the call to fill the strucure > > ///// > ' Convert the pointer to our structure > Dim theLayerInfo As GM_LayerInfo_t > theLayerInfo = CType(Marshal.PtrToStructure(theLayerInfoPtr, GetType(GM_LayerInfo_t)), > GM_LayerInfo_t) > ///// > Lance wrote:
Show quoteHide quote > Hi all, VBFixedArray is not appropriate for marshalling scenarios... You> > I've got a some structures defined as > > ////// > <StructLayout(LayoutKind.Sequential)> Public Structure GM_LayerInfo_t > Public mDescription As String > Public mNativeRect As GM_Rectangle_t > Public mGlobalRect As GM_Rectangle_t > Public mPixelWidth As Int32 > Public mPixelHeight As Int32 > Public mNativeProj As GM_Projection_t > Public mControlPoints As IntPtr > Public mNumGCPs As Int32 > Public mMinElevation As Single > Public mMaxElevation As Single > Public mNumAreas As Int32 > Public mNumLines As Int32 > Public mNumPoints As Int32 > Public mPixelSizeX As Double > Public mPixelSizeY As Double > Public mHasRasterData As Byte > Public mEnabled As Byte > Public mHasVectorData As Byte > Public mUsedDefaultPos As Byte > Public mFilename As String > Public mArchiveFilename As String > Public mTypeName As String > End Structure > > <StructLayout(LayoutKind.Sequential)> Public Structure GM_ProjAttrValue_t > Public mAttr As PROJATTR > Public mValue As Double > End Structure > > <StructLayout(LayoutKind.Sequential)> Public Structure GM_Projection_t > Public mProjSys As PROJSYS > Public mDatum As DATUM > Public mUnit As UNIT > Public mNumAttrs As Int32 > <VBFixedArray(15)> Public mAttrList() As GM_ProjAttrValue_t > End Structure > /////// should be using: <MarshalAs (UnmanagedType.ByValArray, SizeConst:=15)> Of course, this isn't going to work either in .NET 1.1 or lower. The marshaller doesn't support arrays of structs inside of a structure. -- Tom Shelton hey! that nearly fixed it! now it correctly reads the only existing attribute, but the
remaining 15 (remember, it was a typo-the array holds up to 16 values) all return an attribute value of 0 (which is a valid enum in PROJATTR). Preferably, they'd be empty but i guess that's just not possible. thanks tom! Show quoteHide quote "Tom Shelton" <t**@mtogden.com> wrote in message news:1155391827.784301.241090@i42g2000cwa.googlegroups.com... > > Lance wrote: >> Hi all, >> >> I've got a some structures defined as >> >> ////// >> <StructLayout(LayoutKind.Sequential)> Public Structure GM_LayerInfo_t >> Public mDescription As String >> Public mNativeRect As GM_Rectangle_t >> Public mGlobalRect As GM_Rectangle_t >> Public mPixelWidth As Int32 >> Public mPixelHeight As Int32 >> Public mNativeProj As GM_Projection_t >> Public mControlPoints As IntPtr >> Public mNumGCPs As Int32 >> Public mMinElevation As Single >> Public mMaxElevation As Single >> Public mNumAreas As Int32 >> Public mNumLines As Int32 >> Public mNumPoints As Int32 >> Public mPixelSizeX As Double >> Public mPixelSizeY As Double >> Public mHasRasterData As Byte >> Public mEnabled As Byte >> Public mHasVectorData As Byte >> Public mUsedDefaultPos As Byte >> Public mFilename As String >> Public mArchiveFilename As String >> Public mTypeName As String >> End Structure >> >> <StructLayout(LayoutKind.Sequential)> Public Structure GM_ProjAttrValue_t >> Public mAttr As PROJATTR >> Public mValue As Double >> End Structure >> >> <StructLayout(LayoutKind.Sequential)> Public Structure GM_Projection_t >> Public mProjSys As PROJSYS >> Public mDatum As DATUM >> Public mUnit As UNIT >> Public mNumAttrs As Int32 >> <VBFixedArray(15)> Public mAttrList() As GM_ProjAttrValue_t >> End Structure >> /////// > > VBFixedArray is not appropriate for marshalling scenarios... You > should be using: > > <MarshalAs (UnmanagedType.ByValArray, SizeConst:=15)> > > Of course, this isn't going to work either in .NET 1.1 or lower. The > marshaller doesn't support arrays of structs inside of a structure. > > -- > Tom Shelton > 
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