Image capture using mixed mode c++/cli

Question

I have an ActiveX control that when called returns a handle to image memory.  In native code use, that memory is locked via GlobalLock to be used as image data in a graphic object.  The return type of the GlobalLock function is casted to a pointer to BITMAPINFOHEADER

LPBITMAPINFOHEADER  Info = (LPBITMAPINFOHEADER)GlobalLock(Handle);

This is lifted from an MFC app that perfroms image capture from an USB imaging device which I want to change into a CLR WinForm project without using MFC.

I am trying to use the variable Info to create Bitmap data for use in a WinForm with LPBITMAPINFOHEADER as  the source of image data

The disconnect is getting from GDI functions (or GDI+ classes) to the System::Drawing namspace classes.  GDI+ has one mehod that is useful.  The list of constructors has creating a Bitmap from a BITMAPINFO and data array.

The problem is in the constructor.  I get an error:  error C2061: syntax error : identifier '{ctor}'

The call is as follows:

bm = new Gdiplus::Bitmap::Bitmap(bmi, _imgPtr->Bits);

bm is defined earlier as:
Gdiplus::Bitmap* bm;


The alternative is to call explicitly the FromBITMAPINFO method:

bm = Gdiplus::Bitmap::FromBITMAPINFO(bmi, _imgPtr->Bits);

This builds but I need to get Bitmap to draw an image to a picturebox on a form.  If I have a returned Bitmap in memory how can I get that into a picture box wihout writing to a file?  The Image and Graphics classes don't look like a solution or maybe I'm missing something.

Thanks in advance

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Jer 29:11

Answer 1

bm = new Gdiplus::Bitmap(bmi, _imgPtr->Bits);

Answer 2

Hello Al_S

Thanks for your post.

If you can get the gdiplus::Bitmap object, you can the call the Bitmap::GetHBITMAP Method to get the handle to bitmap(GDI), then in managed code call the Image.FromHbitmap Method (IntPtr) to get the image.

More info
http://msdn.microsoft.com/en-us/library/ms536295%28VS.85%29.aspx
http://msdn.microsoft.com/en-us/library/k061we7x.aspx

Thanks,
Rong-Chun Zhang
MSDN Subscriber Support in Forum
If you have any feedback on our support, please contact [e-mail]

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Answer 3

bm = new Gdiplus::Bitmap(bmi, _imgPtr->Bits);

Right!  I had one too many classes there.
bm = new Gdiplus::Bitmap::Bitmap(bmi, _imgPtr->Bits);

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Jer 29:11

Answer 4

Hello Al_S

Thanks for your post.

If you can get the gdiplus::Bitmap object, you can the call the Bitmap::GetHBITMAP Method to get the handle to bitmap(GDI), then in managed code call the Image. FromHbitmap Method (IntPtr) to get the image.

More info
http://msdn.microsoft.com/en-us/library/ms536295%28VS.85%29.aspx
http://msdn.microsoft.com/en-us/library/k061we7x.aspx

Thanks,
Rong-Chun Zhang
MSDN Subscriber Support in Forum
If you have any feedback on our support, please contact [e-mail]

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Please remember to mark the replies as answers if they help and unmark them if they provide no help.
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I am getting ambiguous symbol errors:

Error    1    error C2872: 'Bitmap' : ambiguous symbol Form1.h    271    CameraViewer
Error    2    error C2872: 'Image' : ambiguous symbol  271    CameraViewer


Code so far:
bm = new Gdiplus::Bitmap(bmi, _imgPtr->Bits);
Gdiplus::Color col;
HBITMAP hBM;
bm->GetHBITMAP(col, &hBM);
Bitmap image = Image::FromHbitmap((IntPtr)hBM);

The IDE shows that image is part of System::Drawing::Bitmap.

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Jer 29:11

Answer 5

I changed the calls to better define the member.

System::Drawing::Bitmap^ image = System::Drawing::Image::FromHbitmap((IntPtr)hBM);

Is this necessary or is there a better way to remove ambiguous errors?

How can I capture color settings from what I have in the image data from the native code?  Gdiplus::Color col =  Argb    0xff000000.  As expected the image is grey.

I suspect I need more calls into GDI+ to get the image information back into a picturebox.

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Jer 29:11

Answer 6

I think the reason I don't have a valid image is due to mixing GDI+ on a GDI memory HBITMAP

I found this article about interop between GDI+ and GDI

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Jer 29:11

Answer 7

Hello Al_S,

Is the problem resolved. If not, could you please send me a simple project that can reproduce this issue to my mail box(v-rzhang[at]microsoft.com)? I will dig into it and keep you updated.

Thanks,
Rong-Chun Zhang
MSDN Subscriber Support in Forum
If you have any feedback on our support, please contact [e-mail]

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Answer 8

Hope what I sent illustrates the issue.

Thanks.

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Jer 29:11

Answer 9

For other community members, the solution can be found on another discussion
http://social.msdn.microsoft.com/Forums/en-US/vcgeneral/thread/15b18c4b-a8ba-4c8f-9db8-d0a823c4b42e

Thanks,
Rong-Chun Zhang
MSDN Subscriber Support in Forum
If you have any feedback on our support, please contact [e-mail]

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Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.