0

I'm trying to create an enhanced metafile like this:

// Obtain a handle to a reference device context.  

HDC hdcRef = GetDC(hwnd); 

// Determine the picture frame dimensions.  

int iWidthMM = GetDeviceCaps(hdcRef, HORZSIZE); 
int iHeightMM = GetDeviceCaps(hdcRef, VERTSIZE); 
int iWidthPels = GetDeviceCaps(hdcRef, HORZRES); 
int iHeightPels = GetDeviceCaps(hdcRef, VERTRES); 

// Retrieve the coordinates of the client  
// rectangle, in pixels.  
RECT rect;
GetClientRect(hwnd, &rect); 

// Convert client coordinates to .01-mm units.  
// Use iWidthMM, iWidthPels, iHeightMM, and  
// iHeightPels to determine the number of  
// .01-millimeter units per pixel in the x-  
//  and y-directions.  

rect.left = (rect.left * iWidthMM * 100)/iWidthPels; 
rect.top = (rect.top * iHeightMM * 100)/iHeightPels; 
rect.right = (rect.right * iWidthMM * 100)/iWidthPels; 
rect.bottom = (rect.bottom * iHeightMM * 100)/iHeightPels; 


// Create the metafile device context.  

CreateEnhMetaFile(hdcRef, (LPTSTR)"temp.emf", &rect, NULL); 

// Release the reference device context.  

ReleaseDC(hwnd, hdcRef);

Took the code here

All I got in the end is some 0 bytes non-extension file with strangely encoded name, smth like 整灭攮晭.

What can be the problem?

P.S. Also, I'm calling it in a mixed-mode app, from c# through a c++/cli object.

EDIT The problem with the strange encoding is solved, but the file created is still 0 bytes length. How can it be solved?

Community
  • 1
  • 1
tube-builder
  • 686
  • 1
  • 13
  • 29

1 Answers1

1

The cast is the problem, don't use casts unless you really have to.

Amazing that you got that cast from a Microsoft web site! You have to wonder about the quality of people MS hire. But in their code it's not wrong just superfluous. When you translated it to your code it is wrong.

CreateEnhMetaFile(hdcRef, _T("temp.emf"), &rect, NULL);

The _T macro is the official way to write a string literal that will be interpreted as either a Unicode string or a ANSI string depending on your compiler settings.

john
  • 85,011
  • 4
  • 57
  • 81
  • @tube-builder OK I'm surprised, it seemed a pretty good explanation for the bug to me. – john Oct 11 '13 at 07:58
  • hell, I'm really sorry, wasn't attentive, now the file is created (tho still empty). Thanks a lot! – tube-builder Oct 11 '13 at 08:00
  • btw do you have any idea why the created file can still be 0 bytes size? I tried to find smth about it but failed so far. Not experienced with c++ at all. – tube-builder Oct 11 '13 at 09:29
  • 1
    @tube-builder You aren't adding anything to your meta file. I would expect to see you use `hdcRef` in some graphics operations. – john Oct 11 '13 at 09:55
  • fan också! i thought it was enough to just pass a handle to my already drawn window to this method.. thanks again for pointing in the right direction! – tube-builder Oct 11 '13 at 10:37