PlayEnhMetaFile fails, without any GetLastError response

Question

PlayEnhMetaFile fails, without any GetLastError response

radarhere-3869 40

Over at https://github.com/python-pillow/Pillow/issues/6980, a user has posted a zip containing an EMF file - https://github.com/python-pillow/Pillow/files/10852640/test_libuemf_ref.zip

PlayEnhMetaFile fails to process the file. I attempted find out why with GetLastError, but it returned 0 (aka ERROR_SUCCESS, indicating that there is no problem).

HDC dc = CreateCompatibleDC(NULL);
BITMAPINFO info;
memset(&info, 0, sizeof(BITMAPINFO));
info.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
info.bmiHeader.biWidth = 14030;
info.bmiHeader.biHeight = 9920;
info.bmiHeader.biPlanes = 1;
info.bmiHeader.biBitCount = 24;
info.bmiHeader.biCompression = BI_RGB;
void *ptr;
bitmap = CreateDIBSection(dc, &info, DIB_RGB_COLORS, &ptr, NULL, 0);
SelectObject(dc, bitmap);
HENHMETAFILE hemf = GetEnhMetaFile("test.emf");
RECT rect;
rect.left = 0;
rect.top = 0;
rect.right = 14030;
rect.bottom = 9920;
if (!PlayEnhMetaFile(dc, hemf, &rect)) {
	printf("error %d\n", GetLastError());
}

Is anyone able to help me figure out why this file is failing? Is it corrupted? Is there something that would persuade PlayEnhMetaFile to accept it?

Thanks.

RLWA32 49,636 Reputation points

2024-10-09T08:07:40.82+00:00

The documentation at PlayEnhMetaFile function does not indicate that extended error information is available with GetLastError(). So the value returned by the function is probably not meaningful in this case. Also, you might consider testing whether GetEnhMetaFile succeeded.
Jeanine Zhang-MSFT 11,356 Reputation points Microsoft External Staff

2024-10-09T09:07:24.38+00:00

What do you mean PlayEnhMetaFile fails to process the file? Does it mean that PlayEnhMetaFile returns a value of 0? Have you checked if the file is corrupted? I suggest you can try testing with another EMF file.

I suggest you could also refer to the official sample: Opening an Enhanced Metafile and Displaying Its Contents
radarhere-3869 40 Reputation points

2024-10-09T09:22:23.0133333+00:00

I checked GetEnhMetaFile as you suggested, and it succeeds.
radarhere-3869 40 Reputation points

2024-10-09T09:28:53.4833333+00:00

Yes, I meant that PlayEnhMetaFile returns 0, indicating failure.

The code can work with another file, so I don't expect my code to be completely broken. I thought it might be possible that this particular file has a feature that my code isn't accounting for.

Other programs can apparently open the problem file. Beyond that, is there a definitive way to check if the file is corrupted or not? And if it is corrupted, is that it, there is nothing else to do to read the file?
radarhere-3869 40 Reputation points

2024-10-09T09:32:45.6133333+00:00

[unintended duplicate comment]

Accepted answer

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Your answer

RLWA32 49,636 Reputation points

2024-10-09T08:07:40.82+00:00

The documentation at PlayEnhMetaFile function does not indicate that extended error information is available with GetLastError(). So the value returned by the function is probably not meaningful in this case. Also, you might consider testing whether GetEnhMetaFile succeeded.
Jeanine Zhang-MSFT 11,356 Reputation points Microsoft External Staff

2024-10-09T09:07:24.38+00:00

What do you mean PlayEnhMetaFile fails to process the file? Does it mean that PlayEnhMetaFile returns a value of 0? Have you checked if the file is corrupted? I suggest you can try testing with another EMF file.

I suggest you could also refer to the official sample: Opening an Enhanced Metafile and Displaying Its Contents
radarhere-3869 40 Reputation points

2024-10-09T09:22:23.0133333+00:00

I checked GetEnhMetaFile as you suggested, and it succeeds.
radarhere-3869 40 Reputation points

2024-10-09T09:28:53.4833333+00:00

Yes, I meant that PlayEnhMetaFile returns 0, indicating failure.

The code can work with another file, so I don't expect my code to be completely broken. I thought it might be possible that this particular file has a feature that my code isn't accounting for.

Other programs can apparently open the problem file. Beyond that, is there a definitive way to check if the file is corrupted or not? And if it is corrupted, is that it, there is nothing else to do to read the file?
radarhere-3869 40 Reputation points

2024-10-09T09:32:45.6133333+00:00

[unintended duplicate comment]

Answer 1

The file seems to contain records that are invalid intentionally. The purpose of the file is probably to check the rendering engines, which should not crash in case of complex or bad files. To find such records, try this code:

BOOL b = EnumEnhMetaFile( dc, hemf, 
   []( HDC hdc, HANDLETABLE FAR* lpht, CONST ENHMETARECORD* lpmr, int nHandles, LPARAM data ) -> BOOL
   {
      if( !PlayEnhMetaFileRecord( hdc, lpht, lpmr, nHandles ) )
      {

      }

      return TRUE;
   }, 
   NULL, &rect );

Use it instead of PlayEnhMetaFile. It will draw the good records, and b will be TRUE. Inside the if, you can see the unexpected records that cannot be drawn. (The details of ENHMETARECORD can be found in documentation).

The rendering programs seems to give different results in case of such special test files.

Answer 2

This test works on my Windows 10 22H2 OS, by drawing your .emf in the client area of the main window (also works on the screen DC with nWidth, nHeight, but larger than screen) :

HENHMETAFILE hEmf = GetEnhMetaFile(TEXT("test_libuemf_ref.emf"));					
if (hEmf)
{
				ENHMETAHEADER pEmfHeader;
				if (GetEnhMetaFileHeader(hEmf, sizeof(pEmfHeader), &pEmfHeader) != 0)
				{
					HDC hDC = GetDC(hWnd);

					// For test
					RECT rcBounds;
					rcBounds.left = MulDiv(pEmfHeader.rclFrame.left, pEmfHeader.szlDevice.cx, pEmfHeader.szlMillimeters.cx * 100);
					rcBounds.top = MulDiv(pEmfHeader.rclFrame.top, pEmfHeader.szlDevice.cy, pEmfHeader.szlMillimeters.cy * 100);
					rcBounds.right = MulDiv(pEmfHeader.rclFrame.right, pEmfHeader.szlDevice.cx, pEmfHeader.szlMillimeters.cx * 100);
					rcBounds.bottom = MulDiv(pEmfHeader.rclFrame.bottom, pEmfHeader.szlDevice.cy, pEmfHeader.szlMillimeters.cy * 100);
					int nWidth = rcBounds.right - rcBounds.left;
					int nHeight = rcBounds.bottom - rcBounds.top;

					BITMAPINFO BitmapInfo;
					ZeroMemory(&BitmapInfo, sizeof(BITMAPINFO));
					BitmapInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
					BitmapInfo.bmiHeader.biWidth = nWidth;
					BitmapInfo.bmiHeader.biHeight = nHeight;
					BitmapInfo.bmiHeader.biPlanes = 1;
					BitmapInfo.bmiHeader.biBitCount = 32;
					BitmapInfo.bmiHeader.biCompression = BI_RGB;
					HBITMAP hBitmap = CreateDIBSection(hDC, &BitmapInfo, DIB_RGB_COLORS, NULL, NULL, 0);
					if (hBitmap != NULL)
					{								
						HBITMAP hBitmapOld = (HBITMAP)SelectObject(hDC, hBitmap);
						/*RECT rect = { 0, 0, nWidth, nHeight };*/
						RECT rect;
						GetClientRect(hWnd, &rect);
						BOOL bRet = PlayEnhMetaFile(hDC, hEmf, &rect);
						SelectObject(hDC, hBitmapOld);
						DeleteObject(hBitmap);
					}
					ReleaseDC(hWnd, hDC);
				}
				DeleteEnhMetaFile(hEmf);
}

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PlayEnhMetaFile fails, without any GetLastError response

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