Microsoft KB Archive/142319

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HOWTO: How to Decipher EMR_SELECTOBJECT Records in Enhanced Meta File

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Q142319

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The information in this article applies to:


 * Microsoft Win32 Software Development Kit (SDK)
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Professional

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SUMMARY
The EMR_SELECTOBJECT record in an enhanced metafile can indicate that the object to be selected is a stock object. It does so by setting the high order bit in the handle. This article shows how to decipher those records to get a handle to the stock object.

MORE INFORMATION
If an EMR_SELECTOBJECT record is encountered while enumerating the records in an enhanced metafile, the dParm member of the ENHMETARECORD parameter is normally an index into the handle table of the object to be selected.

However, if the high order bit of dParm[0] is set, the remaining bits indicate the index that can be used with GetStockObject to obtain a handle to the object of interest.

For example, consider the following enumeration callback function:

  int CALLBACK EnumEnhMetafileProc( HDC hDC,                                  HANDLETABLE *lpHTable,                                  ENHMETARECORD *lpEMFR,                                  int nObj, LPARAM lpData ) {   DWORD    dwIndex; HGDIOBJ hObj;

// Which record type is this record? switch( lpEMFR->iType ) {       case EMR_SELECTOBJECT: // It's a SelectObject record // Is the high order bit set? if( lpEMFR->dParm[0] & 0x80000000 ) {               // High order bit is set - its a stock object // Strip the high bit to get the index dwIndex = lpEMFR->dParm[0] & 0x7fffffff; // Pass the index to GetStockObject hObj = GetStockObject( dwIndex ); // Select the object into the DC               SelectObject( hDC, hObj ); }           else {               // High order bit wasn't set - not a stock object SelectObject( hDC,                         lpHTable->objectHandle[lpEMFR->dParm[0]] ); }       break; default: // Process other records PlayEnhMetaFileRecord( hDC, lpHTable, lpEMFR, nObj ); break; }   // Return non-zero to continue enumeration return 1; } Note that this information is important only if the application needs to decipher the record. Simply passing the EMR_SELECTOBJECT record to PlayEnhMetaFileRecord is valid independent of whether or not the object of interest is a stock object.

In Windows 95, optimizations built into the operating system can result in a stock object record being recorded into the metafile even when a specific non-stock object is requested. This can happen, for example, when an application requests a solid brush of color RGB(128,128,128). The operating system recognizes this as the GRAY_BRUSH stock object and enters the stock object record into the metafile accordingly.

Additional query words: Windows 95 4.00 3.50 Enumerate EnumEnhMetaFile EnhMetaFileProc missing EMR_CREATEBRUSHINDIRECT

Keywords : kbOSWin2000 kbSDKWin32

Issue type : kbhowto

Technology : kbwin2000AdvServ kbwin2000AdvServSearch kbwin2000Serv kbwin2000ServSearch kbwin2000Search kbwin2000ProSearch kbwin2000Pro kbWin32SDKSearch kbAudDeveloper kbSDKSearch kbWinAdvServSearch kbWin32sSearch