retrieving previously stored compressed bitmap?

[[EMAIL PROTECTED]]

Hi all,

I have been trying to do the following (in OS5):
1. compress and save an offscreen window's bitmap to
   an existing record in the storage heap.
2. read the bitmap at a later date.


Part 1 seemed simple. I did something like this:
void Save (WinHandle srcWinH, UInt16 index)
{
  BitmapType    *destBmP;
  WinHandle     destWinH;
  Err           err;
  UInt32        headerSize, bitsSize;
  MemHandle     recH;
  MemPtr        recP;
        

  recH = DmGetRecord (g_dbRef, index);
  if (recH)
  {
    destBmP = BmpCreate (g_width, g_height, g_depth, NULL, &err);
    destWinH = WinCreateBitmapWindow (destBmP, &err);
    WinCopyRectangle (srcWinH, destWinH, &g_bounds, 0, 0, winPaint);

    BmpCompress (destBmP, BitmapCompressionTypeRLE);
    BmpGetSizes (destBmP, &bitsSize, &headerSize);
                
    recH = DmResizeRecord (g_dbRef, index, bitsSize + headerSize);
    recP = MemHandleLock (recH);
    if (recP)
    {
      if (BmpSize (destBmP) == headerSize + bitsSize)
      {
        DmWrite (recP, 0, destBmP, bitsSize + headerSize);

      } else
      {
        // bitmap data not contiguous with header
        DmWrite (recP, 0, destBmP, headerSize);
        DmWrite (recP, headerSize, BmpGetBits (destBmP), bitsSize);
      }
      MemHandleUnlock (recH);
    }
    DmReleaseRecord (g_dbRef, index, true);
  }
  WinDeleteWindow (destWinH, false);
  BmpDelete (destBmP);
}
        

Part 2 however has me stumped. I did this:
void Load (WinHandle destWinH, UInt16 index)
{
  MemHandle  recH, bmH;
  BitmapType *storedBmP, *bmP;
  WinHandle  oldWin;


  recH = DmQueryRecord (g_dbRef, index);
  if (recH)
  {
    storedBmP = (BitmapType *) MemHandleLock (recH);

    bmH = MemHandleNew (MemPtrSize (storedBmP));
    bmP = (BitmapType *) MemHandleLock (bmH);

    MemMove (bmP, storedBmP, MemPtrSize (storedBmP));
    
    // LINE 1
    BmpCompress (bmP, BitmapCompressionTypeNone);

    oldWin = WinSetDrawWindow (destWinH);
    // LINE 2
    WinDrawBitmap (bmP, 0, 0);
    WinSetDrawWindow (oldWin);

    MemHandleUnlock (recH);
    MemHandleUnlock (bmH);
  }
}

When run through the Debug Simulator 5.3, I observed that:
- BmpCompress (LINE 1) fails: "invalid bitmapP"
- if I comment out BmpCompress (LINE 1), Sim crashes at
  WinDrawBitmap (LINE 2)

Seems obvious that I have an invalid bitmap header. I just
can't figure out how to store it and retrieve it properly.

Any help/advice would be greatly appreciated.

Thanks
Alex


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