While changing one of our applications to run on the OSX platform, we had issues showing embedded pictures inside the database’s memo fields. This is because the software program was originally written for Windows, which embeds pics without delay in RTF statistics using a percent keyword accompanied by diverse key phrases indicating the size of the picture, the dimensions of its goal rectangle on the record, and the vertical and horizontal scale. More facts on those may be observed at Microsoft’s MSDN website online.

For example one of the images embedded in an RTF facts block reads;

This decodes as;

Picture

WMF 8-bit document

Picture Width = 4286

Picture Height = 2048

Target Width= 2430

Target Height = 1365

The facts that follow the RTF header is ASCII Hex – this is every byte written as 2 ASCII characters in the variety 0 -> F – and word statistics, in which it exists, is little-endian – the LSB (Least Significant Byte) is first, followed with the aid of the MSB (Most Significant Byte).

Looking at the first few bytes of the image records gives;

This is part of the picture header and a short search of the Internet-famous how to decode this;

The header is eighteen bytes in the period and is dependent as follows:

typedef struct _WindowsMetaHeader

WORD HeaderSize; /* Size of header in WORDS (continually nine) */

WORD Version; /* Version of Windows used */

DWORD FileSize; /* Total size of the information in WORDs */

WORD NumOfObjects; /* Number of gadgets in the statistics */

DWORD MaxRecordSize; /* The size of largest report in WORDs */

WORD NoParameters; /* Not Used (always 0) */

WMFHEAD;

FileType carries a cost that shows the vicinity of the metafile information. A price of one indicates that the metafile is stored in reminiscence, even as a 2 indicates that it is saved on disk. Version shops the version quantity of Microsoft Windows that created the metafile. This value continually studies in hexadecimal format. For example, in a metafile created using Windows three. Zero, this object could have the cost 300h.

FileSize specifies the total length of the metafile in 16-bit WORDs. NumOfObjects specifies the number of items that might be within the metafile. MaxRecordSize specifies the size of the biggest record inside the metafile in WORDs. NumOfParams isn’t used and is set to a price of zero. So we have evidence that the photograph facts embedded inside the RTF records have been stored in WMF format. This, lamentably, isn’t a local Mac layout, so it would require a few kinds of conversion to display the picture. The subsequent aspect we need to discover is whether the image facts inside the embedded WMF records are a vector or bitmap photo.

The WMF format is largely a listing of commands for your computer’s snapshots card, telling it a way to draw the photograph. In our case, we may be almost positive that the image facts are a bitmap as this is how our software saves embedded images in RTF memo fields. This is something we can take a look at with the aid of looking at the data information after the header;