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Programmer's Reference Manual


Appendix B: File formats

Draw files

The Draw file format (see Draw files) has been extended in RISC OS 3.6:


A new object has been defined for including JPEG images within a Draw file. It uses the same object header as other Draw objects; see Object header. The rest of the data for the object is as follows:

JPEG object
Object type number 16
Size Description
4 width of image, in Draw units
4 height of image, in Draw units
4 x pixel density, in dpi
4 y pixel density, in dpi
24 transformation matrix
4 length n of the JPEG image data
n JPEG image data in JFIF format
0 - 3 up to 3 bytes, to pad to a word boundary

The first four words can be derived from information returned by JPEG_Info. The transformation matrix is as described in Font_Paint, in the same format used elsewhere in the Draw module and for other Draw file objects.

For more details of JPEG images, see JPEG images, and CompressJPEG.

The Draw applications supplied with RISC OS 2 and RISC OS 3 do not use this object type.

This edition Copyright © 3QD Developments Ltd 2015
Last Edit: Tue,03 Nov 2015