OS_ChangedBox Block (changes)
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Programmer's OS Reference SWI Manuals Calls
» Part OS_ChangedBox 15 – SWI Calls
» BlockOS
» OS_ChangedBox
» Block
| Offset | Contents |
|---|---|
| +0 | New disable/enable flag |
| +4 | X co-ordinate of left edge of box |
| +8 | Y co-ordinate of bottom edge of box |
| +12 | X co-ordinate of right edge of box |
| +16 | Y co-ordinate of top edge of box |
Notes
The data pointed to by R1 on exit at offsets 4 – 16 are only valid if the change box calculations were in an enabled state immediately after the call; otherwise they are undefined.
This call checks which areas of the screen were changed by VDU commands and returns the smallest rectangle which covers all changed pixels.
See also
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