On 4 Nov 2013, at 22:49, Martyn Hill wrote:
On an entirely different topic, and perhaps naively, can I ask how to query a
window in SBASIC to discover the current Paper/Strip and Ink settings -
specifically after using the COLOUR_PAL command in QPC2?
My aim is to (arbitrarily) manipulate the colours on a window that's passed
to my SBASIC routine and to then reset the colours back to what they were on
entry, before returning.
When using the default QL (8 colour) palette, the current Paper etc, could be
found in the window's channel definition block at offsets 68 - 70 (decimal).
Old-school, but effective, seeing as there doesn't appear to be a trap or
vectored routine to officially query such properties of a window.
Once the 256 colour palette is selected, the values at these offsets appear
to get hammered (or at least reset to zero, regardless of what is set through
the PAPER/STRIP and INK commands.)
Am I missing something really obvious?
The colour words for paper and strip are at positions $66 and $68 in the
channel block for a particular CON/SCR. The address of the channel block for
channel number n (system channel number NOT BASIC channel number) is in the nth
long word from the start of the channel base ($2BC60).
If you are using QPC2 and GD2 colours and the default palette, the colour word
for mustard, number 16 is $9480. Suppose you set COLOUR_PAL and then PAPER 16
then when you look at the positions $66 and $68 of the channel block you will
see $8094 because of the byte reversal.
If you now set STRIP 2, you will see $00F8 in position $68, since $F800 is the
word for red and palette number 2 is, normally, red.
George
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