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MustardMan

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Joined: 30/08/2019
Location: Australia
Posts: 175

Posted: 01:59am 28 Oct 2020

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Hi,

I am thinking about options for implementing a warning/fault indicator on a project, and thought a nice way to do that would be where the background of the screen flashes between red and black, but leaves the rest of the screen (graphics or text) intact.

Changing the pallette is the obvious solution, but to my knowledge the SSD1963 based displays do not use a pallette, the colours seen on-screen are the values as-read from the frame buffer. And unfortunately there is also only one frame buffer, negating the possibility of drawing the same screen twice, with two different backgrounds, and then simply flicking between them.

I am fairly sure that filling the screen with a single colour or a "full" bitmap (all values are written and there is no transparancy) involves setting the bounds [X1,Y1,X2,Y2] and then just streaming data to the display to fill that area, but I have not delved deep enough into the source code to find out how transparency is achieved, and then further to ascertain if a 'reverse' transparent function (ie:the background is changed, but the foreground is left alone) is possible.

And of course it should be possible to select any colour to replace - like all &H00FF00 pixels with &H008000 pixels to change from bright green to dark green. Such a thing could also be used to change red text to blue text, or just get all psychedelic on ya.

Any thoughts?

Cheers,

Geoffg

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Joined: 06/06/2011
Location: Australia
Posts: 3308

Posted: 01:25pm 28 Oct 2020

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Yes, you are quite right... it cannot be done.

As you said, the firmware writes the colours to the display's memory and if the colours need to be changed that will require a complete refresh. You are probably thinking of the CMM2 which has an on chip video processor where you can change the colour pallet on the fly using the MAP command.

You could have a coloured border around the edge of the display, say 20 pixels thick. That would take very little time to redraw and would still be attention grabbing.

Geoff

Geoff Graham - http://geoffg.net

MustardMan

Senior Member

Joined: 30/08/2019
Location: Australia
Posts: 175

Posted: 09:30pm 28 Oct 2020

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Hi Geoff,

I like the idea of the coloured/flashing border!

Attention grabbing, and significantly easier to implement.

Cheers,

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