Re: how to get the true physical viewable size of my CRT monitor?
From: Ray Trent (rat_at_synaptics.com.spamblock)
Date: 08/04/04
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Date: Wed, 04 Aug 2004 15:57:53 -0700
Well, it depends on what you're trying to accomplish. Yes, you could
theoretically ask the user to only adjust their display using your
controls, but you still can't tell how the monitor was adjusted in the
first place.
I'm assuming you're trying to do some kind of "true scale" display or
something like that...
The usual technique I've seen people use when you *really* need to know
the true physical size of the screen is to show a line of a known number
of pixels, ask the user to measure it on the screen with a ruler, type
in the length of the line, and then compute the resulting total scale
and true size.
As for how you get/set these timings, all of that will be specific to
particular display adapters, so you're still going to need to either
reverse engineer or (if you're very lucky :-) find the specs for the
internals of the cards you want to support and write a driver to tweak
them directly (at significant risk of screwing something up, I might
add). There are no OS APIs for this stuff.
lucy wrote:
> "Ray Trent" <rat@synaptics.com.spamblock> wrote in message
> news:%23rgCqjkeEHA.3916@TK2MSFTNGP11.phx.gbl...
>
>>Ivan's comment seemed intuitively true to me, but I was curious to prove
>>that it was true.
>>
>>I installed PowerStrip, took a screenshot of the display timings,
>>adjusted my monitor's horizontal width to the minimum possible, and
>>looked again at PowerStrip's timings.
>>
>>Indeed, there was no change. These timings are unrelated to the actual
>>viewable area. I'm afraid you're out of luck even if you can read these
>>timings, OP.
>>
>>They do install a .sys file. I haven't tried looking at it in detail,
>>but I suspect that as Maxim says, it must be doing portIO hackery. It
>>certainly is doing Monitor-specific stuff, because if it were doing
>>something universal, it would support all monitors, instead of having a
>>list of monitors that it supports.
>>
>>Cute toy, though...
>>
>>Ivan Dimitrov wrote:
>>
>>>Hi, Luci
>>>
>>>
>>>
>>>>But actually users can
>>>>adjust the viewable area of CRT using the monitor buttons. The values I
>>>>obtained did not change with users' adjusting of viewable area... so it
>
> is
>
>>>>wrong. I hope GDIINFO can give me information about this viewable size,
>>>>which should be set according to users' adjustment.
>>>
>>>
>>>Actually when the user adjusts viewable area settings through monitor
>>>control buttons it does not change the timings (here I mean when he/she
>>>changes width, height or horizontal/vertical positions). In this case
>
> the
>
>>>only things that he/she changes are horizontal and/or vertical
>
> deflection
>
>>>voltages applied to the CRT tube and these don't change the horizontal
>
> or
>
>>>vertical frequency, hence he/she couldn't change the timings in any way
>
> by
>
>>>changing these settings.
>>>
>>>___________________________________________
>>>Best regards,
>>>Ivan Dimitrov
>>>
>>>
>
>
> Very interesting. On my computer it works.
>
> I am using an ATI Radeon 300, and DELL FP2001 LCD.
>
> I did the experiment again. Now I see what is the problem:
>
> there are two sets of "sizing" settings on our display system:
>
> 1) monitor's control button;
> 2) display adapter card output timing.
>
> If you adjust the size using monitor's control button, there is no way that
> OS or software such as Powerstrip can know.
>
> But if you adjust the soft button in Powerstrip to change the display card
> output timing, you can also change the monitor viewable area size.
> Interesting.
>
> So in order to obtain the true viewable area size, I should either prompt
> user to use the soft button controlling the display card output timing, then
> I can read the values and compute the size. In order to do this, I need not
> only to read out the timing information, but also need to set the timing.
>
> But how to do that, similar to Powerstrip's work?
>
> Any more thoughts?
>
> Thanks a lot,
>
> -Lucy
>
>
>
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