Changing from color to mono

[Keith E. Black]

Is there a few a lines of code that I can write at the start of my program to
determine if the computer monitor is set up for monochrome?
If not, what statement can I write at the beginning of the program
that when the operator makes a choice the program will automatically
go to mono mode even though it has color code?
Thanks,
Keith

[Eric Pearson]

SUB ScrnInit                                                                  
        LOCAL VidMode%                                                        
        REG 1, &H0F00                     'AH = 15                            
        CALL INTERRUPT &H10               'video services                     
        VidMode% = REG(1) AND &H00FF      'AL                                 
        IF VidMode% <> 7 THEN 
                'COLOR
        ELSE
                'MONO 
        END IF
END SUB

It's also a good idea to have a method (like a config file or a commandline option) that can be used to "force" the use of monochrome, because some video cards do not report their mode accurately. For example, if a system is using a "mono vga" monitor, the video card thinks that the display is in color when it's really not. Lots of old laptops also have this problem. Also, visually-impared users will appreciate the ability to use a high-contrast mono mode.

-- Eric

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Perfect Sync: Perfect Sync Development Tools
Email: mailto:[email protected][email protected]</A>



[This message has been edited by Eric Pearson (edited April 14, 2000).]

[Tom Hanlin]

Check the online help on internal variables on pbvScrnCard, which can
help you identify color display adapters. However, there's no way to tell
if someone's using, say, a grayscale monitor with a VGA card, so it's wise
to allow setting monochrome mode explicitly. Many programs use /B
as a command-line switch to select "black & white" (mono) mode.

There is no one statement you can use to change the color settings
for your entire program. Instead, you need to set up a list of variables
to use when setting the color. At the start of your program, when you
detect whether the display is color or mono, you can set the color
variables accordingly.

------------------
Tom Hanlin
PowerBASIC Staff

[Eric Pearson]

Tom's right, of course. I forgot that pbvScrnCard was added at PB/DOS version 3.2 (I think). The code I posted will work with all versions of PB/DOS, including FirstBASIC, but if you've got a recent version of PB examining the first bit of pbvScrnCard is certainly easier.

IF (pbvScrnCard AND 1) THEN
   PRINT "M0NO"
ELSE
   PRINT "COLOR"
END IF

As far as a "global switch" goes, some of my PB/DOS programs use a function I call SetColors instead of the COLOR statement. That way, I "centralize" all COLOR operations and it's easy to add a global switch that uses black and white instead of colors.

This has worked pretty well for me...

	%Black           = 0
	%LowBlue         = 1
	%LowGreen        = 2
	%LowCyan         = 3
	%LowRed          = 4
	%LowMagenta      = 5
	%Brown           = 6
	%LowWhite        = 7
 
	%Gray            = 8
	%HighBlue        = 9
	%HighGreen       = 10
	%HighCyan        = 11
	%HighRed         = 12
	%HighMagenta     = 13
	%Yellow          = 14
	%HighWhite       = 15

	%BlackBlink      = 16
	%LowBlueBlink    = 17
	%LowGreenBlink   = 18
	%LowCyanBlink    = 19
	%LowRedBlink     = 20
	%LowMagentaBlink = 21
	%BrownBlink      = 22
	%LowWhiteBlink   = 23
 
	%GrayBlink       = 24
	%HighBlueBlink   = 25
	%HighGreenBlink  = 26
	%HighCyanBlink   = 27
	%HighRedBlink    = 28
	%HighMagentaBlink= 29
	%YellowBlink     = 30
	%HighWhiteBlink  = 31
 
SUB SetColors(BYVAL ForeColor%,BYVAL BackColor%)
	SHARED MonoDisplay%  'set to nonzero value for mono display
	IF MonoDisplay% THEN
		IF BackColor% <> %Black THEN
			'we have to do an inverse of some types for Mono VGA
			BackColor% = %LowWhite            
			IF ForeColor% > %HighWhite THEN 
                                ForeColor% = %BlackBlink
                        ELSE 
                                ForeColor% = %Black
                        END IF
		ELSE
			IF ForeColor% MOD 16 <> 0 THEN 
                                ForeColor% = ((ForeColor%\8)*8)+7
                        END IF
		END IF
	END IF
	COLOR ForeColor%,BackColor%
END SUB

Then you use SetColors instead of COLOR everywhere in your program.

--Eric

------------------
Perfect Sync: Perfect Sync Development Tools
Email: mailto:[email protected][email protected]</A>



[This message has been edited by Eric Pearson (edited April 14, 2000).]

[Alan Earnshaw]

FYI, pbvScrnCard was introduced in PowerBASIC 3.00a.

------------------
Alan C. Earnshaw
Information Management Systems, Inc.