Re: scale problem

[John Cupitt ng-london org uk]

Chris Roadfeldt wrote:
> 	I am having an annoying problem with a couple of scale widgets. The
> code to create the scales is quite large, but it works. The core of the
> problem is the scale allows a value 1 larger than the adjustment max.
> The adjustment max I am setting is 2147483647, but when the scale is
> moved to the max, it returns 2147483648 as the adjustment value. This
> causes my app to do bad things. I can set the adjustment max to a lower
> value, but this seems like a hack. I would rather fix the problem
> itself. Does anyone have any ideas?

Hi Chris, could this just be the page_size thing in GtkAdjustment? I 
know this bit me several times.

If your model is:

struct _MyScale {
	... stuff

	double from;
	double to;
	double value;
	
	stuff ...
}

then to set up the adjustment from your model you need something like:

   double range = myscale->to - myscale->from;

   adj->page_size = range / 10;
   adj->page_increment = range / 10;
   adj->step_increment = range / 100;

   adj->lower = myscale->from;
   adj->upper = myscale->to + adj->page_size;

now adj->value will change in the range [myscale->from, myscale->to].

Hope I've not misunderstood.

John




========================================================== 
Aelbert Cuyp 13 February - 12 May 2002 

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