But per my earlier email -- not really performant to do 2 function calls
every time width changes, eh?
gse
On Mon, 25 Sep 2006, Henry Minsky wrote:
> In the debugger component, I see that I overrode setWidth, to do this
>
> <method name="setWidth" args="w" >
> super.setWidth( Math.max( 170 , Math.min( w , canvas.width) ) );
> </method>
>
>
>
> On 9/25/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> > I'll be damned. It works. I swear that I tried this yesterday and it
> > didn't work. I must be losing it.
> >
> >
> >
> >
> > Quoting P T Withington <[EMAIL PROTECTED]>:
> >
> > > You can do the same thing in Javascript, since true -> 1 and false -> 0
> > > in a numeric context.
> > >
> > > On 2006-09-25, at 20:34 EDT, [EMAIL PROTECTED] wrote:
> > >
> > >> Hmmm. I have an idea. In my situation, I just need to stop the width
> > >> from going below zero.
> > >>
> > >> In C I'd do something like this...
> > >>
> > >> width = (parentwidth-20} * (parentwidth-20 > 0);
> > >>
> > >> Is there some mathematical trickery I can use to convert true/false to
> > >> 1/0 in a constraint?
> > >>
> > >> The best I can come up with is the ternary operator...
> > >>
> > >> width="${(parent.width-20) * (parent.width-20 > 0)?1:0}"
> > >>
> > >>
> > >>
> > >>
> > >>
> > >> Quoting P T Withington <[EMAIL PROTECTED]>:
> > >>
> > >>> If I wanted to be a pedant (ok, I do) I would tell you that
> > >>> [functions](http://en.wikipedia.org/wiki/
> > >>> Functional_programming#Pure_functions) are just fine in constraints,
> > >>> it is 'procedures' that are not.
> > >>>
> > >>> On 2006-09-25, at 16:21 EDT, John Sundman wrote:
> > >>>
> > >>>> Please consult the Developer's Guide on the hazards of using
> > >>>> functions within constraints.
> > >>>>
> > >>>> http://labs.openlaszlo.org/trunk-nightly/docs/guide/
> > >>>> constraints.html#d0e13355
> > >>>>
> > >>>> It can sometimes be done, but there be dangers there, and you do so
> > >>>> at your own risk.
> > >>>>
> > >>>> jrs
> > >>>>
> > >>>> On Sep 23, 2006, at 2:48 PM, Benjamin Shine wrote:
> > >>>>
> > >>>>>
> > >>>>> Constraints can hold complex javascript. To cap constraints to a
> > >>>>> range (100-500 in this example), I use something like
> > >>>>> width="{max(100, min(500, sizeslider.value))}"
> > >>>>>
> > >>>>> A nest of trinary ? expressions would probably be faster by avoiding
> > >>>>> two function calls. With whitespace added for clarity:
> > >>>>> width="${ sizeslider.value < 100
> > >>>>> ? 100
> > >>>>> : ( sizeslider.value > 500 ?
> > >>>>> 500
> > >>>>> : sizeslider.value)) }"
> > >>>>>
> > >>>>> It is sometimes clearer to express this as a handler for
> > >>>>> sizeslider.onvalue, something like this:
> > >>>>> <handler reference="sizeslider" event="onvalue"
> > >>>>> method="setClampedSize" />
> > >>>>> <method name="setClampedSize" args="x">
> > >>>>> var xclamp = min(100, max(500, x));
> > >>>>> mybox.setAttribute("width", xclamp);
> > >>>>> </method>
> > >>>>>
> > >>>>> The compiler probably turns the first and third forms above into the
> > >>>>> same thing; if the compiler has an optimization for min and max (but
> > >>>>> I don't think it does) then all three forms would be equivalent.
> > >>>>>
> > >>>>> -ben
> > >>>>>
> > >>>>> On Sep 22, 2006, at 10:25 PM, [EMAIL PROTECTED] wrote:
> > >>>>>
> > >>>>>> In my example below, I create a view with a smaller nested view.
> > >>>>>> The
> > >>>>>> inner view gets its size from constraints based on the its parent.
> > >>>>>> The problem is, when the parent is resized too small, the
> > >>>>>> constraints
> > >>>>>> on the inner view become negative. If you run my app, you can
> > >>>>>> adjust
> > >>>>>> the size with the slider and see what happens. Basically, I need
> > >>>>>> some
> > >>>>>> way to have a constraint that tracks the parent, but cannot become
> > >>>>>> negative. Is there some way to do this in a contstraint? Or
> > >>>>>> possibly
> > >>>>>> a different solution that doesn't have the negative constraint
> > >>>>>> problem?
> > >>>>>>
> > >>>>>>
> > >>>>>> <canvas>
> > >>>>>>
> > >>>>>> <view x="20" y="20" layout="axis:y">
> > >>>>>> <view layout="axis:x">
> > >>>>>> <text text="outer view size: "/>
> > >>>>>> <slider id="sizeslider" width="100" showvalue="true"
> > >>>>>> value="50"/>
> > >>>>>> </view>
> > >>>>>> <view layout="axis:x">
> > >>>>>> <text text="inner view size: "/>
> > >>>>>> <text text="${box.subviews[0].height}" bgcolor="silver"/>
> > >>>>>> </view>
> > >>>>>> </view>
> > >>>>>>
> > >>>>>> <view id="box" x="20" y="80" bgcolor="blue"
> > >>>>>> width="${sizeslider.value}" height="${sizeslider.value}">
> > >>>>>> <view bgcolor="green" x="10" y="10"
> > >>>>>> width="${parent.width - 20}" height="${parent.height -
> > >>>>>> 20}"/>
> > >>>>>> </view>
> > >>>>>>
> > >>>>>>
> > >>>>>> </canvas>
> > >>>>>>
> > >>>>>>
> > >>
> > >>
> > >>
> > >> _______________________________________________
> > >> Laszlo-user mailing list
> > >> [email protected]
> > >> http://www.openlaszlo.org/mailman/listinfo/laszlo-user
> >
> >
> >
> >
> > _______________________________________________
> > Laszlo-user mailing list
> > [email protected]
> > http://www.openlaszlo.org/mailman/listinfo/laszlo-user
> >
>
>
> --
> Henry Minsky
> Software Architect
> [EMAIL PROTECTED]
>
> _______________________________________________
> Laszlo-user mailing list
> [email protected]
> http://www.openlaszlo.org/mailman/listinfo/laszlo-user
>
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