[Drawkit] Questions on control knobs

[Brad Larson]

On Jun 25, 2008, at 8:22 PM, Graham Cox wrote:

>
> On 26 Jun 2008, at 6:32 am, Brad Larson wrote:
>> I like your implementation of the 80% radius control point better  
>> than than just using the center (0% radius), it's a lot easier to  
>> line up and size an arc that way.
>
> I've actually moved it to be 100% (on the arc itself) which has the  
> advantage of tracking the mouse more accurately. There's probably a  
> case here for using a custom DKKnob appearance (or adding a new  
> style to the existing knob class) that unambiguously indicates the  
> knob's function. Also, by angling the knobs to match the local  
> angle, they look better and have a more obvious function.

The final arc control design is really slick.  I don't know that I've  
worked with a vector drawing program that did as good a job as what  
you have now.

> I plan to include this in DK for the next release since now I see it  
> in use there's no doubt it's a very useful shape type.
>

I agree, it is a very nice implementation of a common shape.

There's just one issue I have with the current implementation, and  
that's when you are drawing the arc it currently uses a stroke width  
of 2.0 for the initial radius line.  At the high magnifications that  
we're dealing with, that becomes enormous.  For someone who is zoomed  
out, it might also present a problem.  This could be fixed by copying  
the current style and changing its color to make the temporary stroke  
style used at the beginning of DKArcPath's  arcCreateLoop: method,  
rather than generating it from scratch using the  
styleWithFillColour:strokeColour:strokeWidth: method as is done now.   
This should be simple, but I can't figure out an easy way to reach  
into a DKStyle and address its DKStroke so that I can set the  
DKStroke's properties.

Additionally, I have one last shape (source attached) that is simply a  
point.  We use it to represent a single droplet put down by our  
dispenser, so it's a very simple object that can't be resized, only  
placed on the drawing and moved.  Internally, its path just consists  
of a MoveTo the center of the point and a LineTo the same center  
point.  We use a feature style that has rounded endcaps and is as wide  
as the droplet would be.  I cribbed most of its code from the  
DKArcPath example you provided.  I can load and save the object using  
our XML file handling routines that programmatically create it, drag  
on its center to move it around, and delete it, but when I go to draw  
it, I click on the drawing and see it appear, then immediately  
disappear as I lift up the mouse.  There didn't seem to be a path  
drawing routine that handled stamping an object onto the drawing, so I  
repurposed lineCreateLoop:, but nothing leaps out at me as to what's  
going wrong.  I'll keep digging, but any suggestions as to what I  
might be missing would be greatly appreciated.

______________________
Brad Larson
SonoPlot, Inc.
3030 Laura Lane, Suite 120
Middleton, WI 53562

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