As part of the never ending Weather station project I’m making a rotary dial morph that can be used to display things such as barometers, speedometers, vu meters, clocks, compasses etc - pretty much anything where a needle thing rotates about a pivot in order to point to a value on a scale.

Clearly one can be ultra simplistic and use a LineMorph over a CircleMorph but that isn't terribly pretty. Right now I have things set up to simply add submorphs to build whatever background and borders and tick marks are wanted, plus the needle. With an ImageMorph (or should it be a SketchMorph?) providing a picture of the dial/scale/frame it can look quite nice. 

However, the needle is a problem. A simple Line or PolygonMorph can be used and then it is possible to set the rotationCenter such that subsequent #rotationDegrees: make it turn about that centre. So far, so good. I’d prefer to allow arbitrary morphs for the needle - again, an image would be good in a lot of cases - but I cannot for the life of me find how to make general morphs rotate about a set point. I can use #rotationCenter: and the value is stuck in the extension as expected. If I use the halo rotate after doing that the new center point is clearly shown in the right place BUT it still rotates about the center of the bounds. I can’t find any illuminating usages of #rotationCenter to show how the new center point is used and certainly nothing that makes it look like it is ever treated as the pivot.

I’ve dug into using asFlexShell and friends with no improvement. I’ve searched through the swiki. I’ve compared a 5.0 image with the 6alpha image. To cause further concern pretty much all the rotate related code I can find seems to be in the EToys package, which may mean it would go away when we make a more typical release image. Isn’t rotating morphs a relatively basic part of using them?

What have I missed, or looked at without actually seeing?

tim
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tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
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