How do you get an impoly class object from its handle?

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Andrew Diamond
Andrew Diamond on 5 Jun 2012
Commented: Image Analyst on 31 May 2015
I created impoly objects with impoly. Their tag is impoly. At some later point I want to get all the properties of all the created impolys. I can use findall on a Tag of impoly but that apparently just returns the handles as opposed to the class objects. I know this because when I try calling the impoly methods (e.g. getColor) on a returned handle it barfs because the handle, which is a double, isn't an impoly class object. Calling impoly on the class does not cast it.
I could store the objects when they are created to work on them later but they user might delete them etc. In any even it seems silly to do that.
=
specifics: On my gui a botton links to a callback which calls impoly. impoly returns an impoly object that the impoly members can operate. Eg h=impoly(axeshandle) setColor(h,'red');
When the user clicks my "Save" button, another callback is called and in that I use a H=findall(axeshandle, 'Tag', 'impoly') to find and return all the polygons. However, H is all double type graphics handles and so a call like GetColor(H(1)) will fail with the error :
Conversion to double from cell is not possible.

Answers (2)

Andrew Diamond
Andrew Diamond on 5 Jun 2012
Apparently the function aptgetapi gives access to the methods.
Given h, a returned simple handle (by findobj or findall)
api=iptgetapi(h)
PtsList = api.getPosition();
yields a nx2 list of polygon points. I'm sure the other methods work accordingly.
I simply can't believe what it took to find this out. Searching support didn't seem to yield anything. You'd think I was the first person to do it or it was plainly obvious. I find either hard to believe.
It's like original sin.
  3 Comments
Image Analyst
Image Analyst on 31 May 2015
"I simply can't believe what it took to find this out." - probably because hardly anyone ever does that, and if they did, they'd just save the poly objects in a cell array if they knew they'd need them later.

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Walter Roberson
Walter Roberson on 5 Jun 2012
imh = handle(h);
imh.setColor('red');
  1 Comment
Andrew Diamond
Andrew Diamond on 5 Jun 2012
This doesn't seem to work as the handle(h) returns an object of class hggroup vs impoly.( and impoly, not hggroup, has the setColor etc methods)

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