I’ve just introduced a new class TRExtensibleLabelShape and TRLabelShape. This will ease the problem we are experiencing with using labels in a composed shape. 

I would like now to discuss about how to compose shapes. This has been a big discussion for at least 5 years. I propose a solution in this email, I hope this will make most of us happy :-)

Consider the example:

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| v s1 s2 c es |
v := RTView new.

s1 := (RTEllipse new size: #yourself; color: (Color blue alpha: 0.4)).
s2 := (RTLabel new text: 'Hello World'; height: 10).

c := RTCompositeShape new 
shape1: s1; 
shape2: s2;
offset2: 0 @ -30.

es := c elementsOn: #(30 60 80).
es @ RTDraggable.
v addAll: es.

es when: TRMouseClick do: [ :evt | evt element remove. v signalUpdate ].

RTHorizontalLineLayout on: v elements.
v open

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This is the output:

If you click on an element, then the element with its label is properly removed. Yupi! Leo will be happy with that :-)

The reason is that how can I specify to have s2 above s1? What should I put in offset2 ? Instead of fiddling with blocks like [:shape1 :shape2 :element | … ] I have introduced RTHorizontalCompositeShape and RTVerticalCompositeShape just to try whether it make sense or not.

We can have 

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| v s1 s2 c es |
v := RTView new.

s1 := (RTEllipse new size: #yourself; color: (Color blue alpha: 0.4)).
s2 := (RTLabel new text: 'Hello World'; height: 10).

c := RTHorizontalCompositeShape new 
shape1: s1; 
shape2: s2.

es := c elementsOn: #(30 60 80).
es @ RTDraggable.
v addAll: es.

RTHorizontalLineLayout on: v elements.
v 

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Replacing Horizontal by Vertical works as expected. 

You can also compose these things. Look at that:

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| v s1 s2 c es |
v := RTView new.

s1 := (RTEllipse new size: #yourself; color: (Color blue alpha: 0.4)).
s2 := (RTLabel new text: 'Hello World'; height: 10).

c2 := RTVerticalCompositeShape new
shape1: s1;
shape2: s2.
c := RTHorizontalCompositeShape new 
shape1: s1; 
shape2: c2.

es := c elementsOn: #(30 60 80).
es @ RTDraggable.
v addAll: es.

RTHorizontalLineLayout on: v elements.
v 

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Are we happy with RTVerticalCompositeShape, RTHorizontalCompositeShape and RTCompositeShape ?

If yes, then RTLabelling (and its problem of passing the view along :-) will be obsolete.

Cheers,

Alexandre