Here is an example that shows the distinction between edge and line:
elementToVisualize := BlChicken chicken.
root := BlElement new constraintsDo: [:c |
c horizontal matchParent. c vertical matchParent].
elementToVisualize allChildrenBreadthFirstDo: [ :each |
| label |
label := BlTextElement new
text: each gtDisplayString asRopedText;
background: Color white;
effect: (BlDropShadowEffect color: (Color gray alpha: 0.5) width: 10 offset: 0@0).
label userData at: #model put: each.
detect: [ :child |
(child userData at: #model ifAbsent: [ nil ]) = each parent ]
ifFound: [ :parentLabel |
| edge |
edge := GtGraphEdge new from: parentLabel to: label.
parentLabel constraints graph addConnectedEdge: edge.
label constraints graph addConnectedEdge: edge ].
root addChild: label].
root layout: (GtGraphHorizontalTreeLayout new layered; verticalGap: 20).
With this we visualize the elements that make the chicken element demo:
- we create a label for each element
- we find the parentLabel corresponding to the parent element
- we create an edge between the parentLabel and the current label
The example gives us this:
The edge is a constraint. It has no visual impact. And the graph layouts take the edge
constraints into account. The cool thing is the GtGraphEdge is defined next to the graph
layout classes, not in the core of Bloc.
To add a visual impact, we have to create a separate line:
Thanks for the question. This email is now a comment in the graph layout examples and can
be viewed like this:
On Dec 9, 2017, at 8:43 AM, Stéphane Ducasse
Super super cool.
> On 9 Dec 2017, at 08:14, Tudor Girba <tudor(a)tudorgirba.com> wrote:
> We are happy to announce GT Mondrian, a graph visualization engine built on top of
> It is similar to the original Mondrian and the Mondrian from Roassal, but it is
different in that it is built directly out of Bloc elements. This is interesting because
it allows us to combine typical widgets with visualizations. The other interesting thing
about it is that it validates the design of Bloc: right now, the implementation has 509
lines of code (excluding graph-specific layouts). The goal is to make visualization a
first class citizen and an integral part of the IDE.
> The key ingredient that made this happen is that Bloc can now treat graph layouts,
such as tree or force based, behave under the same rules as typical widget layouts, such
as grid or flow. The challenge comes from the fact that a graph layout depends on the
notion of edges between elements, and we did not want to have elements know about edges in
the core of Bloc.
> The solution was to split the typical edge implementation in graph visualization
libraries into two distinct concepts:
> • Line is an element that draws the connections.
> • Edge defines constraints imposed by connections between elements.
Can you give an example?
BTW doru did you think about having a bloc layer on top of telescope model?
Because from that perspective telescope offers a visualisation model while
roassal/mondrian like design are
more a pen-oriented metaphor.
I wanted to do it to learn Bloc but I’m running against time and trying to flush pilling
duties (I want to also release
the book that we wrote with luc and olivier and convert the seaside book and and and…..
> Thus, edges form constraints, and constraints are what layouts deal with. That is one
reason why elements in bloc have the ability of defining layout-specific constraints.
Using this, we can nicely define edges between elements as a plugin to Bloc, but still be
able to connect arbitrary elements. What's more, it turns out that we need constraints
for other layouts as well. For example, an element in a grid layout might specify the
> The API of GT Mondrian is similar to the one from Roassal, but there are a few
differences as well. These are described in the Pillar documentation available in the
> The best way to experience GT Mondrian and its documentation is to load the GToolkit
as described here:
> If you download the GT code through Iceberg, the documentation can be experienced
live by inspecting:
> The feenk team
> "Quality cannot be an afterthought."
> Moose-dev mailing list
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