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Content

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	1	+{{warning}}
	2	+We haven't finished writing this page yet.
	3	+{{/warning}}
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3	3	This page describes how automatic layout can be configured for a given application. This includes how layout options can be set on graph elements, and how they are applied by KIML during the layout process. After having read this, you should be able to answer the following questions:
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36	36	</extension>
37	37	{{/code}}
38	38
39		-(% style="line-height: 1.4285715;" %)Let's walk through the attributes available for layout options (not every available attribute appears in the example above):
	41	+(% style="line-height: 1.4285715;" %)Let's walk through the parameters available for layout options (not every available parameter appears in the example above):
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41	41	* (% style="line-height: 1.4285715;" %){{code language="none"}}id{{/code}} – A unique identifier for this layout option. It is recommended that the identifier be prefixed by the plug-in name, to guarantee uniqueness.(%%)\\
42	42	* {{code language="none"}}type{{/code}} – Defines the data type of this option; must be either {{code language="none"}}boolean{{/code}}, {{code language="none"}}string{{/code}}, {{code language="none"}}int{{/code}}, {{code language="none"}}float{{/code}}, {{code language="none"}}enum{{/code}}, {{code language="none"}}enumset{{/code}}, or {{code language="none"}}object{{/code}}. The types {{code language="none"}}enum{{/code}}, {{code language="none"}}enumset{{/code}}, and {{code language="none"}}object{{/code}} require the {{code language="none"}}class{{/code}} attribute to be set.
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50	50	* (% style="line-height: 1.4285715;" %){{code language="none"}}class{{/code}} – An optional Java class giving more detail on the data type. For {{code language="none"}}enum{{/code}} and {{code language="none"}}enumset{{/code}} options this attribute must hold the Enum class of the option. For {{code language="none"}}object{{/code}} options it must hold the class name of an {{code language="none"}}IDataObject{{/code}} implementation.
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52	52	* (% style="line-height: 1.4285715;" %){{code language="none"}}default{{/code}} – The default value to use when no other value can be determined for this option.
53		-* (% style="line-height: 1.4285715;" %){{code language="none"}}lowerBound{{/code}} – An optional lower bound on the values of this layout option.
54		-* (% style="line-height: 1.4285715;" %){{code language="none"}}upperBound{{/code}} – An optional upper bound on the values of this layout option.
55		-* (% style="line-height: 1.4285715;" %){{code language="none"}}variance{{/code}} – An optional variance for values of this layout option. The variance is taken as multiplier for Gaussian distributions when new values are determined. Options with uniform distibution, such as Boolean or enumeration types, do not need a variance value, since all values have equal probability. A variance of 0 implies that the option shall not be used in automatic configuration, regardless of its type.
	55	+* (% style="line-height: 1.4285715;" %){{code language="none"}}lowerBound{{/code}} – An optional lower bound on the values of this layout option. This is used when a layout configuration is determined automatically.
	56	+* (% style="line-height: 1.4285715;" %){{code language="none"}}upperBound{{/code}} – An optional upper bound on the values of this layout option. This is used when a layout configuration is determined automatically.
	57	+* (% style="line-height: 1.4285715;" %){{code language="none"}}variance{{/code}} – An optional variance for values of this layout option. This is used when a layout configuration is determined automatically. The variance is taken as multiplier for Gaussian distributions when new values are determined. Options with uniform distibution, such as Boolean or enumeration types, do not need a variance value, since all values have equal probability. A variance of 0 implies that the option shall not be used in automatic configuration, regardless of its type.
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57	57
58		-(% style="line-height: 1.4285715;" %)The latter three attributes are used when a layout configuration is determined automatically, e.g. with an evolutionary algorithm. They are mainly meant for scientific experiments and can be ignored in most applications.
	60	+{{warning title="ToDo"}}
	61	+Provide a better explanation of what the latter three parameters are used for. Are they only relevant to evolutionary layout?
	62	+{{/warning}}
59	59
60	60	(% style="line-height: 1.4285715;" %)If a layout algorithm supports a particular layout option, it must tell KIML so. Here's an example:
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74	74
75	75	= (% style="line-height: 1.4285715;" %)The Layout Options Manager(%%) =
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77		-(% style="line-height: 1.4285715;" %)By now, we have an idea of what layout options do and why they are important in the first place. However, we haven't looked at how layout options end up on [[KGraph>>doc:KGraph Meta Model]] elements yet. This is where the [[{{code language="none"}}LayoutOptionsManager{{/code}}>>url:http://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml.ui/src/de/cau/cs/kieler/kiml/ui/service/LayoutOptionManager.java||shape="rect"]] comes in.
	81	+(% style="line-height: 1.4285715;" %)By now, we have an idea of what layout options do and why they are important in the first place. However, we haven't looked at how layout options end up on KGraph elements yet. This is where the [[{{code language="none"}}LayoutOptionsManager{{/code}}>>url:http://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml.ui/src/de/cau/cs/kieler/kiml/ui/service/LayoutOptionManager.java||shape="rect"]] comes in.
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79		-(% style="line-height: 1.4285715;" %)After a diagram layout manager has finished turning a given diagram into its KGraph representation, the layout options manager is asked to enrich the KGraph elements with layout options. The option values can come from different sources: the user might have set some using the layout view; there might be some defaults for certain kinds of diagrams; or the programmer might have decided to attach some layout options to certain elements for just this one layout run. Whatever the source, the options manager is in charge of collecting all these layout option values and making sure they find their way to the correct KGraph element. To start off with a clean plate, it first makes sure there are no layout options attached to the KGraph elements. It then does two things: collect every eligible source of layout options, and transfer values of layout options to the associated KGraph elements. Sounds easy enough.
	83	+{{tip}}
	84	+The [[KIML page>>doc:Infrastructure for Meta Layout (KIML)]] has a high-level explanation of what happens when during the layout process. To take a look at it if you haven't already – it will make the following concepts easier to understand. Plus, there's a nice picture that took Miro quite some time to create.
	85	+{{/tip}}
80	80
81		-(% style="line-height: 1.4285715;" %)The question remains how the layout options sources work. Each source is represented by a class that implements the [[{{code language="none"}}ILayoutConfig{{/code}}>>url:https://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml/src/de/cau/cs/kieler/kiml/config/ILayoutConfig.java||shape="rect"]] interface, called a //layout configurator//. KIML currently provides the following layout configurators, each representing a particular source of layout options, listed here in order of increasing priority:
	87	+(% style="line-height: 1.4285715;" %)After a layout manager has finished turning a given diagram into its KGraph representation, the layout options manager is asked to enrich the KGraph elements with layout options. The option values can come from different sources: the user might have set some using the layout view; there might be some defaults for certain kinds of diagrams; or the programmer might have decided to attach some layout options to certain elements for just this one layout run. Whatever the source, the options manager is in charge of collecting all these layout option values and making sure they find their way to the correct KGraph element. To start off with a clean plate, it first makes sure there are no layout options attached to the KGraph elements. It then does two things: collect every eligible source of layout options, and transfer layout options to the correct KGraph elements. Sounds easy enough.
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83		-* [[DefaultLayoutConfig>>url:https://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml/src/de/cau/cs/kieler/kiml/config/DefaultLayoutConfig.java||shape="rect"]]{{code language="none"}}{{/code}} – Applies fixed default values defined in the meta data of layout options. This is important for the Layout View, which displays the default values if nothing else has been specified.
84		-* [[EclipseLayoutConfig>>url:https://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml.service/src/de/cau/cs/kieler/kiml/service/EclipseLayoutConfig.java||shape="rect"]]{{code language="none"}}{{/code}} – Users can define default layout options to be set on elements that meet certain criteria via the KIML preference page. This layout configurator takes these options and applies them. Furthermore, it also applies options configured through the extension point.
85		-* [[SemanticLayoutConfig>>url:https://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml/src/de/cau/cs/kieler/kiml/config/SemanticLayoutConfig.java||shape="rect"]]{{code language="none"}}{{/code}} – An abstract superclass for configurators that base their computation of layout option values on the //semantic// model, a.k.a. //domain// model.
86		-* [[GmfLayoutConfig>>url:https://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml.gmf/src/de/cau/cs/kieler/kiml/gmf/GmfLayoutConfig.java||shape="rect"]]{{code language="none"}}{{/code}} / [[GraphitiLayoutConfig>>url:https://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml.graphiti/src/de/cau/cs/kieler/kiml/graphiti/GraphitiLayoutConfig.java||shape="rect"]]{{code language="none"}}{{/code}} – These configurators apply layout option values set by the user in the Layout View. The values are stored in the notational model file of a diagram.
87		-* [[VolatileLayoutConfig>>url:https://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml/src/de/cau/cs/kieler/kiml/config/VolatileLayoutConfig.java||shape="rect"]]{{code language="none"}}{{/code}} – A configurator for setting certain layout option values in one particular layout run. As the name says it, the values are volatile and thus they are not persisted.
	89	+{{note}}
	90	+Since the options manager starts by removing all layout options set on graph elements, setting layout options on the graph elements in the layout manager is a futile endeavor.
	91	+{{/note}}
88	88
89		-The options manager collects all available and applicable layout configurators and sorts them by priority. For every graph element, each configurator is asked to provide layout options, starting with the one with lowest priority and working through the priority chain. Hereby configurators with higher priority are able to override values set by those with lower priority.
	93	+(% style="line-height: 1.4285715;" %)The question remains how the layout options sources work. Each source is represented by a class that implements the [[{{code language="none"}}ILayoutConfig{{/code}}>>url:https://git.rtsys.informatik.uni-kiel.de/projects/KIELER/repos/pragmatics/browse/plugins/de.cau.cs.kieler.kiml/src/de/cau/cs/kieler/kiml/config/ILayoutConfig.java||shape="rect"]] interface, called a //layout configuration//. KIML currently provides the following layout configurations, each representing a particular source of layout options:
90	90
	95	+* {{code language="none"}}DefaultLayoutConfig{{/code}} – Sets fixed default values defined for layout options.
	96	+* {{code language="none"}}EclipseLayoutConfig{{/code}} – Users can define default layout options to be set on elements that meet certain criteria via the KIML preference page. This layout configuration takes these options and applies them.
	97	+* {{code language="none"}}SemanticLayoutConfig{{/code}} – A configuration that bases its layout option values on the semantic objects represented by the KGraph elements.
	98	+* {{code language="none"}}GmfLayoutConfig{{/code}} / {{code language="none"}}GraphitiLayoutConfig{{/code}} – These configurations apply layout options set by the user in the layout view or stored in the notation model file of a diagram.
	99	+* {{code language="none"}}VolatileLayoutConfig{{/code}} – A configuration whose only purpose it is to make sure certain layout options are set on certain diagram elements in a particular layout run.
	100	+
	101	+The options manager collects all available and applicable layout configurations and sorts them by priority (incidentally, the configurations were sorted by increasing priority just now). For every graph element, each configuration is asked to provide layout options, starting with the default layout configuration and working through the priority chain.
	102	+
91	91	== A Few Details on Layout Configurations ==
92	92
93	93	What we just learned is a bit of a simplification of what happens. Before we look at the details, let's take a look at the methods each layout configuration provides:

Confluence.Code.ConfluencePageClass[0]

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	1	+9469977

URL

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1		-https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/KIELER/pages/9469979/Configuring Automatic Layout
	1	+https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/KIELER/pages/9469977/Configuring Automatic Layout