spaghetti_rendering.md

FSM graph rendering

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This library does not produce graphical rendering of the state machine. But it provides a function to generate a standard dot file that can be used to generate the corresponding image with Graphviz.

To use it with default options:

	fsm_t fsm;
	...
	fsm.writeDotFile( "myDotFile" );

This will produce in the current folder the file myDotFile.dot. You can render into an svg image with:

$ dot -Tsvg myDotFile.dot > myGraph.svg

or

$ dot -Tpng myDotFile.dot > myGraph.png

for a png image.

Several options can be used, they are embedded in the spag::DotFileOptions data type.

The available options and default values are:

showActiveState = false
showTimeOuts    = true
showInnerEvents = true
showAAT         = true
showStateIndex  = true
showStateString = true
showEventIndex  = true
showEventString = true
showUnreachableStates = true
fixedNodeWidth = false
useColorsEventType = true

If you want to change one of these, instanciate this object, change one of the members value, and call the function by adding the options. For example:

	spag::DotFileOptions dfo;
	dfo.showActiveState = true;
	fsm.writeDotFile( "myDotFile", dfo );

The included test file tests/testA_2.cpp does a demo of these options. It has unreachable states to show how these can be removed from the rendering. This can be useful when handling a complex situation where you would want to printout a rendering while FSM is partially configured. The table below shows for the same FSM different renderings, when one option changes from the default value.

Option	Rendering
Default
showActiveState=true
showInnerEvents=false
showAAT=false
showTimeOuts=false
showEventIndex=false
showEventString=false
showStateIndex=false
showStateString=false
showUnreachableStates=false
fixedNodeWidth=true
useColorsEventType=false

When rendering with Graphviz, the size of the nodes are set automatically. If you prefer a fixed size, then you can set fixedNodeWidth to true, and assign the requested size (in inches) with nodeWidth. The default value is "1.5". For example:

	spag::DotFileOptions dfo;
	dfo.fixedNodeWidth = true;
	dfo.nodeWidth = "1.2";
	fsm.writeDotFile( "myDotFile", dfo );

The edges are colored depending on their type

• external event: black
• time out event: blue
• Internal event: red
• Always Active Transition (AAT): green

This can be disabled by setting useColorsEventType to false.

--- Copyright S. Kramm - 2018-2020 ---