MSAGL heuristic layout

Question

Hi,

 I also have the same requirement as specified int the thread http://social.msdn.microsoft.com/Forums/en-US/automaticgraphlayout/thread/0b68df07-a598-4c15-aef7-6b297e8d157f

It will be helpful if you can tell me how can i set the GraphAttr.AspectRatio proprty to achieve this.

Thanks
Rub

Answer 1

I think I did reply to this question at the referenced thread. I am probably missing something.
Thanks,
Lev

---

Lev Nachmanson

Answer 2

Hi Lev,

 I am sorry that i was not clear from my side. Graph.Attr.AspectRatio is a expecing a double value and by setting that property how can i achieve a graph as mentioned in the ftp://ftp.research.microsoft.com/pub/tr/TR-2007-72.pdf Figure 1.

I tried setting this property to some random values but it increases the distance between the nodes in a single row. Do i need to address any other property along with the AspectRation property?

Thanks
Rub

Answer 3

Hi Rub,
I see. To achieve the effect of this picture you need to set GeometryGraph.SimpleStretch=false;
If SimpleStretch is set to true then just a simple transformation is applied to get the required aspect ratio.
Thanks,
Lev

---

Lev Nachmanson

Answer 4

Hello everybody,

I stumble over the same problem, but I can't figure out *when* I have to set the AspectRatio and SimpleStrech properties. Could someone provide a more complete example?

And another question: What is the unit in which MSAGL "thinks"? In what unit are properties like LabelMargin, XRadius and so on given and settable?

 

---

Best Regards, Stefan Falk

Answer 5

Hi Stefan,

To change the SimpleStretch property one needs to have access to the GeometryGraph object. I modified NodesWithImagesSample by adding these twlines

//setting the aspect ratio

geomGraph.SimpleStretch=false;

geomGraph.AspectRatio = 1;

// aspect ratio is set

geomGraph.CalculateLayout();

============

There is no good API to set it on the level of Microsoft.Drawing.Graph. I believe I did not provide such an API because I was not satisfied with the quality of the layouts produced by the algorithm when SimpleStretch is false.

 

Answering the question on the units: MSAGL draws in the same units as GDI+. Those are "logical units". The real size of a unit is defined by the device DPI ( Dots Per Inch).

 

 

 

---

Lev Nachmanson

Answer 6

Hello Lev,

oh, an answer from the creator of these fine algorithms himself - Chapeau!

I still do not see any difference in the diagrams created. I use a PowerShell script, here is a code excerpt:

$graph.Attr.LayerDirection = $layerDirection
$graph.Attr.AspectRatio = 1.3
$graph.GeometryGraph.SimpleStretch = $false
$renderer = New-Object Microsoft.Msagl.GraphViewerGdi.GraphRenderer($graph)
$renderer.CalculateLayout()
$scale = 2
$bitmap = New-Object System.Drawing.Bitmap(($scale * [int]$graph.Width), ($scale * [int]$graph.Height))
$renderer.Render($bitmap)

However, this does not produce any differend graph if I ommit or keep the statements with set the AspectRatio and SimpleStrech properties. Do I have to change the order of the statements?

 

---

Best Regards, Stefan Falk

Answer 7

Hi Stefan,

This will not work since under the hood GraphRenderer will create a new GeometryGraph and your settings will be forgotten.

The source of GraphRenderer is inside of the distribution, so you should have it. GraphRenderer in the and calls  GViewer.LayoutAndDGraph . You can also see how  GViewer.LayoutAndDGraph works. So, for your experiments you need to change method LayoutAndDGraph to take your settings into account, just before the call to

gleeGraph.CalculateLayout();

Thanks,

Lev

---

Lev Nachmanson