Bug in Shape.DistanceFrom ??

[Tsung-Yuan Liu]

I tried to use the DistanceFrom property of the Shape object in Visio to
compute the distances between two shapes.
However, I found that for two shapes A and B, the values for
A.DistanceFrom(B, 0)
and
B.DistanceFrom(A, 0)
are sometimes different.

I opened a new Flowchart (Metric) drawing,
placed two "Process"es next to each other horizontally.
resized one so that they are of different sizes,
and making sure that the top and bottom sides of the two rectangles are not
on a straight line.
Then I tried the code:
Debug.Print
ActiveWindow.Page.Shapes.ItemFromID(1).DistanceFrom(ActiveWindow.Page.Shapes.ItemFromID(2), 0)
Debug.Print
ActiveWindow.Page.Shapes.ItemFromID(2).DistanceFrom(ActiveWindow.Page.Shapes.ItemFromID(1), 0)
and found that they output different values.

Is this normal?

 

[JuneTheSecond]

No, I cold not found difference.
If you turn one shape, then the difference appears.
I don't know why, because I don't know what the DistanceFrom method measures.

 

[Tsung-Yuan Liu]

Thanks for your response.
According to the MSDN documentation
(
http://msdn.microsoft.com/library/d...issdk11/html/viproDistanceFrom_HV81901685.asp )
DistanceFrom supposes to "Returns the distance from one shape to another",
which I assume to be the closest distance between the boundaries of 2D-shapes,
and that the distance from A to B should be equal to the distance from B to
A....

 

[John Marshall, MVP]

DistanceFromPoint goes to the nearest edge, but I am not sure of the logic
for DistanceFrom. It appears that it is the closest edge, but there is no
indication of the starting point. There is a difference going from B to A
rather than A to B for some shapes, so it may be related to the PinX and
PinY. Hopefully one of the MS team will see this message and comment.

John... Visio MVP

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[JuneTheSecond]

I am not sure, but I assume that the smaller value may be the right distance.

 

[Tsung-Yuan Liu]

I am guessing that A.DistanceFrom(B )
returns the closest distance between the vertices of A to the edges in B,
resulting in different distances between A to B and B to A.

Perhaps the implementation of DistanceFrom just runs a loop over the
vertices and compute DistanceFromPoint for each one...

 

[JuneTheSecond]

Here is an example where the distances differs much.An inverted trapezoid and
a circle.
When measured from inverted trapezoid. the DistanceFrom returns 17.9mm,
but when measured from the circle it returns 52.7mm , it's hard to believe.
http://www.mster.co.jp/visiosquare/cgi-bin/cbbs/file/DistanceFrom.gif