bounding boxes in schematic

[Satya Mishra]

Hi All

I had been vexed by the bounding box problem with schematics for a
long time. Every once in a while, the bounding box for schematic would
be incorrect. This resulted in the fit to window not working quite
properly. (dbComputeBBox (geGetEditCellView)) didn't fix the problem.

Recently, I figured out that many (but not all) of these cases were
cause by pin labels when they are in 'textOnRight' or 'textOnLeft'
modes! If I change those pin-labels to 'textOnTop' the bounding box is
correct again.

Has any one else seen this kind of behaviour?

Regards
Satya

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[fogh]

Satya Mishra wrote:

Hi All

I had been vexed by the bounding box problem with schematics for a
long time. Every once in a while, the bounding box for schematic would
be incorrect. This resulted in the fit to window not working quite
properly. (dbComputeBBox (geGetEditCellView)) didn't fix the problem.

Recently, I figured out that many (but not all) of these cases were
cause by pin labels when they are in 'textOnRight' or 'textOnLeft'
modes! If I change those pin-labels to 'textOnTop' the bounding box is
correct again.

Has any one else seen this kind of behaviour?

Regards
Satya

Interesting story. Can you give a testcase ?

 

[Satya Mishra]

"fogh" == fogh <cad_support@skipthisandunderscores.catena.nl> writes:
fogh> Date: Thu, 26 May 2005 19:21:15 +0200

fogh> Satya Mishra wrote:

Hi All I had been vexed by the bounding box problem with
schematics for a long time. Every once in a while, the bounding
box for schematic would be incorrect. This resulted in the fit
to window not working quite properly. (dbComputeBBox
(geGetEditCellView)) didn't fix the problem. Recently, I
figured out that many (but not all) of these cases were cause
by pin labels when they are in 'textOnRight' or 'textOnLeft'
modes! If I change those pin-labels to 'textOnTop' the bounding
box is correct again. Has any one else seen this kind of
behaviour? Regards Satya

fogh> Interesting story. Can you give a testcase ?

Here's a test schematic with minimal components. There is a library
bboxtest, with one cell bboxtest. If you try to use "fit" command,
there is a lot of space on the left side of the schematic. If I change
the only pin to "textOnTop" everything is fine again.

Satya

 

[Gerry Vandevalk]

This is likely due to the concept of boundingboxes and what generates them.

Back several cadence generations ago ( say 3.2 ... ) the schematic and
layout
viewers were actually the same tool.

You could draw a rectangle on the "instance drawing" layer to override the
creation of the bBox based
simply on the extents of all data that is in the cell.
Typically text and changeLayer would cause me all sorts of grief wrt this.

YMMV



"fogh" <cad_support@skipthisandunderscores.catena.nl> wrote in message
news:119c1d8ne71t03f@news.supernews.com...

Satya Mishra wrote:

Hi All

I had been vexed by the bounding box problem with schematics for a
long time. Every once in a while, the bounding box for schematic would
be incorrect. This resulted in the fit to window not working quite
properly. (dbComputeBBox (geGetEditCellView)) didn't fix the problem.

Recently, I figured out that many (but not all) of these cases were
cause by pin labels when they are in 'textOnRight' or 'textOnLeft'
modes! If I change those pin-labels to 'textOnTop' the bounding box is
correct again.

Has any one else seen this kind of behaviour?

Regards
Satya

Interesting story. Can you give a testcase ?