Calculator in input fields

I'll second this request.

I'm designing a woodworking project, and would very much like to enter sizes in fractions of an inch. (Yes, I know, but they don't have mm size lumber here.)

It would also be nice to enter distances and sizes with units, e.g. "35 mm" even if your default units were inches.
As a quick hack, the expression could be exported to the Unix program "units".

I also think this would be a very handy addition. In my case I would like to be able to type "+30" and have the current number increased by 30.

There is a blueprint related to this feature: https://blueprints.launchpad.net/inkscape/+spec/smart-edit-box

This would be a very useful feature. It would be great to see this in Inkscape, Gimp, and any other programs with number input boxes. Maybe this would/could be better implemented as a system wide feature by the OS so any number inputboxes (irrelevant of the program) could have the option of parsing formulas.

New duplicate:
Bug #720694 “Mathematical operators in numeric input fields”

working on it :)

Marking as Fix Committed. Most spinboxes should have this functionality now. Please open a new bug report if you find that it does not work somewhere.
"Pagewidth" and "pageheight" does not work.
For some dialogs (like the guideline dialog), I am thinking about adding support for the % unit, that specifies the percentage of pageheight / pagewidth.

That looks great Johan and working well.
Questions are :
- could i use object name in calculations (this is kind of similar to keyword usage like pagewidth). For example, if i want the size of an object to be half of another, i'd just write : object2.height=object1.height/2
- only the result of the calculation is kept in the field. Would it be feasible to keep the formula so that (taking previous example) if i change object1 size, object2 would be affected.

I know, clone can do that but using clones assumes the objects have the same shape.
In fact, i don't know if that's not too much, these are just ideas

On 17-4-2011 17:57, pygmee wrote:
> - could i use object name in calculations (this is kind of similar to keyword usage like pagewidth). For example, if i want the size of an object to be half of another, i'd just write : object2.height=object1.height/2

Although this functionality is somewhat easier to add than the next
point, I think it will only make sense in conjunction with the next:

> - only the result of the calculation is kept in the field. Would it be feasible to keep the formula so that (taking previous example) if i change object1 size, object2 would be affected.

I think SVG supports defining sizes of objects in terms of variables.
But it will be a lot of work to implement this in Inkscape. Although I
see some benefit of this, it is just too much for me to do. (and it
seems a bit too much for Inkscape at this moment too)

Of course. you've already done a very nice add. Thanks again.

Follow-up report (as requested in comment #7):
Bug #773636 “Use expression evaluator for spinboxes of the 'Tiled Clones' dialog”
<https://bugs.launchpad.net/inkscape/+bug/773636>

Follow-up report to enhance the current implementation:
 Bug #1024362 “RFE: enhance expression evaluator in input boxes”