font + string --> text bounding box size?

[HakimBey]

As a part of a bigger application I want to draw a graph
with labeled nodes and lines connecting the labels.
The node positions will be in the "db" and editable,
but the drawing I want generic, so that there should
be a way to calculate the size of the label,
"obj.BoundingBox()" so to say.

An example:

Code:

test: func [spec] [
   view layout [box 400x800 black effect [draw spec]]
]
bold20: make face/font [style: 'bold size: 20]
test [
   pen yellow
   line 30x30 60x260

   fill-pen yellow
   pen navy
   box 18x18 220x42
   font bold20 text anti-aliased "Some labeled graph" 20x20

   box 50x250 110x280
   text "Hello!" 52x252
]

How that can be done? I can restrict the app to
have only one font size and only one font, and
it is OK if there is only an approximative estimation
for the bounding box (yellow box in the code).
And the font can be fixed to be Arial or something with
regular spacing. But if there is an even more generic
way, the better...

(I have used Rebol many years, but have not
done many visual apps with it).

Any help appreciated, and Happy New year too!

[CarlRead]

You can find the area used by text with SIZE-TEXT.  ie...

>> layout [t: text "abc"]
>> size-text t
== 22x15
>> layout [t: text "abcdef"]
>> size-text t
== 39x15

Note that this is different than the size of the face the text is within...

>> layout [t: text "abcdef"]
>> size-text t
== 39x15
>> t/size
== 43x19

Hope that's of some use.
 

[Guest]

Thx a lot, that is OK, I can afford that when new
label gets added, it is once processed by
"layout" and the tex-size recorded with it
for the future...