[cl-typesetting-devel] How does rotation work?

[Peter Seibel]

On Jul 20, 2005, at 10:38 AM, Marc Battyani wrote:

> Peter Seibel wrote:
>
>> On Jul 20, 2005, at 10:25 AM, Marc Battyani wrote:
>>
>>
>>> Peter Seibel wrote:
>>>
>>> Hi Peter,
>>>
>>> Sorry for the long reply delay, I'm just coming back from
>>> backpacking in the
>>> Alps :-)
>>>
>>>
>>>> I'm trying to set set a block of text rotated 90 degrees but the
>>>> rotation seems to rotate the box right off the page. Around what  
>>>> axis
>>>> does pdf:rotate rotate stuff? Or more to the point, what's the
>>>> easiest way to draw a block at a particular place but rotated 90
>>>> degrees?
>>>>
>>>>
>>>
>>> You can use the rotation parameter of draw-block. The rotation is
>>> around the
>>> top left corner of the block IIRC.
>>>
>>
>> Actually I think the rotation is around 0,0. So the trick is to use
>> pdf:translate to translate the coordinate system to where you want
>> the top left corner of the box to be and then draw-block at 0, 0 with
>> whatever rotation you want. But if you draw-block at some x,y with a
>> rotation it requires advanced trig to figure out where the box is
>> actually going to end up. At least it seems that way to my math
>> impaired brain.
>>
>
> No, draw-block already does the translate + rotation:
>
> ;;; from top-level.lisp
>
> (defmethod draw-block (content x y dx dy
>                        &key border (padding 5) rotation (v-align :top)
> special-fn)
>   (pdf:with-saved-state
>     (pdf:translate x y)
>     (when rotation
>       (pdf:rotate rotation))
> ...

Hmmm. I'll have to look back at my code when I get a chance. I got it  
working but I seem to recall having to manage the translation myself.

-Peter

-- 
Peter Seibel           * peter at gigamonkeys.com
Gigamonkeys Consulting * http://www.gigamonkeys.com/
Practical Common Lisp  * http://www.gigamonkeys.com/book/