[reportlab-users] Several questions about text output

[Robin Becker]

Grzegorz Adam Hankiewicz wrote:

> 

> El 13/07/2008, a las 22:48, Grzegorz Adam Hankiewicz escribió:

> 

>> On the font issue, how can I clip the text to a region? Let's say that 

>> I have a text too long to fit and don't want it to go out of the page. 

>> Is this done with the paths?

> 

> I found the answer at 

> http://two.pairlist.net/pipermail/reportlab-users/2005-February/003717.html. 

> However, now I am having a problem calculating the bounding box of a font.

> 

> When I draw a text string at 0,0, letters like 'g' or 'j' descend below 

> the 0 y coordinate into negative numbers. I know the font size, but I 

> don't know how much do I have to displace my bounding box in order to 

> not have the lower part of the letters being clipped.

> 

> In the reference manual I found the word "baseline" ppear in the setRise 

> documentation, but that doesn't help me. Any suggestions?

......

if you use String objects from the graphics library you can see the 
bounding boxes with getBounds, but as in the canvas we use the old 
standards from Gutenberg etc etc.

When we draw a string the x coord is the start of the first character, 
but the y coord always refers to the baseline of the font. Typically in 
western glyphs that's the same as the bottom of cap A. That being the 
case then always stuff like y/j descends below. In recent reportlab you 
can do this

ascent,descent = getAscentDescent(fontName,fontSize)

if you don't specify fontSize then 1000 is assumed.

This will return the values for the ascent and descent of the font from 
the baseline. So for fontSize x your string box will be


x,y-descent,x+stringWidth(s,fontName,fontSize),y+ascent

hope this isn't too arcane
-- 
Robin Becker