Re: Pango, set height in pixels

[Dennis Bjorklund <db zigo dhs org>]

On 13 Jan 2002, Havoc Pennington wrote:

> > The doc of pango_font_description_set_size () says
> > 
> > size : the size for the font description in pango units. (PANGO_SCALE 
> > pango units equals one point)
> 
> PANGO_SCALE pango units equals one "device unit" which for the screen
> is pixels and for printed output would probably be points. The docs
> there are broken, yeah. I'll fix them.

I'm not sure that is correct either. I talked a bit on #gtk+ and there 
doesn't seem to be any connection to pixels at all. You can end up with 
any size, usually close to what you want, but you never know.

I made a small test program and put up some screenshots of how the text
rendering looks when I set the size to 20*PANGO_SCALE. 

http://www.zigo.dhs.org/~dennis/pango-test/

The reason I want to know approx. how high the text is in pixels is 
because I draw a chess board and want the coordinates to match the square 
size. And the square size changes when I resize the window, so the 
coordinate will have to change size as well.

The solution I have so far is to have a loop where I set the size, render 
and then do pango_layout_get_pixel_extents () until the height is not to 
big. In my test program when I set the height to 20*PANGO_SCALE the 
logical rect was 36 pixels high.

Also notice the big difference in logical rect when I run with 
GDK_USE_XFT=1. But probably it has chosen another font in this case.

It seems the loop (or binary search) is the correct way to get what I
need.

-- 
/Dennis