Odd Question About Fonts

[chris319]

I have an odd question about fonts.

When I draw a character in PB there is an enclosing background box which extends above and below the character forms themselves. Is this a function of PB, Windows, or the font itself? Does anyone know how the size of this enclosing box is calculated? I'm trying to align some text based on the tops and bottoms of the actual characters, rather than the enclosing box.

[luis]

That's the cell around the char. It's there to make room for the ascending and descending part of the chars and their accents.
The height of the cell should be constant, the width is variable.
The chars are all aligned on a base line with part of some chars ascending and other descending from that.

You may find some of the info you are looking for in the TEXTMETRIC structure
http://msdn.microsoft.com/en-us/library ... 85%29.aspx

Some background on the nomenclature used
http://support.microsoft.com/kb/74299

[chris319]

How would I set up and access a textMetric structure in PB for a given font?

[luis]

How would I set up and access a textMetric structure in PB for a given font?

Code: Select all

 Define TM.TEXTMETRIC
 
 pointsize = 48
 
 ; http://msdn.microsoft.com/en-us/library/dd183499%28v=vs.85%29.aspx
 fnt = LoadFont(#PB_Any, "Arial", -pointsize)
 font_obj = FontID(fnt)
 
 HWnd = 0 ; handle of your win here, 0 = desktop
 hDC = GetDC_(HWnd)
 
 Debug "logical height requested = " + StrF((pointsize * GetDeviceCaps_(hDC, #LOGPIXELSY)) / 72.0)
 
 old_obj = SelectObject_(hDC, font_obj)
 GetTextMetrics_(hDC, @TM)
 SelectObject_(hDC, old_obj)
 
 Debug "Height = " + TM\tmHeight
 Debug "InternalLeading = " + TM\tmInternalLeading
 Debug "Ascent = " + TM\tmAscent
 Debug "Descent = " + TM\tmDescent 
 Debug "cell height = " + Str(TM\tmHeight + TM\tmInternalLeading)

[chris319]

Thank you for posting that sample code. Nice!

[chris319]

Here is a good description of font metrics:

http://www.freetype.org/freetype2/docs/ ... phs-3.html

[IdeasVacuum]

It is indeed, thanks for that link! You can by the way use PB's 2D drawing lib to determine text size. That would be cross-platform so might be worth considering.