python - ImageFont's getsize() does not get correct text size?

Question

I use the following two methods to to generate text preview image for a .ttf font file

PIL method:

def make_preview(text, fontfile, imagefile, fontsize=30):
    try:
        font = ImageFont.truetype(fontfile, fontsize)
        text_width, text_height = font.getsize(text)
        img = Image.new('RGBA', (text_width, text_height))
        draw = ImageDraw.Draw(img)
        draw.text((0, 0), text, font=font, fill=(0, 0, 0))
        return True
    except:
        return False

ImageMagick method:

def make_preview(text, fontfile, imagefile, fontsize=30):
    p = subprocess.Popen(['convert', '-font', fontfile, '-background',
            'transparent', '-gravity', 'center', '-pointsize', str(fontsize),
            '-trim', '+repage', 'label:%s' % text, image_file])
    return p==0

Both methods create correct preview images most of time but in some rare cases (<2%), the font.getsize(text) just cannot get the correct text size which result in text overflowed provided canvas. ImageMagick has same problem.

Sample fonts and previews:

HANFORD.TTF http://download.appfile.com/HANFORD.png

NEWTOW.TTF http://download.appfile.com/NEWTOW.png

MILF.TTF http://download.appfile.com/MILF.png

SWANSE.TTF http://download.appfile.com/SWANSE.png

I have looked into ImageMagick's documentations and found the explanation of this problem at http://www.imagemagick.org/Usage/text/#overflow.

Is it possible to detect such text overflows and draw text to fit the canvas as we expected?

Answer 1

Not a programming solution, but when I regenerate your problem, its only happens on your fonts (other fonts like Arial is no problem at all), so I have fixed your font files (by changing ascent/decent metrics). you can download here,

And sorry about Hanford Script Font, its not perfect as you see, height seems ok, but left side is not get drawed, its out of my understanding.

UPDATE: Regarding Hanford Font, Here is a work around, pass extra space in text like " Handford Script", and then crop the extra space in image like img=img.crop(img.getbbox())

alt text http://img64.imageshack.us/img64/1903/hanfordfontworkaround.jpg

UPDATE2:I had to pass color=(255,255,255) in Image.New to get Black Text on White background

img = Image.new('RGBA', (text_width, text_height),color=(255,255,255))