From: Tim Hunter <TimHunter@...>
Date: 2008-04-01T07:20:32+09:00
Subject: Re: metrics rmagick problem

Eduard Bondarenko wrote:
> Thanks Tim,
> 
> But centerGravity don't works as expects.
> I've added
> d.gravity = Magick::CenterGravity
> 
> and changed
> d.text(0,0, text)
> 
> but the text isn't in the image center.
> annotate give the same result.
>

Sorry this is so much trouble.

Try this. For me, this exactly centers the word "RMagick" on the image. 
I'm using ImageMagick 6.4.0 and RMagick 2.3.0, but I would expect this 
to work with any relatively recent version of ImageMagick and RMagick. 
If it doesn't work for you, please open a support request on the RMagick 
project on RubyForge, let me know what versions of ImageMagick and 
RMagick you're using, include a simple reproduction of your problem and 
attach the output image you get.

require 'RMagick'

img = Magick::Image.new(500, 500)

gc = Magick::Draw.new
gc.stroke "red"
gc.fill "white"
gc.circle 249.5, 249.5, 249.5, 255
gc.line 0, 0, 499, 499
gc.line 0, 499, 499, 0
gc.draw img

translucent_blue = Magick::Pixel.from_color "blue"
translucent_blue.opacity = Magick::QuantumRange * 0.50
translucent_blue = translucent_blue.to_color(Magick::AllCompliance, 
true)

gc = Magick::Draw.new
gc.gravity Magick::CenterGravity
gc.text_undercolor translucent_blue
gc.pointsize 48
gc.fill "rgba(100%, 100%, 100%, 0.50)"
gc.text 0, 0, "RMagick"
gc.draw img

img.matte = false
img.display

-- 
RMagick: http://rmagick.rubyforge.org/
RMagick 2: http://rmagick.rubyforge.org/rmagick2.html