Eduard said:
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:

raw.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:

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

raw.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