Centering text in Gosu - ruby

Question

I've been having trouble centering text in the Gosu library to the absolute middle of the screen.
require 'gosu'
class GameWindow < Gosu::Window
def initialize (width=800, height=600, fullscreen=false)
super
self.caption = 'Hello'
#message = Gosu::Image.from_text(
self, 'HELLO WORLD', Gosu.default_font_name, 45)
end
def draw
#message.draw(377.5,277.5,0)
end
end
window = GameWindow.new
window.show
My first approach was to take the height of the screen, subtract it by the height of the text 45, and then divide by 2. Now that seemed to work when aligning vertically.
However, horizontally is a different story...It seems to
be taking the top left corner of the text and centering it which I expected it to do, instead of the middle of the text.
Anyone got a formula for this ? I tried a whole bunch of things, and only came close.

Answer 1

class GameWindow < Gosu::Window
def initialize (width=800, height=600, fullscreen=false)
super
self.caption = 'Hello'
#message = Gosu::Image.from_text(
self, 'HELLO WORLD', Gosu.default_font_name, 45)
end
def draw
#message.draw(377.5,277.5,0)
end
end
Your #message is an instance of Gosu::Image
As far as I can see, the class has a method that allows you to align the image's rotational center to a specified point, draw_rot
Using draw_rot instead of draw should work for you once you've found the center of the frame.

Answer 2

I know this is an old question, but I was having this issue earlier today and came up with this solution.
def draw_centered_text(text, size, font)
centered_text = Gosu::Image.from_text(text, size, {:width => WIDTH, :align => :center, :font => font})
end
The above function converts the passed text to an image with a width equal to WIDTH (which in my case is a constant that stores the window width) and the text centred. You can then call the function like so:
draw_centered_text("Your text", 20, "Arial Bold").draw(0, 50, 0, 1, 1, Gosu::Color::WHITE)
You can replace 20 and 50 with any line height (font size) and y-position you want, just as you can change "Arial Bold" to "Arial" or any other font on your system. However, keep the 0 for the x-position (first parameter of draw()), since the centred text image is the same width as the window width.
See the links below for further information on from_text() and draw():
https://www.rubydoc.info/github/gosu/gosu/Gosu/Image#from_text-class_method
https://www.rubydoc.info/github/gosu/gosu/Gosu/Image#draw-instance_method

Answer 3

Better late than never...
No need to convert your text to an image. Just center the text using two parameters available on the Font.draw_text_rel method: rel_x and rel_y. See your code (modified a bit) below.
See: https://www.rubydoc.info/gems/gosu/Gosu%2FFont:draw_text_rel
require 'gosu'
class GameWindow < Gosu::Window
def initialize (width=800, height=600, fullscreen=false)
super
self.caption = 'Hello'
# #message = Gosu::Image.from_text(
# self, 'HELLO WORLD', Gosu.default_font_name, 45)
#font = Gosu::Font.new(45)
#message = "HELLO WORLD"
end
def draw
#font.draw_text_rel(#message, width / 2, height / 2, 1, rel_x = 0.5, rel_y = 0.5)
end
end
window = GameWindow.new
window.show