From: "Carlo E. Prelz" <fluido@...>
Date: 2012-11-05T05:46:29+09:00
Subject: Re: Display Text as Image

	Subject: Display Text as Image
	Date: Mon 05 Nov 12 01:17:13AM +0900

Quoting Adriana Mikolaskova (lists@ruby-forum.com):

> Hello,
> 
> I have a String, which I want to display as a bitmap image. What is the
> best way to do this?
> 
> I tried f.e. the code below (RMagick), but the image displayed did not
> contain the whole Text I stored in the variable myText. What can I do to
> get the whole text displayed in an image? Or is there another, better
> approach to do this?
> 
> Best Regards
> 
> Adriana
> 
> img = Image.read("caption:"+myText) do
>          self.size = "2000"
>          self.height=1000
>          self.pointsize = 20
>         self.font = "Tahoma"
> 
> 
>        end

I am not sure I understand what you would like to obtain.

Here is the way to create a RMagick Image object, composed of given pixels
passed in a string:

def make_image(x,y,pixels)	
  im=Magick::Image::new(x,y)
  im.import_pixels(0,0,x,y,'RGB',pixels)
  im
end

The string must be made up of x*y*3 bytes - the RGB values for each
pixel.

But from your example, it seems that you want to make an image which
includes a given message (characters to be read). This requires
something more complex:

def make_image_with_text(x,y,backg_col,foreg_col,text,font,pointsize)
  im=Magick::Image::new(x,y) do  
    self.background_color=backg_col
  end	
  gc=Magick::Draw::new()  
  gc.annotate(im,x,y,0,0,text) do
    self.font_family=font
    self.fill=foreg_col
    self.stroke=foreg_col
    self.pointsize=pointsize
    self.gravity=Magick::CenterGravity
  end
  im
end	

To have a 2000x1000 black image with "This is a test" written in
20point Tahoma in red in it you should call the above as follows:

im=make_image_with_text(2000,1000,'black','red','This is a test','Tahoma',20)
im.display

Of course you can do the two things in sequence - first draw some
pixels, and then superimpose some text...

Have a look at

http://studio.imagemagick.org/RMagick/doc/draw.html#annotate

Remember to destroy Image objects after using them, with

im.destroy!

Otherwise they are not garbage-collected, and if you generate many
images you soon end up with a full ram...

Carlo

-- 
  *         Se la Strada e la sua Virtu' non fossero state messe da parte,
* K * Carlo E. Prelz - fluido@fluido.as             che bisogno ci sarebbe
  *               di parlare tanto di amore e di rettitudine? (Chuang-Tzu)