Friday, January 4, 2008

Tioga and text sizes

Tioga is powerful, as I undoubtedly mentioned here already. But, so far, it had a dreadful drawback: it was not possible to know the (TeX) text size other than by guesswork. This has now changed: starting from revision 453, it can find out and provide the information. All you need to do is to give a 'measure' => 'name' argument to show_text, and you can get information about the text size using get_text_size('name'). I used this new feature in figures.rb for a small demonstration:

    def text_size

      equation = '\int_{-\infty}^{\infty} \! e^{-x^{2}}\, \! dx = \sqrt{\pi}'
      text = "\\fbox{$\\displaystyle #{equation}$}"

      nb = 5
      nb.times do |i|
        scale = 0.5 + i * 0.2
        angle = i * 37
        x = (i+1)/(nb+1.0)
        y = x
        color = [1.0 - i * 0.2, i*0.2, 0]
        t.show_text('text' => text, 'color' => color, 'x' => x, 
                    'y' => x,
                    'alignment' => ALIGNED_AT_MIDHEIGHT,
                    'scale' => scale , 'measure' => "box#{i}", 
                    'angle' => angle )
        size = t.get_text_size("box#{i}")
        w = size['width']
        h = size['height']
        t.stroke_color = color
        t.stroke_rect(x - w/2, x - h/2, w, h)

This works really simply: Tioga uses a wrapper TeX function that displays the size of the text on pdflatex output. If Tioga detects that a size was requested, it fills in the information, gives it back to the program via get_text_size and runs pdflatex a second time use the information. For the first call, dummy values are given by get_text_size. It seems that the last showstopper of Tioga has finally fallen today !

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