How to perfectly fit text in a box

hello everybody,

I'd love some help in trying to find a way to perfectly fit some text in a rectangular box, in order to get as little margin as possible.
'Perfectly' here means to get the real vertical size of the text box.

If I have a string, I can get the estimate of the coordinates of the text bounds in a couple of ways, but neither is really satisfying.
I've tried so far:
a) using textheight & textwidth
b) using the textpath.bounds
they do return different values.

my test code:

size(600, 600)
 
font("Courier")
fontsize(10)
 
myX = 100
myY = -100
myTest = 80 # box width
myString = "Neque porro quisquam est qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit..."
#myString = "adipisci velit..."
 
tp = textpath(myString, x=myX, y=myY, width= myTest)
(tp_x, tp_y), (tp_w, tp_h) = tp.bounds
#print tp_x, tp_y, tp_w, tp_h
 
# gray rect from textpath.bounds coordinates
fill(0, 0.4)
rect(tp_x, -tp_y, tp_w, tp_h)
 
# red rect from textmetrics coordinates
fill(1, 0, 0, 0.4)
rect(tp_x, -tp_y, textwidth(myString, width=myTest), textheight(myString, width=myTest))
 
fill(0)
#align(RIGHT)
text(myString, x=tp_x, y=-tp_y, width=tp_w, height=tp_h)

here's a slightly better version of the fit-text-in-a-rect code.
still, as you wil see, sometimes the last line of the text flows out of the box.
any ideas?

size(600, 600)
grid = ximport("grid") # so that we can use the new text.fit_fontsize method
font("Helvetica")
 
myX = 50
myY = -50
 
var("myW", NUMBER, 135, 10, 600) # desired box width
var("myH", NUMBER, 83, 10, 600)# desired box height
 
 
myString = "Neque porro quisquam est qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit last line etc etc..."
fSize = grid.text.fit_fontsize(myString, myW, myH)
fontsize(fSize)
 
 
tp = textpath(myString, x=myX, y=myY, width=myW, height=myH)
(tpX, tpY), (tpW, tpH) = tp.bounds
#print tpX, tpY, tpW, tpH
 
deltaY = tpY - myY
 
 
# gray rect from textpath.bounds coordinates
nofill()
stroke(0, 0.4)
rect(tpX, -tpY, tpW, tpH)
 
# red rect from textmetrics coordinates
stroke(1, 0, 0, 0.4)
rect(myX, -myY-deltaY, textwidth(myString, width=myW), textheight(myString, width=myW)-deltaY)
 
 
fill(0)
#align(RIGHT)
text(myString, x=tpX, y=-tpY-deltaY, width=tpW, height=tpH)

Hi Giorgio,

Some tough questions :-)

First of all, as you mention there is a difference between textmetrics() and path.bounds. The bounds is the box that fits exactly around the given path, whereas texmetrics is the hidden paragraph box - which is more complex do to spacing etc.

Second, the grid.text.fit_fontsize() matches text size to the width of a given box. What you want is vertical fitting as well, which is more difficult. But we can start from fit_fontsize() which is quite a solid algorithm. The most elegant solution I've found so far is to then do additional lineheight() tweaking:

grid = ximport("grid")
 
txt = "Neque porro quisquam est qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit..."
x = 40
y = 70
var("w", NUMBER, 200, 50, 400)
var("h", NUMBER, 200, 50, 400)
 
f = grid.text.fit_fontsize(txt, w+10, h)
fontsize(f)
 
# Increase line spacing until the last line touches the bottom of the box.
for i in range(100):
    if textheight(txt, w+10) < h:
        lineheight(lineheight()+0.01)
    else:
        break
fill(0)
text(txt, x, y, width=w+10)
rect(x, y-fontsize(), w, h, fill=None, stroke=0)

Hello Tom,

thanks for the answers! I'll posto soon the result of the experiment I'm working on.

Hey Giorgio,

I've added a text.fit_lineheight() to the latest release of the grid library, based on the code above.