Given a certain available width, how do I define the font size for a snippet of text, so that it matches the available width?

Posted on StackOverflow on Apr 12, 2013 by Mark Edwards

First you need a PdfFont object. For instance:

PdfFont font = PdfFontFactory.createFont(FontConstants.COURIER, PdfEncodings.WINANSI, false);

Now you can ask the base font for the width of this String in 'normalized 1000 units' (these are units used in 'Glyph space'; see ISO-32000-1 for more info):

float glyphWidth = font.getWidth("WHAT IS THE WIDTH OF THIS STRING?");

Now we can convert these 'normalized 1000 units' to an actual size in points (actually user units, but let's assume that 1 user unit = 1 pt for the sake of simplicity).

For instance: the width of the text "WHAT IS THE WIDTH OF THIS STRING?" when using Courier with size 16pt is:

 float width = glyphWidth * 0.001f * 16f;

Your question is different: you want to know the font size for a given width. That's done like this:

 float fontSize = 1000 * width / glyphwidth;

There is also a shortcut to get the width of a String in points: you can put the string in a Text and do text.getWidth() (if you didn't define a font for the Text, the default font Helvetica with the default font size 12 will be used).

Click How to choose the optimal size for a font? if you want to see how to answer this question in iText 5.