This function calculates and returns the bounding box in pixels for a TrueType text.
The string to be measured.
The font size in pixels.
The name of the TrueType font file. (Can also be a URL.) Depending on which version of the GD library that PHP is using, it may attempt to search for files that do not begin with a leading '/' by
appending '.ttf' to the filename and searching along a library-defined font path.
Angle in degrees in which text will be measured.
imagettfbbox() returns an array with 8 elements representing four points making the bounding box of the text:
lower left corner, X position
lower left corner, Y position
lower right corner, X position
lower right corner, Y position
upper right corner, X position
upper right corner, Y position
upper left corner, X position
upper left corner, Y position
The points are relative to the text regardless of the angle, so "upper left" means in the top left-hand corner seeing the text horizontally.
This function requires both the GD library and the FreeType library.