Java Glossary : point

Java definitions: 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

You are here : home : Java Glossary : P words : point.

point

Originally, a point was a unit of measure in the typesetting industry. A printer's point is 1/72.27 inch.
In PostScript a point is 1/72 of in an inch.
In Java, a point is one pixel width/height. If you had a old fashioned low-resolution monitor with 72 dpi resolution, then a point would also mean 1/72 of an inch. So when you ask for a 10 point Font in Java, you don't get what printers call a 10-point font. You get a font about 10 pixels high, which could be tiny or huge depending on your monitor resolution.
In Java, with Graphics, a Point with a capital P, is a class describing a location on the screen, or a location within a window relative to its upper left corner, with an x and y co-ordinate. Points have two public int fields x and y, however the getX and getY methods return doubles. x is measured across from the left in pixels. y is measured down from the top in pixels.
In Java, with Graphics2D, a Point2D with a capital P, is a class describing a location on the screen, or a location within a window in user-defined co-ordinates, which are much more flexible. Using AffineTransform, you can transform the co-ordinates to go in any direction you want and aren't even necessarily orthogonal. Point2D.Float that Point2D.Double are similar to Point, but they store the x, y in float and double respectively. The strange dot in the name comes about because Float and Double are inner classes of Point2D.

Here is what various point sizes look like on your screen in HTML:

point sizes in html

Here is what various point sizes look like on your screen in Java:

You need Java to see this image.

If you have the Opera browser, experiment with the View | Zoom command. You will see the green HTML images magnify, but the blue Java ones do not.

To see what type looks like at various point sizes see Font Shower.

home	Canadian Mind Products
	mindprod.com IP:[24.87.56.253]
	Your IP:[80.134.30.163]
	You are visitor number 228.
	Please send errors, omissions and suggestions
	to improve this page to Roedy Green.
	You can get a fresh copy of this page from:	or possibly from your local J: drive mirror:
	http://mindprod.com/jgloss/point.html	J:\mindprod\jgloss\point.html