CODEWITHSUNDEEP
javaswing
Ben
Ben

Reputation: 21

Resize font based on string length

From an xml file, I'm given a width, height and id. All of them can and do vary very quickly. Now, I'm asked to draw a rectangle using the width and height (an easy task), and place the id at its center. The id must not overflow out of the rectangle it's contained it.

For single-character strings, this is also easy - set the font size to the height, play a bit with the x position maybe, and it's centered. The problem is when it's multi-character strings.

So given a width and height and a string, how can you determine what font-size the string should appear in? Assume you have every bit of information you need on the rectangle you're drawing the string in.

[Edit]: I'm using the Graphics 2D class to draw everything.

Upvotes: 2

Views: 1332

Answers (3)

Michael
Michael

Reputation: 2746

Don't quite have the time to give you a full working example, but here are a couple pointers that should get you going in the right direction. The graphics object you are using to draw with has a getFontMetrics() method, one of the methods on FontMetrics is stringWidth(String str) which gives you the width of a string in the current Font.

If the width is too big for your rectangle set the Font on the Graphics object to the same font just with a smaller size until it fits.

To horizontally center a string in a container (learned long ago in typing class in high school):

(rectangleWidth / 2) - (stringWidth / 2)

http://download.oracle.com/javase/1.5.0/docs/api/java/awt/FontMetrics.html

To create a Font with a smaller size, something like:

Font font = graphics.getFont();
Font smallerFont = font.derive(font.getSize() - 1);
graphics.setFont(smallerFont);

Hope this gets you going in the right direction.

Upvotes: 1

Joachim Sauer
Joachim Sauer

Reputation: 308269

  1. Start with selecting a Font at your preferred (i.e. maximum) size.
  2. Grab the FontRenderContext from your Graphics2D object using getFontRenderContext.
  3. Use getStringBounds() on the Font to be rendered to get a Rectangle2D object for the specific String to be rendered. That object describes the final size of the String using that Font
  4. Check if the size specified by that Rectangle2D is small enough.
    4a.  If it is small enough, you're done. Use the last Font you've checked.
    4b.  If it is too big, use Font.derive() to produce a smaller version of the Font and continue to use that and loop back to 3.

Upvotes: 2

Ali
Ali

Reputation: 12684

I would recommend for this problem to remove as many unknowns as possible. In this case, the problem chiefly is that font characters can vary in width... well most. That's why I would use a good monospace font like courier new for the ID, that way you know what the width of each character is, you know the width of your rectangle and you know the number of characters in your string. You can simply reduce the pixel size of each character will till your string fits the available width.

Example, if the width of each character is 12px and you have 10 characters in your ID, then you need 120px to fit everything in. If you only have 80px available, it's simple math 80/10 = 8px font-size (reduce half a pixel for padding if you want.

Just my suggestion.

Upvotes: 0

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