> i got the correct result by scaling the roatated image by the hight in the
> x direction and by the width in the y direction(see code below), but this
> will work only for multiples of 90degrees as you can see. If this is the
> only solution(which i dearly hope is not), how can we generalize it to
> work for any angle?
>
Welcome to the Wonderful World of matrix math. </sarcasm>
One of the handy things about matrices is that they can be combined. The order
in which they are combined is Important.
2D transformation matrices can be expressed in a 3x2 grid, thusly:
a b
c d
e f
A & B make up the x, c & d the y, and e & f are x & y offsets, respectively.
An "identity" matrix looks like this:
1 0
0 1
0 0
AKA 1 0 0 1 0 0
So a rotation matrix looks like:
cos sin
-sin cos
0 0
NOTE: Rotation is always around 0,0... this can lead to Weirdness if you're not
compensating for it.
And a scale matrix looks like:
x-scale 0
0 y-scale
0 0
You need to combine a scale matrix and a rotation matrix. In Java,
AffineTransform will do the heavy lifting for you:
AffineTransform combinedTrans = AffineTransform.getScaleInstance( scaleX,
scaleY );
combinedTrans.rotate( theta, anchorX, anchorY ); // allows you to specify
// a center of rotation.
// Very Handy
combinedTrans.translate( newX, newY );
double matrix[] = new double[6];
combinedTras.getMatrix( matrix );
contentByte.addImage( workImage, matrix[0], matrix[1],
matrix[2], matrix[3],
matrix[4], matrix[5]);
------------
I can never remember which order to do things in, so you might need to start
with the translation, and then rotate it, or something goofy like that. I
always end up trying different orders till I find the "correct" one. Quite
Annoying.
--Mark Storer
Senior Software Engineer
Cardiff.com
#include <disclaimer>
typedef std::disclaimer<Cardiff> DisCard;
------------------------------------------------------------------------------
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