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AffineTransform.java: Corrected comments on the field definitions for m11 and m10.

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* java/awt/geom/AffineTransform.java:
	Corrected comments on the field definitions for
	m11 and m10.
	(shear): Fixed few errors that caused shear
	transformation to be performed incorrectly.
	(createInverse): Fixed to return correct
	inverse of the given matrix.

From-SVN: r77261
This commit is contained in:
Olga Rodimina 2004-02-04 18:43:54 +00:00 committed by Olga Rodimina
parent 9baa27a975
commit e530f3709e
2 changed files with 57 additions and 8 deletions
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10
libjava/ChangeLog
View File

@ -1,3 +1,13 @@
2004-02-04 Olga Rodimina <rodimina@redhat.com>
* java/awt/geom/AffineTransform.java:
Corrected comments on the field definitions for
m11 and m10.
(shear): Fixed few errors that caused shear
transformation to be performed incorrectly.
(createInverse): Fixed to return correct
inverse of the given matrix.
2004-02-03 Tom Tromey <tromey@redhat.com>
* java/lang/natPosixProcess.cc (startProcess): Handle case where

55
libjava/java/awt/geom/AffineTransform.java
View File

@ -226,7 +226,7 @@ public class AffineTransform implements Cloneable, Serializable
private double m00;
/**
* The Y coordinate scaling element of the transform matrix.
* The Y coordinate shearing element of the transform matrix.
*
* @serial matrix[1,0]
*/
@ -240,7 +240,7 @@ public class AffineTransform implements Cloneable, Serializable
private double m01;
/**
* The Y coordinate shearing element of the transform matrix.
* The Y coordinate scaling element of the transform matrix.
*
* @serial matrix[1,1]
*/
@ -738,10 +738,10 @@ public class AffineTransform implements Cloneable, Serializable
*/
public void shear(double shx, double shy)
{
double n00 = m00 + shx * m01;
double n01 = shx * m00 + m01;
double n10 = m10 * shy + m11;
double n11 = shx * m10 + m11;
double n00 = m00 + (shy * m01);
double n01 = m01 + (shx * m00);
double n10 = m10 + (shy * m11);
double n11 = m11 + (shx * m10);
m00 = n00;
m01 = n01;
m10 = n10;
@ -996,6 +996,38 @@ public class AffineTransform implements Cloneable, Serializable
* map multiple points to the same line or point). A transform exists only
* if getDeterminant() has a non-zero value.
*
* The inverse is calculated as:
*
* <pre>
*
* Let A be the matrix for which we want to find the inverse:
*
* A = [ m00 m01 m02 ]
* [ m10 m11 m12 ]
* [ 0 0 1 ]
*
*
* 1
* inverse (A) = --- x adjoint(A)
* det
*
*
*
* = 1 [ m11 -m01 m01*m12-m02*m11 ]
* --- x [ -m10 m00 -m00*m12+m10*m02 ]
* det [ 0 0 m00*m11-m10*m01 ]
*
*
*
* = [ m11/det -m01/det m01*m12-m02*m11/det ]
* [ -m10/det m00/det -m00*m12+m10*m02/det ]
* [ 0 0 1 ]
*
*
* </pre>
*
*
*
* @return a new inverse transform
* @throws NoninvertibleTransformException if inversion is not possible
* @see #getDeterminant()
@ -1006,8 +1038,15 @@ public class AffineTransform implements Cloneable, Serializable
double det = getDeterminant();
if (det == 0)
throw new NoninvertibleTransformException("can't invert transform");
return new AffineTransform(m11 / det, -m10 / det, m01 / det, -m00 / det,
-m02, -m12);
double im00 = m11 / det;
double im10 = -m10 / det;
double im01 = -m01 / det;
double im11 = m00 / det;
double im02 = (m01 * m12 - m02 * m11) / det;
double im12 = (-m00 * m12 + m10 * m02) / det;
return new AffineTransform (im00, im10, im01, im11, im02, im12);
}
/**