diff options
| author | Olga Rodimina <rodimina@redhat.com> | 2004-02-04 18:43:54 +0000 |
|---|---|---|
| committer | Olga Rodimina <rodimina@gcc.gnu.org> | 2004-02-04 18:43:54 +0000 |
| commit | e530f3709ec88e516fcc810cc7109d9255d578a8 (patch) | |
| tree | 775a19e62616e1935eff711bf6eb537f6114a488 /libjava/java | |
| parent | 9baa27a975e184773ffb8ec4297db8ce34291246 (diff) | |
| download | gcc-e530f3709ec88e516fcc810cc7109d9255d578a8.zip gcc-e530f3709ec88e516fcc810cc7109d9255d578a8.tar.gz gcc-e530f3709ec88e516fcc810cc7109d9255d578a8.tar.bz2 | |
AffineTransform.java: Corrected comments on the field definitions for m11 and m10.
* 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
Diffstat (limited to 'libjava/java')
| -rw-r--r-- | libjava/java/awt/geom/AffineTransform.java | 55 |
1 files changed, 47 insertions, 8 deletions
diff --git a/libjava/java/awt/geom/AffineTransform.java b/libjava/java/awt/geom/AffineTransform.java index d479763..1410d90 100644 --- a/libjava/java/awt/geom/AffineTransform.java +++ b/libjava/java/awt/geom/AffineTransform.java @@ -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); } /** |