Module org.apache.sis.referencing
Class AffineTransforms2D
Bridge between
Matrix
and Java2D AffineTransform
instances.
Those AffineTransform
instances can be viewed as 3×3 matrices.
Contains also utility methods operating on AffineTransform
instances. Since:
 0.4

Method Summary
Modifier and TypeMethodDescriptionstatic AffineTransform
castOrCopy
(MathTransform transform) Returns the given transform as a Java2D affine transform.static AffineTransform
castOrCopy
(Matrix matrix) Returns the given matrix as a Java2D affine transform.static int
getFlip
(AffineTransform transform) Returns1
if one axis has been flipped,+1
if no axis has been flipped, or 0 if unknown.static double
getRotation
(AffineTransform transform) Returns an estimation of the rotation angle in radians.static double
Returns a global scale factor for the specified affine transform.static double
getScaleX0
(AffineTransform transform) Returns the magnitude of scale factor x by canceling the effect of eventual flip and rotation.static double
getScaleY0
(AffineTransform transform) Returns the magnitude of scale factor y by canceling the effect of eventual flip and rotation.static int
getSwapXY
(AffineTransform transform) Returns an estimation about whether the specified transform swaps x and y axes.static Point2D
inverseDeltaTransform
(AffineTransform transform, Point2D vector, Point2D dest) Calculates the inverse transform of a point without applying the translation components.static Rectangle2D
inverseTransform
(AffineTransform transform, Rectangle2D bounds, Rectangle2D dest) Calculates a rectangle which entirely contains the inverse transform ofbounds
.static LinearTransform
toMathTransform
(AffineTransform transform) Creates a math transform from the given affine transform.static Matrix3
toMatrix
(AffineTransform transform) Creates a 3×3 matrix from the given affine transform.static Rectangle2D
transform
(AffineTransform transform, Rectangle2D bounds, Rectangle2D dest) Calculates a rectangle which entirely contains the direct transform ofbounds
.static Shape
transform
(AffineTransform transform, Shape shape, boolean allowOverwrite) Transforms the given shape.

Method Details

castOrCopy
Returns the given transform as a Java2D affine transform. Parameters:
transform
 the transform to convert, ornull
. Returns:
 the transform argument if it can be safely casted (including
null
argument) or converted.  Throws:
IllegalArgumentException
 if the given transform cannot be casted or converted. See Also:

castOrCopy
Returns the given matrix as a Java2D affine transform. If the given matrix is already an instance ofAffineTransform
, then it is returned directly. Otherwise the values are copied in a newAffineTransform
instance. Parameters:
matrix
 the matrix to return as an affine transform, ornull
. Returns:
 the matrix argument if it can be safely casted (including
null
argument), or a copy of the given matrix otherwise.  Throws:
IllegalArgumentException
 if the given matrix size is not 3×3 or if the matrix is not affine. See Also:

toMatrix
Creates a 3×3 matrix from the given affine transform. Parameters:
transform
 the affine transform to copy as a matrix. Returns:
 a matrix containing the same terms than the given affine transform.

toMathTransform
Creates a math transform from the given affine transform. This method is the converse ofcastOrCopy(MathTransform)
. Parameters:
transform
 the affine transform to cast or copy as aMathTransform
, ornull
. Returns:
 a
MathTransform
doing the same operation than the givenAffineTransform
, ornull
if the given transform was null.  Since:
 1.1
 See Also:

transform
Transforms the given shape. This method is similar toAffineTransform.createTransformedShape(Shape)
except that: It tries to preserve the shape kind when possible. For example if the given shape
is an instance of
RectangularShape
and the given transform does not involve rotation, then the returned shape may be some instance of the same class.  It tries to recycle the given object if
overwrite
istrue
.
 Parameters:
transform
 the affine transform to use.shape
 the shape to transform, ornull
.allowOverwrite
 iftrue
, this method is allowed to overwriteshape
with the transform result. Iffalse
, thenshape
is never modified. Returns:
 the transform of the given shape, or
null
if the given shape was null. May or may not be the same instance than the given shape.  See Also:
 It tries to preserve the shape kind when possible. For example if the given shape
is an instance of

transform
public static Rectangle2D transform(AffineTransform transform, Rectangle2D bounds, Rectangle2D dest) Calculates a rectangle which entirely contains the direct transform ofbounds
. This operation is equivalent to the following code, except that it can reuse the givendest
rectangle and is potentially more efficient:return transform.createTransformedShape(bounds).getBounds2D();
 Parameters:
transform
 the affine transform to use.bounds
 the rectangle to transform, ornull
. this rectangle will not be modified except ifdest
references the same object.dest
 rectangle in which to place the result. Ifnull
, a new rectangle will be created. Returns:
 the direct transform of the
bounds
rectangle, ornull
ifbounds
was null.  See Also:

inverseTransform
public static Rectangle2D inverseTransform(AffineTransform transform, Rectangle2D bounds, Rectangle2D dest) throws NoninvertibleTransformException Calculates a rectangle which entirely contains the inverse transform ofbounds
. This operation is equivalent to the following code, except that it can reuse the givendest
rectangle and is potentially more efficient:return createInverse().createTransformedShape(bounds).getBounds2D();
 Parameters:
transform
 the affine transform to use.bounds
 the rectangle to transform, ornull
. this rectangle will not be modified except ifdest
references the same object.dest
 rectangle in which to place the result. Ifnull
, a new rectangle will be created. Returns:
 the inverse transform of the
bounds
rectangle, ornull
ifbounds
was null.  Throws:
NoninvertibleTransformException
 if the affine transform cannot be inverted.

inverseDeltaTransform
public static Point2D inverseDeltaTransform(AffineTransform transform, Point2D vector, Point2D dest) throws NoninvertibleTransformException Calculates the inverse transform of a point without applying the translation components. In other words, calculates the inverse transform of a displacement vector. Parameters:
transform
 the affine transform to use.vector
 the vector to transform stored as a point. this point will not be modified except ifdest
references the same object.dest
 point in which to place the result. Ifnull
, a new point will be created. Returns:
 the inverse transform of the
vector
, ornull
ifsource
was null.  Throws:
NoninvertibleTransformException
 if the affine transform cannot be inverted.

getSwapXY
Returns an estimation about whether the specified transform swaps x and y axes. This method assumes that the specified affine transform is built from arbitrary translations, scales or rotations, but no shear. It returns+1
if the (x, y) axis order seems to be preserved,1
if the transform seems to swap axis to the (y, x) axis order, or0
if this method cannot make a decision. Parameters:
transform
 the affine transform to inspect. Returns:
true
if the given transform seems to swap axis order.

getRotation
Returns an estimation of the rotation angle in radians. This method assumes that the specified affine transform is built from arbitrary translations, scales or rotations, but no shear. If a flip has been applied, then this method assumes that the flipped axis is the y one in source CRS space. For a grid to world CRS transform, this is the row number in grid coordinates. Parameters:
transform
 the affine transform to inspect. Returns:
 an estimation of the rotation angle in radians,
or
NaN
if the angle cannot be estimated.

getFlip
Returns1
if one axis has been flipped,+1
if no axis has been flipped, or 0 if unknown. A flipped axis in an axis with direction reversed (typically the y axis). This method assumes that the specified affine transform is built from arbitrary translations, scales or rotations, but no shear. Note that it is not possible to determine which of the x or y axis has been flipped.This method can be used in order to set the sign of a scale according the flipping state. The example below choose to apply the sign on the y scale, but this is an arbitrary (while common) choice:
double scaleX0 = getScaleX0(transform); double scaleY0 = getScaleY0(transform); int flip = getFlip(transform); if (flip != 0) { scaleY0 *= flip; // ... continue the process here. }
boolean flipped = (tr.getType() & TYPE_FLIP) != 0;
 Parameters:
transform
 the affine transform to inspect. Returns:
 1 if an axis has been flipped, +1 if no flipping, or 0 if unknown.

getScaleX0
Returns the magnitude of scale factor x by canceling the effect of eventual flip and rotation. This factor is calculated by: Parameters:
transform
 the affine transform to inspect. Returns:
 the magnitude of scale factor x.

getScaleY0
Returns the magnitude of scale factor y by canceling the effect of eventual flip and rotation. This factor is calculated by: Parameters:
transform
 the affine transform to inspect. Returns:
 the magnitude of scale factor y.

getScale
Returns a global scale factor for the specified affine transform. This scale factor combinesgetScaleX0(tr)
andgetScaleY0(tr)
. The way to compute such a "global" scale is somewhat arbitrary and may change in any future version. Parameters:
tr
 the affine transform to inspect. Returns:
 a "global" scale factor.
