public class Affine2D extends AffineBase
Affine2D class represents a 2D affine transform
that performs a linear mapping from 2D coordinates to other 2D
coordinates that preserves the "straightness" and
"parallelness" of lines. Affine transformations can be constructed
using sequences of translations, scales, flips, rotations, and shears.
Such a coordinate transformation can be represented by a 3 row by
3 column matrix with an implied last row of [ 0 0 1 ]. This matrix
transforms source coordinates (x,y) into
destination coordinates (x',y') by considering
them to be a column vector and multiplying the coordinate vector
by the matrix according to the following process:
[ x'] [ m00 m01 m02 ] [ x ] [ m00x + m01y + m02 ] [ y'] = [ m10 m11 m12 ] [ y ] = [ m10x + m11y + m12 ] [ 1 ] [ 0 0 1 ] [ 1 ] [ 1 ]
In some variations of the rotate methods in the
Affine2D class, a double-precision argument
specifies the angle of rotation in radians.
These methods have special handling for rotations of approximately
90 degrees (including multiples such as 180, 270, and 360 degrees),
so that the common case of quadrant rotation is handled more
efficiently.
This special handling can cause angles very close to multiples of
90 degrees to be treated as if they were exact multiples of
90 degrees.
For small multiples of 90 degrees the range of angles treated
as a quadrant rotation is approximately 0.00000121 degrees wide.
This section explains why such special care is needed and how
it is implemented.
Since 90 degrees is represented as PI/2 in radians,
and since PI is a transcendental (and therefore irrational) number,
it is not possible to exactly represent a multiple of 90 degrees as
an exact double precision value measured in radians.
As a result it is theoretically impossible to describe quadrant
rotations (90, 180, 270 or 360 degrees) using these values.
Double precision floating point values can get very close to
non-zero multiples of PI/2 but never close enough
for the sine or cosine to be exactly 0.0, 1.0 or -1.0.
The implementations of Math.sin() and
Math.cos() correspondingly never return 0.0
for any case other than Math.sin(0.0).
These same implementations do, however, return exactly 1.0 and
-1.0 for some range of numbers around each multiple of 90
degrees since the correct answer is so close to 1.0 or -1.0 that
the double precision significand cannot represent the difference
as accurately as it can for numbers that are near 0.0.
The net result of these issues is that if the
Math.sin() and Math.cos() methods
are used to directly generate the values for the matrix modifications
during these radian-based rotation operations then the resulting
transform is never strictly classifiable as a quadrant rotation
even for a simple case like rotate(Math.PI/2.0),
due to minor variations in the matrix caused by the non-0.0 values
obtained for the sine and cosine.
If these transforms are not classified as quadrant rotations then
subsequent code which attempts to optimize further operations based
upon the type of the transform will be relegated to its most general
implementation.
Because quadrant rotations are fairly common,
this class should handle these cases reasonably quickly, both in
applying the rotations to the transform and in applying the resulting
transform to the coordinates.
To facilitate this optimal handling, the methods which take an angle
of rotation measured in radians attempt to detect angles that are
intended to be quadrant rotations and treat them as such.
These methods therefore treat an angle theta as a quadrant
rotation if either Math.sin(theta) or
Math.cos(theta) returns exactly 1.0 or -1.0.
As a rule of thumb, this property holds true for a range of
approximately 0.0000000211 radians (or 0.00000121 degrees) around
small multiples of Math.PI/2.0.
BaseTransform.Degree| Modifier and Type | Field and Description |
|---|---|
private static long |
BASE_HASH |
APPLY_2D_DELTA_MASK, APPLY_2D_MASK, APPLY_3D, APPLY_IDENTITY, APPLY_SCALE, APPLY_SHEAR, APPLY_TRANSLATE, HI_3D, HI_IDENTITY, HI_SCALE, HI_SHEAR, HI_SHIFT, HI_TRANSLATE, mxt, mxx, mxy, myt, myx, myy, state, typeEPSILON_ABSOLUTE, IDENTITY_TRANSFORM, TYPE_AFFINE_3D, TYPE_AFFINE2D_MASK, TYPE_FLIP, TYPE_GENERAL_ROTATION, TYPE_GENERAL_SCALE, TYPE_GENERAL_TRANSFORM, TYPE_IDENTITY, TYPE_MASK_ROTATION, TYPE_MASK_SCALE, TYPE_QUADRANT_ROTATION, TYPE_TRANSLATION, TYPE_UNIFORM_SCALE, TYPE_UNKNOWN| Modifier | Constructor and Description |
|---|---|
|
Affine2D()
Constructs a new
Affine2D representing the
Identity transformation. |
|
Affine2D(BaseTransform Tx)
Constructs a new
Affine2D that uses the same transform
as the specified BaseTransform object. |
|
Affine2D(double mxx,
double myx,
double mxy,
double myy,
double mxt,
double myt)
Constructs a new
Affine2D from 6 double
precision values representing the 6 specifiable entries of the 3x3
transformation matrix. |
private |
Affine2D(double mxx,
double myx,
double mxy,
double myy,
double mxt,
double myt,
int state) |
|
Affine2D(float mxx,
float myx,
float mxy,
float myy,
float mxt,
float myt)
Constructs a new
Affine2D from 6 floating point
values representing the 6 specifiable entries of the 3x3
transformation matrix. |
| Modifier and Type | Method and Description |
|---|---|
private static double |
_matround(double matval) |
BaseTransform |
copy() |
Affine2D |
createInverse()
Returns an
Affine2D object representing the
inverse transformation. |
Point2D |
deltaTransform(Point2D ptSrc,
Point2D ptDst)
Transforms the relative distance vector specified by
ptSrc and stores the result in ptDst. |
BaseTransform |
deriveWithConcatenation(BaseTransform tx) |
BaseTransform |
deriveWithConcatenation(double mxx,
double myx,
double mxy,
double myy,
double mxt,
double myt) |
BaseTransform |
deriveWithConcatenation(double mxx,
double mxy,
double mxz,
double mxt,
double myx,
double myy,
double myz,
double myt,
double mzx,
double mzy,
double mzz,
double mzt) |
BaseTransform |
deriveWithNewTransform(BaseTransform tx) |
BaseTransform |
deriveWithPreConcatenation(BaseTransform tx) |
BaseTransform |
deriveWithPreTranslation(double mxt,
double myt) |
BaseTransform |
deriveWithRotation(double theta,
double axisX,
double axisY,
double axisZ) |
BaseTransform |
deriveWithScale(double mxx,
double myy,
double mzz) |
BaseTransform |
deriveWithTranslation(double mxt,
double myt) |
BaseTransform |
deriveWithTranslation(double mxt,
double myt,
double mzt) |
boolean |
equals(java.lang.Object obj)
Returns
true if this Affine2D
represents the same coordinate transform as the specified
argument. |
BaseTransform.Degree |
getDegree() |
int |
hashCode()
Returns the hashcode for this transform.
|
boolean |
is2D() |
void |
preConcatenate(BaseTransform Tx)
Concatenates a
BaseTransform Tx to
this Affine2D Cx
in a less commonly used way such that Tx modifies the
coordinate transformation relative to the absolute pixel
space rather than relative to the existing user space. |
void |
quadrantRotate(int numquadrants)
Concatenates this transform with a transform that rotates
coordinates by the specified number of quadrants.
|
void |
quadrantRotate(int numquadrants,
double anchorx,
double anchory)
Concatenates this transform with a transform that rotates
coordinates by the specified number of quadrants around
the specified anchor point.
|
protected void |
reset3Delements()
Resets the 3D (Z) components of the matrix to identity settings
(if they are present).
|
void |
restoreTransform(double mxx,
double myx,
double mxy,
double myy,
double mxt,
double myt)
This function is only guaranteed to succeed if the transform is
of degree AFFINE2D or less and the matrix
parameters specified came from this same instance.
|
void |
restoreTransform(double mxx,
double mxy,
double mxz,
double mxt,
double myx,
double myy,
double myz,
double myt,
double mzx,
double mzy,
double mzz,
double mzt)
This function is only guaranteed to succeed if the matrix
parameters specified came from this same instance.
|
void |
rotate(double vecx,
double vecy)
Concatenates this transform with a transform that rotates
coordinates according to a rotation vector.
|
void |
rotate(double theta,
double anchorx,
double anchory)
Concatenates this transform with a transform that rotates
coordinates around an anchor point.
|
void |
rotate(double vecx,
double vecy,
double anchorx,
double anchory)
Concatenates this transform with a transform that rotates
coordinates around an anchor point according to a rotation
vector.
|
void |
setToQuadrantRotation(int numquadrants)
Sets this transform to a rotation transformation that rotates
coordinates by the specified number of quadrants.
|
void |
setToQuadrantRotation(int numquadrants,
double anchorx,
double anchory)
Sets this transform to a translated rotation transformation
that rotates coordinates by the specified number of quadrants
around the specified anchor point.
|
void |
setToRotation(double theta)
Sets this transform to a rotation transformation.
|
void |
setToRotation(double vecx,
double vecy)
Sets this transform to a rotation transformation that rotates
coordinates according to a rotation vector.
|
void |
setToRotation(double theta,
double anchorx,
double anchory)
Sets this transform to a translated rotation transformation.
|
void |
setToRotation(double vecx,
double vecy,
double anchorx,
double anchory)
Sets this transform to a rotation transformation that rotates
coordinates around an anchor point according to a rotation
vector.
|
void |
setToScale(double sx,
double sy)
Sets this transform to a scaling transformation.
|
void |
setToTranslation(double tx,
double ty)
Sets this transform to a translation transformation.
|
void |
setTransform(BaseTransform Tx)
Sets this transform to a copy of the transform in the specified
BaseTransform object. |
java.lang.String |
toString()
Returns a
String that represents the value of this
Object. |
void |
transform(Point2D[] ptSrc,
int srcOff,
Point2D[] ptDst,
int dstOff,
int numPts)
Transforms an array of point objects by this transform.
|
calculateType, concatenate, concatenate, createTransformedShape, deltaTransform, deltaTransform, deltaTransform, getDeterminant, getMxt, getMxx, getMxy, getMyt, getMyx, getMyy, getType, inverseDeltaTransform, inverseDeltaTransform, inverseTransform, inverseTransform, inverseTransform, inverseTransform, inverseTransform, inverseTransform, invert, isIdentity, isTranslateOrIdentity, rotate, rotate180, rotate270, rotate90, scale, setToIdentity, setToShear, setTransform, shear, stateError, transform, transform, transform, transform, transform, transform, transform, transform, transform, translate, updateState, updateState2DalmostZero, degreeError, getInstance, getInstance, getInstance, getMxz, getMyz, getMzt, getMzx, getMzy, getMzz, getRotateInstance, getScaleInstance, getTranslateInstance, makePointprivate Affine2D(double mxx,
double myx,
double mxy,
double myy,
double mxt,
double myt,
int state)
public Affine2D()
Affine2D representing the
Identity transformation.public Affine2D(BaseTransform Tx)
Affine2D that uses the same transform
as the specified BaseTransform object.Tx - the BaseTransform object to copypublic Affine2D(float mxx,
float myx,
float mxy,
float myy,
float mxt,
float myt)
Affine2D from 6 floating point
values representing the 6 specifiable entries of the 3x3
transformation matrix.mxx - the X coordinate scaling element of the 3x3 matrixmyx - the Y coordinate shearing element of the 3x3 matrixmxy - the X coordinate shearing element of the 3x3 matrixmyy - the Y coordinate scaling element of the 3x3 matrixmxt - the X coordinate translation element of the 3x3 matrixmyt - the Y coordinate translation element of the 3x3 matrixpublic Affine2D(double mxx,
double myx,
double mxy,
double myy,
double mxt,
double myt)
Affine2D from 6 double
precision values representing the 6 specifiable entries of the 3x3
transformation matrix.mxx - the X coordinate scaling element of the 3x3 matrixmyx - the Y coordinate shearing element of the 3x3 matrixmxy - the X coordinate shearing element of the 3x3 matrixmyy - the Y coordinate scaling element of the 3x3 matrixmxt - the X coordinate translation element of the 3x3 matrixmyt - the Y coordinate translation element of the 3x3 matrixpublic BaseTransform.Degree getDegree()
getDegree in class BaseTransformprotected void reset3Delements()
AffineBasereset3Delements in class AffineBasepublic void rotate(double theta,
double anchorx,
double anchory)
This operation is equivalent to the following sequence of calls:
translate(anchorx, anchory); // S3: final translation
rotate(theta); // S2: rotate around anchor
translate(-anchorx, -anchory); // S1: translate anchor to origin
Rotating by a positive angle theta rotates points on the positive
X axis toward the positive Y axis.
Note also the discussion of
Handling 90-Degree Rotations
above.theta - the angle of rotation measured in radiansanchorx - the X coordinate of the rotation anchor pointanchory - the Y coordinate of the rotation anchor pointpublic void rotate(double vecx,
double vecy)
vecx and vecy are 0.0,
no additional rotation is added to this transform.
This operation is equivalent to calling:
rotate(Math.atan2(vecy, vecx));
vecx - the X coordinate of the rotation vectorvecy - the Y coordinate of the rotation vectorpublic void rotate(double vecx,
double vecy,
double anchorx,
double anchory)
vecx and vecy are 0.0,
the transform is not modified in any way.
This method is equivalent to calling:
rotate(Math.atan2(vecy, vecx), anchorx, anchory);
vecx - the X coordinate of the rotation vectorvecy - the Y coordinate of the rotation vectoranchorx - the X coordinate of the rotation anchor pointanchory - the Y coordinate of the rotation anchor pointpublic void quadrantRotate(int numquadrants)
rotate(numquadrants * Math.PI / 2.0);
Rotating by a positive number of quadrants rotates points on
the positive X axis toward the positive Y axis.numquadrants - the number of 90 degree arcs to rotate bypublic void quadrantRotate(int numquadrants,
double anchorx,
double anchory)
rotate(numquadrants * Math.PI / 2.0, anchorx, anchory);
Rotating by a positive number of quadrants rotates points on
the positive X axis toward the positive Y axis.numquadrants - the number of 90 degree arcs to rotate byanchorx - the X coordinate of the rotation anchor pointanchory - the Y coordinate of the rotation anchor pointpublic void setToTranslation(double tx,
double ty)
[ 1 0 tx ]
[ 0 1 ty ]
[ 0 0 1 ]
tx - the distance by which coordinates are translated in the
X axis directionty - the distance by which coordinates are translated in the
Y axis directionpublic void setToRotation(double theta)
[ cos(theta) -sin(theta) 0 ]
[ sin(theta) cos(theta) 0 ]
[ 0 0 1 ]
Rotating by a positive angle theta rotates points on the positive
X axis toward the positive Y axis.
Note also the discussion of
Handling 90-Degree Rotations
above.theta - the angle of rotation measured in radianspublic void setToRotation(double theta,
double anchorx,
double anchory)
This operation is equivalent to the following sequence of calls:
setToTranslation(anchorx, anchory); // S3: final translation
rotate(theta); // S2: rotate around anchor
translate(-anchorx, -anchory); // S1: translate anchor to origin
The matrix representing this transform becomes:
[ cos(theta) -sin(theta) x-x*cos+y*sin ]
[ sin(theta) cos(theta) y-x*sin-y*cos ]
[ 0 0 1 ]
Rotating by a positive angle theta rotates points on the positive
X axis toward the positive Y axis.
Note also the discussion of
Handling 90-Degree Rotations
above.theta - the angle of rotation measured in radiansanchorx - the X coordinate of the rotation anchor pointanchory - the Y coordinate of the rotation anchor pointpublic void setToRotation(double vecx,
double vecy)
vecx and vecy are 0.0,
the transform is set to an identity transform.
This operation is equivalent to calling:
setToRotation(Math.atan2(vecy, vecx));
vecx - the X coordinate of the rotation vectorvecy - the Y coordinate of the rotation vectorpublic void setToRotation(double vecx,
double vecy,
double anchorx,
double anchory)
vecx and vecy are 0.0,
the transform is set to an identity transform.
This operation is equivalent to calling:
setToTranslation(Math.atan2(vecy, vecx), anchorx, anchory);
vecx - the X coordinate of the rotation vectorvecy - the Y coordinate of the rotation vectoranchorx - the X coordinate of the rotation anchor pointanchory - the Y coordinate of the rotation anchor pointpublic void setToQuadrantRotation(int numquadrants)
setToRotation(numquadrants * Math.PI / 2.0);
Rotating by a positive number of quadrants rotates points on
the positive X axis toward the positive Y axis.numquadrants - the number of 90 degree arcs to rotate bypublic void setToQuadrantRotation(int numquadrants,
double anchorx,
double anchory)
setToRotation(numquadrants * Math.PI / 2.0, anchorx, anchory);
Rotating by a positive number of quadrants rotates points on
the positive X axis toward the positive Y axis.numquadrants - the number of 90 degree arcs to rotate byanchorx - the X coordinate of the rotation anchor pointanchory - the Y coordinate of the rotation anchor pointpublic void setToScale(double sx,
double sy)
[ sx 0 0 ]
[ 0 sy 0 ]
[ 0 0 1 ]
sx - the factor by which coordinates are scaled along the
X axis directionsy - the factor by which coordinates are scaled along the
Y axis directionpublic void setTransform(BaseTransform Tx)
BaseTransform object.setTransform in class BaseTransformTx - the BaseTransform object from which to
copy the transformpublic void preConcatenate(BaseTransform Tx)
BaseTransform Tx to
this Affine2D Cx
in a less commonly used way such that Tx modifies the
coordinate transformation relative to the absolute pixel
space rather than relative to the existing user space.
Cx is updated to perform the combined transformation.
Transforming a point p by the updated transform Cx' is
equivalent to first transforming p by the original transform
Cx and then transforming the result by
Tx like this:
Cx'(p) = Tx(Cx(p))
In matrix notation, if this transform Cx
is represented by the matrix [this] and Tx is
represented by the matrix [Tx] then this method does the
following:
[this] = [Tx] x [this]
Tx - the BaseTransform object to be
concatenated with this Affine2D object.AffineBase.concatenate(com.sun.javafx.geom.transform.BaseTransform)public Affine2D createInverse() throws NoninvertibleTransformException
Affine2D object representing the
inverse transformation.
The inverse transform Tx' of this transform Tx
maps coordinates transformed by Tx back
to their original coordinates.
In other words, Tx'(Tx(p)) = p = Tx(Tx'(p)).
If this transform maps all coordinates onto a point or a line
then it will not have an inverse, since coordinates that do
not lie on the destination point or line will not have an inverse
mapping.
The getDeterminant method can be used to determine if this
transform has no inverse, in which case an exception will be
thrown if the createInverse method is called.
createInverse in class BaseTransformAffine2D object representing the
inverse transformation.NoninvertibleTransformException - if the matrix cannot be inverted.AffineBase.getDeterminant()public void transform(Point2D[] ptSrc, int srcOff, Point2D[] ptDst, int dstOff, int numPts)
ptDst array is
null, a new Point2D object is allocated
and stored into that element before storing the results of the
transformation.
Note that this method does not take any precautions to
avoid problems caused by storing results into Point2D
objects that will be used as the source for calculations
further down the source array.
This method does guarantee that if a specified Point2D
object is both the source and destination for the same single point
transform operation then the results will not be stored until
the calculations are complete to avoid storing the results on
top of the operands.
If, however, the destination Point2D object for one
operation is the same object as the source Point2D
object for another operation further down the source array then
the original coordinates in that point are overwritten before
they can be converted.
ptSrc - the array containing the source point objectsptDst - the array into which the transform point objects are
returnedsrcOff - the offset to the first point object to be
transformed in the source arraydstOff - the offset to the location of the first
transformed point object that is stored in the destination arraynumPts - the number of point objects to be transformedpublic Point2D deltaTransform(Point2D ptSrc, Point2D ptDst)
ptSrc and stores the result in ptDst.
A relative distance vector is transformed without applying the
translation components of the affine transformation matrix
using the following equations:
[ x' ] [ m00 m01 (m02) ] [ x ] [ m00x + m01y ] [ y' ] = [ m10 m11 (m12) ] [ y ] = [ m10x + m11y ] [ (1) ] [ (0) (0) ( 1 ) ] [ (1) ] [ (1) ]If
ptDst is null, a new
Point2D object is allocated and then the result of the
transform is stored in this object.
In either case, ptDst, which contains the
transformed point, is returned for convenience.
If ptSrc and ptDst are the same object,
the input point is correctly overwritten with the transformed
point.ptSrc - the distance vector to be delta transformedptDst - the resulting transformed distance vectorptDst, which contains the result of the
transformation.private static double _matround(double matval)
public java.lang.String toString()
String that represents the value of this
Object.toString in class BaseTransformString representing the value of this
Object.public boolean is2D()
is2D in class AffineBasepublic void restoreTransform(double mxx,
double myx,
double mxy,
double myy,
double mxt,
double myt)
BaseTransformrestoreTransform in class BaseTransformpublic void restoreTransform(double mxx,
double mxy,
double mxz,
double mxt,
double myx,
double myy,
double myz,
double myt,
double mzx,
double mzy,
double mzz,
double mzt)
BaseTransformrestoreTransform in class BaseTransformpublic BaseTransform deriveWithTranslation(double mxt, double myt)
deriveWithTranslation in class BaseTransformpublic BaseTransform deriveWithTranslation(double mxt, double myt, double mzt)
deriveWithTranslation in class BaseTransformpublic BaseTransform deriveWithScale(double mxx, double myy, double mzz)
deriveWithScale in class BaseTransformpublic BaseTransform deriveWithRotation(double theta, double axisX, double axisY, double axisZ)
deriveWithRotation in class BaseTransformpublic BaseTransform deriveWithPreTranslation(double mxt, double myt)
deriveWithPreTranslation in class BaseTransformpublic BaseTransform deriveWithConcatenation(double mxx, double myx, double mxy, double myy, double mxt, double myt)
deriveWithConcatenation in class BaseTransformpublic BaseTransform deriveWithConcatenation(double mxx, double mxy, double mxz, double mxt, double myx, double myy, double myz, double myt, double mzx, double mzy, double mzz, double mzt)
deriveWithConcatenation in class BaseTransformpublic BaseTransform deriveWithConcatenation(BaseTransform tx)
deriveWithConcatenation in class BaseTransformpublic BaseTransform deriveWithPreConcatenation(BaseTransform tx)
deriveWithPreConcatenation in class BaseTransformpublic BaseTransform deriveWithNewTransform(BaseTransform tx)
deriveWithNewTransform in class BaseTransformpublic BaseTransform copy()
copy in class BaseTransformpublic int hashCode()
BaseTransform class. This implementation is just a
faster way of computing the same value knowing which elements of
the transform matrix are populated.hashCode in class BaseTransformpublic boolean equals(java.lang.Object obj)
true if this Affine2D
represents the same coordinate transform as the specified
argument.equals in class BaseTransformobj - the Object to test for equality with this
Affine2Dtrue if obj equals this
Affine2D object; false otherwise.