public class AffineTransform extends Object implements Cloneable, Serializable
The AffineTransform
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 AffineTransform
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
.
public static final int TYPE_IDENTITY
This constant indicates that the transform defined by this object is an identity transform. An identity transform is one in which the output coordinates are always the same as the input coordinates. If this transform is anything other than the identity transform, the type will either be the constant GENERAL_TRANSFORM or a combination of the appropriate flag bits for the various coordinate conversions that this transform performs.
TYPE_TRANSLATION
, TYPE_UNIFORM_SCALE
, TYPE_GENERAL_SCALE
, TYPE_FLIP
, TYPE_QUADRANT_ROTATION
, TYPE_GENERAL_ROTATION
, TYPE_GENERAL_TRANSFORM
, getType()
, Constant Field Valuespublic static final int TYPE_TRANSLATION
This flag bit indicates that the transform defined by this object performs a translation in addition to the conversions indicated by other flag bits. A translation moves the coordinates by a constant amount in x and y without changing the length or angle of vectors.
TYPE_IDENTITY
, TYPE_UNIFORM_SCALE
, TYPE_GENERAL_SCALE
, TYPE_FLIP
, TYPE_QUADRANT_ROTATION
, TYPE_GENERAL_ROTATION
, TYPE_GENERAL_TRANSFORM
, getType()
, Constant Field Valuespublic static final int TYPE_UNIFORM_SCALE
This flag bit indicates that the transform defined by this object performs a uniform scale in addition to the conversions indicated by other flag bits. A uniform scale multiplies the length of vectors by the same amount in both the x and y directions without changing the angle between vectors. This flag bit is mutually exclusive with the TYPE_GENERAL_SCALE flag.
TYPE_IDENTITY
, TYPE_TRANSLATION
, TYPE_GENERAL_SCALE
, TYPE_FLIP
, TYPE_QUADRANT_ROTATION
, TYPE_GENERAL_ROTATION
, TYPE_GENERAL_TRANSFORM
, getType()
, Constant Field Valuespublic static final int TYPE_GENERAL_SCALE
This flag bit indicates that the transform defined by this object performs a general scale in addition to the conversions indicated by other flag bits. A general scale multiplies the length of vectors by different amounts in the x and y directions without changing the angle between perpendicular vectors. This flag bit is mutually exclusive with the TYPE_UNIFORM_SCALE flag.
TYPE_IDENTITY
, TYPE_TRANSLATION
, TYPE_UNIFORM_SCALE
, TYPE_FLIP
, TYPE_QUADRANT_ROTATION
, TYPE_GENERAL_ROTATION
, TYPE_GENERAL_TRANSFORM
, getType()
, Constant Field Valuespublic static final int TYPE_MASK_SCALE
This constant is a bit mask for any of the scale flag bits.
TYPE_UNIFORM_SCALE
, TYPE_GENERAL_SCALE
, Constant Field Valuespublic static final int TYPE_FLIP
This flag bit indicates that the transform defined by this object performs a mirror image flip about some axis which changes the normally right handed coordinate system into a left handed system in addition to the conversions indicated by other flag bits. A right handed coordinate system is one where the positive X axis rotates counterclockwise to overlay the positive Y axis similar to the direction that the fingers on your right hand curl when you stare end on at your thumb. A left handed coordinate system is one where the positive X axis rotates clockwise to overlay the positive Y axis similar to the direction that the fingers on your left hand curl. There is no mathematical way to determine the angle of the original flipping or mirroring transformation since all angles of flip are identical given an appropriate adjusting rotation.
TYPE_IDENTITY
, TYPE_TRANSLATION
, TYPE_UNIFORM_SCALE
, TYPE_GENERAL_SCALE
, TYPE_QUADRANT_ROTATION
, TYPE_GENERAL_ROTATION
, TYPE_GENERAL_TRANSFORM
, getType()
, Constant Field Valuespublic static final int TYPE_QUADRANT_ROTATION
This flag bit indicates that the transform defined by this object performs a quadrant rotation by some multiple of 90 degrees in addition to the conversions indicated by other flag bits. A rotation changes the angles of vectors by the same amount regardless of the original direction of the vector and without changing the length of the vector. This flag bit is mutually exclusive with the TYPE_GENERAL_ROTATION flag.
TYPE_IDENTITY
, TYPE_TRANSLATION
, TYPE_UNIFORM_SCALE
, TYPE_GENERAL_SCALE
, TYPE_FLIP
, TYPE_GENERAL_ROTATION
, TYPE_GENERAL_TRANSFORM
, getType()
, Constant Field Valuespublic static final int TYPE_GENERAL_ROTATION
This flag bit indicates that the transform defined by this object performs a rotation by an arbitrary angle in addition to the conversions indicated by other flag bits. A rotation changes the angles of vectors by the same amount regardless of the original direction of the vector and without changing the length of the vector. This flag bit is mutually exclusive with the TYPE_QUADRANT_ROTATION flag.
TYPE_IDENTITY
, TYPE_TRANSLATION
, TYPE_UNIFORM_SCALE
, TYPE_GENERAL_SCALE
, TYPE_FLIP
, TYPE_QUADRANT_ROTATION
, TYPE_GENERAL_TRANSFORM
, getType()
, Constant Field Valuespublic static final int TYPE_MASK_ROTATION
This constant is a bit mask for any of the rotation flag bits.
TYPE_QUADRANT_ROTATION
, TYPE_GENERAL_ROTATION
, Constant Field Valuespublic static final int TYPE_GENERAL_TRANSFORM
This constant indicates that the transform defined by this object performs an arbitrary conversion of the input coordinates. If this transform can be classified by any of the above constants, the type will either be the constant TYPE_IDENTITY or a combination of the appropriate flag bits for the various coordinate conversions that this transform performs.
TYPE_IDENTITY
, TYPE_TRANSLATION
, TYPE_UNIFORM_SCALE
, TYPE_GENERAL_SCALE
, TYPE_FLIP
, TYPE_QUADRANT_ROTATION
, TYPE_GENERAL_ROTATION
, getType()
, Constant Field Valuespublic AffineTransform()
Constructs a new AffineTransform
representing the Identity transformation.
public AffineTransform(AffineTransform Tx)
Constructs a new AffineTransform
that is a copy of the specified AffineTransform
object.
Tx
- the AffineTransform
object to copy@ConstructorProperties(value={"scaleX","shearY","shearX","scaleY","translateX","translateY"}) public AffineTransform(float m00, float m10, float m01, float m11, float m02, float m12)
Constructs a new AffineTransform
from 6 floating point values representing the 6 specifiable entries of the 3x3 transformation matrix.
m00
- the X coordinate scaling element of the 3x3 matrixm10
- the Y coordinate shearing element of the 3x3 matrixm01
- the X coordinate shearing element of the 3x3 matrixm11
- the Y coordinate scaling element of the 3x3 matrixm02
- the X coordinate translation element of the 3x3 matrixm12
- the Y coordinate translation element of the 3x3 matrixpublic AffineTransform(float[] flatmatrix)
Constructs a new AffineTransform
from an array of floating point values representing either the 4 non-translation entries or the 6 specifiable entries of the 3x3 transformation matrix. The values are retrieved from the array as { m00 m10 m01 m11 [m02 m12]}.
flatmatrix
- the float array containing the values to be set in the new AffineTransform
object. The length of the array is assumed to be at least 4. If the length of the array is less than 6, only the first 4 values are taken. If the length of the array is greater than 6, the first 6 values are taken.public AffineTransform(double m00, double m10, double m01, double m11, double m02, double m12)
Constructs a new AffineTransform
from 6 double precision values representing the 6 specifiable entries of the 3x3 transformation matrix.
m00
- the X coordinate scaling element of the 3x3 matrixm10
- the Y coordinate shearing element of the 3x3 matrixm01
- the X coordinate shearing element of the 3x3 matrixm11
- the Y coordinate scaling element of the 3x3 matrixm02
- the X coordinate translation element of the 3x3 matrixm12
- the Y coordinate translation element of the 3x3 matrixpublic AffineTransform(double[] flatmatrix)
Constructs a new AffineTransform
from an array of double precision values representing either the 4 non-translation entries or the 6 specifiable entries of the 3x3 transformation matrix. The values are retrieved from the array as { m00 m10 m01 m11 [m02 m12]}.
flatmatrix
- the double array containing the values to be set in the new AffineTransform
object. The length of the array is assumed to be at least 4. If the length of the array is less than 6, only the first 4 values are taken. If the length of the array is greater than 6, the first 6 values are taken.public static AffineTransform getTranslateInstance(double tx, double ty)
Returns a transform representing a translation transformation. The matrix representing the returned transform is:
[ 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 directionAffineTransform
object that represents a translation transformation, created with the specified vector.public static AffineTransform getRotateInstance(double theta)
Returns a transform representing a rotation transformation. The matrix representing the returned transform is:
[ 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 radiansAffineTransform
object that is a rotation transformation, created with the specified angle of rotation.public static AffineTransform getRotateInstance(double theta, double anchorx, double anchory)
Returns a transform that rotates coordinates around an anchor point. This operation is equivalent to translating the coordinates so that the anchor point is at the origin (S1), then rotating them about the new origin (S2), and finally translating so that the intermediate origin is restored to the coordinates of the original anchor point (S3).
This operation is equivalent to the following sequence of calls:
AffineTransform Tx = new AffineTransform(); Tx.translate(anchorx, anchory); // S3: final translation Tx.rotate(theta); // S2: rotate around anchor Tx.translate(-anchorx, -anchory); // S1: translate anchor to originThe matrix representing the returned transform is:
[ 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 pointAffineTransform
object that rotates coordinates around the specified point by the specified angle of rotation.public static AffineTransform getRotateInstance(double vecx, double vecy)
Returns a transform that rotates coordinates according to a rotation vector. All coordinates rotate about the origin by the same amount. The amount of rotation is such that coordinates along the former positive X axis will subsequently align with the vector pointing from the origin to the specified vector coordinates. If both vecx
and vecy
are 0.0, an identity transform is returned. This operation is equivalent to calling:
AffineTransform.getRotateInstance(Math.atan2(vecy, vecx));
vecx
- the X coordinate of the rotation vectorvecy
- the Y coordinate of the rotation vectorAffineTransform
object that rotates coordinates according to the specified rotation vector.public static AffineTransform getRotateInstance(double vecx, double vecy, double anchorx, double anchory)
Returns a transform that rotates coordinates around an anchor point according to a rotation vector. All coordinates rotate about the specified anchor coordinates by the same amount. The amount of rotation is such that coordinates along the former positive X axis will subsequently align with the vector pointing from the origin to the specified vector coordinates. If both vecx
and vecy
are 0.0, an identity transform is returned. This operation is equivalent to calling:
AffineTransform.getRotateInstance(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 pointAffineTransform
object that rotates coordinates around the specified point according to the specified rotation vector.public static AffineTransform getQuadrantRotateInstance(int numquadrants)
Returns a transform that rotates coordinates by the specified number of quadrants. This operation is equivalent to calling:
AffineTransform.getRotateInstance(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 byAffineTransform
object that rotates coordinates by the specified number of quadrants.public static AffineTransform getQuadrantRotateInstance(int numquadrants, double anchorx, double anchory)
Returns a transform that rotates coordinates by the specified number of quadrants around the specified anchor point. This operation is equivalent to calling:
AffineTransform.getRotateInstance(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 pointAffineTransform
object that rotates coordinates by the specified number of quadrants around the specified anchor point.public static AffineTransform getScaleInstance(double sx, double sy)
Returns a transform representing a scaling transformation. The matrix representing the returned transform is:
[ 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 directionAffineTransform
object that scales coordinates by the specified factors.public static AffineTransform getShearInstance(double shx, double shy)
Returns a transform representing a shearing transformation. The matrix representing the returned transform is:
[ 1 shx 0 ] [ shy 1 0 ] [ 0 0 1 ]
shx
- the multiplier by which coordinates are shifted in the direction of the positive X axis as a factor of their Y coordinateshy
- the multiplier by which coordinates are shifted in the direction of the positive Y axis as a factor of their X coordinateAffineTransform
object that shears coordinates by the specified multipliers.public int getType()
Retrieves the flag bits describing the conversion properties of this transform. The return value is either one of the constants TYPE_IDENTITY or TYPE_GENERAL_TRANSFORM, or a combination of the appropriate flag bits. A valid combination of flag bits is an exclusive OR operation that can combine the TYPE_TRANSLATION flag bit in addition to either of the TYPE_UNIFORM_SCALE or TYPE_GENERAL_SCALE flag bits as well as either of the TYPE_QUADRANT_ROTATION or TYPE_GENERAL_ROTATION flag bits.
TYPE_IDENTITY
, TYPE_TRANSLATION
, TYPE_UNIFORM_SCALE
, TYPE_GENERAL_SCALE
, TYPE_QUADRANT_ROTATION
, TYPE_GENERAL_ROTATION
, TYPE_GENERAL_TRANSFORM
public double getDeterminant()
Returns the determinant of the matrix representation of the transform. The determinant is useful both to determine if the transform can be inverted and to get a single value representing the combined X and Y scaling of the transform.
If the determinant is non-zero, then this transform is invertible and the various methods that depend on the inverse transform do not need to throw a NoninvertibleTransformException
. If the determinant is zero then this transform can not be inverted since the transform maps all input coordinates onto a line or a point. If the determinant is near enough to zero then inverse transform operations might not carry enough precision to produce meaningful results.
If this transform represents a uniform scale, as indicated by the getType
method then the determinant also represents the square of the uniform scale factor by which all of the points are expanded from or contracted towards the origin. If this transform represents a non-uniform scale or more general transform then the determinant is not likely to represent a value useful for any purpose other than determining if inverse transforms are possible.
Mathematically, the determinant is calculated using the formula:
| m00 m01 m02 | | m10 m11 m12 | = m00 * m11 - m01 * m10 | 0 0 1 |
getType()
, createInverse()
, inverseTransform(java.awt.geom.Point2D, java.awt.geom.Point2D)
, TYPE_UNIFORM_SCALE
public void getMatrix(double[] flatmatrix)
Retrieves the 6 specifiable values in the 3x3 affine transformation matrix and places them into an array of double precisions values. The values are stored in the array as { m00 m10 m01 m11 m02 m12 }. An array of 4 doubles can also be specified, in which case only the first four elements representing the non-transform parts of the array are retrieved and the values are stored into the array as { m00 m10 m01 m11 }
flatmatrix
- the double array used to store the returned values.getScaleX()
, getScaleY()
, getShearX()
, getShearY()
, getTranslateX()
, getTranslateY()
public double getScaleX()
Returns the X coordinate scaling element (m00) of the 3x3 affine transformation matrix.
getMatrix(double[])
public double getScaleY()
Returns the Y coordinate scaling element (m11) of the 3x3 affine transformation matrix.
getMatrix(double[])
public double getShearX()
Returns the X coordinate shearing element (m01) of the 3x3 affine transformation matrix.
getMatrix(double[])
public double getShearY()
Returns the Y coordinate shearing element (m10) of the 3x3 affine transformation matrix.
getMatrix(double[])
public double getTranslateX()
Returns the X coordinate of the translation element (m02) of the 3x3 affine transformation matrix.
getMatrix(double[])
public double getTranslateY()
Returns the Y coordinate of the translation element (m12) of the 3x3 affine transformation matrix.
getMatrix(double[])
public void translate(double tx, double ty)
Concatenates this transform with a translation transformation. This is equivalent to calling concatenate(T), where T is an AffineTransform
represented by the following matrix:
[ 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 rotate(double theta)
Concatenates this transform with a rotation transformation. This is equivalent to calling concatenate(R), where R is an AffineTransform
represented by the following matrix:
[ 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 rotate(double theta, double anchorx, double anchory)
Concatenates this transform with a transform that rotates coordinates around an anchor point. This operation is equivalent to translating the coordinates so that the anchor point is at the origin (S1), then rotating them about the new origin (S2), and finally translating so that the intermediate origin is restored to the coordinates of the original anchor point (S3).
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 originRotating 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)
Concatenates this transform with a transform that rotates coordinates according to a rotation vector. All coordinates rotate about the origin by the same amount. The amount of rotation is such that coordinates along the former positive X axis will subsequently align with the vector pointing from the origin to the specified vector coordinates. If both 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)
Concatenates this transform with a transform that rotates coordinates around an anchor point according to a rotation vector. All coordinates rotate about the specified anchor coordinates by the same amount. The amount of rotation is such that coordinates along the former positive X axis will subsequently align with the vector pointing from the origin to the specified vector coordinates. If both 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)
Concatenates this transform with a transform that rotates coordinates by the specified number of quadrants. This is equivalent to calling:
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)
Concatenates this transform with a transform that rotates coordinates by the specified number of quadrants around the specified anchor point. This method is equivalent to calling:
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 scale(double sx, double sy)
Concatenates this transform with a scaling transformation. This is equivalent to calling concatenate(S), where S is an AffineTransform
represented by the following matrix:
[ 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 shear(double shx, double shy)
Concatenates this transform with a shearing transformation. This is equivalent to calling concatenate(SH), where SH is an AffineTransform
represented by the following matrix:
[ 1 shx 0 ] [ shy 1 0 ] [ 0 0 1 ]
shx
- the multiplier by which coordinates are shifted in the direction of the positive X axis as a factor of their Y coordinateshy
- the multiplier by which coordinates are shifted in the direction of the positive Y axis as a factor of their X coordinatepublic void setToIdentity()
Resets this transform to the Identity transform.
public void setToTranslation(double tx, double ty)
Sets this transform to a translation transformation. The matrix representing this transform becomes:
[ 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)
Sets this transform to a rotation transformation. The matrix representing this transform becomes:
[ 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)
Sets this transform to a translated rotation transformation. This operation is equivalent to translating the coordinates so that the anchor point is at the origin (S1), then rotating them about the new origin (S2), and finally translating so that the intermediate origin is restored to the coordinates of the original anchor point (S3).
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 originThe 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)
Sets this transform to a rotation transformation that rotates coordinates according to a rotation vector. All coordinates rotate about the origin by the same amount. The amount of rotation is such that coordinates along the former positive X axis will subsequently align with the vector pointing from the origin to the specified vector coordinates. If both 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)
Sets this transform to a rotation transformation that rotates coordinates around an anchor point according to a rotation vector. All coordinates rotate about the specified anchor coordinates by the same amount. The amount of rotation is such that coordinates along the former positive X axis will subsequently align with the vector pointing from the origin to the specified vector coordinates. If both 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)
Sets this transform to a rotation transformation that rotates coordinates by the specified number of quadrants. This operation is equivalent to calling:
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)
Sets this transform to a translated rotation transformation that rotates coordinates by the specified number of quadrants around the specified anchor point. This operation is equivalent to calling:
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)
Sets this transform to a scaling transformation. The matrix representing this transform becomes:
[ 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 setToShear(double shx, double shy)
Sets this transform to a shearing transformation. The matrix representing this transform becomes:
[ 1 shx 0 ] [ shy 1 0 ] [ 0 0 1 ]
shx
- the multiplier by which coordinates are shifted in the direction of the positive X axis as a factor of their Y coordinateshy
- the multiplier by which coordinates are shifted in the direction of the positive Y axis as a factor of their X coordinatepublic void setTransform(AffineTransform Tx)
Sets this transform to a copy of the transform in the specified AffineTransform
object.
Tx
- the AffineTransform
object from which to copy the transformpublic void setTransform(double m00, double m10, double m01, double m11, double m02, double m12)
Sets this transform to the matrix specified by the 6 double precision values.
m00
- the X coordinate scaling element of the 3x3 matrixm10
- the Y coordinate shearing element of the 3x3 matrixm01
- the X coordinate shearing element of the 3x3 matrixm11
- the Y coordinate scaling element of the 3x3 matrixm02
- the X coordinate translation element of the 3x3 matrixm12
- the Y coordinate translation element of the 3x3 matrixpublic void concatenate(AffineTransform Tx)
Concatenates an AffineTransform
Tx
to this AffineTransform
Cx in the most commonly useful way to provide a new user space that is mapped to the former user space by Tx
. Cx is updated to perform the combined transformation. Transforming a point p by the updated transform Cx' is equivalent to first transforming p by Tx
and then transforming the result by the original transform Cx like this: Cx'(p) = Cx(Tx(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] = [this] x [Tx]
Tx
- the AffineTransform
object to be concatenated with this AffineTransform
object.preConcatenate(java.awt.geom.AffineTransform)
public void preConcatenate(AffineTransform Tx)
Concatenates an AffineTransform
Tx
to this AffineTransform
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 AffineTransform
object to be concatenated with this AffineTransform
object.concatenate(java.awt.geom.AffineTransform)
public AffineTransform createInverse() throws NoninvertibleTransformException
Returns an AffineTransform
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.
AffineTransform
object representing the inverse transformation.NoninvertibleTransformException
- if the matrix cannot be inverted.getDeterminant()
public void invert() throws NoninvertibleTransformException
Sets this transform to the inverse of itself. 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 invert
method is called.
NoninvertibleTransformException
- if the matrix cannot be inverted.getDeterminant()
public Point2D transform(Point2D ptSrc, Point2D ptDst)
Transforms the specified ptSrc
and stores the result in ptDst
. If ptDst
is null
, a new Point2D
object is allocated and then the result of the transformation 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 specified Point2D
to be transformedptDst
- the specified Point2D
that stores the result of transforming ptSrc
ptDst
after transforming ptSrc
and storing the result in ptDst
.public void transform(Point2D[] ptSrc, int srcOff, Point2D[] ptDst, int dstOff, int numPts)
Transforms an array of point objects by this transform. If any element of the 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 void transform(float[] srcPts, int srcOff, float[] dstPts, int dstOff, int numPts)
Transforms an array of floating point coordinates by this transform. The two coordinate array sections can be exactly the same or can be overlapping sections of the same array without affecting the validity of the results. This method ensures that no source coordinates are overwritten by a previous operation before they can be transformed. The coordinates are stored in the arrays starting at the specified offset in the order [x0, y0, x1, y1, ..., xn, yn]
.
srcPts
- the array containing the source point coordinates. Each point is stored as a pair of x, y coordinates.dstPts
- the array into which the transformed point coordinates are returned. Each point is stored as a pair of x, y coordinates.srcOff
- the offset to the first point to be transformed in the source arraydstOff
- the offset to the location of the first transformed point that is stored in the destination arraynumPts
- the number of points to be transformedpublic void transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)
Transforms an array of double precision coordinates by this transform. The two coordinate array sections can be exactly the same or can be overlapping sections of the same array without affecting the validity of the results. This method ensures that no source coordinates are overwritten by a previous operation before they can be transformed. The coordinates are stored in the arrays starting at the indicated offset in the order [x0, y0, x1, y1, ..., xn, yn]
.
srcPts
- the array containing the source point coordinates. Each point is stored as a pair of x, y coordinates.dstPts
- the array into which the transformed point coordinates are returned. Each point is stored as a pair of x, y coordinates.srcOff
- the offset to the first point to be transformed in the source arraydstOff
- the offset to the location of the first transformed point that is stored in the destination arraynumPts
- the number of point objects to be transformedpublic void transform(float[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)
Transforms an array of floating point coordinates by this transform and stores the results into an array of doubles. The coordinates are stored in the arrays starting at the specified offset in the order [x0, y0, x1, y1, ..., xn, yn]
.
srcPts
- the array containing the source point coordinates. Each point is stored as a pair of x, y coordinates.dstPts
- the array into which the transformed point coordinates are returned. Each point is stored as a pair of x, y coordinates.srcOff
- the offset to the first point to be transformed in the source arraydstOff
- the offset to the location of the first transformed point that is stored in the destination arraynumPts
- the number of points to be transformedpublic void transform(double[] srcPts, int srcOff, float[] dstPts, int dstOff, int numPts)
Transforms an array of double precision coordinates by this transform and stores the results into an array of floats. The coordinates are stored in the arrays starting at the specified offset in the order [x0, y0, x1, y1, ..., xn, yn]
.
srcPts
- the array containing the source point coordinates. Each point is stored as a pair of x, y coordinates.dstPts
- the array into which the transformed point coordinates are returned. Each point is stored as a pair of x, y coordinates.srcOff
- the offset to the first point to be transformed in the source arraydstOff
- the offset to the location of the first transformed point that is stored in the destination arraynumPts
- the number of point objects to be transformedpublic Point2D inverseTransform(Point2D ptSrc, Point2D ptDst) throws NoninvertibleTransformException
Inverse transforms the specified ptSrc
and stores the result in ptDst
. 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 point to be inverse transformedptDst
- the resulting transformed pointptDst
, which contains the result of the inverse transform.NoninvertibleTransformException
- if the matrix cannot be inverted.public void inverseTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) throws NoninvertibleTransformException
Inverse transforms an array of double precision coordinates by this transform. The two coordinate array sections can be exactly the same or can be overlapping sections of the same array without affecting the validity of the results. This method ensures that no source coordinates are overwritten by a previous operation before they can be transformed. The coordinates are stored in the arrays starting at the specified offset in the order [x0, y0, x1, y1, ..., xn, yn]
.
srcPts
- the array containing the source point coordinates. Each point is stored as a pair of x, y coordinates.dstPts
- the array into which the transformed point coordinates are returned. Each point is stored as a pair of x, y coordinates.srcOff
- the offset to the first point to be transformed in the source arraydstOff
- the offset to the location of the first transformed point that is stored in the destination arraynumPts
- the number of point objects to be transformedNoninvertibleTransformException
- if the matrix cannot be inverted.public Point2D deltaTransform(Point2D ptSrc, Point2D ptDst)
Transforms the relative distance vector specified by 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.public void deltaTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)
Transforms an array of relative distance vectors by this transform. 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) ]The two coordinate array sections can be exactly the same or can be overlapping sections of the same array without affecting the validity of the results. This method ensures that no source coordinates are overwritten by a previous operation before they can be transformed. The coordinates are stored in the arrays starting at the indicated offset in the order
[x0, y0, x1, y1, ..., xn, yn]
. srcPts
- the array containing the source distance vectors. Each vector is stored as a pair of relative x, y coordinates.dstPts
- the array into which the transformed distance vectors are returned. Each vector is stored as a pair of relative x, y coordinates.srcOff
- the offset to the first vector to be transformed in the source arraydstOff
- the offset to the location of the first transformed vector that is stored in the destination arraynumPts
- the number of vector coordinate pairs to be transformedpublic Shape createTransformedShape(Shape pSrc)
Returns a new Shape
object defined by the geometry of the specified Shape
after it has been transformed by this transform.
pSrc
- the specified Shape
object to be transformed by this transform.Shape
object that defines the geometry of the transformed Shape
, or null if pSrc
is null.public String toString()
Returns a String
that represents the value of this Object
.
toString
in class Object
String
representing the value of this Object
.public boolean isIdentity()
Returns true
if this AffineTransform
is an identity transform.
true
if this AffineTransform
is an identity transform; false
otherwise.public Object clone()
Returns a copy of this AffineTransform
object.
clone
in class Object
Object
that is a copy of this AffineTransform
object.Cloneable
public int hashCode()
Returns the hashcode for this transform.
hashCode
in class Object
Object.equals(java.lang.Object)
, System.identityHashCode(java.lang.Object)
public boolean equals(Object obj)
Returns true
if this AffineTransform
represents the same affine coordinate transform as the specified argument.
equals
in class Object
obj
- the Object
to test for equality with this AffineTransform
true
if obj
equals this AffineTransform
object; false
otherwise.Object.hashCode()
, HashMap
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