public class AffineTransform extends Objectimplements Cloneable , Serializable
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.
| Modifier and Type | Field and Description |
|---|---|
static 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.
|
static 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.
|
static 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.
|
static int |
TYPE_GENERAL_TRANSFORM
This constant indicates that the transform defined by this object performs an arbitrary conversion of the input coordinates.
|
static int |
TYPE_IDENTITY
This constant indicates that the transform defined by this object is an identity transform.
|
static int |
TYPE_MASK_ROTATION
This constant is a bit mask for any of the rotation flag bits.
|
static int |
TYPE_MASK_SCALE
This constant is a bit mask for any of the scale flag bits.
|
static 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.
|
static 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.
|
static 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.
|
| Constructor and Description |
|---|
AffineTransform()
Constructs a new
AffineTransform representing the Identity transformation.
|
AffineTransform(AffineTransform
Constructs a new
AffineTransform that is a copy of the specified
AffineTransform object.
|
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.
|
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.
|
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.
|
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.
|
| Modifier and Type | Method and Description |
|---|---|
Object |
clone()
Returns a copy of this
AffineTransform object.
|
void |
concatenate(AffineTransform
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.
|
AffineTransform |
createInverse()
Returns an
AffineTransform object representing the inverse transformation.
|
Shape |
createTransformedShape(Shape
Returns a new
Shape object defined by the geometry of the specified
Shape after it has been transformed by this transform.
|
void |
deltaTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)
Transforms an array of relative distance vectors by this transform.
|
Point2D |
deltaTransform(Point2D
Transforms the relative distance vector specified by
ptSrc and stores the result in
ptDst.
|
boolean |
equals(Object
Returns
true if this
AffineTransform represents the same affine coordinate transform as the specified argument.
|
double |
getDeterminant()
Returns the determinant of the matrix representation of the transform.
|
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.
|
static AffineTransform |
getQuadrantRotateInstance(int numquadrants)
Returns a transform that rotates coordinates by the specified number of quadrants.
|
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.
|
static AffineTransform |
getRotateInstance(double theta)
Returns a transform representing a rotation transformation.
|
static AffineTransform |
getRotateInstance(double vecx, double vecy)
Returns a transform that rotates coordinates according to a rotation vector.
|
static AffineTransform |
getRotateInstance(double theta, double anchorx, double anchory)
Returns a transform that rotates coordinates around an anchor point.
|
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.
|
static AffineTransform |
getScaleInstance(double sx, double sy)
Returns a transform representing a scaling transformation.
|
double |
getScaleX()
Returns the X coordinate scaling element (m00) of the 3x3 affine transformation matrix.
|
double |
getScaleY()
Returns the Y coordinate scaling element (m11) of the 3x3 affine transformation matrix.
|
static AffineTransform |
getShearInstance(double shx, double shy)
Returns a transform representing a shearing transformation.
|
double |
getShearX()
Returns the X coordinate shearing element (m01) of the 3x3 affine transformation matrix.
|
double |
getShearY()
Returns the Y coordinate shearing element (m10) of the 3x3 affine transformation matrix.
|
static AffineTransform |
getTranslateInstance(double tx, double ty)
Returns a transform representing a translation transformation.
|
double |
getTranslateX()
Returns the X coordinate of the translation element (m02) of the 3x3 affine transformation matrix.
|
double |
getTranslateY()
Returns the Y coordinate of the translation element (m12) of the 3x3 affine transformation matrix.
|
int |
getType()
Retrieves the flag bits describing the conversion properties of this transform.
|
int |
hashCode()
Returns the hashcode for this transform.
|
void |
inverseTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)
Inverse transforms an array of double precision coordinates by this transform.
|
Point2D |
inverseTransform(Point2D
Inverse transforms the specified
ptSrc and stores the result in
ptDst.
|
void |
invert()
Sets this transform to the inverse of itself.
|
boolean |
isIdentity()
Returns
true if this
AffineTransform is an identity transform.
|
void |
preConcatenate(AffineTransform
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.
|
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.
|
void |
rotate(double theta)
Concatenates this transform with a rotation transformation.
|
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 |
scale(double sx, double sy)
Concatenates this transform with a scaling transformation.
|
void |
setToIdentity()
Resets this transform to the Identity transform.
|
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 |
setToShear(double shx, double shy)
Sets this transform to a shearing transformation.
|
void |
setToTranslation(double tx, double ty)
Sets this transform to a translation transformation.
|
void |
setTransform(AffineTransform
Sets this transform to a copy of the transform in the specified
AffineTransform object.
|
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.
|
void |
shear(double shx, double shy)
Concatenates this transform with a shearing transformation.
|
String |
toString()
Returns a
String that represents the value of this
Object.
|
void |
transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)
Transforms an array of double precision coordinates by this transform.
|
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.
|
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.
|
void |
transform(float[] srcPts, int srcOff, float[] dstPts, int dstOff, int numPts)
Transforms an array of floating point coordinates by this transform.
|
void |
transform(Point2D
Transforms an array of point objects by this transform.
|
Point2D |
transform(Point2D
Transforms the specified
ptSrc and stores the result in
ptDst.
|
void |
translate(double tx, double ty)
Concatenates this transform with a translation transformation.
|
public static final int TYPE_IDENTITY
public static final int TYPE_TRANSLATION
public static final int TYPE_UNIFORM_SCALE
public static final int TYPE_GENERAL_SCALE
public static final int TYPE_MASK_SCALE
TYPE_UNIFORM_SCALE,
TYPE_GENERAL_SCALE,
Constant Field Values
public static final int TYPE_FLIP
public static final int TYPE_QUADRANT_ROTATION
TYPE_IDENTITY,
TYPE_TRANSLATION,
TYPE_UNIFORM_SCALE,
TYPE_GENERAL_SCALE,
TYPE_FLIP,
TYPE_GENERAL_ROTATION,
TYPE_GENERAL_TRANSFORM,
getType(),
Constant Field Values
public static final int TYPE_GENERAL_ROTATION
TYPE_IDENTITY,
TYPE_TRANSLATION,
TYPE_UNIFORM_SCALE,
TYPE_GENERAL_SCALE,
TYPE_FLIP,
TYPE_QUADRANT_ROTATION,
TYPE_GENERAL_TRANSFORM,
getType(),
Constant Field Values
public static final int TYPE_MASK_ROTATION
TYPE_QUADRANT_ROTATION,
TYPE_GENERAL_ROTATION,
Constant Field Values
public static final int TYPE_GENERAL_TRANSFORM
TYPE_IDENTITY,
TYPE_TRANSLATION,
TYPE_UNIFORM_SCALE,
TYPE_GENERAL_SCALE,
TYPE_FLIP,
TYPE_QUADRANT_ROTATION,
TYPE_GENERAL_ROTATION,
getType(),
Constant Field Values
public AffineTransform()
AffineTransform representing the Identity transformation.
public AffineTransform(AffineTransformTx)
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)
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 matrix
m10 - the Y coordinate shearing element of the 3x3 matrix
m01 - the X coordinate shearing element of the 3x3 matrix
m11 - the Y coordinate scaling element of the 3x3 matrix
m02 - the X coordinate translation element of the 3x3 matrix
m12 - the Y coordinate translation element of the 3x3 matrix
public AffineTransform(float[] flatmatrix)
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)
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 matrix
m10 - the Y coordinate shearing element of the 3x3 matrix
m01 - the X coordinate shearing element of the 3x3 matrix
m11 - the Y coordinate scaling element of the 3x3 matrix
m02 - the X coordinate translation element of the 3x3 matrix
m12 - the Y coordinate translation element of the 3x3 matrix
public AffineTransform(double[] flatmatrix)
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 AffineTransformgetTranslateInstance(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 direction
ty - the distance by which coordinates are translated in the Y axis direction
AffineTransform object that represents a translation transformation, created with the specified vector.
public static AffineTransformgetRotateInstance(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 radians
AffineTransform object that is a rotation transformation, created with the specified angle of rotation.
public static AffineTransformgetRotateInstance(double theta, double anchorx, double anchory)
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 origin
The 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 radians
anchorx - the X coordinate of the rotation anchor point
anchory - the Y coordinate of the rotation anchor point
AffineTransform object that rotates coordinates around the specified point by the specified angle of rotation.
public static AffineTransformgetRotateInstance(double vecx, double vecy)
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 vector
vecy - the Y coordinate of the rotation vector
AffineTransform object that rotates coordinates according to the specified rotation vector.
public static AffineTransformgetRotateInstance(double vecx, double vecy, double anchorx, double anchory)
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 vector
vecy - the Y coordinate of the rotation vector
anchorx - the X coordinate of the rotation anchor point
anchory - the Y coordinate of the rotation anchor point
AffineTransform object that rotates coordinates around the specified point according to the specified rotation vector.
public static AffineTransformgetQuadrantRotateInstance(int numquadrants)
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 by
AffineTransform object that rotates coordinates by the specified number of quadrants.
public static AffineTransformgetQuadrantRotateInstance(int numquadrants, double anchorx, double anchory)
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 by
anchorx - the X coordinate of the rotation anchor point
anchory - the Y coordinate of the rotation anchor point
AffineTransform object that rotates coordinates by the specified number of quadrants around the specified anchor point.
public static AffineTransformgetScaleInstance(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 direction
sy - the factor by which coordinates are scaled along the Y axis direction
AffineTransform object that scales coordinates by the specified factors.
public static AffineTransformgetShearInstance(double shx, double shy)
[ 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 coordinate
shy - the multiplier by which coordinates are shifted in the direction of the positive Y axis as a factor of their X coordinate
AffineTransform object that shears coordinates by the specified multipliers.
public int getType()
TYPE_IDENTITY,
TYPE_TRANSLATION,
TYPE_UNIFORM_SCALE,
TYPE_GENERAL_SCALE,
TYPE_QUADRANT_ROTATION,
TYPE_GENERAL_ROTATION,
TYPE_GENERAL_TRANSFORM
public double getDeterminant()
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)
flatmatrix - the double array used to store the returned values.
getScaleX(),
getScaleY(),
getShearX(),
getShearY(),
getTranslateX(),
getTranslateY()
public double getScaleX()
getMatrix(double[])
public double getScaleY()
getMatrix(double[])
public double getShearX()
getMatrix(double[])
public double getShearY()
getMatrix(double[])
public double getTranslateX()
getMatrix(double[])
public double getTranslateY()
getMatrix(double[])
public void translate(double tx,
double ty)
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 direction
ty - the distance by which coordinates are translated in the Y axis direction
public void rotate(double theta)
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 radians
public 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 radians
anchorx - the X coordinate of the rotation anchor point
anchory - the Y coordinate of the rotation anchor point
public 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 vector
vecy - the Y coordinate of the rotation vector
public 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 vector
vecy - the Y coordinate of the rotation vector
anchorx - the X coordinate of the rotation anchor point
anchory - the Y coordinate of the rotation anchor point
public 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 by
public 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 by
anchorx - the X coordinate of the rotation anchor point
anchory - the Y coordinate of the rotation anchor point
public void scale(double sx,
double sy)
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 direction
sy - the factor by which coordinates are scaled along the Y axis direction
public void shear(double shx,
double shy)
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 coordinate
shy - the multiplier by which coordinates are shifted in the direction of the positive Y axis as a factor of their X coordinate
public void setToIdentity()
public 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 direction
ty - the distance by which coordinates are translated in the Y axis direction
public 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 radians
public 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 radians
anchorx - the X coordinate of the rotation anchor point
anchory - the Y coordinate of the rotation anchor point
public 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 vector
vecy - the Y coordinate of the rotation vector
public 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 vector
vecy - the Y coordinate of the rotation vector
anchorx - the X coordinate of the rotation anchor point
anchory - the Y coordinate of the rotation anchor point
public 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 by
public 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 by
anchorx - the X coordinate of the rotation anchor point
anchory - the Y coordinate of the rotation anchor point
public 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 direction
sy - the factor by which coordinates are scaled along the Y axis direction
public void setToShear(double shx,
double shy)
[ 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 coordinate
shy - the multiplier by which coordinates are shifted in the direction of the positive Y axis as a factor of their X coordinate
public void setTransform(AffineTransformTx)
AffineTransform object.
Tx - the
AffineTransform object from which to copy the transform
public void setTransform(double m00,
double m10,
double m01,
double m11,
double m02,
double m12)
m00 - the X coordinate scaling element of the 3x3 matrix
m10 - the Y coordinate shearing element of the 3x3 matrix
m01 - the X coordinate shearing element of the 3x3 matrix
m11 - the Y coordinate scaling element of the 3x3 matrix
m02 - the X coordinate translation element of the 3x3 matrix
m12 - the Y coordinate translation element of the 3x3 matrix
public void concatenate(AffineTransformTx)
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(AffineTransformTx)
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 AffineTransformcreateInverse() throws NoninvertibleTransformException
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
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 Point2Dtransform(Point2D ptSrc, Point2D ptDst)
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 transformed
ptDst - 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)
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 objects
ptDst - the array into which the transform point objects are returned
srcOff - the offset to the first point object to be transformed in the source array
dstOff - the offset to the location of the first transformed point object that is stored in the destination array
numPts - the number of point objects to be transformed
public void transform(float[] srcPts,
int srcOff,
float[] dstPts,
int dstOff,
int numPts)
[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 array
dstOff - the offset to the location of the first transformed point that is stored in the destination array
numPts - the number of points to be transformed
public void transform(double[] srcPts,
int srcOff,
double[] dstPts,
int dstOff,
int numPts)
[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 array
dstOff - the offset to the location of the first transformed point that is stored in the destination array
numPts - the number of point objects to be transformed
public void transform(float[] srcPts,
int srcOff,
double[] dstPts,
int dstOff,
int numPts)
[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 array
dstOff - the offset to the location of the first transformed point that is stored in the destination array
numPts - the number of points to be transformed
public void transform(double[] srcPts,
int srcOff,
float[] dstPts,
int dstOff,
int numPts)
[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 array
dstOff - the offset to the location of the first transformed point that is stored in the destination array
numPts - the number of point objects to be transformed
public Point2DinverseTransform(Point2D ptSrc, Point2D ptDst) throws NoninvertibleTransformException
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 transformed
ptDst - the resulting transformed point
ptDst, 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
[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 array
dstOff - the offset to the location of the first transformed point that is stored in the destination array
numPts - the number of point objects to be transformed
NoninvertibleTransformException - if the matrix cannot be inverted.
public Point2DdeltaTransform(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 transformed
ptDst - the resulting transformed distance vector
ptDst, which contains the result of the transformation.
public void deltaTransform(double[] srcPts,
int srcOff,
double[] dstPts,
int dstOff,
int numPts)
[ 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 array
dstOff - the offset to the location of the first transformed vector that is stored in the destination array
numPts - the number of vector coordinate pairs to be transformed
public ShapecreateTransformedShape(Shape pSrc)
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 boolean isIdentity()
true if this
AffineTransform is an identity transform.
true if this
AffineTransform is an identity transform;
false otherwise.
public Objectclone()
AffineTransform object.
public int hashCode()
hashCode in class
Object
Object.equals(java.lang.Object) ,
System.identityHashCode(java.lang.Object)
public boolean equals(Objectobj)
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