android.graphics
Class Matrix

java.lang.Object
  android.graphics.Matrix

public class Matrix
extends Object

The Matrix class holds a 3x3 matrix for transforming coordinates. Matrix does not have a constructor, so it must be explicitly initialized using either reset() - to construct an identity matrix, or one of the set..() functions (e.g. setTranslate, setRotate, etc.).

Nested Class Summary

static class

Matrix.ScaleToFit Controlls how the src rect should align into the dst rect for setRectToRect().

Field Summary

static int	MPERSP_0
static int	MPERSP_1
static int	MPERSP_2
static int	MSCALE_X
static int	MSCALE_Y
static int	MSKEW_X
static int	MSKEW_Y
static int	MTRANS_X
static int	MTRANS_Y
(package private) int	native_instance

Constructor Summary

Matrix()
Create an identity matrix

Matrix(Matrix src)
Create a matrix that is a (deep) copy of src

Method Summary

boolean	equals(Object obj) Returns true iff obj is a Matrix and its values equal our values.
protected void	finalize() Called by the virtual machine when there are no longer any (non-weak) references to the receiver.
void	getValues(float[] values) Copy 9 values from the matrix into the array.
boolean	invert(Matrix inverse) If this matrix can be inverted, return true and if inverse is not null, set inverse to be the inverse of this matrix.
boolean	isIdentity() Returns true if the matrix is identity.
void	mapPoints(float[] pts) Apply this matrix to the array of 2D points, and write the transformed points back into the array
void	mapPoints(float[] dst, float[] src) Apply this matrix to the array of 2D points specified by src, and write the transformed points into the array of points specified by dst.
void	mapPoints(float[] dst, int dstIndex, float[] src, int srcIndex, int pointCount) Apply this matrix to the array of 2D points specified by src, and write the transformed points into the array of points specified by dst.
float	mapRadius(float radius) Return the mean radius of a circle after it has been mapped by this matrix.
boolean	mapRect(RectF rect) Apply this matrix to the rectangle, and write the transformed rectangle back into it.
boolean	mapRect(RectF dst, RectF src) Apply this matrix to the src rectangle, and write the transformed rectangle into dst.
void	mapVectors(float[] vecs) Apply this matrix to the array of 2D vectors, and write the transformed vectors back into the array.
void	mapVectors(float[] dst, float[] src) Apply this matrix to the array of 2D vectors specified by src, and write the transformed vectors into the array of vectors specified by dst.
void	mapVectors(float[] dst, int dstIndex, float[] src, int srcIndex, int vectorCount) Apply this matrix to the array of 2D vectors specified by src, and write the transformed vectors into the array of vectors specified by dst.
(package private) int	ni()
boolean	postConcat(Matrix other) Postconcats the matrix with the specified matrix.
boolean	postRotate(float degrees) Postconcats the matrix with the specified rotation.
boolean	postRotate(float degrees, float px, float py) Postconcats the matrix with the specified rotation.
boolean	postScale(float sx, float sy) Postconcats the matrix with the specified scale.
boolean	postScale(float sx, float sy, float px, float py) Postconcats the matrix with the specified scale.
boolean	postSkew(float kx, float ky) Postconcats the matrix with the specified skew.
boolean	postSkew(float kx, float ky, float px, float py) Postconcats the matrix with the specified skew.
boolean	postTranslate(float dx, float dy) Postconcats the matrix with the specified translation.
boolean	preConcat(Matrix other) Preconcats the matrix with the specified matrix.
boolean	preRotate(float degrees) Preconcats the matrix with the specified rotation.
boolean	preRotate(float degrees, float px, float py) Preconcats the matrix with the specified rotation.
boolean	preScale(float sx, float sy) Preconcats the matrix with the specified scale.
boolean	preScale(float sx, float sy, float px, float py) Preconcats the matrix with the specified scale.
boolean	preSkew(float kx, float ky) Preconcats the matrix with the specified skew.
boolean	preSkew(float kx, float ky, float px, float py) Preconcats the matrix with the specified skew.
boolean	preTranslate(float dx, float dy) Preconcats the matrix with the specified translation.
boolean	rectStaysRect() Returns true if will map a rectangle to another rectangle.
void	reset() Set the matrix to identity
void	set(Matrix src) (deep) copy the src matrix into this matrix.
boolean	setConcat(Matrix a, Matrix b) Set the matrix to the concatenation of the two specified matrices, returning true if the the result can be represented.
boolean	setPolyToPoly(float[] src, int srcIndex, float[] dst, int dstIndex, int pointCount) Set the matrix such that the specified src points would map to the specified dst points.
boolean	setRectToRect(RectF src, RectF dst, Matrix.ScaleToFit stf) Set the matrix to the scale and translate values that map the source rectangle to the destination rectangle, returning true if the the result can be represented.
void	setRotate(float degrees) Set the matrix to rotate about (0,0) by the specified number of degrees.
void	setRotate(float degrees, float px, float py) Set the matrix to rotate by the specified number of degrees, with a pivot point at (px, py).
void	setScale(float sx, float sy) Set the matrix to scale by sx and sy.
void	setScale(float sx, float sy, float px, float py) Set the matrix to scale by sx and sy, with a pivot point at (px, py).
void	setSinCos(float sinValue, float cosValue) Set the matrix to rotate by the specified sine and cosine values.
void	setSinCos(float sinValue, float cosValue, float px, float py) Set the matrix to rotate by the specified sine and cosine values, with a pivot point at (px, py).
void	setSkew(float kx, float ky) Set the matrix to skew by sx and sy.
void	setSkew(float kx, float ky, float px, float py) Set the matrix to skew by sx and sy, with a pivot point at (px, py).
void	setTranslate(float dx, float dy) Set the matrix to translate by (dx, dy).
void	setValues(float[] values) Copy 9 values from the array into the matrix.
String	toShortString()
String	toString() Returns a string containing a concise, human-readable description of the receiver.

Methods inherited from class java.lang.Object

clone, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

MSCALE_X

public static final int MSCALE_X

See Also:

Constant Field Values

MSKEW_X

public static final int MSKEW_X

See Also:

Constant Field Values

MTRANS_X

public static final int MTRANS_X

See Also:

Constant Field Values

MSKEW_Y

public static final int MSKEW_Y

See Also:

Constant Field Values

MSCALE_Y

public static final int MSCALE_Y

See Also:

Constant Field Values

MTRANS_Y

public static final int MTRANS_Y

See Also:

Constant Field Values

MPERSP_0

public static final int MPERSP_0

See Also:

Constant Field Values

MPERSP_1

public static final int MPERSP_1

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Constant Field Values

MPERSP_2

public static final int MPERSP_2

See Also:

Constant Field Values

native_instance

int native_instance

Constructor Detail

Matrix

public Matrix()

Create an identity matrix

Matrix

public Matrix(Matrix src)

Create a matrix that is a (deep) copy of src

Parameters:

src - The matrix to copy into this matrix

Method Detail

isIdentity

public boolean isIdentity()

Returns true if the matrix is identity. This maybe faster than testing if (getType() == 0)

rectStaysRect

public boolean rectStaysRect()

Returns true if will map a rectangle to another rectangle. This can be true if the matrix is identity, scale-only, or rotates a multiple of 90 degrees.

set

public void set(Matrix src)

(deep) copy the src matrix into this matrix. If src is null, reset this matrix to the identity matrix.

equals

public boolean equals(Object obj)

Returns true iff obj is a Matrix and its values equal our values.

Overrides:

equals in class Object

Parameters:

obj - Object the object to compare with this object.

Returns:

boolean true if the object is the same as this object false if it is different from this object.

See Also:

Object.hashCode()

reset

public void reset()

Set the matrix to identity

setTranslate

public void setTranslate(float dx,
                         float dy)

Set the matrix to translate by (dx, dy).

setScale

public void setScale(float sx,
                     float sy,
                     float px,
                     float py)

Set the matrix to scale by sx and sy, with a pivot point at (px, py). The pivot point is the coordinate that should remain unchanged by the specified transformation.

setScale

public void setScale(float sx,
                     float sy)

Set the matrix to scale by sx and sy.

setRotate

public void setRotate(float degrees,
                      float px,
                      float py)

Set the matrix to rotate by the specified number of degrees, with a pivot point at (px, py). The pivot point is the coordinate that should remain unchanged by the specified transformation.

setRotate

public void setRotate(float degrees)

Set the matrix to rotate about (0,0) by the specified number of degrees.

setSinCos

public void setSinCos(float sinValue,
                      float cosValue,
                      float px,
                      float py)

Set the matrix to rotate by the specified sine and cosine values, with a pivot point at (px, py). The pivot point is the coordinate that should remain unchanged by the specified transformation.

setSinCos

public void setSinCos(float sinValue,
                      float cosValue)

Set the matrix to rotate by the specified sine and cosine values.

setSkew

public void setSkew(float kx,
                    float ky,
                    float px,
                    float py)

Set the matrix to skew by sx and sy, with a pivot point at (px, py). The pivot point is the coordinate that should remain unchanged by the specified transformation.

setSkew

public void setSkew(float kx,
                    float ky)

Set the matrix to skew by sx and sy.

setConcat

public boolean setConcat(Matrix a,
                         Matrix b)

Set the matrix to the concatenation of the two specified matrices, returning true if the the result can be represented. Either of the two matrices may also be the target matrix. this = a * b

preTranslate

public boolean preTranslate(float dx,
                            float dy)

Preconcats the matrix with the specified translation. M' = M * T(dx, dy)

preScale

public boolean preScale(float sx,
                        float sy,
                        float px,
                        float py)

Preconcats the matrix with the specified scale. M' = M * S(sx, sy, px, py)

preScale

public boolean preScale(float sx,
                        float sy)

Preconcats the matrix with the specified scale. M' = M * S(sx, sy)

preRotate

public boolean preRotate(float degrees,
                         float px,
                         float py)

Preconcats the matrix with the specified rotation. M' = M * R(degrees, px, py)

preRotate

public boolean preRotate(float degrees)

Preconcats the matrix with the specified rotation. M' = M * R(degrees)

preSkew

public boolean preSkew(float kx,
                       float ky,
                       float px,
                       float py)

Preconcats the matrix with the specified skew. M' = M * K(kx, ky, px, py)

preSkew

public boolean preSkew(float kx,
                       float ky)

Preconcats the matrix with the specified skew. M' = M * K(kx, ky)

preConcat

public boolean preConcat(Matrix other)

Preconcats the matrix with the specified matrix. M' = M * other

postTranslate

public boolean postTranslate(float dx,
                             float dy)

Postconcats the matrix with the specified translation. M' = T(dx, dy) * M

postScale

public boolean postScale(float sx,
                         float sy,
                         float px,
                         float py)

Postconcats the matrix with the specified scale. M' = S(sx, sy, px, py) * M

postScale

public boolean postScale(float sx,
                         float sy)

Postconcats the matrix with the specified scale. M' = S(sx, sy) * M

postRotate

public boolean postRotate(float degrees,
                          float px,
                          float py)

Postconcats the matrix with the specified rotation. M' = R(degrees, px, py) * M

postRotate

public boolean postRotate(float degrees)

Postconcats the matrix with the specified rotation. M' = R(degrees) * M

postSkew

public boolean postSkew(float kx,
                        float ky,
                        float px,
                        float py)

Postconcats the matrix with the specified skew. M' = K(kx, ky, px, py) * M

postSkew

public boolean postSkew(float kx,
                        float ky)

Postconcats the matrix with the specified skew. M' = K(kx, ky) * M

postConcat

public boolean postConcat(Matrix other)

Postconcats the matrix with the specified matrix. M' = other * M

setRectToRect

public boolean setRectToRect(RectF src,
                             RectF dst,
                             Matrix.ScaleToFit stf)

Set the matrix to the scale and translate values that map the source rectangle to the destination rectangle, returning true if the the result can be represented.

Parameters:

src - the source rectangle to map from.

dst - the destination rectangle to map to.

stf - the ScaleToFit option

Returns:

true if the matrix can be represented by the rectangle mapping.

setPolyToPoly

public boolean setPolyToPoly(float[] src,
                             int srcIndex,
                             float[] dst,
                             int dstIndex,
                             int pointCount)

Set the matrix such that the specified src points would map to the specified dst points. The "points" are represented as an array of floats, order [x0, y0, x1, y1, ...], where each "point" is 2 float values.

Parameters:

src - The array of src [x,y] pairs (points)

srcIndex - Index of the first pair of src values

dst - The array of dst [x,y] pairs (points)

dstIndex - Index of the first pair of dst values

pointCount - The number of pairs/points to be used. Must be [0..4]

Returns:

true if the matrix was set to the specified transformation

invert

public boolean invert(Matrix inverse)

If this matrix can be inverted, return true and if inverse is not null, set inverse to be the inverse of this matrix. If this matrix cannot be inverted, ignore inverse and return false.

mapPoints

public void mapPoints(float[] dst,
                      int dstIndex,
                      float[] src,
                      int srcIndex,
                      int pointCount)

Apply this matrix to the array of 2D points specified by src, and write the transformed points into the array of points specified by dst. The two arrays represent their "points" as pairs of floats [x, y].

Parameters:

dst - The array of dst points (x,y pairs)

dstIndex - The index of the first [x,y] pair of dst floats

src - The array of src points (x,y pairs)

srcIndex - The index of the first [x,y] pair of src floats

pointCount - The number of points (x,y pairs) to transform

mapVectors

public void mapVectors(float[] dst,
                       int dstIndex,
                       float[] src,
                       int srcIndex,
                       int vectorCount)

Apply this matrix to the array of 2D vectors specified by src, and write the transformed vectors into the array of vectors specified by dst. The two arrays represent their "vectors" as pairs of floats [x, y].

Parameters:

dst - The array of dst vectors (x,y pairs)

dstIndex - The index of the first [x,y] pair of dst floats

src - The array of src vectors (x,y pairs)

srcIndex - The index of the first [x,y] pair of src floats

vectorCount - The number of vectors (x,y pairs) to transform

mapPoints

public void mapPoints(float[] dst,
                      float[] src)

Apply this matrix to the array of 2D points specified by src, and write the transformed points into the array of points specified by dst. The two arrays represent their "points" as pairs of floats [x, y].

Parameters:

dst - The array of dst points (x,y pairs)

src - The array of src points (x,y pairs)

mapVectors

public void mapVectors(float[] dst,
                       float[] src)

Apply this matrix to the array of 2D vectors specified by src, and write the transformed vectors into the array of vectors specified by dst. The two arrays represent their "vectors" as pairs of floats [x, y].

Parameters:

dst - The array of dst vectors (x,y pairs)

src - The array of src vectors (x,y pairs)

mapPoints

public void mapPoints(float[] pts)

Apply this matrix to the array of 2D points, and write the transformed points back into the array

Parameters:

pts - The array [x0, y0, x1, y1, ...] of points to transform.

mapVectors

public void mapVectors(float[] vecs)

Apply this matrix to the array of 2D vectors, and write the transformed vectors back into the array.

Parameters:

vecs - The array [x0, y0, x1, y1, ...] of vectors to transform.

mapRect

public boolean mapRect(RectF dst,
                       RectF src)

Apply this matrix to the src rectangle, and write the transformed rectangle into dst. This is accomplished by transforming the 4 corners of src, and then setting dst to the bounds of those points.

Parameters:

dst - Where the transformed rectangle is written.

src - The original rectangle to be transformed.

Returns:

the result of calling rectStaysRect()

mapRect

public boolean mapRect(RectF rect)

Apply this matrix to the rectangle, and write the transformed rectangle back into it. This is accomplished by transforming the 4 corners of rect, and then setting it to the bounds of those points

Parameters:

rect - The rectangle to transform.

Returns:

the result of calling rectStaysRect()

mapRadius

public float mapRadius(float radius)

Return the mean radius of a circle after it has been mapped by this matrix. NOTE: in perspective this value assumes the circle has its center at the origin.

getValues

public void getValues(float[] values)

Copy 9 values from the matrix into the array.

setValues

public void setValues(float[] values)

Copy 9 values from the array into the matrix. Depending on the implementation of Matrix, these may be transformed into 16.16 integers in the Matrix, such that a subsequent call to getValues() will not yield exactly the same values.

toString

public String toString()

Description copied from class: Object

Returns a string containing a concise, human-readable description of the receiver.

Overrides:

toString in class Object

Returns:

String a printable representation for the receiver.

toShortString

public String toShortString()

finalize

protected void finalize()
                 throws Throwable

Description copied from class: Object

Called by the virtual machine when there are no longer any (non-weak) references to the receiver. Subclasses can use this facility to guarantee that any associated resources are cleaned up before the receiver is garbage collected. Uncaught exceptions which are thrown during the running of the method cause it to terminate immediately, but are otherwise ignored.

Note: The virtual machine assumes that the implementation in class Object is empty.

Overrides:

finalize in class Object

Throws:

Throwable - The virtual machine ignores any exceptions which are thrown during finalization.

ni

final int ni()