Matrix


public class Matrix
extends Object

java.lang.Object
   ↳ android.graphics.Matrix


The Matrix class holds a 3x3 matrix for transforming coordinates.

Summary

Constants

int MPERSP_0

int MPERSP_1

int MPERSP_2

int MSCALE_X

int MSCALE_Y

int MSKEW_X

int MSKEW_Y

int MTRANS_X

int MTRANS_Y

Fields

public static final Matrix IDENTITY_MATRIX

The identity matrix.

Public constructors

Matrix()

Create an identity matrix

Matrix(Matrix src)

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

Public methods

final void dump(PrintWriter pw)

Dumps a human-readable shortened string of the matrix into the given stream

boolean equals(Object obj)

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

void getValues(float[] values)

Copy 9 values from the matrix into the array.

int hashCode()

Returns a hash code value for the object.

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 isAffine()

Gets whether this matrix is affine.

boolean isIdentity()

Returns true if the matrix is identity.

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.

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[] pts)

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

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, 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.

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.

boolean postConcat(Matrix other)

Postconcats the matrix with the specified matrix.

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

Postconcats the matrix with the specified rotation.

boolean postRotate(float degrees)

Postconcats the matrix with the specified rotation.

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

Postconcats the matrix with the specified scale.

boolean postScale(float sx, float sy)

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 and return true.

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 result can be represented.

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 setRotate(float degrees)

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

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, float px, float py)

Set the matrix to rotate by the specified sine and cosine values, 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 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 representation of the object.

Inherited methods

Constants

MPERSP_0

Added in API level 1
public static final int MPERSP_0

Constant Value: 6 (0x00000006)

MPERSP_1

Added in API level 1
public static final int MPERSP_1

Constant Value: 7 (0x00000007)

MPERSP_2

Added in API level 1
public static final int MPERSP_2

Constant Value: 8 (0x00000008)

MSCALE_X

Added in API level 1
public static final int MSCALE_X

Constant Value: 0 (0x00000000)

MSCALE_Y

Added in API level 1
public static final int MSCALE_Y

Constant Value: 4 (0x00000004)

MSKEW_X

Added in API level 1
public static final int MSKEW_X

Constant Value: 1 (0x00000001)

MSKEW_Y

Added in API level 1
public static final int MSKEW_Y

Constant Value: 3 (0x00000003)

MTRANS_X

Added in API level 1
public static final int MTRANS_X

Constant Value: 2 (0x00000002)

MTRANS_Y

Added in API level 1
public static final int MTRANS_Y

Constant Value: 5 (0x00000005)

Fields

IDENTITY_MATRIX

Added in API level 31
public static final Matrix IDENTITY_MATRIX

The identity matrix. Multiplying by another matrix M returns M. This matrix is immutable, and attempting to modify it will throw an IllegalStateException.

Public constructors

Matrix

Added in API level 1
public Matrix ()

Create an identity matrix

Matrix

Added in API level 1
public Matrix (Matrix src)

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

Parameters
src Matrix: The matrix to copy into this matrix

Public methods

dump

Added in API level 31
public final void dump (PrintWriter pw)

Dumps a human-readable shortened string of the matrix into the given stream

Parameters
pw PrintWriter: The PrintWriter into which the string representation of the matrix will be written. This value cannot be null.

equals

Added in API level 1
public boolean equals (Object obj)

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

Parameters
obj Object: the reference object with which to compare.

Returns
boolean true if this object is the same as the obj argument; false otherwise.

getValues

Added in API level 1
public void getValues (float[] values)

Copy 9 values from the matrix into the array.

Parameters
values float

hashCode

Added in API level 1
public int hashCode ()

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

The general contract of hashCode is:

  • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
  • If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
  • It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

Returns
int a hash code value for this object.

invert

Added in API level 1
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.

Parameters
inverse Matrix

Returns
boolean

isAffine

Added in API level 21
public boolean isAffine ()

Gets whether this matrix is affine. An affine matrix preserves straight lines and has no perspective.

Returns
boolean Whether the matrix is affine.

isIdentity

Added in API level 1
public boolean isIdentity ()

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

Returns
boolean

mapPoints

Added in API level 1
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 float: The array of dst points (x,y pairs)

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

src float: The array of src points (x,y pairs)

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

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

mapPoints

Added in API level 1
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 float: The array of dst points (x,y pairs)

src float: The array of src points (x,y pairs)

mapPoints

Added in API level 1
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 float: The array [x0, y0, x1, y1, ...] of points to transform.

mapRadius

Added in API level 1
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.

Parameters
radius float

Returns
float

mapRect

Added in API level 1
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 RectF: The rectangle to transform.

Returns
boolean the result of calling rectStaysRect()

mapRect

Added in API level 1
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 RectF: Where the transformed rectangle is written.

src RectF: The original rectangle to be transformed.

Returns
boolean the result of calling rectStaysRect()

mapVectors

Added in API level 1
public void mapVectors (float[] vecs)

Apply this matrix to the array of 2D vectors, and write the transformed vectors back into the array. Note: this method does not apply the translation associated with the matrix. Use Matrix#mapPoints(float[]) if you want the translation to be applied.

Parameters
vecs float: The array [x0, y0, x1, y1, ...] of vectors to transform.

mapVectors

Added in API level 1
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]. Note: this method does not apply the translation associated with the matrix. Use Matrix#mapPoints(float[], int, float[], int, int) if you want the translation to be applied.

Parameters
dst float: The array of dst vectors (x,y pairs)

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

src float: The array of src vectors (x,y pairs)

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

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

mapVectors

Added in API level 1
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]. Note: this method does not apply the translation associated with the matrix. Use Matrix#mapPoints(float[], float[]) if you want the translation to be applied.

Parameters
dst float: The array of dst vectors (x,y pairs)

src float: The array of src vectors (x,y pairs)

postConcat

Added in API level 1
public boolean postConcat (Matrix other)

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

Parameters
other Matrix

Returns
boolean

postRotate

Added in API level 1
public boolean postRotate (float degrees, 
                float px, 
                float py)

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

Parameters
degrees float

px float

py float

Returns
boolean

postRotate

Added in API level 1
public boolean postRotate (float degrees)

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

Parameters
degrees float

Returns
boolean

postScale

Added in API level 1
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

Parameters
sx float

sy float

px float

py float

Returns
boolean

postScale

Added in API level 1
public boolean postScale (float sx, 
                float sy)

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

Parameters
sx float

sy float

Returns
boolean

postSkew

Added in API level 1
public boolean postSkew (float kx, 
                float ky)

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

Parameters
kx float

ky float

Returns
boolean

postSkew

Added in API level 1
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

Parameters
kx float

ky float

px float

py float

Returns
boolean

postTranslate

Added in API level 1
public boolean postTranslate (float dx, 
                float dy)

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

Parameters
dx float

dy float

Returns
boolean

preConcat

Added in API level 1
public boolean preConcat (Matrix other)

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

Parameters
other Matrix

Returns
boolean

preRotate

Added in API level 1
public boolean preRotate (float degrees)

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

Parameters
degrees float

Returns
boolean

preRotate

Added in API level 1
public boolean preRotate (float degrees, 
                float px, 
                float py)

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

Parameters
degrees float

px float

py float

Returns
boolean

preScale

Added in API level 1
public boolean preScale (float sx, 
                float sy)

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

Parameters
sx float

sy float

Returns
boolean

preScale

Added in API level 1
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)

Parameters
sx float

sy float

px float

py float

Returns
boolean

preSkew

Added in API level 1
public boolean preSkew (float kx, 
                float ky)

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

Parameters
kx float

ky float

Returns
boolean

preSkew

Added in API level 1
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)

Parameters
kx float

ky float

px float

py float

Returns
boolean

preTranslate

Added in API level 1
public boolean preTranslate (float dx, 
                float dy)

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

Parameters
dx float

dy float

Returns
boolean

rectStaysRect

Added in API level 1
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.

Returns
boolean

reset

Added in API level 1
public void reset ()

Set the matrix to identity

set

Added in API level 1
public void set (Matrix src)

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

Parameters
src Matrix

setConcat

Added in API level 1
public boolean setConcat (Matrix a, 
                Matrix b)

Set the matrix to the concatenation of the two specified matrices and return true.

Either of the two matrices may also be the target matrix, that is matrixA.setConcat(matrixA, matrixB); is valid.

In Build.VERSION_CODES.GINGERBREAD_MR1 and below, this function returns true only if the result can be represented. In Build.VERSION_CODES.HONEYCOMB and above, it always returns true.

Parameters
a Matrix

b Matrix

Returns
boolean

setPolyToPoly

Added in API level 1
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 float: The array of src [x,y] pairs (points)

srcIndex int: Index of the first pair of src values

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

dstIndex int: Index of the first pair of dst values

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

Returns
boolean true if the matrix was set to the specified transformation

setRectToRect

Added in API level 1
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 result can be represented.

Parameters
src RectF: the source rectangle to map from.

dst RectF: the destination rectangle to map to.

stf Matrix.ScaleToFit: the ScaleToFit option

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

setRotate

Added in API level 1
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.

Parameters
degrees float

px float

py float

setRotate

Added in API level 1
public void setRotate (float degrees)

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

Parameters
degrees float

setScale

Added in API level 1
public void setScale (float sx, 
                float sy)

Set the matrix to scale by sx and sy.

Parameters
sx float

sy float

setScale

Added in API level 1
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.

Parameters
sx float

sy float

px float

py float

setSinCos

Added in API level 1
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.

Parameters
sinValue float

cosValue float

px float

py float

setSinCos

Added in API level 1
public void setSinCos (float sinValue, 
                float cosValue)

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

Parameters
sinValue float

cosValue float

setSkew

Added in API level 1
public void setSkew (float kx, 
                float ky)

Set the matrix to skew by sx and sy.

Parameters
kx float

ky float

setSkew

Added in API level 1
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.

Parameters
kx float

ky float

px float

py float

setTranslate

Added in API level 1
public void setTranslate (float dx, 
                float dy)

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

Parameters
dx float

dy float

setValues

Added in API level 1
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.

Parameters
values float

toShortString

Added in API level 1
public String toShortString ()

Returns
String

toString

Added in API level 1
public String toString ()

Returns a string representation of the object.

Returns
String a string representation of the object.