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# Matrix

`public class Matrix`
`extends Object` ``

java.lang.Object
↳ | android.graphics.Matrix

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

## Summary

### Nested classes
`enum` | `Matrix.ScaleToFit` Controls how the src rect should align into the dst rect for setRectToRect().

### 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 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
From class `java.lang.Object`
`Object` | `clone()` Creates and returns a copy of this object.
`boolean` | `equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void` | `finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>` | `getClass()` Returns the runtime class of this `Object`.
`int` | `hashCode()` Returns a hash code value for the object.
`final void` | `notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void` | `notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String` | `toString()` Returns a string representation of the object.
`final void` | `wait(long timeout, int nanos)` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
`final void` | `wait(long timeout)` Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
`final void` | `wait()` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.

## Constants

### MPERSP_0

    public static final int MPERSP_0

Constant Value: 6 (0x00000006)

### MPERSP_1

    public static final int MPERSP_1

Constant Value: 7 (0x00000007)

### MPERSP_2

    public static final int MPERSP_2

Constant Value: 8 (0x00000008)

### MSCALE_X

    public static final int MSCALE_X

Constant Value: 0 (0x00000000)

### MSCALE_Y

    public static final int MSCALE_Y

Constant Value: 4 (0x00000004)

### MSKEW_X

    public static final int MSKEW_X

Constant Value: 1 (0x00000001)

### MSKEW_Y

    public static final int MSKEW_Y

Constant Value: 3 (0x00000003)

### MTRANS_X

    public static final int MTRANS_X

Constant Value: 2 (0x00000002)

### MTRANS_Y

    public static final int MTRANS_Y

Constant Value: 5 (0x00000005)

## Fields

### IDENTITY_MATRIX

    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

    public Matrix ()

Create an identity matrix

### Matrix

    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

    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

    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

    public void getValues (float[] values)

Copy 9 values from the matrix into the array.

Parameters
`values` | `float`

### hashCode

    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(Object)` 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(java.lang.Object)` 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.

As much as is reasonably practical, the hashCode method defined by class `Object` does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java™ programming language.)

Returns
`int` | a hash code value for this object.

### 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.

Parameters
`inverse` | `Matrix`

Returns
`boolean` |

### isAffine

    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

    public boolean isIdentity ()

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

Returns
`boolean` |

### 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` | `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

    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

    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

    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

    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

    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

    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

    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

    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

    public boolean postConcat (Matrix other)

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

Parameters
`other` | `Matrix`

Returns
`boolean` |

### postRotate

    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

    public boolean postRotate (float degrees)

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

Parameters
`degrees` | `float`

Returns
`boolean` |

### 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

Parameters
`sx` | `float`
`sy` | `float`
`px` | `float`
`py` | `float`

Returns
`boolean` |

### postScale

    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

    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

    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

    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

    public boolean preConcat (Matrix other)

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

Parameters
`other` | `Matrix`

Returns
`boolean` |

### preRotate

    public boolean preRotate (float degrees)

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

Parameters
`degrees` | `float`

Returns
`boolean` |

### preRotate

    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

    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

    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

    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

    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

    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

    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

    public void reset ()

Set the matrix to identity

### 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.

Parameters
`src` | `Matrix`

### setConcat

    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

    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

    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` | `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

    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

    public void setRotate (float degrees)

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

Parameters
`degrees` | `float`

### setScale

    public void setScale (float sx,
                    float sy)

Set the matrix to scale by sx and sy.

Parameters
`sx` | `float`
`sy` | `float`

### 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.

Parameters
`sx` | `float`
`sy` | `float`
`px` | `float`
`py` | `float`

### 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.

Parameters
`sinValue` | `float`
`cosValue` | `float`
`px` | `float`
`py` | `float`

### setSinCos

    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

    public void setSkew (float kx,
                    float ky)

Set the matrix to skew by sx and sy.

Parameters
`kx` | `float`
`ky` | `float`

### 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.

Parameters
`kx` | `float`
`ky` | `float`
`px` | `float`
`py` | `float`

### setTranslate

    public void setTranslate (float dx,
                    float dy)

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

Parameters
`dx` | `float`
`dy` | `float`

### 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.

Parameters
`values` | `float`

### toShortString

    public String toShortString ()

Returns
`String` |

### toString

    public String toString ()

Returns a string representation of the object. In general, the `toString` method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The `toString` method for class `Object` returns a string consisting of the name of the class of which the object is an instance, the at-sign character ``@`', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

>      getClass().getName() + '@' + Integer.toHexString(hashCode())

Returns
`String` | a string representation of the object.

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