SkMatrix Reference === ---

class SkMatrix {

    static SkMatrix MakeScale(SkScalar sx, SkScalar sy);
    static SkMatrix MakeScale(SkScalar scale);
    static SkMatrix MakeTrans(SkScalar dx, SkScalar dy);
    static SkMatrix MakeAll(SkScalar scaleX, SkScalar skewX, SkScalar transX,
                            SkScalar skewY, SkScalar scaleY, SkScalar transY,
                            SkScalar pers0, SkScalar pers1, SkScalar pers2);

    enum TypeMask {
        kIdentity_Mask = 0,
        kTranslate_Mask = 0x01,
        kScale_Mask = 0x02,
        kAffine_Mask = 0x04,
        kPerspective_Mask = 0x08,
    };

    TypeMask getType() const;
    bool isIdentity() const;
    bool isScaleTranslate() const;
    bool isTranslate() const;
    bool rectStaysRect() const;
    bool preservesAxisAlignment() const;
    bool hasPerspective() const;
    bool isSimilarity(SkScalar tol = SK_ScalarNearlyZero) const;
    bool preservesRightAngles(SkScalar tol = SK_ScalarNearlyZero) const;

    static constexpr int kMScaleX = 0    static constexpr int kMSkewX = 1    static constexpr int kMTransX = 2    static constexpr int kMSkewY = 3    static constexpr int kMScaleY = 4    static constexpr int kMTransY = 5    static constexpr int kMPersp0 = 6    static constexpr int kMPersp1 = 7    static constexpr int kMPersp2 = 8    static constexpr int kAScaleX = 0    static constexpr int kASkewY = 1    static constexpr int kASkewX = 2    static constexpr int kAScaleY = 3    static constexpr int kATransX = 4    static constexpr int kATransY = 5
    SkScalar operator[](int index) const;
    SkScalar get(int index) const;
    SkScalar getScaleX() const;
    SkScalar getScaleY() const;
    SkScalar getSkewY() const;
    SkScalar getSkewX() const;
    SkScalar getTranslateX() const;
    SkScalar getTranslateY() const;
    SkScalar getPerspX() const;
    SkScalar getPerspY() const;
    SkScalar& operator[](int index);
    void set(int index, SkScalar value);
    void setScaleX(SkScalar v);
    void setScaleY(SkScalar v);
    void setSkewY(SkScalar v);
    void setSkewX(SkScalar v);
    void setTranslateX(SkScalar v);
    void setTranslateY(SkScalar v);
    void setPerspX(SkScalar v);
    void setPerspY(SkScalar v);
    void setAll(SkScalar scaleX, SkScalar skewX, SkScalar transX,
                SkScalar skewY, SkScalar scaleY, SkScalar transY,
                SkScalar persp0, SkScalar persp1, SkScalar persp2);
    void get9(SkScalar buffer[9]) const;
    void set9(const SkScalar buffer[9]);
    void reset();
    void setIdentity();
    void setTranslate(SkScalar dx, SkScalar dy);
    void setTranslate(const SkVector& v);
    void setScale(SkScalar sx, SkScalar sy, SkScalar px, SkScalar py);
    void setScale(SkScalar sx, SkScalar sy);
    void setRotate(SkScalar degrees, SkScalar px, SkScalar py);
    void setRotate(SkScalar degrees);
    void setSinCos(SkScalar sinValue, SkScalar cosValue,
                   SkScalar px, SkScalar py);
    void setSinCos(SkScalar sinValue, SkScalar cosValue);
    SkMatrix& setRSXform(const SkRSXform& rsxForm);
    void setSkew(SkScalar kx, SkScalar ky, SkScalar px, SkScalar py);
    void setSkew(SkScalar kx, SkScalar ky);
    void setConcat(const SkMatrix& a, const SkMatrix& b);
    void preTranslate(SkScalar dx, SkScalar dy);
    void preScale(SkScalar sx, SkScalar sy, SkScalar px, SkScalar py);
    void preScale(SkScalar sx, SkScalar sy);
    void preRotate(SkScalar degrees, SkScalar px, SkScalar py);
    void preRotate(SkScalar degrees);
    void preSkew(SkScalar kx, SkScalar ky, SkScalar px, SkScalar py);
    void preSkew(SkScalar kx, SkScalar ky);
    void preConcat(const SkMatrix& other);
    void postTranslate(SkScalar dx, SkScalar dy);
    void postScale(SkScalar sx, SkScalar sy, SkScalar px, SkScalar py);
    void postScale(SkScalar sx, SkScalar sy);
    bool postIDiv(int divx, int divy);
    void postRotate(SkScalar degrees, SkScalar px, SkScalar py);
    void postRotate(SkScalar degrees);
    void postSkew(SkScalar kx, SkScalar ky, SkScalar px, SkScalar py);
    void postSkew(SkScalar kx, SkScalar ky);
    void postConcat(const SkMatrix& other);

    enum ScaleToFit {
        kFill_ScaleToFit,
        kStart_ScaleToFit,
        kCenter_ScaleToFit,
        kEnd_ScaleToFit,
    };

    bool setRectToRect(const SkRect& src, const SkRect& dst, ScaleToFit stf);
    static SkMatrix MakeRectToRect(const SkRect& src, const SkRect& dst, ScaleToFit stf);
    bool setPolyToPoly(const SkPoint src[], const SkPoint dst[], int count);
    bool invert(SkMatrix* inverse) const;
    static void SetAffineIdentity(SkScalar affine[6]);
    bool asAffine(SkScalar affine[6]) const;
    void setAffine(const SkScalar affine[6]);
    void mapPoints(SkPoint dst[], const SkPoint src[], int count) const;
    void mapPoints(SkPoint pts[], int count) const;
    void mapHomogeneousPoints(SkPoint3 dst[], const SkPoint3 src[], int count) const;
    void mapXY(SkScalar x, SkScalar y, SkPoint* result) const;
    SkPoint mapXY(SkScalar x, SkScalar y) const;
    void mapVectors(SkVector dst[], const SkVector src[], int count) const;
    void mapVectors(SkVector vecs[], int count) const;
    void mapVector(SkScalar dx, SkScalar dy, SkVector* result) const;
    SkVector mapVector(SkScalar dx, SkScalar dy) const;
    bool mapRect(SkRect* dst, const SkRect& src) const;
    bool mapRect(SkRect* rect) const;
    SkRect mapRect(const SkRect& src) const;
    void mapRectToQuad(SkPoint dst[4], const SkRect& rect) const;
    void mapRectScaleTranslate(SkRect* dst, const SkRect& src) const;
    SkScalar mapRadius(SkScalar radius) const;
    bool isFixedStepInX() const;
    SkVector fixedStepInX(SkScalar y) const;
    bool cheapEqualTo(const SkMatrix& m) const;
    friend bool operator==(const SkMatrix& a, const SkMatrix& b);
    friend bool operator!=(const SkMatrix& a, const SkMatrix& b);
    void dump() const;
    SkScalar getMinScale() const;
    SkScalar getMaxScale() const;
    bool getMinMaxScales(SkScalar scaleFactors[2]) const;
    bool decomposeScale(SkSize* scale, SkMatrix* remaining = nullptr) const;
    static const SkMatrix& I();
    static const SkMatrix& InvalidMatrix();
    static SkMatrix Concat(const SkMatrix& a, const SkMatrix& b);
    void dirtyMatrixTypeCache();
    void setScaleTranslate(SkScalar sx, SkScalar sy, SkScalar tx, SkScalar ty);
    bool isFinite() const;
};

Matrix holds a 3 by 3 matrix for transforming coordinates. This allows mapping Points and Vectors with translation, scaling, skewing, rotation, and perspective. Matrix elements are in row major order. Matrix does not have a constructor, so it must be explicitly initialized. setIdentity initializes Matrix so it has no effect. setTranslate, setScale, setSkew, setRotate, set9 and setAll initializes all Matrix elements with the corresponding mapping. Matrix includes a hidden variable that classifies the type of matrix to improve performance. Matrix is not thread safe unless getType is called first. ---

static SkMatrix MakeScale(SkScalar sx, SkScalar sy)

Sets SkMatrix to scale by (sx, sy). Returned matrix is: | sx 0 0 | | 0 sy 0 | | 0 0 1 | ### Parameters

`sx`	horizontal scale factor
`sy`	vertical scale factor

### Return Value SkMatrix with scale ### Example

### See Also setScale postScale preScale ---

static SkMatrix MakeScale(SkScalar scale)

scale horizontal and vertical scale factor

### Return Value SkMatrix with scale ### Example

### See Also setScale postScale preScale ---

static SkMatrix MakeTrans(SkScalar dx, SkScalar dy)

Sets SkMatrix to translate by (dx, dy). Returned matrix is: | 1 0 dx | | 0 1 dy | | 0 0 1 | ### Parameters

`dx`	horizontal translation
`dy`	vertical translation

### Return Value SkMatrix with translation ### Example

### See Also setTranslate postTranslate preTranslate ---

static SkMatrix MakeAll(SkScalar scaleX, SkScalar skewX, SkScalar transX, SkScalar skewY,
                        SkScalar scaleY, SkScalar transY, SkScalar pers0, SkScalar pers1,
                        SkScalar pers2)

`scaleX`	horizontal scale factor
`skewX`	horizontal skew factor
`transX`	horizontal translation
`skewY`	vertical skew factor
`scaleY`	vertical scale factor
`transY`	vertical translation
`pers0`	input x-axis perspective factor
`pers1`	input y-axis perspective factor
`pers2`	perspective scale factor

### Return Value SkMatrix constructed from parameters ### Example

### See Also setAll set9 postConcat preConcat ---

    enum TypeMask {
        kIdentity_Mask = 0,
        kTranslate_Mask = 0x01,
        kScale_Mask = 0x02,
        kAffine_Mask = 0x04,
        kPerspective_Mask = 0x08,
    };

Enumeration of bit fields for mask returned by getType. Used to identify the complexity of Matrix, to optimize performance. ### Constants

Const	Value	Description
`SkMatrix::kIdentity_Mask`	0	all bits clear if Matrix is identity
`SkMatrix::kTranslate_Mask`	1	set if Matrix has translation
`SkMatrix::kScale_Mask`	2	set if Matrix scales x-axis or y-axis
`SkMatrix::kAffine_Mask`	4	set if Matrix skews or rotates
`SkMatrix::kPerspective_Mask`	8	set if Matrix has perspective

### Example

#### Example Output ~~~~ after reset: kIdentity_Mask after postTranslate: kTranslate_Mask after postScale: kTranslate_Mask kScale_Mask after postScale: kTranslate_Mask kScale_Mask kAffine_Mask after setPolyToPoly: kTranslate_Mask kScale_Mask kAffine_Mask kPerspective_Mask ~~~~

### See Also getType ---

TypeMask getType()const

Returns a bit field describing the transformations the matrix may perform. The bit field is computed conservatively, so it may include false positives. For example, when kPerspective_Mask is set, all other bits are set. ### Return Value kIdentity_Mask, or combinations of: kTranslate_Mask, kScale_Mask, kAffine_Mask, kPerspective_Mask ### Example

#### Example Output ~~~~ identity flags hex: 0 decimal: 0 set all flags hex: f decimal: 15 ~~~~

### See Also TypeMask ---

bool isIdentity()const

Returns true if SkMatrix is identity. Identity matrix is: | 1 0 0 | | 0 1 0 | | 0 0 1 | ### Return Value true if SkMatrix has no effect ### Example

#### Example Output ~~~~ is identity: true is identity: false ~~~~

### See Also reset() setIdentity getType ---

bool isScaleTranslate()const

Returns true if SkMatrix at most scales and translates. SkMatrix may be identity, contain only scale elements, only translate elements, or both. SkMatrix form is: | scale-x 0 translate-x | | 0 scale-y translate-y | | 0 0 1 | ### Return Value true if SkMatrix is identity; or scales, translates, or both ### Example

#### Example Output ~~~~ is scale-translate: true is scale-translate: true is scale-translate: true is scale-translate: true ~~~~

### See Also setScale isTranslate setTranslate getType ---

bool isTranslate()const

#### Example Output ~~~~ is translate: true is translate: true is translate: false is translate: false ~~~~

### See Also setTranslate getType ---

bool rectStaysRect()const

Returns true SkMatrix maps SkRect to another SkRect. If true, SkMatrix is identity, or scales, or rotates a multiple of 90 degrees, or mirrors on axes. In all cases, SkMatrix may also have translation. SkMatrix form is either: | scale-x 0 translate-x | | 0 scale-y translate-y | | 0 0 1 | or | 0 rotate-x translate-x | | rotate-y 0 translate-y | | 0 0 1 | for non-zero values of scale-x, scale-y, rotate-x, and rotate-y. Also called preservesAxisAlignment(); use the one that provides better inline documentation. ### Return Value true if SkMatrix maps one SkRect into another ### Example

#### Example Output ~~~~ rectStaysRect: true rectStaysRect: true rectStaysRect: true rectStaysRect: true ~~~~

### See Also preservesAxisAlignment preservesRightAngles ---

bool preservesAxisAlignment()const

Returns true SkMatrix maps SkRect to another SkRect. If true, SkMatrix is identity, or scales, or rotates a multiple of 90 degrees, or mirrors on axes. In all cases, SkMatrix may also have translation. SkMatrix form is either: | scale-x 0 translate-x | | 0 scale-y translate-y | | 0 0 1 | or | 0 rotate-x translate-x | | rotate-y 0 translate-y | | 0 0 1 | for non-zero values of scale-x, scale-y, rotate-x, and rotate-y. Also called rectStaysRect(); use the one that provides better inline documentation. ### Return Value true if SkMatrix maps one SkRect into another ### Example

#### Example Output ~~~~ preservesAxisAlignment: true preservesAxisAlignment: true preservesAxisAlignment: true preservesAxisAlignment: true ~~~~

### See Also rectStaysRect preservesRightAngles ---

bool hasPerspective()const

Returns true if the matrix contains perspective elements. SkMatrix form is: | -- -- -- | | -- -- -- | | perspective-x perspective-y perspective-scale | where perspective-x or perspective-y is non-zero, or perspective-scale is not one. All other elements may have any value. ### Return Value true if SkMatrix is in most general form ### Example

### See Also setAll set9 MakeAll ---

bool isSimilarity(SkScalar tol = SK_ScalarNearlyZero)const

Returns true if SkMatrix contains only translation, rotation, reflection, and uniform scale. Returns false if SkMatrix contains different scales, skewing, perspective, or degenerate forms that collapse to a line or point. Describes that the SkMatrix makes rendering with and without the matrix are visually alike; a transformed circle remains a circle. Mathematically, this is referred to as similarity of a Euclidean space, or a similarity transformation. Preserves right angles, keeping the arms of the angle equal lengths. ### Parameters

tol to be deprecated

### Return Value true if SkMatrix only rotates, uniformly scales, translates ### Example

String is drawn four times through but only two are visible. Drawing the pair with isSimilarity false reveals the pair not visible through the matrix.

### See Also isScaleTranslate preservesRightAngles rectStaysRect isFixedStepInX ---

bool preservesRightAngles(SkScalar tol = SK_ScalarNearlyZero)const

Returns true if SkMatrix contains only translation, rotation, reflection, and scale. Scale may differ along rotated axes. Returns false if SkMatrix skewing, perspective, or degenerate forms that collapse to a line or point. Preserves right angles, but not requiring that the arms of the angle retain equal lengths. ### Parameters

tol to be deprecated

### Return Value true if SkMatrix only rotates, scales, translates ### Example

Equal scale is both similar and preserves right angles. Unequal scale is not similar but preserves right angles. Skews are not similar and do not preserve right angles.

### See Also isScaleTranslate isSimilarity rectStaysRect isFixedStepInX ---

    static constexpr int kMScaleX = 0;
    static constexpr int kMSkewX = 1;
    static constexpr int kMTransX = 2;
    static constexpr int kMSkewY = 3;
    static constexpr int kMScaleY = 4;
    static constexpr int kMTransY = 5;
    static constexpr int kMPersp0 = 6;
    static constexpr int kMPersp1 = 7;
    static constexpr int kMPersp2 = 8;

Matrix organizes its values in row order. These members correspond to each value in Matrix. ### Constants

Const	Value	Description
`SkMatrix::kMScaleX`	0	horizontal scale factor
`SkMatrix::kMSkewX`	1	horizontal skew factor
`SkMatrix::kMTransX`	2	horizontal translation
`SkMatrix::kMSkewY`	3	vertical skew factor
`SkMatrix::kMScaleY`	4	vertical scale factor
`SkMatrix::kMTransY`	5	vertical translation
`SkMatrix::kMPersp0`	6	input x perspective factor
`SkMatrix::kMPersp1`	7	input y perspective factor
`SkMatrix::kMPersp2`	8	perspective bias

### Example

### See Also get() set() ---

Affine arrays are in column major order to match the matrix used by PDF and XPS. ### Constants

Const	Value	Description
`SkMatrix::kAScaleX`	0	horizontal scale factor
`SkMatrix::kASkewY`	1	vertical skew factor
`SkMatrix::kASkewX`	2	horizontal skew factor
`SkMatrix::kAScaleY`	3	vertical scale factor
`SkMatrix::kATransX`	4	horizontal translation
`SkMatrix::kATransY`	5	vertical translation

### See Also SetAffineIdentity asAffine setAffine ---

SkScalar operator[](int index)const

### Example

#### Example Output ~~~~ matrix[SkMatrix::kMScaleX] == 42 matrix[SkMatrix::kMScaleY] == 24 ~~~~

### See Also get set ---

SkScalar get(int index)const

Returns one matrix value. Asserts if index is out of range and SK_DEBUG is defined. ### Parameters

index one of: kMScaleX, kMSkewX, kMTransX, kMSkewY, kMScaleY, kMTransY,

kMPersp0, kMPersp1, kMPersp2 ### Return Value value corresponding to index ### Example

#### Example Output ~~~~ matrix.get(SkMatrix::kMSkewX) == 42 matrix.get(SkMatrix::kMSkewY) == 24 ~~~~

### See Also operator[](int index) set ---

SkScalar getScaleX()const

Returns scale factor multiplied by x-axis input, contributing to x-axis output. With mapPoints(), scales SkPoint along the x-axis. ### Return Value horizontal scale factor ### Example

#### Example Output ~~~~ matrix.getScaleX() == 42 ~~~~

### See Also get getScaleY setScaleX setScale ---

SkScalar getScaleY()const

Returns scale factor multiplied by y-axis input, contributing to y-axis output. With mapPoints(), scales SkPoint along the y-axis. ### Return Value vertical scale factor ### Example

#### Example Output ~~~~ matrix.getScaleY() == 24 ~~~~

### See Also get getScaleX setScaleY setScale ---

SkScalar getSkewY()const

Returns scale factor multiplied by x-axis input, contributing to y-axis output. With mapPoints(), skews SkPoint along the y-axis. Skewing both axes can rotate SkPoint. ### Return Value vertical skew factor ### Example

#### Example Output ~~~~ matrix.getSkewY() == 24 ~~~~

### See Also get getSkewX setSkewY setSkew ---

SkScalar getSkewX()const

Returns scale factor multiplied by y-axis input, contributing to x-axis output. With mapPoints(), skews SkPoint along the x-axis. Skewing both axes can rotate SkPoint. ### Return Value horizontal scale factor ### Example

#### Example Output ~~~~ matrix.getSkewX() == 42 ~~~~

### See Also get getSkewY setSkewX setSkew ---

SkScalar getTranslateX()const

Returns translation contributing to x-axis output. With mapPoints(), moves SkPoint along the x-axis. ### Return Value horizontal translation factor ### Example

#### Example Output ~~~~ matrix.getTranslateX() == 42 ~~~~

### See Also get getTranslateY setTranslateX setTranslate ---

SkScalar getTranslateY()const

Returns translation contributing to y-axis output. With mapPoints(), moves SkPoint along the y-axis. ### Return Value vertical translation factor ### Example

#### Example Output ~~~~ matrix.getTranslateY() == 24 ~~~~

### See Also get getTranslateX setTranslateY setTranslate ---

SkScalar getPerspX()const

Returns factor scaling input x-axis relative to input y-axis. ### Return Value input x-axis perspective factor ### Example

### See Also kMPersp0 getPerspY ---

SkScalar getPerspY()const

Returns factor scaling input y-axis relative to input x-axis. ### Return Value input y-axis perspective factor ### Example

### See Also kMPersp1 getPerspX ---

SkScalar& operator[](int index)

### Example

#### Example Output ~~~~ with identity matrix: x = 24 after skew x mod: x = 24 after 2nd skew x mod: x = 24 after dirty cache: x = 66 ~~~~

### See Also get dirtyMatrixTypeCache set ---

void set(int index, SkScalar value)

Sets SkMatrix value. Asserts if index is out of range and SK_DEBUG is defined. Safer than operator[]; internal cache is always maintained. ### Parameters

index one of: kMScaleX, kMSkewX, kMTransX, kMSkewY, kMScaleY, kMTransY,

kMPersp0, kMPersp1, kMPersp2 ### Parameters

value scalar to store in SkMatrix

### Example

#### Example Output ~~~~ with identity matrix: x = 24 after skew x mod: x = 24 after 2nd skew x mod: x = 66 ~~~~

### See Also operator[] get ---

void setScaleX(SkScalar v)

Sets horizontal scale factor. ### Parameters

`v`	horizontal scale factor to store

### Example

### See Also set setScale setScaleY ---

void setScaleY(SkScalar v)

Sets vertical scale factor. ### Parameters

`v`	vertical scale factor to store

### Example

### See Also set setScale setScaleX ---

void setSkewY(SkScalar v)

Sets vertical skew factor. ### Parameters

`v`	vertical skew factor to store

### Example

### See Also set setSkew setSkewX ---

void setSkewX(SkScalar v)

Sets horizontal skew factor. ### Parameters

`v`	horizontal skew factor to store

### Example

### See Also set setSkew setSkewX ---

void setTranslateX(SkScalar v)

Sets horizontal translation. ### Parameters

`v`	horizontal translation to store

### Example

### See Also set setTranslate setTranslateY ---

void setTranslateY(SkScalar v)

Sets vertical translation. ### Parameters

`v`	vertical translation to store

### Example

### See Also set setTranslate setTranslateX ---

void setPerspX(SkScalar v)

Sets input x-axis perspective factor, which causes mapXY() to vary input x-axis values inversely proportional to input y-axis values. ### Parameters

`v`	perspective factor

### Example

### See Also getPerspX set setAll set9 MakeAll ---

void setPerspY(SkScalar v)

Sets input y-axis perspective factor, which causes mapXY() to vary input y-axis values inversely proportional to input x-axis values. ### Parameters

`v`	perspective factor

### Example

### See Also getPerspY set setAll set9 MakeAll ---

void setAll(SkScalar scaleX, SkScalar skewX, SkScalar transX, SkScalar skewY, SkScalar scaleY,
            SkScalar transY, SkScalar persp0, SkScalar persp1, SkScalar persp2)

`scaleX`	horizontal scale factor to store
`skewX`	horizontal skew factor to store
`transX`	horizontal translation to store
`skewY`	vertical skew factor to store
`scaleY`	vertical scale factor to store
`transY`	vertical translation to store
`persp0`	input x-axis values perspective factor to store
`persp1`	input y-axis values perspective factor to store
`persp2`	perspective scale factor to store

### Example

### See Also set9 MakeAll ---

void get9(SkScalar buffer[9])const

Copies nine scalar values contained by SkMatrix into buffer, in member value ascending order: kMScaleX, kMSkewX, kMTransX, kMSkewY, kMScaleY, kMTransY, kMPersp0, kMPersp1, kMPersp2. ### Parameters

buffer storage for nine scalar values

### Example

#### Example Output ~~~~ {4, 0, 3}, {0, 5, 4}, {0, 0, 1} ~~~~

### See Also set9 ---

void set9(const SkScalar buffer[9])

Sets SkMatrix to nine scalar values in buffer, in member value ascending order: kMScaleX, kMSkewX, kMTransX, kMSkewY, kMScaleY, kMTransY, kMPersp0, kMPersp1, kMPersp2. Sets matrix to: | buffer[0] buffer[1] buffer[2] | | buffer[3] buffer[4] buffer[5] | | buffer[6] buffer[7] buffer[8] | In the future, set9 followed by get9 may not return the same values. Since SkMatrix maps non-homogeneous coordinates, scaling all nine values produces an equivalent transformation, possibly improving precision. ### Parameters

buffer nine scalar values

### Example

### See Also setAll get9 MakeAll ---

void reset()

Sets SkMatrix to identity; which has no effect on mapped SkPoint. Sets SkMatrix to: | 1 0 0 | | 0 1 0 | | 0 0 1 | Also called setIdentity(); use the one that provides better inline documentation. ### Example

#### Example Output ~~~~ m.isIdentity(): true ~~~~

### See Also isIdentity setIdentity ---

void setIdentity()

Sets SkMatrix to identity; which has no effect on mapped SkPoint. Sets SkMatrix to: | 1 0 0 | | 0 1 0 | | 0 0 1 | Also called reset(); use the one that provides better inline documentation. ### Example

#### Example Output ~~~~ m.isIdentity(): true ~~~~

### See Also isIdentity reset ---

void setTranslate(SkScalar dx, SkScalar dy)

Sets SkMatrix to translate by (dx, dy). ### Parameters

`dx`	horizontal translation
`dy`	vertical translation

### Example

### See Also setTranslateX setTranslateY ---

void setTranslate(const SkVector& v)

Sets SkMatrix to translate by (v.fX, v.fY). ### Parameters

`v`	vector containing horizontal and vertical translation

### Example

### See Also setTranslateX setTranslateY MakeTrans ---

void setScale(SkScalar sx, SkScalar sy, SkScalar px, SkScalar py)

Sets SkMatrix to scale by sx and sy, about a pivot point at (px, py). The pivot point is unchanged when mapped with SkMatrix. ### Parameters

`sx`	horizontal scale factor
`sy`	vertical scale factor
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also setScaleX setScaleY MakeScale preScale postScale ---

void setScale(SkScalar sx, SkScalar sy)

Sets SkMatrix to scale by sx and sy about at pivot point at (0, 0). ### Parameters

`sx`	horizontal scale factor
`sy`	vertical scale factor

### Example

### See Also setScaleX setScaleY MakeScale preScale postScale ---

void setRotate(SkScalar degrees, SkScalar px, SkScalar py)

Sets SkMatrix to rotate by degrees about a pivot point at (px, py). The pivot point is unchanged when mapped with SkMatrix. Positive degrees rotates clockwise. ### Parameters

`degrees`	angle of axes relative to upright axes
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also setSinCos preRotate postRotate ---

void setRotate(SkScalar degrees)

Sets SkMatrix to rotate by degrees about a pivot point at (0, 0). Positive degrees rotates clockwise. ### Parameters

degrees angle of axes relative to upright axes

### Example

### See Also setSinCos preRotate postRotate ---

void setSinCos(SkScalar sinValue, SkScalar cosValue, SkScalar px, SkScalar py)

Sets SkMatrix to rotate by sinValue and cosValue, about a pivot point at (px, py). The pivot point is unchanged when mapped with SkMatrix. Vector (sinValue, cosValue) describes the angle of rotation relative to (0, 1). Vector length specifies scale. ### Parameters

`sinValue`	rotation vector x-axis component
`cosValue`	rotation vector y-axis component
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also setRotate setScale setRSXform ---

void setSinCos(SkScalar sinValue, SkScalar cosValue)

Sets SkMatrix to rotate by sinValue and cosValue, about a pivot point at (0, 0). Vector (sinValue, cosValue) describes the angle of rotation relative to (0, 1). Vector length specifies scale. ### Parameters

`sinValue`	rotation vector x-axis component
`cosValue`	rotation vector y-axis component

### Example

Canvas needs offset after applying Matrix to pivot about Rect center.

### See Also setRotate setScale setRSXform ---

SkMatrix& setRSXform(const SkRSXform& rsxForm)

Sets SkMatrix to rotate, scale, and translate using a compressed matrix form. Vector (rsxForm.fSSin, rsxForm.fSCos) describes the angle of rotation relative to (0, 1). Vector length specifies scale. Mapped point is rotated and scaled by vector, then translated by (rsxForm.fTx, rsxForm.fTy). ### Parameters

rsxForm compressed SkRSXform matrix

### Return Value reference to SkMatrix ### Example

Canvas needs offset after applying Matrix to pivot about Rect center.

### See Also setSinCos setScale setTranslate ---

void setSkew(SkScalar kx, SkScalar ky, SkScalar px, SkScalar py)

Sets SkMatrix to skew by kx and ky, about a pivot point at (px, py). The pivot point is unchanged when mapped with SkMatrix. ### Parameters

`kx`	horizontal skew factor
`ky`	vertical skew factor
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also setSkewX setSkewY preSkew postSkew ---

void setSkew(SkScalar kx, SkScalar ky)

Sets SkMatrix to skew by kx and ky, about a pivot point at (0, 0). ### Parameters

`kx`	horizontal skew factor
`ky`	vertical skew factor

### Example

### See Also setSkewX setSkewY preSkew postSkew ---

void setConcat(const SkMatrix& a, const SkMatrix& b)

Sets SkMatrix to SkMatrix a multiplied by SkMatrix b. Either a or b may be this. Given: | A B C | | J K L | a = | D E F |, b = | M N O | | G H I | | P Q R | sets SkMatrix to: | A B C | | J K L | | AJ+BM+CP AK+BN+CQ AL+BO+CR | a * b = | D E F | * | M N O | = | DJ+EM+FP DK+EN+FQ DL+EO+FR | | G H I | | P Q R | | GJ+HM+IP GK+HN+IQ GL+HO+IR | ### Parameters

`a`	SkMatrix on left side of multiply expression
`b`	SkMatrix on right side of multiply expression

### Example

setPolyToPoly creates perspective matrices, one the inverse of the other. Multiplying the matrix by its inverse turns into an identity matrix.

### See Also Concat preConcat postConcat SkCanvas::concat ---

void preTranslate(SkScalar dx, SkScalar dy)

Sets SkMatrix to SkMatrix multiplied by SkMatrix constructed from translation (dx, dy). This can be thought of as moving the point to be mapped before applying SkMatrix. Given: | A B C | | 1 0 dx | Matrix = | D E F |, T(dx, dy) = | 0 1 dy | | G H I | | 0 0 1 | sets SkMatrix to: | A B C | | 1 0 dx | | A B A*dx+B*dy+C | Matrix * T(dx, dy) = | D E F | | 0 1 dy | = | D E D*dx+E*dy+F | | G H I | | 0 0 1 | | G H G*dx+H*dy+I | ### Parameters

`dx`	x-axis translation before applying SkMatrix
`dy`	y-axis translation before applying SkMatrix

### Example

### See Also postTranslate setTranslate MakeTrans ---

void preScale(SkScalar sx, SkScalar sy, SkScalar px, SkScalar py)

Sets SkMatrix to SkMatrix multiplied by SkMatrix constructed from scaling by (sx, sy) about pivot point (px, py). This can be thought of as scaling about a pivot point before applying SkMatrix. Given: | A B C | | sx 0 dx | Matrix = | D E F |, S(sx, sy, px, py) = | 0 sy dy | | G H I | | 0 0 1 | where dx = px - sx * px dy = py - sy * py sets SkMatrix to: | A B C | | sx 0 dx | | A*sx B*sy A*dx+B*dy+C | Matrix * S(sx, sy, px, py) = | D E F | | 0 sy dy | = | D*sx E*sy D*dx+E*dy+F | | G H I | | 0 0 1 | | G*sx H*sy G*dx+H*dy+I | ### Parameters

`sx`	horizontal scale factor
`sy`	vertical scale factor
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also postScale setScale MakeScale ---

void preScale(SkScalar sx, SkScalar sy)

Sets SkMatrix to SkMatrix multiplied by SkMatrix constructed from scaling by (sx, sy) about pivot point (0, 0). This can be thought of as scaling about the origin before applying SkMatrix. Given: | A B C | | sx 0 0 | Matrix = | D E F |, S(sx, sy) = | 0 sy 0 | | G H I | | 0 0 1 | sets SkMatrix to: | A B C | | sx 0 0 | | A*sx B*sy C | Matrix * S(sx, sy) = | D E F | | 0 sy 0 | = | D*sx E*sy F | | G H I | | 0 0 1 | | G*sx H*sy I | ### Parameters

`sx`	horizontal scale factor
`sy`	vertical scale factor

### Example

### See Also postScale setScale MakeScale ---

void preRotate(SkScalar degrees, SkScalar px, SkScalar py)

Sets SkMatrix to SkMatrix multiplied by SkMatrix constructed from rotating by degrees about pivot point (px, py). This can be thought of as rotating about a pivot point before applying SkMatrix. Positive degrees rotates clockwise. Given: | A B C | | c -s dx | Matrix = | D E F |, R(degrees, px, py) = | s c dy | | G H I | | 0 0 1 | where c = cos(degrees) s = sin(degrees) dx = s * py + (1 - c) * px dy = -s * px + (1 - c) * py sets SkMatrix to: | A B C | | c -s dx | | Ac+Bs -As+Bc A*dx+B*dy+C | Matrix * R(degrees, px, py) = | D E F | | s c dy | = | Dc+Es -Ds+Ec D*dx+E*dy+F | | G H I | | 0 0 1 | | Gc+Hs -Gs+Hc G*dx+H*dy+I | ### Parameters

`degrees`	angle of axes relative to upright axes
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also postRotate setRotate ---

void preRotate(SkScalar degrees)

Sets SkMatrix to SkMatrix multiplied by SkMatrix constructed from rotating by degrees about pivot point (0, 0). This can be thought of as rotating about the origin before applying SkMatrix. Positive degrees rotates clockwise. Given: | A B C | | c -s 0 | Matrix = | D E F |, R(degrees, px, py) = | s c 0 | | G H I | | 0 0 1 | where c = cos(degrees) s = sin(degrees) sets SkMatrix to: | A B C | | c -s 0 | | Ac+Bs -As+Bc C | Matrix * R(degrees, px, py) = | D E F | | s c 0 | = | Dc+Es -Ds+Ec F | | G H I | | 0 0 1 | | Gc+Hs -Gs+Hc I | ### Parameters

degrees angle of axes relative to upright axes

### Example

### See Also postRotate setRotate ---

void preSkew(SkScalar kx, SkScalar ky, SkScalar px, SkScalar py)

Sets SkMatrix to SkMatrix multiplied by SkMatrix constructed from skewing by (kx, ky) about pivot point (px, py). This can be thought of as skewing about a pivot point before applying SkMatrix. Given: | A B C | | 1 kx dx | Matrix = | D E F |, K(kx, ky, px, py) = | ky 1 dy | | G H I | | 0 0 1 | where dx = -kx * py dy = -ky * px sets SkMatrix to: | A B C | | 1 kx dx | | A+B*ky A*kx+B A*dx+B*dy+C | Matrix * K(kx, ky, px, py) = | D E F | | ky 1 dy | = | D+E*ky D*kx+E D*dx+E*dy+F | | G H I | | 0 0 1 | | G+H*ky G*kx+H G*dx+H*dy+I | ### Parameters

`kx`	horizontal skew factor
`ky`	vertical skew factor
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also postSkew setSkew ---

void preSkew(SkScalar kx, SkScalar ky)

Sets SkMatrix to SkMatrix multiplied by SkMatrix constructed from skewing by (kx, ky) about pivot point (0, 0). This can be thought of as skewing about the origin before applying SkMatrix. Given: | A B C | | 1 kx 0 | Matrix = | D E F |, K(kx, ky) = | ky 1 0 | | G H I | | 0 0 1 | sets SkMatrix to: | A B C | | 1 kx 0 | | A+B*ky A*kx+B C | Matrix * K(kx, ky) = | D E F | | ky 1 0 | = | D+E*ky D*kx+E F | | G H I | | 0 0 1 | | G+H*ky G*kx+H I | ### Parameters

`kx`	horizontal skew factor
`ky`	vertical skew factor

### Example

### See Also postSkew setSkew ---

void preConcat(const SkMatrix& other)

Sets SkMatrix to SkMatrix multiplied by SkMatrix other. This can be thought of mapping by other before applying SkMatrix. Given: | A B C | | J K L | Matrix = | D E F |, other = | M N O | | G H I | | P Q R | sets SkMatrix to: | A B C | | J K L | | AJ+BM+CP AK+BN+CQ AL+BO+CR | Matrix * other = | D E F | * | M N O | = | DJ+EM+FP DK+EN+FQ DL+EO+FR | | G H I | | P Q R | | GJ+HM+IP GK+HN+IQ GL+HO+IR | ### Parameters

other SkMatrix on right side of multiply expression

### Example

setPolyToPoly creates perspective matrices, one the inverse of the other. Multiplying the matrix by its inverse turns into an identity matrix.

### See Also postConcat setConcat Concat ---

void postTranslate(SkScalar dx, SkScalar dy)

Sets SkMatrix to SkMatrix constructed from translation (dx, dy) multiplied by SkMatrix. This can be thought of as moving the point to be mapped after applying SkMatrix. Given: | J K L | | 1 0 dx | Matrix = | M N O |, T(dx, dy) = | 0 1 dy | | P Q R | | 0 0 1 | sets SkMatrix to: | 1 0 dx | | J K L | | J+dx*P K+dx*Q L+dx*R | T(dx, dy) * Matrix = | 0 1 dy | | M N O | = | M+dy*P N+dy*Q O+dy*R | | 0 0 1 | | P Q R | | P Q R | ### Parameters

`dx`	x-axis translation after applying SkMatrix
`dy`	y-axis translation after applying SkMatrix

### Example

Compare with preTranslate example.

### See Also preTranslate setTranslate MakeTrans ---

void postScale(SkScalar sx, SkScalar sy, SkScalar px, SkScalar py)

Sets SkMatrix to SkMatrix constructed from scaling by (sx, sy) about pivot point (px, py), multiplied by SkMatrix. This can be thought of as scaling about a pivot point after applying SkMatrix. Given: | J K L | | sx 0 dx | Matrix = | M N O |, S(sx, sy, px, py) = | 0 sy dy | | P Q R | | 0 0 1 | where dx = px - sx * px dy = py - sy * py sets SkMatrix to: | sx 0 dx | | J K L | | sx*J+dx*P sx*K+dx*Q sx*L+dx+R | S(sx, sy, px, py) * Matrix = | 0 sy dy | | M N O | = | sy*M+dy*P sy*N+dy*Q sy*O+dy*R | | 0 0 1 | | P Q R | | P Q R | ### Parameters

`sx`	horizontal scale factor
`sy`	vertical scale factor
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also preScale setScale MakeScale ---

void postScale(SkScalar sx, SkScalar sy)

Sets SkMatrix to SkMatrix constructed from scaling by (sx, sy) about pivot point (0, 0), multiplied by SkMatrix. This can be thought of as scaling about the origin after applying SkMatrix. Given: | J K L | | sx 0 0 | Matrix = | M N O |, S(sx, sy) = | 0 sy 0 | | P Q R | | 0 0 1 | sets SkMatrix to: | sx 0 0 | | J K L | | sx*J sx*K sx*L | S(sx, sy) * Matrix = | 0 sy 0 | | M N O | = | sy*M sy*N sy*O | | 0 0 1 | | P Q R | | P Q R | ### Parameters

`sx`	horizontal scale factor
`sy`	vertical scale factor

### Example

### See Also preScale setScale MakeScale ---

bool postIDiv(int divx, int divy)

Sets Matrix to Matrix constructed from scaling by (1/divx, 1/divy), multiplied by Matrix. Returns false if either divx or divy is zero. Given:

         | J K L |                   | sx  0  0 |
Matrix = | M N O |,  I(divx, divy) = |  0 sy  0 |
         | P Q R |                   |  0  0  1 |

where

sx = 1 / divx
sy = 1 / divy

sets Matrix to:

                         | sx  0  0 | | J K L |   | sx*J sx*K sx*L |
I(divx, divy) * Matrix = |  0 sy  0 | | M N O | = | sy*M sy*N sy*O |
                         |  0  0  1 | | P Q R |   |    P    Q    R |

### Parameters

`divx`	integer divisor for inverse scale on x-axis
`divy`	integer divisor for inverse scale on y-axis

### Return Value true on successful scale ### Example

### See Also postScale MakeScale ---

void postRotate(SkScalar degrees, SkScalar px, SkScalar py)

Sets SkMatrix to SkMatrix constructed from rotating by degrees about pivot point (px, py), multiplied by SkMatrix. This can be thought of as rotating about a pivot point after applying SkMatrix. Positive degrees rotates clockwise. Given: | J K L | | c -s dx | Matrix = | M N O |, R(degrees, px, py) = | s c dy | | P Q R | | 0 0 1 | where c = cos(degrees) s = sin(degrees) dx = s * py + (1 - c) * px dy = -s * px + (1 - c) * py sets SkMatrix to: |c -s dx| |J K L| |cJ-sM+dx*P cK-sN+dx*Q cL-sO+dx+R| R(degrees, px, py) * Matrix = |s c dy| |M N O| = |sJ+cM+dy*P sK+cN+dy*Q sL+cO+dy*R| |0 0 1| |P Q R| | P Q R| ### Parameters

`degrees`	angle of axes relative to upright axes
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also preRotate setRotate ---

void postRotate(SkScalar degrees)

Sets SkMatrix to SkMatrix constructed from rotating by degrees about pivot point (0, 0), multiplied by SkMatrix. This can be thought of as rotating about the origin after applying SkMatrix. Positive degrees rotates clockwise. Given: | J K L | | c -s 0 | Matrix = | M N O |, R(degrees, px, py) = | s c 0 | | P Q R | | 0 0 1 | where c = cos(degrees) s = sin(degrees) sets SkMatrix to: | c -s dx | | J K L | | cJ-sM cK-sN cL-sO | R(degrees, px, py) * Matrix = | s c dy | | M N O | = | sJ+cM sK+cN sL+cO | | 0 0 1 | | P Q R | | P Q R | ### Parameters

degrees angle of axes relative to upright axes

### Example

### See Also preRotate setRotate ---

void postSkew(SkScalar kx, SkScalar ky, SkScalar px, SkScalar py)

Sets SkMatrix to SkMatrix constructed from skewing by (kx, ky) about pivot point (px, py), multiplied by SkMatrix. This can be thought of as skewing about a pivot point after applying SkMatrix. Given: | J K L | | 1 kx dx | Matrix = | M N O |, K(kx, ky, px, py) = | ky 1 dy | | P Q R | | 0 0 1 | where dx = -kx * py dy = -ky * px sets SkMatrix to: | 1 kx dx| |J K L| |J+kx*M+dx*P K+kx*N+dx*Q L+kx*O+dx+R| K(kx, ky, px, py) * Matrix = |ky 1 dy| |M N O| = |ky*J+M+dy*P ky*K+N+dy*Q ky*L+O+dy*R| | 0 0 1| |P Q R| | P Q R| ### Parameters

`kx`	horizontal skew factor
`ky`	vertical skew factor
`px`	pivot on x-axis
`py`	pivot on y-axis

### Example

### See Also preSkew setSkew ---

void postSkew(SkScalar kx, SkScalar ky)

Sets SkMatrix to SkMatrix constructed from skewing by (kx, ky) about pivot point (0, 0), multiplied by SkMatrix. This can be thought of as skewing about the origin after applying SkMatrix. Given: | J K L | | 1 kx 0 | Matrix = | M N O |, K(kx, ky) = | ky 1 0 | | P Q R | | 0 0 1 | sets SkMatrix to: | 1 kx 0 | | J K L | | J+kx*M K+kx*N L+kx*O | K(kx, ky) * Matrix = | ky 1 0 | | M N O | = | ky*J+M ky*K+N ky*L+O | | 0 0 1 | | P Q R | | P Q R | ### Parameters

`kx`	horizontal skew factor
`ky`	vertical skew factor

### Example

### See Also preSkew setSkew ---

void postConcat(const SkMatrix& other)

Sets SkMatrix to SkMatrix other multiplied by SkMatrix. This can be thought of mapping by other after applying SkMatrix. Given: | J K L | | A B C | Matrix = | M N O |, other = | D E F | | P Q R | | G H I | sets SkMatrix to: | A B C | | J K L | | AJ+BM+CP AK+BN+CQ AL+BO+CR | other * Matrix = | D E F | * | M N O | = | DJ+EM+FP DK+EN+FQ DL+EO+FR | | G H I | | P Q R | | GJ+HM+IP GK+HN+IQ GL+HO+IR | ### Parameters

other SkMatrix on left side of multiply expression

### Example

### See Also preConcat setConcat Concat ---

    enum ScaleToFit {
        kFill_ScaleToFit,
        kStart_ScaleToFit,
        kCenter_ScaleToFit,
        kEnd_ScaleToFit,
    };

ScaleToFit describes how Matrix is constructed to map one Rect to another. ScaleToFit may allow Matrix to have unequal horizontal and vertical scaling, or may restrict Matrix to square scaling. If restricted, ScaleToFit specifies how Matrix maps to the side or center of the destination Rect. ### Constants

Const	Value	Description
`SkMatrix::kFill_ScaleToFit`	0	Computes Matrix that scales about x-axis and y-axis independently, so that source Rect is mapped to completely fill destination Rect. The aspect ratio of source Rect may change.
`SkMatrix::kStart_ScaleToFit`	1	Computes Matrix that maintains source Rect aspect ratio, mapping source Rect width or height to destination Rect. Aligns mapping to left and top edges of destination Rect.
`SkMatrix::kCenter_ScaleToFit`	2	Computes Matrix that maintains source Rect aspect ratio, mapping source Rect width or height to destination Rect. Aligns mapping to center of destination Rect.
`SkMatrix::kEnd_ScaleToFit`	3	Computes Matrix that maintains source Rect aspect ratio, mapping source Rect width or height to destination Rect. Aligns mapping to right and bottom edges of destination Rect.

### Example

### See Also setRectToRect MakeRectToRect setPolyToPoly ---

bool setRectToRect(const SkRect& src, const SkRect& dst, ScaleToFit stf)

Sets SkMatrix to scale and translate src SkRect to dst SkRect. stf selects whether mapping completely fills dst or preserves the aspect ratio, and how to align src within dst. Returns false if src is empty, and sets SkMatrix to identity. Returns true if dst is empty, and sets SkMatrix to: | 0 0 0 | | 0 0 0 | | 0 0 1 | ### Parameters

`src`	SkRect to map from
`dst`	SkRect to map to
`stf`	one of: kFill_ScaleToFit, kStart_ScaleToFit,

kCenter_ScaleToFit, kEnd_ScaleToFit ### Return Value true if SkMatrix can represent SkRect mapping ### Example

#### Example Output ~~~~ src: 0, 0, 0, 0 dst: 0, 0, 0, 0 success: false [ 1.0000 0.0000 0.0000][ 0.0000 1.0000 0.0000][ 0.0000 0.0000 1.0000] src: 0, 0, 0, 0 dst: 5, 6, 8, 9 success: false [ 1.0000 0.0000 0.0000][ 0.0000 1.0000 0.0000][ 0.0000 0.0000 1.0000] src: 1, 2, 3, 4 dst: 0, 0, 0, 0 success: true [ 0.0000 0.0000 0.0000][ 0.0000 0.0000 0.0000][ 0.0000 0.0000 1.0000] src: 1, 2, 3, 4 dst: 5, 6, 8, 9 success: true [ 1.5000 0.0000 3.5000][ 0.0000 1.5000 3.0000][ 0.0000 0.0000 1.0000] ~~~~

### See Also MakeRectToRect ScaleToFit setPolyToPoly SkRect::isEmpty ---

static SkMatrix MakeRectToRect(const SkRect& src, const SkRect& dst, ScaleToFit stf)

Returns SkMatrix set to scale and translate src SkRect to dst SkRect. stf selects whether mapping completely fills dst or preserves the aspect ratio, and how to align src within dst. Returns the identity SkMatrix if src is empty. If dst is empty, returns SkMatrix set to: | 0 0 0 | | 0 0 0 | | 0 0 1 | ### Parameters

`src`	SkRect to map from
`dst`	SkRect to map to
`stf`	one of: kFill_ScaleToFit, kStart_ScaleToFit,

kCenter_ScaleToFit, kEnd_ScaleToFit ### Return Value SkMatrix mapping src to dst ### Example

#### Example Output ~~~~ src: 0, 0, 0, 0 dst: 0, 0, 0, 0 [ 1.0000 0.0000 0.0000][ 0.0000 1.0000 0.0000][ 0.0000 0.0000 1.0000] src: 0, 0, 0, 0 dst: 5, 6, 8, 9 [ 1.0000 0.0000 0.0000][ 0.0000 1.0000 0.0000][ 0.0000 0.0000 1.0000] src: 1, 2, 3, 4 dst: 0, 0, 0, 0 [ 0.0000 0.0000 0.0000][ 0.0000 0.0000 0.0000][ 0.0000 0.0000 1.0000] src: 1, 2, 3, 4 dst: 5, 6, 8, 9 [ 1.5000 0.0000 3.5000][ 0.0000 1.5000 3.0000][ 0.0000 0.0000 1.0000] ~~~~

### See Also setRectToRect ScaleToFit setPolyToPoly SkRect::isEmpty ---

bool setPolyToPoly(const SkPoint src[], const SkPoint dst[], int count)

Sets SkMatrix to map src to dst. count must be zero or greater, and four or less. If count is zero, sets SkMatrix to identity and returns true. If count is one, sets SkMatrix to translate and returns true. If count is two or more, sets SkMatrix to map SkPoint if possible; returns false if SkMatrix cannot be constructed. If count is four, SkMatrix may include perspective. ### Parameters

`src`	SkPoint to map from
`dst`	SkPoint to map to
`count`	number of SkPoint in src and dst

### Return Value true if SkMatrix was constructed successfully ### Example

### See Also setRectToRect MakeRectToRect ---

bool invert(SkMatrix* inverse)const

Sets inverse to reciprocal matrix, returning true if SkMatrix can be inverted. Geometrically, if SkMatrix maps from source to destination, inverse SkMatrix maps from destination to source. If SkMatrix can not be inverted, inverse is unchanged. ### Parameters

inverse storage for inverted SkMatrix; may be nullptr

### Return Value true if SkMatrix can be inverted ### Example

### See Also Concat ---

static void SetAffineIdentity(SkScalar affine[6])

Fills affine with identity values in column major order. Sets affine to: | 1 0 0 | | 0 1 0 | Affine 3 by 2 matrices in column major order are used by OpenGL and XPS. ### Parameters

affine storage for 3 by 2 affine matrix

### Example

#### Example Output ~~~~ ScaleX: 1 SkewY: 0 SkewX: 0 ScaleY: 1 TransX: 0 TransY: 0 ~~~~

### See Also setAffine asAffine ---

bool asAffine(SkScalar affine[6])const

Fills affine in column major order. Sets affine to: | scale-x skew-x translate-x | | skew-y scale-y translate-y | If SkMatrix contains perspective, returns false and leaves affine unchanged. ### Parameters

affine storage for 3 by 2 affine matrix; may be nullptr

### Return Value true if SkMatrix does not contain perspective ### Example

#### Example Output ~~~~ ScaleX: 2 SkewY: 5 SkewX: 3 ScaleY: 6 TransX: 4 TransY: 7 ~~~~

### See Also setAffine SetAffineIdentity ---

void setAffine(const SkScalar affine[6])

affine 3 by 2 affine matrix

### Example

#### Example Output ~~~~ ScaleX: 2 SkewY: 5 SkewX: 3 ScaleY: 6 TransX: 4 TransY: 7 [ 2.0000 3.0000 4.0000][ 5.0000 6.0000 7.0000][ 0.0000 0.0000 1.0000] ~~~~

### See Also asAffine SetAffineIdentity ---

void mapPoints(SkPoint dst[], const SkPoint src[], int count)const

Maps src SkPoint array of length count to dst SkPoint array of equal or greater length. SkPoint are mapped by multiplying each SkPoint by SkMatrix. Given: | A B C | | x | Matrix = | D E F |, pt = | y | | G H I | | 1 | where for (i = 0; i < count; ++i) { x = src[i].fX y = src[i].fY } each dst SkPoint is computed as: |A B C| |x| Ax+By+C Dx+Ey+F Matrix * pt = |D E F| |y| = |Ax+By+C Dx+Ey+F Gx+Hy+I| = ------- , ------- |G H I| |1| Gx+Hy+I Gx+Hy+I src and dst may point to the same storage. ### Parameters

`dst`	storage for mapped SkPoint
`src`	SkPoint to transform
`count`	number of SkPoint to transform

### Example

### See Also mapXY mapHomogeneousPoints mapVectors ---

void mapPoints(SkPoint pts[], int count)const

Maps pts SkPoint array of length count in place. SkPoint are mapped by multiplying each SkPoint by SkMatrix. Given: | A B C | | x | Matrix = | D E F |, pt = | y | | G H I | | 1 | where for (i = 0; i < count; ++i) { x = pts[i].fX y = pts[i].fY } each resulting pts SkPoint is computed as: |A B C| |x| Ax+By+C Dx+Ey+F Matrix * pt = |D E F| |y| = |Ax+By+C Dx+Ey+F Gx+Hy+I| = ------- , ------- |G H I| |1| Gx+Hy+I Gx+Hy+I ### Parameters

`pts`	storage for mapped SkPoint
`count`	number of SkPoint to transform

### Example

### See Also mapXY mapHomogeneousPoints mapVectors ---

void mapHomogeneousPoints(SkPoint3 dst[], const SkPoint3 src[], int count)const

Maps src SkPoint3 array of length count to dst SkPoint3 array, which must of length count or greater. SkPoint3 array is mapped by multiplying each SkPoint3 by SkMatrix. Given: | A B C | | x | Matrix = | D E F |, src = | y | | G H I | | z | each resulting dst SkPoint is computed as: |A B C| |x| Matrix * src = |D E F| |y| = |Ax+By+Cz Dx+Ey+Fz Gx+Hy+Iz| |G H I| |z| ### Parameters

`dst`	storage for mapped SkPoint3 array
`src`	SkPoint3 array to transform
`count`	items in SkPoint3 array to transform

### Example

### See Also mapPoints mapXY mapVectors ---

void mapXY(SkScalar x, SkScalar y, SkPoint* result)const

Maps SkPoint (x, y) to result. SkPoint is mapped by multiplying by SkMatrix. Given: | A B C | | x | Matrix = | D E F |, pt = | y | | G H I | | 1 | result is computed as: |A B C| |x| Ax+By+C Dx+Ey+F Matrix * pt = |D E F| |y| = |Ax+By+C Dx+Ey+F Gx+Hy+I| = ------- , ------- |G H I| |1| Gx+Hy+I Gx+Hy+I ### Parameters

`x`	x-axis value of SkPoint to map
`y`	y-axis value of SkPoint to map
`result`	storage for mapped SkPoint

### Example

### See Also mapPoints mapVectors ---

SkPoint mapXY(SkScalar x, SkScalar y)const

Returns SkPoint (x, y) multiplied by SkMatrix. Given: | A B C | | x | Matrix = | D E F |, pt = | y | | G H I | | 1 | result is computed as: |A B C| |x| Ax+By+C Dx+Ey+F Matrix * pt = |D E F| |y| = |Ax+By+C Dx+Ey+F Gx+Hy+I| = ------- , ------- |G H I| |1| Gx+Hy+I Gx+Hy+I ### Parameters

`x`	x-axis value of SkPoint to map
`y`	y-axis value of SkPoint to map

### Return Value mapped SkPoint ### Example

### See Also mapPoints mapVectors ---

void mapVectors(SkVector dst[], const SkVector src[], int count)const

Maps src vector array of length count to vector SkPoint array of equal or greater length. Vectors are mapped by multiplying each vector by SkMatrix, treating SkMatrix translation as zero. Given: | A B 0 | | x | Matrix = | D E 0 |, src = | y | | G H I | | 1 | where for (i = 0; i < count; ++i) { x = src[i].fX y = src[i].fY } each dst vector is computed as: |A B 0| |x| Ax+By Dx+Ey Matrix * src = |D E 0| |y| = |Ax+By Dx+Ey Gx+Hy+I| = ------- , ------- |G H I| |1| Gx+Hy+I Gx+Hy+I src and dst may point to the same storage. ### Parameters

`dst`	storage for mapped vectors
`src`	vectors to transform
`count`	number of vectors to transform

### Example

### See Also mapVector mapPoints mapXY ---

void mapVectors(SkVector vecs[], int count)const

Maps vecs vector array of length count in place, multiplying each vector by SkMatrix, treating SkMatrix translation as zero. Given: | A B 0 | | x | Matrix = | D E 0 |, vec = | y | | G H I | | 1 | where for (i = 0; i < count; ++i) { x = vecs[i].fX y = vecs[i].fY } each result vector is computed as: |A B 0| |x| Ax+By Dx+Ey Matrix * vec = |D E 0| |y| = |Ax+By Dx+Ey Gx+Hy+I| = ------- , ------- |G H I| |1| Gx+Hy+I Gx+Hy+I ### Parameters

`vecs`	vectors to transform, and storage for mapped vectors
`count`	number of vectors to transform

### Example

### See Also mapVector mapPoints mapXY ---

void mapVector(SkScalar dx, SkScalar dy, SkVector* result)const

Maps vector (dx, dy) to result. Vector is mapped by multiplying by SkMatrix, treating SkMatrix translation as zero. Given: | A B 0 | | dx | Matrix = | D E 0 |, vec = | dy | | G H I | | 1 | each result vector is computed as: |A B 0| |dx| A*dx+B*dy D*dx+E*dy Matrix * vec = |D E 0| |dy| = |A*dx+B*dy D*dx+E*dy G*dx+H*dy+I| = ----------- , ----------- |G H I| | 1| G*dx+H*dy+I G*dx+*dHy+I ### Parameters

`dx`	x-axis value of vector to map
`dy`	y-axis value of vector to map
`result`	storage for mapped vector

### Example

### See Also mapVectors mapPoints mapXY ---

SkVector mapVector(SkScalar dx, SkScalar dy)const

Returns vector (dx, dy) multiplied by SkMatrix, treating SkMatrix translation as zero. Given: | A B 0 | | dx | Matrix = | D E 0 |, vec = | dy | | G H I | | 1 | each result vector is computed as: |A B 0| |dx| A*dx+B*dy D*dx+E*dy Matrix * vec = |D E 0| |dy| = |A*dx+B*dy D*dx+E*dy G*dx+H*dy+I| = ----------- , ----------- |G H I| | 1| G*dx+H*dy+I G*dx+*dHy+I ### Parameters

`dx`	x-axis value of vector to map
`dy`	y-axis value of vector to map

### Return Value mapped vector ### Example

### See Also mapVectors mapPoints mapXY ---

bool mapRect(SkRect* dst, const SkRect& src)const

Sets dst to bounds of src corners mapped by SkMatrix. Returns true if mapped corners are dst corners. Returned value is the same as calling rectStaysRect(). ### Parameters

`dst`	storage for bounds of mapped SkPoint
`src`	SkRect to map

### Return Value true if dst is equivalent to mapped src ### Example

### See Also mapPoints rectStaysRect ---

bool mapRect(SkRect* rect)const

Sets rect to bounds of rect corners mapped by SkMatrix. Returns true if mapped corners are computed rect corners. Returned value is the same as calling rectStaysRect(). ### Parameters

rect rectangle to map, and storage for bounds of mapped corners

### Return Value true if result is equivalent to mapped rect ### Example

### See Also mapRectScaleTranslate mapPoints rectStaysRect ---

SkRect mapRect(const SkRect& src)const

Returns bounds of src corners mapped by SkMatrix. ### Parameters

src rectangle to map

### Return Value mapped bounds ### Example

### See Also mapRectToQuad mapRectScaleTranslate ---

void mapRectToQuad(SkPoint dst[4], const SkRect& rect)const

Maps four corners of rect to dst. SkPoint are mapped by multiplying each rect corner by SkMatrix. rect corner is processed in this order: (rect.fLeft, rect.fTop), (rect.fRight, rect.fTop), (rect.fRight, rect.fBottom), (rect.fLeft, rect.fBottom). rect may be empty: rect.fLeft may be greater than or equal to rect.fRight; rect.fTop may be greater than or equal to rect.fBottom. Given: | A B C | | x | Matrix = | D E F |, pt = | y | | G H I | | 1 | where pt is initialized from each of (rect.fLeft, rect.fTop), (rect.fRight, rect.fTop), (rect.fRight, rect.fBottom), (rect.fLeft, rect.fBottom), each dst SkPoint is computed as: |A B C| |x| Ax+By+C Dx+Ey+F Matrix * pt = |D E F| |y| = |Ax+By+C Dx+Ey+F Gx+Hy+I| = ------- , ------- |G H I| |1| Gx+Hy+I Gx+Hy+I ### Parameters

`dst`	storage for mapped corner SkPoint
`rect`	SkRect to map

### Example

### See Also mapRect mapRectScaleTranslate ---

void mapRectScaleTranslate(SkRect* dst, const SkRect& src)const

Sets dst to bounds of src corners mapped by SkMatrix. If matrix contains elements other than scale or translate: asserts if SK_DEBUG is defined; otherwise, results are undefined. ### Parameters

`dst`	storage for bounds of mapped SkPoint
`src`	SkRect to map

### Example

### See Also mapRect mapRectToQuad isScaleTranslate rectStaysRect ---

SkScalar mapRadius(SkScalar radius)const

Returns geometric mean radius of ellipse formed by constructing circle of size radius, and mapping constructed circle with SkMatrix. The result squared is equal to the major axis length times the minor axis length. Result is not meaningful if SkMatrix contains perspective elements. ### Parameters

radius circle size to map

### Return Value average mapped radius ### Example

The area enclosed by a square with sides equal to mappedRadius is the same as the area enclosed by the ellipse major and minor axes.

### See Also mapVector ---

bool isFixedStepInX()const

Returns true if a unit step on x-axis at some y-axis value mapped through SkMatrix can be represented by a constant vector. Returns true if getType() returns kIdentity_Mask, or combinations of: kTranslate_Mask, kScale_Mask, and kAffine_Mask. May return true if getType() returns kPerspective_Mask, but only when SkMatrix does not include rotation or skewing along the y-axis. ### Return Value true if SkMatrix does not have complex perspective ### Example

#### Example Output ~~~~ [ 1.0000 0.0000 0.0000][ 0.0000 1.0000 0.0000][ 0.0000 0.0000 1.0000] isFixedStepInX: true [ 1.0000 0.0000 0.0000][ 0.0000 2.0000 0.0000][ 0.0000 0.0000 1.0000] isFixedStepInX: true [ 1.0000 0.0000 0.0000][ 0.0000 1.0000 0.0000][ 0.0000 0.1000 1.0000] isFixedStepInX: true [ 1.0000 0.0000 0.0000][ 0.0000 2.0000 0.0000][ 0.0000 0.1000 1.0000] isFixedStepInX: true [ 1.0000 0.0000 0.0000][ 0.0000 1.0000 0.0000][ 0.1000 0.0000 1.0000] isFixedStepInX: false [ 1.0000 0.0000 0.0000][ 0.0000 2.0000 0.0000][ 0.1000 0.0000 1.0000] isFixedStepInX: false [ 1.0000 0.0000 0.0000][ 0.0000 1.0000 0.0000][ 0.1000 0.1000 1.0000] isFixedStepInX: false [ 1.0000 0.0000 0.0000][ 0.0000 2.0000 0.0000][ 0.1000 0.1000 1.0000] isFixedStepInX: false ~~~~

### See Also fixedStepInX getType ---

SkVector fixedStepInX(SkScalar y)const

Returns vector representing a unit step on x-axis at y mapped through SkMatrix. If isFixedStepInX() is false, returned value is undefined. ### Parameters

`y`	position of line parallel to x-axis

### Return Value vector advance of mapped unit step on x-axis ### Example

### See Also isFixedStepInX getType ---

bool cheapEqualTo(const SkMatrix& m)const

Returns true if SkMatrix equals m, using an efficient comparison. Returns false when the sign of zero values is the different; when one matrix has positive zero value and the other has negative zero value. Returns true even when both SkMatrix contain NaN. NaN never equals any value, including itself. To improve performance, NaN values are treated as bit patterns that are equal if their bit patterns are equal. ### Parameters

`m`	SkMatrix to compare

### Return Value true if m and SkMatrix are represented by identical bit patterns ### Example

#### Example Output ~~~~ identity: a == b a.cheapEqualTo(b): true neg zero: a == b a.cheapEqualTo(b): false one NaN: a != b a.cheapEqualTo(b): false both NaN: a != b a.cheapEqualTo(b): true ~~~~

### See Also operator==(const SkMatrix& a, const SkMatrix& b) ---

bool operator==(const SkMatrix& a, const SkMatrix& b)

Compares a and b; returns true if a and b are numerically equal. Returns true even if sign of zero values are different. Returns false if either SkMatrix contains NaN, even if the other SkMatrix also contains NaN. ### Parameters

`a`	SkMatrix to compare
`b`	SkMatrix to compare

### Return Value true if SkMatrix a and SkMatrix b are numerically equal ### Example

#### Example Output ~~~~ identity: a == b a.cheapEqualTo(b): true ~~~~

### See Also cheapEqualTo operator!=(const SkMatrix& a, const SkMatrix& b) ---

bool operator!=(const SkMatrix& a, const SkMatrix& b)

Compares a and b; returns true if a and b are not numerically equal. Returns false even if sign of zero values are different. Returns true if either SkMatrix contains NaN, even if the other SkMatrix also contains NaN. ### Parameters

`a`	SkMatrix to compare
`b`	SkMatrix to compare

### Return Value true if SkMatrix a and SkMatrix b are numerically not equal ### Example

### See Also cheapEqualTo operator==(const SkMatrix& a, const SkMatrix& b) ---

void dump()const

Writes text representation of SkMatrix to standard output. Floating point values are written with limited precision; it may not be possible to reconstruct original SkMatrix from output. ### Example

#### Example Output ~~~~ [ 0.7071 -0.7071 0.0000][ 0.7071 0.7071 0.0000][ 0.0000 0.0000 1.0000] [ 0.7071 -0.7071 0.0000][ 0.7071 0.7071 0.0000][ 0.0000 0.0000 1.0000] matrix != nearlyEqual ~~~~

### See Also SkPath::dump ---

SkScalar getMinScale()const

Returns the minimum scaling factor of SkMatrix by decomposing the scaling and skewing elements. Returns -1 if scale factor overflows or SkMatrix contains perspective. ### Return Value minimum scale factor ### Example

#### Example Output ~~~~ matrix.getMinScale() 24 ~~~~

### See Also getMaxScale getMinMaxScales ---

SkScalar getMaxScale()const

Returns the maximum scaling factor of SkMatrix by decomposing the scaling and skewing elements. Returns -1 if scale factor overflows or SkMatrix contains perspective. ### Return Value maximum scale factor ### Example

#### Example Output ~~~~ matrix.getMaxScale() 42 ~~~~

### See Also getMinScale getMinMaxScales ---

bool getMinMaxScales(SkScalar scaleFactors[2])const

Sets scaleFactors[0] to the minimum scaling factor, and scaleFactors[1] to the maximum scaling factor. Scaling factors are computed by decomposing the SkMatrix scaling and skewing elements. Returns true if scaleFactors are found; otherwise, returns false and sets scaleFactors to undefined values. ### Parameters

scaleFactors storage for minimum and maximum scale factors

### Return Value true if scale factors were computed correctly ### Example

#### Example Output ~~~~ matrix.getMinMaxScales() false 2 2 ~~~~

### See Also getMinScale getMaxScale ---

bool decomposeScale(SkSize* scale, SkMatrix* remaining = nullptr)const

Decomposes Matrix into scale components and whatever remains. Returns false if Matrix could not be decomposed. Sets scale to portion of Matrix that scale axes. Sets remaining to Matrix with scaling factored out. remaining may be passed as nullptr to determine if Matrix can be decomposed without computing remainder. Returns true if scale components are found. scale and remaining are unchanged if Matrix contains perspective; scale factors are not finite, or are nearly zero. On success: Matrix = scale * Remaining. ### Parameters

`scale`	axes scaling factors; may be nullptr
`remaining`	Matrix without scaling; may be nullptr

### Return Value true if scale can be computed ### Example

#### Example Output ~~~~ [ 0.0000 -0.2500 0.0000][ 0.5000 0.0000 0.0000][ 0.0000 0.0000 1.0000] success: true scale: 0.5, 0.25 [ 0.0000 -0.5000 0.0000][ 2.0000 0.0000 0.0000][ 0.0000 0.0000 1.0000] [ 0.0000 -0.2500 0.0000][ 0.5000 0.0000 0.0000][ 0.0000 0.0000 1.0000] ~~~~

### See Also setScale MakeScale ---

static const SkMatrix& I()

Returns reference to const identity SkMatrix. Returned SkMatrix is set to: | 1 0 0 | | 0 1 0 | | 0 0 1 | ### Return Value const identity SkMatrix ### Example

#### Example Output ~~~~ m1 == m2 m2 == m3 ~~~~

### See Also reset() setIdentity ---

static const SkMatrix& InvalidMatrix()

Returns reference to a const SkMatrix with invalid values. Returned SkMatrix is set to: | SK_ScalarMax SK_ScalarMax SK_ScalarMax | | SK_ScalarMax SK_ScalarMax SK_ScalarMax | | SK_ScalarMax SK_ScalarMax SK_ScalarMax | ### Return Value const invalid SkMatrix ### Example

#### Example Output ~~~~ scaleX 3.40282e+38 ~~~~

### See Also getType ---

static SkMatrix Concat(const SkMatrix& a, const SkMatrix& b)

Returns SkMatrix a multiplied by SkMatrix b. Given: | A B C | | J K L | a = | D E F |, b = | M N O | | G H I | | P Q R | sets SkMatrix to: | A B C | | J K L | | AJ+BM+CP AK+BN+CQ AL+BO+CR | a * b = | D E F | * | M N O | = | DJ+EM+FP DK+EN+FQ DL+EO+FR | | G H I | | P Q R | | GJ+HM+IP GK+HN+IQ GL+HO+IR | ### Parameters

`a`	SkMatrix on left side of multiply expression
`b`	SkMatrix on right side of multiply expression

### Return Value SkMatrix computed from a times b ### Example

setPolyToPoly creates perspective matrices, one the inverse of the other. Multiplying the matrix by its inverse turns into an identity matrix.

### See Also preConcat postConcat ---

void dirtyMatrixTypeCache()

Sets internal cache to unknown state. Use to force update after repeated modifications to SkMatrix element reference returned by operator[](int index). ### Example

#### Example Output ~~~~ with identity matrix: x = 24 after skew x mod: x = 24 after 2nd skew x mod: x = 24 after dirty cache: x = 66 ~~~~

### See Also operator[](int index) getType ---

void setScaleTranslate(SkScalar sx, SkScalar sy, SkScalar tx, SkScalar ty)

`sx`	horizontal scale factor to store
`sy`	vertical scale factor to store
`tx`	horizontal translation to store
`ty`	vertical translation to store

### Example

#### Example Output ~~~~ [ 1.0000 0.0000 3.0000][ 0.0000 2.0000 4.0000][ 0.0000 0.0000 1.0000] ~~~~

### See Also setScale preTranslate postTranslate ---

bool isFinite()const

Returns true if all elements of the matrix are finite. Returns false if any element is infinity, or NaN. ### Return Value true if matrix has only finite elements ### Example

#### Example Output ~~~~ [ 1.0000 0.0000 nan][ 0.0000 1.0000 0.0000][ 0.0000 0.0000 1.0000] matrix is finite: false matrix != matrix ~~~~

### See Also operator==