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51 KiB
SkPoint Reference
struct SkPoint { SkScalar fX; SkScalar fY; static constexpr SkPoint Make(SkScalar x, SkScalar y); SkScalar x() const; SkScalar y() const; bool isZero() const; void set(SkScalar x, SkScalar y); void iset(int32_t x, int32_t y); void iset(const SkIPoint& p); void setAbs(const SkPoint& pt); static void Offset(SkPoint points[], int count, const SkVector& offset); static void Offset(SkPoint points[], int count, SkScalar dx, SkScalar dy); void offset(SkScalar dx, SkScalar dy); SkScalar length() const; SkScalar distanceToOrigin() const; bool normalize(); bool setNormalize(SkScalar x, SkScalar y); bool setLength(SkScalar length); bool setLength(SkScalar x, SkScalar y, SkScalar length); void scale(SkScalar scale, SkPoint* dst) const; void scale(SkScalar value); void negate(); SkPoint operator-()_const; void operator+=(const SkVector& v); void operator-=(const SkVector& v); SkPoint operator*(SkScalar scale)_const; SkPoint& operator*=(SkScalar scale); bool isFinite() const; bool equals(SkScalar x, SkScalar y) const; friend bool operator==(const SkPoint& a, const SkPoint& b); friend bool operator!=(const SkPoint& a, const SkPoint& b); friend SkVector operator-(const SkPoint& a, const SkPoint& b); friend SkPoint operator+(const SkPoint& a, const SkVector& b); static SkScalar Length(SkScalar x, SkScalar y); static SkScalar Normalize(SkVector* vec); static SkScalar Distance(const SkPoint& a, const SkPoint& b); static SkScalar DotProduct(const SkVector& a, const SkVector& b); static SkScalar CrossProduct(const SkVector& a, const SkVector& b); SkScalar cross(const SkVector& vec) const; SkScalar dot(const SkVector& vec) const; };
SkPoint holds two 32-bit floating point coordinates.
Type | Member | Description |
---|---|---|
SkScalar | fX |
x-axis value used by both Point and Vector. May contain any value, including infinities and NaN. |
SkScalar | fY |
y-axis value used by both Point and Vector. May contain any value, including infinities and NaN. |
static constexpr SkPoint Make(SkScalar x, SkScalar y)
Sets fX to x, fY to y. Used both to set SkPoint and vector.
Parameters
x |
SkScalar x-axis value of constructed SkPoint or vector |
y |
SkScalar y-axis value of constructed SkPoint or vector |
Return Value
Example
Example Output
all equal
See Also
set() iset[2]() SkIPoint::Make
SkScalar x() const
Returns x-axis value of SkPoint or vector.
Return Value
Example
Example Output
pt1.fX == pt1.x()
See Also
y() SkIPoint::x()
SkScalar y() const
Returns y-axis value of SkPoint or vector.
Return Value
Example
Example Output
pt1.fY == pt1.y()
See Also
x() SkIPoint::y()
bool isZero() const
Returns true if fX and fY are both zero.
Return Value
true if fX is zero and fY is zero
Example
Example Output
pt.fX=+0 pt.fY=-0
pt.isZero() == true
See Also
void set(SkScalar x, SkScalar y)
Parameters
x |
new value for fX |
y |
new value for fY |
Example
Example Output
pt1 == pt2
See Also
void iset(int32_t x, int32_t y)
Sets fX to x and fY to y, promoting integers to SkScalar values.
Assigning a large integer value directly to fX or fY may cause a compiler error, triggered by narrowing conversion of int to SkScalar. This safely casts x and y to avoid the error.
Parameters
x |
new value for fX |
y |
new value for fY |
Example
See Also
void iset(const SkIPoint& p)
Sets fX to p.fX and fY to p.fY, promoting integers to SkScalar values.
Assigning an SkIPoint containing a large integer value directly to fX or fY may cause a compiler error, triggered by narrowing conversion of int to SkScalar. This safely casts p.fX and p.fY to avoid the error.
Parameters
p |
SkIPoint members promoted to SkScalar |
Example
Example Output
iPt: -2147483647, 2147483647
fPt: -2.14748e+09, 2.14748e+09
See Also
void setAbs(const SkPoint& pt)
Sets fX to absolute value of pt.fX; and fY to absolute value of pt.fY.
Parameters
pt |
members providing magnitude for fX and fY |
Example
Example Output
pt: 0, -0 abs: 0, 0
pt: -1, -2 abs: 1, 2
pt: inf, -inf abs: inf, inf
pt: nan, -nan abs: nan, nan
See Also
static void Offset(SkPoint points[], int count, const SkVector& offset)
Adds offset to each SkPoint in points array with count entries.
Parameters
points |
SkPoint array |
count |
entries in array |
offset |
vector added to points |
Example
See Also
offset operator+=(const SkVector& v)
static void Offset(SkPoint points[], int count, SkScalar dx, SkScalar dy)
Adds offset (dx, dy) to each SkPoint in points array of length count.
Parameters
points |
SkPoint array |
count |
entries in array |
dx |
added to fX in points |
dy |
added to fY in points |
Example
See Also
offset operator+=(const SkVector& v)
void offset(SkScalar dx, SkScalar dy)
Adds offset (dx, dy) to SkPoint.
Parameters
dx |
added to fX |
dy |
added to fY |
Example
See Also
Offset[2] operator+=(const SkVector& v)
SkScalar length() const
Returns the Euclidean distance from origin, computed as:
.
Return Value
straight-line distance to origin
Example
See Also
distanceToOrigin Length setLength[2] Distance
SkScalar distanceToOrigin() const
Returns the Euclidean distance from origin, computed as:
.
Return Value
straight-line distance to origin
Example
See Also
length Length setLength[2] Distance
bool normalize()
Scales (fX, fY) so that length() returns one, while preserving ratio of fX to fY, if possible. If prior length is nearly zero, sets vector to (0, 0) and returns false; otherwise returns true.
Return Value
true if former length is not zero or nearly zero
Example
See Also
Normalize setLength[2] length Length
bool setNormalize(SkScalar x, SkScalar y)
Sets vector to (x, y) scaled so length() returns one, and so that (fX, fY) is proportional to (x, y). If (x, y) length is nearly zero, sets vector to (0, 0) and returns false; otherwise returns true.
Parameters
x |
proportional value for fX |
y |
proportional value for fY |
Return Value
true if (x, y) length is not zero or nearly zero
Example
See Also
bool setLength(SkScalar length)
Scales vector so that distanceToOrigin() returns length, if possible. If former length is nearly zero, sets vector to (0, 0) and return false; otherwise returns true.
Parameters
length |
straight-line distance to origin |
Return Value
true if former length is not zero or nearly zero
Example
See Also
length Length setNormalize setAbs
bool setLength(SkScalar x, SkScalar y, SkScalar length)
Sets vector to (x, y) scaled to length, if possible. If former length is nearly zero, sets vector to (0, 0) and return false; otherwise returns true.
Parameters
x |
proportional value for fX |
y |
proportional value for fY |
length |
straight-line distance to origin |
Return Value
true if (x, y) length is not zero or nearly zero
Example
See Also
length Length setNormalize setAbs
void scale(SkScalar scale, SkPoint* dst) const
Sets dst to SkPoint times scale. dst may be SkPoint to modify SkPoint in place.
Parameters
scale |
factor to multiply SkPoint by |
dst |
storage for scaled SkPoint |
Example
See Also
operator*(SkScalar scale) const operator*=(SkScalar scale) setLength[2]
void scale(SkScalar value)
Scales SkPoint in place by scale.
Parameters
value |
factor to multiply SkPoint by |
Example
See Also
operator*(SkScalar scale) const operator*=(SkScalar scale) setLength[2]
void negate()
Changes the sign of fX and fY.
Example
Example Output
pt: 0, -0 negate: -0, 0
pt: -1, -2 negate: 1, 2
pt: inf, -inf negate: -inf, inf
pt: nan, -nan negate: -nan, nan
See Also
SkPoint operator-() const
Returns SkPoint changing the signs of fX and fY.
Return Value
Example
Example Output
pt: 0, -0 negate: -0, 0
pt: -1, -2 negate: 1, 2
pt: inf, -inf negate: -inf, inf
pt: nan, -nan negate: -nan, nan
See Also
negate operator-(const SkPoint& a, const SkPoint& b) operator-=(const SkVector& v) SkIPoint::operator-() const
void operator+=(const SkVector& v)
Adds Vector v to Point. Sets Point to: (fX + v.fX, fY + v.fY)
.
Parameters
v |
Vector to add |
Example
See Also
offset() operator+(const SkPoint& a, const SkVector& b) SkIPoint::operator+=(const SkIVector& v)
void operator-=(const SkVector& v)
Subtracts Vector v from Point. Sets Point to: (fX - v.fX, fY - v.fY)
.
Parameters
v |
Vector to subtract |
Example
See Also
offset() operator-(const SkPoint& a, const SkPoint& b) SkIPoint::operator-=(const SkIVector& v)
SkPoint operator*(SkScalar scale) const
Returns SkPoint multiplied by scale.
Parameters
scale |
scalar to multiply by |
Return Value
SkPoint as (fX * scale, fY * scale)
Example
See Also
operator*=(SkScalar scale) scale[2]() setLength[2] setNormalize
SkPoint& operator*=(SkScalar scale)
Multiplies Point by scale. Sets Point to: (fX * scale, fY * scale)
.
Parameters
scale |
Scalar to multiply by |
Return Value
reference to Point
Example
See Also
operator*(SkScalar scale) const scale[2]() setLength[2] setNormalize
bool isFinite() const
Returns true if both fX and fY are measurable values.
Return Value
true for values other than infinities and NaN
Example
Example Output
pt: 0, -0 finite: true
pt: -1, -2 finite: true
pt: inf, 1 finite: false
pt: nan, -1 finite: false
See Also
SkRect::isFinite SkPath::isFinite
bool equals(SkScalar x, SkScalar y) const
Returns true if SkPoint is equivalent to SkPoint constructed from (x, y).
Parameters
x |
value compared with fX |
y |
value compared with fY |
Return Value
Example
Example Output
pt: 0, -0 == pt
pt: -1, -2 == pt
pt: inf, 1 == pt
pt: nan, -1 != pt
See Also
operator==(const SkPoint& a, const SkPoint& b)
bool operator==(const SkPoint& a, const SkPoint& b)
Returns true if a is equivalent to b.
Parameters
a |
SkPoint to compare |
b |
SkPoint to compare |
Return Value
true if a.fX == b.fX and a.fY == b.fY
Example
Example Output
pt: 0, -0 == pt
pt: -1, -2 == pt
pt: inf, 1 == pt
pt: nan, -1 != pt
See Also
equals() operator!=(const SkPoint& a, const SkPoint& b)
bool operator!=(const SkPoint& a, const SkPoint& b)
Returns true if a is not equivalent to b.
Parameters
a |
SkPoint to compare |
b |
SkPoint to compare |
Return Value
true if a.fX != b.fX or a.fY != b.fY
Example
Example Output
pt: 0, -0 == pt
pt: -1, -2 == pt
pt: inf, 1 == pt
pt: nan, -1 != pt
See Also
operator==(const SkPoint& a, const SkPoint& b) equals()
SkVector operator-(const SkPoint& a, const SkPoint& b)
Returns Vector from b to a, computed as (a.fX - b.fX, a.fY - b.fY)
.
Can also be used to subtract Vector from Point, returning Point. Can also be used to subtract Vector from Vector, returning Vector.
Parameters
a |
Point to subtract from |
b |
Point to subtract |
Return Value
Example
See Also
operator-=(const SkVector& v) offset()
SkPoint operator+(const SkPoint& a, const SkVector& b)
Returns Point resulting from Point a offset by Vector b, computed as:
(a.fX + b.fX, a.fY + b.fY)
.
Can also be used to offset Point b by Vector a, returning Point. Can also be used to add Vector to Vector, returning Vector.
Parameters
a |
Point or Vector to add to |
b |
Point or Vector to add |
Return Value
Example
See Also
operator+=(const SkVector& v) offset()
static SkScalar Length(SkScalar x, SkScalar y)
Returns the Euclidean distance from origin, computed as:
.
Parameters
x |
component of length |
y |
component of length |
Return Value
straight-line distance to origin
Example
See Also
length() Distance setLength[2]
static SkScalar Normalize(SkVector* vec)
Scales (vec->fX, vec->fY) so that length() returns one, while preserving ratio of vec->fX to vec->fY, if possible. If original length is nearly zero, sets vec to (0, 0) and returns zero; otherwise, returns length of vec before vec is scaled.
Returned prior length may be SK_ScalarInfinity if it can not be represented by SkScalar.
Note that normalize() is faster if prior length is not required.
Parameters
vec |
normalized to unit length |
Return Value
original vec length
Example
See Also
normalize() setLength[2] Length
static SkScalar Distance(const SkPoint& a, const SkPoint& b)
Returns the Euclidean distance between a and b.
Parameters
a |
line end point |
b |
line end point |
Return Value
straight-line distance from a to b
Example
See Also
static SkScalar DotProduct(const SkVector& a, const SkVector& b)
Returns the dot product of vector a and vector b.
Parameters
a |
left side of dot product |
b |
right side of dot product |
Return Value
product of input magnitudes and cosine of the angle between them
Example
See Also
static SkScalar CrossProduct(const SkVector& a, const SkVector& b)
Returns the cross product of vector a and vector b.
a and b form three-dimensional vectors with z-axis value equal to zero. The cross product is a three-dimensional vector with x-axis and y-axis values equal to zero. The cross product z-axis component is returned.
Parameters
a |
left side of cross product |
b |
right side of cross product |
Return Value
area spanned by vectors signed by angle direction
Example
See Also
SkScalar cross(const SkVector& vec) const
Returns the cross product of vector and vec.
Vector and vec form three-dimensional vectors with z-axis value equal to zero. The cross product is a three-dimensional vector with x-axis and y-axis values equal to zero. The cross product z-axis component is returned.
Parameters
vec |
right side of cross product |
Return Value
area spanned by vectors signed by angle direction
Example
See Also
SkScalar dot(const SkVector& vec) const
Returns the dot product of vector and vector vec.
Parameters
vec |
right side of dot product |
Return Value
product of input magnitudes and cosine of the angle between them
Example
See Also
typedef SkPoint SkVector;
SkVector provides an alternative name for SkPoint. SkVector and SkPoint can be used interchangeably for all purposes.