SkRegion Reference === Region is a compressed one bit mask. Region describes an aliased clipping area on integer boundaries. Region can also describe an array of integer rectangles. Canvas uses Region to reduce the current clip. Region may be drawn to Canvas; Paint determines if Region is filled or stroked, its Color, and so on. Region may be constructed from IRect array or Path. Diagonal lines and curves in Path become integer rectangle edges. Regions operators compute union, intersection, difference, and so on. Canvas allows only intersection and difference; successive clips can only reduce available Canvas area. --- 
class SkRegion {
public:
    SkRegion();
    SkRegion(const SkRegion& region);
    explicit SkRegion(const SkIRect& rect);
    ~SkRegion();
    SkRegion& operator=(const SkRegion& region);
    bool operator==(const SkRegion& other)_const;
    bool operator!=(const SkRegion& other)_const;
    bool set(const SkRegion& src);
    void swap(SkRegion& other);
    bool isEmpty() const;
    bool isRect() const;
    bool isComplex() const;
    const SkIRect& getBounds() const;
    int computeRegionComplexity() const;
    bool getBoundaryPath(SkPath* path) const;
    bool setEmpty();
    bool setRect(const SkIRect& rect);
    bool setRect(int32_t left, int32_t top, int32_t right, int32_t bottom);
    bool setRects(const SkIRect rects[], int count);
    bool setRegion(const SkRegion& region);
    bool setPath(const SkPath& path, const SkRegion& clip);
    bool intersects(const SkIRect& rect) const;
    bool intersects(const SkRegion& other) const;
    bool contains(int32_t x, int32_t y) const;
    bool contains(const SkIRect& other) const;
    bool contains(const SkRegion& other) const;
    bool quickContains(const SkIRect& r) const;
    bool quickContains(int32_t left, int32_t top, int32_t right,
                       int32_t bottom) const;
    bool quickReject(const SkIRect& rect) const;
    bool quickReject(const SkRegion& rgn) const;
    void translate(int dx, int dy);
    void translate(int dx, int dy, SkRegion* dst) const;

    enum Op {
        kDifference_Op,
        kIntersect_Op,
        kUnion_Op,
        kXOR_Op,
        kReverseDifference_Op,
        kReplace_Op,
        kLastOp = kReplace_Op,
    };

    static const int kOpCnt = kLastOp + 1;
    bool op(const SkIRect& rect, Op op);
    bool op(int left, int top, int right, int bottom, Op op);
    bool op(const SkRegion& rgn, Op op);
    bool op(const SkIRect& rect, const SkRegion& rgn, Op op);
    bool op(const SkRegion& rgn, const SkIRect& rect, Op op);
    bool op(const SkRegion& rgna, const SkRegion& rgnb, Op op);
    char* toString();

    class Iterator {
    public:
        Iterator();
        Iterator(const SkRegion& region);
        bool rewind();
        void reset(const SkRegion& region);
        bool done() const;
        void next();
        const SkIRect& rect() const;
        const SkRegion* rgn() const;
    };

    class Cliperator {
    public:
        Cliperator(const SkRegion& region, const SkIRect& clip);
        bool done();
        void next();
        const SkIRect& rect() const;
    };

    class Spanerator {
    public:
        Spanerator(const SkRegion& region, int y, int left, int right);
        bool next(int* left, int* right);
    };

    size_t writeToMemory(void* buffer) const;
    size_t readFromMemory(const void* buffer, size_t length);
};
SkRegion describes the set of pixels used to clip Canvas. SkRegion is compact, efficiently storing a single integer rectangle, or a run length encoded array of rectangles. SkRegion may reduce the current Canvas Clip, or may be drawn as one or more integer rectangles. SkRegion iterator returns the scan lines or rectangles contained by it, optionally intersecting a bounding rectangle. --- 
    class Iterator {
    public:
        Iterator();
        Iterator(const SkRegion& region);
        bool rewind();
        void reset(const SkRegion& region);
        bool done() const;
        void next();
        const SkIRect& rect();
        const SkRegion* rgn();
    };
Returns sequence of rectangles, sorted along y-axis, then x-axis, that make up Region. --- 
Iterator()
Initializes SkRegion::Iterator with an empty SkRegion. done() on SkRegion::Iterator returns true. Call reset() to initialized SkRegion::Iterator at a later time. ### Return Value empty SkRegion iterator ### Example
#### Example Output ~~~~ rect={1,2,3,4} ~~~~
### See Also reset SkRegion --- 
Iterator(const SkRegion& region)
Sets SkRegion::Iterator to return elements of SkIRect array in region. ### Parameters
region SkRegion to iterate
### Return Value SkRegion iterator ### Example
#### Example Output ~~~~ rect={1,2,3,4} ~~~~
### See Also reset SkRegion Cliperator Spanerator --- 
bool rewind()
SkPoint SkRegion::Iterator to start of SkRegion. Returns true if SkRegion was set; otherwise, returns false. ### Return Value true if SkRegion was set ### Example
#### Example Output ~~~~ #Volatile empty iter rewind success=false empty iter rect={0,0,0,0} empty region rewind success=true empty region rect={0,0,0,0} after set rect rect={1,2,3,4} after rewind rewind success=true after rewind rect={1,2,3,4} ~~~~
### See Also reset --- 
void reset(const SkRegion& region)
Resets iterator, using the new SkRegion. ### Parameters
region SkRegion to iterate
### Example
#### Example Output ~~~~ empty region: done=true after set rect: done=true after reset: done=false ~~~~
### See Also rewind --- 
bool done() const
Returns true if SkRegion::Iterator is pointing to final SkIRect in SkRegion. ### Return Value true if data parsing is complete ### Example
#### Example Output ~~~~ done=true done=false ~~~~
### See Also next rect --- 
void next()
Advances SkRegion::Iterator to next SkIRect in SkRegion if it is not done. ### Example
#### Example Output ~~~~ rect={1,2,3,4} rect={5,6,7,8} ~~~~
### See Also done rect --- 
const SkIRect& rect() const
Returns SkIRect element in SkRegion. Does not return predictable results if SkRegion is empty. ### Return Value part of SkRegion as SkIRect ### Example
#### Example Output ~~~~ #Volatile rect={0,0,0,0} rect={1,2,3,4} ~~~~
### See Also next done --- 
const SkRegion* rgn() const
Returns SkRegion if set; otherwise, returns nullptr. ### Return Value iterated SkRegion ### Example
### See Also Iterator reset --- 
    class SK_API Cliperator {
    public:
        Cliperator(const SkRegion& region, const SkIRect& clip);
        bool done();
        void next();
        const SkIRect& rect() const;
    };
Returns the sequence of rectangles, sorted along y-axis, then x-axis, that make up Region intersected with the specified clip rectangle. --- 
Cliperator(const SkRegion& region, const SkIRect& clip)
Sets SkRegion::Cliperator to return elements of SkIRect array in SkRegion within clip. ### Parameters
region SkRegion to iterate
clip bounds of iteration
### Return Value SkRegion iterator ### Example
#### Example Output ~~~~ rect={1,2,2,3} ~~~~
### See Also SkRegion Iterator Spanerator --- 
bool done()
Returns true if SkRegion::Cliperator is pointing to final SkIRect in SkRegion. ### Return Value true if data parsing is complete ### Example
#### Example Output ~~~~ empty region done=true after add rect done=false ~~~~
### See Also next rect --- 
void  next()
Advances iterator to next SkIRect in SkRegion contained by clip. ### Example
#### Example Output ~~~~ rect={1,3,3,4} rect={5,6,7,7} ~~~~
### See Also done --- 
const SkIRect& rect() const
Returns SkIRect element in SkRegion, intersected with clip passed to SkRegion::Cliperator constructor. Does not return predictable results if SkRegion is empty. ### Return Value part of SkRegion inside clip as SkIRect ### Example
#### Example Output ~~~~ #Volatile empty region rect={1094713344,1065353216,0,-1} after set rect rect={1,2,3,3} ~~~~
### See Also next done --- 
    class Spanerator {
    public:
        Spanerator(const SkRegion& region, int y, int left, int right);
        bool next(int* left, int* right);
    };
Returns the line segment ends within Region that intersect a horizontal line. --- 
Spanerator(const SkRegion& region, int y, int left, int right)
Sets SkRegion::Spanerator to return line segments in SkRegion on scan line. ### Parameters
region SkRegion to iterate
y horizontal line to intersect
left bounds of iteration
right bounds of iteration
### Return Value SkRegion iterator ### Example
### See Also SkRegion Iterator Cliperator --- 
bool next(int* left, int* right)
Advances iterator to next span intersecting SkRegion within line segment provided in constructor. Returns true if interval was found. ### Parameters
left pointer to span start; may be nullptr
right pointer to span end; may be nullptr
### Return Value true if interval was found ### Example
#### Example Output ~~~~ empty region: result=false after set rect: result=true left=2 right=3 ~~~~
### See Also done --- 
SkRegion()
Constructs an empty SkRegion. SkRegion is set to empty bounds at (0, 0) with zero width and height. ### Return Value empty SkRegion ### Example
#### Example Output ~~~~ region bounds: {0, 0, 0, 0} ~~~~
### See Also setEmpty --- 
SkRegion(const SkRegion& region)
Constructs a copy of an existing region. Copy constructor makes two regions identical by value. Internally, region and the returned result share pointer values. The underlying SkRect array is copied when modified. Creating a SkRegion copy is very efficient and never allocates memory. SkRegion are always copied by value from the interface; the underlying shared pointers are not exposed. ### Parameters
region SkRegion to copy by value
### Return Value copy of SkRegion ### Example
#### Example Output ~~~~ region bounds: {1,2,3,4} region2 bounds: {1,2,3,4} after region set empty: region bounds: {0,0,0,0} region2 bounds: {1,2,3,4} ~~~~
### See Also setRegion operator=(const SkRegion& region) --- 
explicit SkRegion(const SkIRect& rect)
Constructs a rectangular SkRegion matching the bounds of rect. ### Parameters
rect bounds of constructed SkRegion
### Return Value rectangular SkRegion ### Example
### See Also setRect[2] setRegion --- 
~SkRegion()
Releases ownership of any shared data and deletes data if SkRegion is sole owner. ### Example
delete calls Region destructor, but copy of original in region2 is unaffected.
#### Example Output ~~~~ region2 bounds: {1,2,3,4} ~~~~
### See Also SkRegion() SkRegion(const SkRegion& region) SkRegion(const SkIRect& rect) operator=(const SkRegion& region) --- 
SkRegion& operator=(const SkRegion& region)
Constructs a copy of an existing region. Makes two regions identical by value. Internally, region and the returned result share pointer values. The underlying SkRect array is copied when modified. Creating a SkRegion copy is very efficient and never allocates memory. SkRegion are always copied by value from the interface; the underlying shared pointers are not exposed. ### Parameters
region SkRegion to copy by value
### Return Value SkRegion to copy by value ### Example
#### Example Output ~~~~ region1 bounds: {1,2,3,4} region2 bounds: {1,2,3,4} ~~~~
### See Also set swap SkRegion(const SkRegion& region) --- 
bool operator==(const SkRegion& other) const
Compares SkRegion and other; returns true if they enclose exactly the same area. ### Parameters
other SkRegion to compare
### Return Value true if SkRegion pair are equivalent ### Example
#### Example Output ~~~~ empty one == two set rect one != two set empty one == two ~~~~
### See Also operator!=(const SkRegion& other) const operator=(const SkRegion& region) --- 
bool operator!=(const SkRegion& other) const
Compares SkRegion and other; returns true if they do not enclose the same area. ### Parameters
other SkRegion to compare
### Return Value true if SkRegion pair are not equivalent ### Example
#### Example Output ~~~~ empty one == two set rect one != two union rect one == two ~~~~
### See Also operator==(const SkRegion& other) const operator=(const SkRegion& region) --- 
bool set(const SkRegion& src)
Sets SkRegion to src, and returns true if src bounds is not empty. This makes SkRegion and src identical by value. Internally, SkRegion and src share pointer values. The underlying SkRect array is copied when modified. Creating a SkRegion copy is very efficient and never allocates memory. SkRegion are always copied by value from the interface; the underlying shared pointers are not exposed. ### Parameters
src SkRegion to copy
### Return Value copy of src ### Example
#### Example Output ~~~~ region1 bounds: {1,2,3,4} region2 bounds: {1,2,3,4} ~~~~
### See Also operator=(const SkRegion& region) swap SkRegion(const SkRegion& region) --- 
void swap(SkRegion& other)
Exchanges SkIRect array of SkRegion and other. swap() internally exchanges pointers, so it is lightweight and does not allocate memory. swap() usage has largely been replaced by operator=(const SkRegion& region). SkPath do not copy their content on assignment until they are written to, making assignment as efficient as swap(). ### Parameters
other operator=(const SkRegion& region) set
### Example
#### Example Output ~~~~ region1 bounds: {0,0,0,0} region2 bounds: {1,2,3,4} ~~~~
### See Also operator=(const SkRegion& region) set SkRegion(const SkRegion& region) --- 
bool isEmpty() const
Returns true if SkRegion is empty. Empty SkRegion has bounds width or height less than or equal to zero. SkRegion() constructs empty SkRegion; setEmpty() and setRect() with dimensionless data make SkRegion empty. ### Return Value true if bounds has no width or height ### Example
#### Example Output ~~~~ initial: region is empty set rect: region is not empty set empty: region is empty ~~~~
### See Also isRect isComplex operator==(const SkRegion& other) const --- 
bool isRect() const
Returns true if SkRegion is one SkIRect with positive dimensions. ### Return Value true if SkRegion contains one SkIRect ### Example
#### Example Output ~~~~ initial: region is not rect set rect: region is rect set empty: region is not rect ~~~~
### See Also isEmpty isComplex --- 
bool isComplex() const
Returns true if SkRegion is described by more than one rectangle. ### Return Value true if SkRegion contains more than one SkIRect ### Example
#### Example Output ~~~~ initial: region is not complex set rect: region is not complex op rect: region is complex ~~~~
### See Also isEmpty isRect --- 
const SkIRect& getBounds() const
Returns minimum and maximum axes values of SkIRect array. Returns (0, 0, 0, 0) if SkRegion is empty. ### Return Value combined bounds of all SkIRect elements ### Example
#### Example Output ~~~~ bounds: {1,2,4,5} ~~~~
### See Also isEmpty isRect --- 
int computeRegionComplexity() const
Returns a value that increases with the number of elements in SkRegion. Returns zero if SkRegion is empty. Returns one if SkRegion equals SkIRect; otherwise, returns value greater than one indicating that SkRegion is complex. Call to compare SkRegion for relative complexity. ### Return Value relative complexity ### Example
#### Example Output ~~~~ initial: region complexity 0 set rect: region complexity 1 op rect: region complexity 3 ~~~~
### See Also isRect isComplex --- 
bool getBoundaryPath(SkPath* path) const
Appends outline of SkRegion to path. Returns true if SkRegion is not empty; otherwise, returns false, and leaves path unmodified. ### Parameters
path SkPath to append to
### Return Value true if path changed ### Example
### See Also isEmpty isComplex --- 
bool setEmpty()
Constructs an empty SkRegion. SkRegion is set to empty bounds at (0, 0) with zero width and height. Always returns false. ### Return Value false ### Example
#### Example Output ~~~~ region bounds: {1,2,3,4} after region set empty: region bounds: {0,0,0,0} ~~~~
### See Also SkRegion() --- 
bool setRect(const SkIRect& rect)
Constructs a rectangular SkRegion matching the bounds of rect. If rect is empty, constructs empty and returns false. ### Parameters
rect bounds of constructed SkRegion
### Return Value true if rect is not empty ### Example
#### Example Output ~~~~ region is not empty region is empty setEmpty: false ~~~~
### See Also SkRegion(const SkIRect& rect) --- 
bool setRect(int32_t left, int32_t top, int32_t right, int32_t bottom)
Constructs SkRegion with bounds (left, top, right, bottom). Returns true if left is less than right and top is less than bottom; otherwise, constructs empty SkRegion and returns false. ### Parameters
left edge of bounds on x-axis
top edge of bounds on y-axis
right edge of bounds on x-axis
bottom edge of bounds on y-axis
### Return Value rectangular SkRegion ### Example
#### Example Output ~~~~ set to: 1,2,3,4: success:true {1,2,3,4} set to: 3,2,1,4: success:false {0,0,0,0} ~~~~
### See Also SkRegion(const SkIRect& rect) --- 
bool setRects(const SkIRect rects[], int count)
Constructs SkRegion as the union of SkIRect in rects array. If count is zero, constructs empty SkRegion. Returns false if constructed SkRegion is empty. May be faster than repeated calls to op(). ### Parameters
rects array of SkIRect
count array size
### Return Value true if constructed SkRegion is not empty ### Example
### See Also setRect[2] op[2][3][4][5][6] --- 
bool setRegion(const SkRegion& region)
Constructs a copy of an existing region. Makes two regions identical by value. Internally, region and the returned result share pointer values. The underlying SkRect array is copied when modified. Creating a SkRegion copy is very efficient and never allocates memory. SkRegion are always copied by value from the interface; the underlying shared pointers are not exposed. ### Parameters
region SkRegion to copy by value
### Return Value SkRegion to copy by value ### Example
#### Example Output ~~~~ region bounds: {1,2,3,4} region2 bounds: {1,2,3,4} after region set empty: region bounds: {1,2,3,4} region2 bounds: {0,0,0,0} ~~~~
### See Also SkRegion(const SkRegion& region) --- 
bool setPath(const SkPath& path, const SkRegion& clip)
Constructs SkRegion to match outline of path within clip. Returns false if constructed SkRegion is empty. Constructed SkRegion draws the same pixels as path through clip when anti-aliasing is disabled. ### Parameters
path SkPath providing outline
clip SkRegion containing path
### Return Value true if constructed SkRegion is not empty ### Example
### See Also setRects op[2][3][4][5][6] --- 
bool intersects(const SkIRect& rect) const
Returns true if SkRegion intersects rect. Returns false if either rect or SkRegion is empty, or do not intersect. ### Parameters
rect SkIRect to intersect
### Return Value true if rect and SkRegion have area in common ### Example
### See Also contains[2][3] SkRect::intersects[2] --- 
bool intersects(const SkRegion& other) const
Returns true if SkRegion intersects other. Returns false if either other or SkRegion is empty, or do not intersect. ### Parameters
other SkRegion to intersect
### Return Value true if other and SkRegion have area in common ### Example
### See Also contains[2][3] SkRect::intersects[2] --- 
bool contains(int32_t x, int32_t y) const
Returns true if SkIPoint (x, y) is inside SkRegion. Returns false if SkRegion is empty. ### Parameters
x test SkIPoint x-coordinate
y test SkIPoint y-coordinate
### Return Value true if (x, y) is inside SkRegion ### Example
### See Also intersects[2] SkRect::contains[2][3] --- 
bool contains(const SkIRect& other) const
Returns true if other is completely inside SkRegion. Returns false if SkRegion or other is empty. ### Parameters
other SkIRect to contain
### Return Value true if other is inside SkRegion ### Example
### See Also intersects[2] SkRect::contains[2][3] --- 
bool contains(const SkRegion& other) const
Returns true if other is completely inside SkRegion. Returns false if SkRegion or other is empty. ### Parameters
other SkRegion to contain
### Return Value true if other is inside SkRegion ### Example
### See Also intersects[2] SkRect::contains[2][3] --- 
bool quickContains(const SkIRect& r) const
Returns true if SkRegion is a single rectangle and contains r. May return false even though SkRegion contains r. ### Parameters
r SkIRect to contain
### Return Value true quickly if r points are equal or inside ### Example
#### Example Output ~~~~ quickContains 1: true quickContains 2: true quickContains 3: false ~~~~
### See Also contains[2][3] quickReject[2] intersects[2] --- 
bool quickContains(int32_t left, int32_t top, int32_t right, int32_t bottom) const
Returns true if SkRegion is a single rectangle and contains SkIRect (left, top, right, bottom). Returns false if SkRegion is empty or SkIRect (left, top, right, bottom) is empty. May return false even though SkRegion contains (left, top, right, bottom). ### Parameters
left edge of bounds on x-axis
top edge of bounds on y-axis
right edge of bounds on x-axis
bottom edge of bounds on y-axis
### Return Value true quickly if SkIRect are equal or inside ### Example
#### Example Output ~~~~ quickContains 1: true quickContains 2: true quickContains 3: false ~~~~
### See Also contains[2][3] quickReject[2] intersects[2] --- 
bool quickReject(const SkIRect& rect) const
Returns true if SkRegion does not intersect rect. Returns true if rect is empty or SkRegion is empty. May return false even though SkRegion does not intersect rect. ### Parameters
rect SkIRect to intersect
### Return Value true if rect does not intersect ### Example
#### Example Output ~~~~ quickReject 1: true quickReject 2: true quickReject 3: false ~~~~
### See Also quickContains[2] contains[2][3] intersects[2] --- 
bool quickReject(const SkRegion& rgn) const
Returns true if SkRegion does not intersect rgn. Returns true if rgn is empty or SkRegion is empty. May return false even though SkRegion does not intersect rgn. ### Parameters
rgn SkRegion to intersect
### Return Value true if rgn does not intersect ### Example
#### Example Output ~~~~ quickReject 1: true quickReject 2: true quickReject 3: false ~~~~
### See Also quickContains[2] contains[2][3] intersects[2] --- 
void translate(int dx, int dy)
Offsets SkRegion by ivector (dx, dy). Has no effect if SkRegion is empty. ### Parameters
dx x-axis offset
dy y-axis offset
### Example
### See Also SkCanvas::translate SkIRect::offset[2] SkPath::offset[2] --- 
void translate(int dx, int dy, SkRegion* dst) const
Offsets SkRegion by ivector (dx, dy), writing result to dst. SkRegion may be passed as dst parameter, translating SkRegion in place. Has no effect if dst is nullptr. If SkRegion is empty, sets dst to empty. ### Parameters
dx x-axis offset
dy y-axis offset
dst translated result
### Example
### See Also SkCanvas::translate SkIRect::offset[2] SkPath::offset[2] --- 
    enum Op {
        kDifference_Op,
        kIntersect_Op,
        kUnion_Op,
        kXOR_Op,
        kReverseDifference_Op,
        kReplace_Op,
        kLastOp = kReplace_Op,
    };
The logical operations that can be performed when combining two Regions. ### Constants
Const Value Description
SkRegion::kDifference_Op 0 Subtracts operand Region from target Region.
SkRegion::kIntersect_Op 1 Intersects operand Region and target Region.
SkRegion::kUnion_Op 2 Unions operand Region and target Region.
SkRegion::kXOR_Op 3 Replaces target Region with area exclusive to both Regions.
SkRegion::kReverseDifference_Op 4 Subtracts target Region from operand Region.
SkRegion::kReplace_Op 5 Replaces target Region with operand Region.
SkRegion::kLastOp 5 last operator
### Example
### See Also SkPathOp ### Constants
Const Value Description
SkRegion::kOpCnt 6 May be used to verify that Op is a legal value.
--- 
bool op(const SkIRect& rect, Op op)
Replaces SkRegion with the result of SkRegion op rect. Returns true if replaced SkRegion is not empty. ### Parameters
rect SkIRect operand
op operator, one of:
kDifference_Op, kIntersect_Op, kUnion_Op, kXOR_Op, kReverseDifference_Op, kReplace_Op ### Return Value false if result is empty ### Example
### See Also setRects Op --- 
bool op(int left, int top, int right, int bottom, Op op)
Replaces SkRegion with the result of SkRegion op SkIRect (left, top, right, bottom). Returns true if replaced SkRegion is not empty. ### Parameters
left edge of bounds on x-axis
top edge of bounds on y-axis
right edge of bounds on x-axis
bottom edge of bounds on y-axis
op operator, one of:
kDifference_Op, kIntersect_Op, kUnion_Op, kXOR_Op, kReverseDifference_Op, kReplace_Op ### Return Value false if result is empty ### Example
### See Also setRects Op --- 
bool op(const SkRegion& rgn, Op op)
Replaces SkRegion with the result of SkRegion op rgn. Returns true if replaced SkRegion is not empty. ### Parameters
rgn SkRegion operand
op operator, one of:
kDifference_Op, kIntersect_Op, kUnion_Op, kXOR_Op, kReverseDifference_Op, kReplace_Op ### Return Value false if result is empty ### Example
### See Also setRects Op --- 
bool op(const SkIRect& rect, const SkRegion& rgn, Op op)
Replaces SkRegion with the result of rect op rgn. Returns true if replaced SkRegion is not empty. ### Parameters
rect SkIRect operand
rgn SkRegion operand
op operator, one of:
kDifference_Op, kIntersect_Op, kUnion_Op, kXOR_Op, kReverseDifference_Op, kReplace_Op ### Return Value false if result is empty ### Example
### See Also setRects Op --- 
bool op(const SkRegion& rgn, const SkIRect& rect, Op op)
Replaces SkRegion with the result of rgn op rect. Returns true if replaced SkRegion is not empty. ### Parameters
rgn SkRegion operand
rect SkIRect operand
op operator, one of:
kDifference_Op, kIntersect_Op, kUnion_Op, kXOR_Op, kReverseDifference_Op, kReplace_Op ### Return Value false if result is empty ### Example
### See Also setRects Op --- 
bool op(const SkRegion& rgna, const SkRegion& rgnb, Op op)
Replaces SkRegion with the result of rgna op rgnb. Returns true if replaced SkRegion is not empty. ### Parameters
rgna SkRegion operand
rgnb SkRegion operand
op operator, one of:
kDifference_Op, kIntersect_Op, kUnion_Op, kXOR_Op, kReverseDifference_Op, kReplace_Op ### Return Value false if result is empty ### Example
### See Also setRects Op --- 
char* toString()
Private: Android framework only. ### Return Value string representation of Region --- 
size_t writeToMemory(void* buffer) const
Writes SkRegion to buffer, and returns number of bytes written. If buffer is nullptr, returns number number of bytes that would be written. ### Parameters
buffer storage for binary data
### Return Value size of SkRegion ### Example
### See Also readFromMemory --- 
size_t readFromMemory(const void* buffer, size_t length)
Constructs SkRegion from buffer of size length. Returns bytes read. Returned value will be multiple of four or zero if length was too small. ### Parameters
buffer storage for binary data
length size of buffer
### Return Value bytes read ### Example
### See Also writeToMemory