SkPicture Reference === # Picture # Class SkPicture ## Constructor SkPicture can be constructed or initialized by these functions, including C++ class constructors.
Topic Description
MakeFromData constructs Picture from data
MakeFromStream constructs Picture from stream
MakePlaceholder constructs placeholder with unique identifier
Picture records drawing commands made to Canvas. The command stream may be played in whole or in part at a later time. Picture is an abstract class. Picture may be generated by Picture Recorder or Drawable, or from Picture previously saved to Data or Stream. Picture may contain any Canvas drawing command, as well as one or more Canvas Matrix or Canvas Clip. Picture has a cull Rect, which is used as a bounding box hint. To limit Picture bounds, use Canvas Clip when recording or drawing Picture. ## Overview
Topic Description
Class Declarations embedded class members
Constructors functions that construct SkPicture
Functions global and class member functions
## Class SkPicture uses C++ classes to declare the public data structures and interfaces.
Topic Description
AbortCallback utility to stop picture playback
## Member Function SkPicture member functions read and modify the structure properties.
Topic Description
MakeFromData constructs Picture from data
MakeFromStream constructs Picture from stream
MakePlaceholder constructs placeholder with unique identifier
approximateBytesUsed returns approximate size
approximateOpCount returns approximate operation count
cullRect returns bounds used to record Picture
playback replays drawing commands on canvas
serialize writes Picture to Data
uniqueID returns identifier for Picture
# Class SkPicture::AbortCallback ## Constructor SkPicture::AbortCallback can be constructed or initialized by these functions, including C++ class constructors.
Topic Description
AbortCallback() defines default constructor
defines default destructor
## Member_Function SkPicture::AbortCallback member functions read and modify the structure properties.
Topic Description
AbortCallback() defines default constructor
abort aborts playback by callback
    class AbortCallback {
    public:
        AbortCallback() {}
        virtual
AbortCallback is an abstract class. An implementation of AbortCallback may passed as a parameter to SkPicture::playback, to stop it before all drawing commands have been processed. If AbortCallback::abort returns true, SkPicture::playback is interrupted. ## AbortCallback
AbortCallback()
Has no effect. ### Return Value abstract class cannot be instantiated ### See Also playback --- ## ~AbortCallback
virtual
Has no effect. ### See Also playback --- ## abort
virtual bool abort() = 0
Stops Picture playback when some condition is met. A subclass of AbortCallback provides an override for abort that can stop SkPicture::playback. The part of Picture drawn when aborted is undefined. Picture instantiations are free to stop drawing at different points during playback. If the abort happens inside one or more calls to SkCanvas::save(), stack of Canvas Matrix and Canvas Clip values is restored to its state before SkPicture::playback was called. ### Return Value true to stop playback ### See Also playback --- ### Example
JustOneDraw allows the black rectangle to draw but stops playback before the white rectangle appears.
## MakeFromStream
static sk sp<SkPicture> MakeFromStream(SkStream* stream, const SkDeserialProcs* procs = nullptr)
Recreates Picture that was serialized into a stream. Returns constructed Picture if successful; otherwise, returns nullptr. Fails if data does not permit constructing valid Picture. procs.fPictureProc permits supplying a custom function to decode Picture. If procs.fPictureProc is nullptr, default decoding is used. procs.fPictureCtx may be used to provide user context to procs.fPictureProc; procs.fPictureProc is called with a pointer to data, data byte length, and user context. ### Parameters
stream container for serial data
procs custom serial data decoders; may be nullptr
### Return Value Picture constructed from stream data ### Example
### See Also MakeFromData[2] SkPictureRecorder --- ## MakeFromData
static sk sp<SkPicture> MakeFromData(const SkData* data, const SkDeserialProcs* procs = nullptr)
Recreates Picture that was serialized into data. Returns constructed Picture if successful; otherwise, returns nullptr. Fails if data does not permit constructing valid Picture. procs.fPictureProc permits supplying a custom function to decode Picture. If procs.fPictureProc is nullptr, default decoding is used. procs.fPictureCtx may be used to provide user context to procs.fPictureProc; procs.fPictureProc is called with a pointer to data, data byte length, and user context. ### Parameters
data container for serial data
procs custom serial data decoders; may be nullptr
### Return Value Picture constructed from data ### Example
### See Also MakeFromStream SkPictureRecorder ---
static sk sp<SkPicture> MakeFromData(const void* data, size_t size,
                                     const SkDeserialProcs* procs = nullptr)
### Parameters Recreates Picture that was serialized into data. Returns constructed Picture if successful; otherwise, returns nullptr. Fails if size is smaller than required data length, or if data does not permit constructing valid Picture. procs.fPictureProc permits supplying a custom function to decode Picture. If procs.fPictureProc is nullptr, default decoding is used. procs.fPictureCtx may be used to provide user context to procs.fPictureProc; procs.fPictureProc is called with a pointer to data, data byte length, and user context.
data pointer to serial data
size size of data
procs custom serial data decoders; may be nullptr
### Return Value Picture constructed from data ### Example
### See Also MakeFromStream SkPictureRecorder --- ## playback
virtual void playback(SkCanvas* canvas, AbortCallback* callback = nullptr) const = 0
Replays the drawing commands on the specified canvas. In the case that the commands are recorded, each command in the Picture is sent separately to canvas. To add a single command to draw Picture to recording canvas, call SkCanvas::drawPicture instead. ### Parameters
canvas receiver of drawing commands
callback allows interruption of playback
### Example
### See Also SkCanvas::drawPicture[2][3][4] --- ## cullRect
virtual SkRect cullRect() const = 0
Returns cull Rect for this picture, passed in when Picture was created. Returned Rect does not specify clipping Rect for Picture; cull is hint of Picture bounds. Picture is free to discard recorded drawing commands that fall outside cull. ### Return Value bounds passed when Picture was created ### Example
Picture recorded bounds are smaller than contents; contents outside recorded bounds may be drawn, and are drawn in this example.
### See Also SkCanvas::clipRect[2][3] --- ## uniqueID
uint32_t uniqueID() const
Returns a non-zero value unique among Pictures in Skia process. ### Return Value identifier for Picture ### Example
#### Example Output ~~~~ empty picture id = 1 placeholder id = 2 ~~~~
### See Also SkRefCnt --- ## serialize
sk sp<SkData> serialize(const SkSerialProcs* procs = nullptr) const
Returns storage containing Data describing Picture, using optional custom encoders. procs.fPictureProc permits supplying a custom function to encode Picture. If procs.fPictureProc is nullptr, default encoding is used. procs.fPictureCtx may be used to provide user context to procs.fPictureProc; procs.fPictureProc is called with a pointer to Picture and user context. ### Parameters
procs custom serial data encoders; may be nullptr
### Return Value storage containing serialized Picture ### Example
### See Also MakeFromData[2] SkData SkSerialProcs ---
void serialize(SkWStream* stream, const SkSerialProcs* procs = nullptr) const
Writes picture to stream, using optional custom encoders. procs.fPictureProc permits supplying a custom function to encode Picture. If procs.fPictureProc is nullptr, default encoding is used. procs.fPictureCtx may be used to provide user context to procs.fPictureProc; procs.fPictureProc is called with a pointer to Picture and user context. ### Parameters
stream writable serial data stream
procs custom serial data encoders; may be nullptr
### Example
### See Also MakeFromStream SkWStream SkSerialProcs --- ## MakePlaceholder
static sk sp<SkPicture> MakePlaceholder(SkRect cull)
Returns a placeholder SkPicture. Result does not draw, and contains only cull Rect, a hint of its bounds. Result is immutable; it cannot be changed later. Result identifier is unique. Returned placeholder can be intercepted during playback to insert other commands into Canvas draw stream. ### Parameters
cull placeholder dimensions
### Return Value placeholder with unique identifier ### Example
### See Also MakeFromStream MakeFromData[2] uniqueID --- ## approximateOpCount
virtual int approximateOpCount() const = 0
Returns the approximate number of operations in Picture. Returned value may be greater or less than the number of SkCanvas calls recorded: some calls may be recorded as more than one operation, other calls may be optimized away. ### Return Value approximate operation count ### Example
### See Also approximateBytesUsed --- ## approximateBytesUsed
virtual size_t approximateBytesUsed() const = 0
Returns the approximate byte size of Picture. Does not include large objects referenced by Picture. ### Return Value approximate size ### Example
### See Also approximateOpCount ---