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
An SkPicture records drawing commands made to a canvas to be played back at a later time. This base class handles serialization and a few other miscellany. ## 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 can be constructed or initialized by these functions, including C++ class constructors.
Topic Description
## Member_Function SkPicture member functions read and modify the structure properties.
Topic Description
    class AbortCallback {
    public:
        AbortCallback() {}
        virtual
Subclasses of this can be passed to playback. During the playback of the picture, this callback will periodically be invoked. If its abort returns true, then picture playback will be interrupted. The resulting drawing is undefined, as there is no guarantee how often the callback will be invoked. If the abort happens inside some level of nested calls to save(), restore will automatically be called to return the state to the same level it was before the playback call was made. ## 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 playback from drawing the entire picture. ### 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 a picture that was serialized into a stream. ### 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 a picture that was serialized into data. ### 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 a picture that was serialized into data.
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. Note that this has the effect of unfurling this picture into the destination canvas. Using the SkCanvas::drawPicture entry point gives the destination canvas the option of just taking a ref. ### 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. Ops recorded into this picture that attempt to draw outside the cull might not be drawn. ### 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 all pictures. ### 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. ### 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. ### 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. This placeholder does not draw anything itself. It has a distinct uniqueID (just like all Pictures) and will always be visible to SkSerialProcs. ### Parameters
cull placeholder dimensions
### Return Value placeholder with unique identifier ### Example
#### Example Output ~~~~ id:1 bounds:{10, 40, 80, 110} id:2 bounds:{10, 40, 80, 110} ~~~~
### See Also MakeFromStream MakeFromData[2] --- ## approximateOpCount 
virtual int approximateOpCount() const = 0
Returns the approximate number of operations in this picture. This number may be greater or less than the number of SkCanvas calls recorded: some calls may be recorded as more than one operation, or some 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 Picture. ### Return Value approximate size ### Example
### See Also approximateOpCount ---