core/SkPicture.h

/*
 * Copyright 2007 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#ifndef SkPicture_DEFINED
#define SkPicture_DEFINED

#include "SkBitmap.h"
#include "SkImageDecoder.h"
#include "SkRefCnt.h"

class SkBBoxHierarchy;
class SkCanvas;
class SkDrawPictureCallback;
class SkData;
class SkPicturePlayback;
class SkPictureRecord;
class SkStream;
class SkWStream;

struct SkPictInfo;

/** \class SkPicture

    The SkPicture class records the drawing commands made to a canvas, to
    be played back at a later time.
*/
class SK_API SkPicture : public SkRefCnt {
public:
    SK_DECLARE_INST_COUNT(SkPicture)

    /** The constructor prepares the picture to record.
        @param width the width of the virtual device the picture records.
        @param height the height of the virtual device the picture records.
    */
    SkPicture();
    /** Make a copy of the contents of src. If src records more drawing after
        this call, those elements will not appear in this picture.
    */
    SkPicture(const SkPicture& src);

    /**
     *  Function signature defining a function that sets up an SkBitmap from encoded data. On
     *  success, the SkBitmap should have its Config, width, height, rowBytes and pixelref set.
     *  If the installed pixelref has decoded the data into pixels, then the src buffer need not be
     *  copied. If the pixelref defers the actual decode until its lockPixels() is called, then it
     *  must make a copy of the src buffer.
     *  @param src Encoded data.
     *  @param length Size of the encoded data, in bytes.
     *  @param dst SkBitmap to install the pixel ref on.
     *  @param bool Whether or not a pixel ref was successfully installed.
     */
    typedef bool (*InstallPixelRefProc)(const void* src, size_t length, SkBitmap* dst);

    /**
     *  Recreate a picture that was serialized into a stream.
     *  @param SkStream Serialized picture data.
     *  @param proc Function pointer for installing pixelrefs on SkBitmaps representing the
     *              encoded bitmap data from the stream.
     *  @return A new SkPicture representing the serialized data, or NULL if the stream is
     *          invalid.
     */
    static SkPicture* CreateFromStream(SkStream*,
                                       InstallPixelRefProc proc = &SkImageDecoder::DecodeMemory);

    virtual ~SkPicture();

    /**
     *  Swap the contents of the two pictures. Guaranteed to succeed.
     */
    void swap(SkPicture& other);

    /**
     *  Creates a thread-safe clone of the picture that is ready for playback.
     */
    SkPicture* clone() const;

    /**
     * Creates multiple thread-safe clones of this picture that are ready for
     * playback. The resulting clones are stored in the provided array of
     * SkPictures.
     */
    void clone(SkPicture* pictures, int count) const;

    enum RecordingFlags {
        /*  This flag specifies that when clipPath() is called, the path will
            be faithfully recorded, but the recording canvas' current clip will
            only see the path's bounds. This speeds up the recording process
            without compromising the fidelity of the playback. The only side-
            effect for recording is that calling getTotalClip() or related
            clip-query calls will reflect the path's bounds, not the actual
            path.
         */
        kUsePathBoundsForClip_RecordingFlag = 0x01,
        /*  This flag causes the picture to compute bounding boxes and build
            up a spatial hierarchy (currently an R-Tree), plus a tree of Canvas'
            usually stack-based clip/etc state. This requires an increase in
            recording time (often ~2x; likely more for very complex pictures),
            but allows us to perform much faster culling at playback time, and
            completely avoid some unnecessary clips and other operations. This
            is ideal for tiled rendering, or any other situation where you're
            drawing a fraction of a large scene into a smaller viewport.

            In most cases the record cost is offset by the playback improvement
            after a frame or two of tiled rendering (and complex pictures that
            induce the worst record times will generally get the largest
            speedups at playback time).

            Note: Currently this is not serializable, the bounding data will be
            discarded if you serialize into a stream and then deserialize.
        */
        kOptimizeForClippedPlayback_RecordingFlag = 0x02,
        /*
            This flag disables all the picture recording optimizations (i.e.,
            those in SkPictureRecord). It is mainly intended for testing the
            existing optimizations (i.e., to actually have the pattern
            appear in an .skp we have to disable the optimization). This
            option doesn't affect the optimizations controlled by
            'kOptimizeForClippedPlayback_RecordingFlag'.
         */
        kDisableRecordOptimizations_RecordingFlag = 0x04
    };

    /** Returns the canvas that records the drawing commands.
        @param width the base width for the picture, as if the recording
                     canvas' bitmap had this width.
        @param height the base width for the picture, as if the recording
                     canvas' bitmap had this height.
        @param recordFlags optional flags that control recording.
        @return the picture canvas.
    */
    SkCanvas* beginRecording(int width, int height, uint32_t recordFlags = 0);

    /** Returns the recording canvas if one is active, or NULL if recording is
        not active. This does not alter the refcnt on the canvas (if present).
    */
    SkCanvas* getRecordingCanvas() const;
    /** Signal that the caller is done recording. This invalidates the canvas
        returned by beginRecording/getRecordingCanvas, and prepares the picture
        for drawing. Note: this happens implicitly the first time the picture
        is drawn.
    */
    void endRecording();

    /** Replays the drawing commands on the specified canvas. This internally
        calls endRecording() if that has not already been called.
        @param canvas the canvas receiving the drawing commands.
    */
    void draw(SkCanvas* canvas, SkDrawPictureCallback* = NULL);

    /** Return the width of the picture's recording canvas. This
        value reflects what was passed to setSize(), and does not necessarily
        reflect the bounds of what has been recorded into the picture.
        @return the width of the picture's recording canvas
    */
    int width() const { return fWidth; }

    /** Return the height of the picture's recording canvas. This
        value reflects what was passed to setSize(), and does not necessarily
        reflect the bounds of what has been recorded into the picture.
        @return the height of the picture's recording canvas
    */
    int height() const { return fHeight; }

    /**
     *  Function to encode an SkBitmap to an SkData. A function with this
     *  signature can be passed to serialize() and SkOrderedWriteBuffer.
     *  Returning NULL will tell the SkOrderedWriteBuffer to use
     *  SkBitmap::flatten() to store the bitmap.
     *  @param pixelRefOffset Output parameter, telling the deserializer what
     *      offset in the bm's pixelRef corresponds to the encoded data.
     *  @return SkData If non-NULL, holds encoded data representing the passed
     *      in bitmap. The caller is responsible for calling unref().
     */
    typedef SkData* (*EncodeBitmap)(size_t* pixelRefOffset, const SkBitmap& bm);

    /**
     *  Serialize to a stream. If non NULL, encoder will be used to encode
     *  any bitmaps in the picture.
     *  encoder will never be called with a NULL pixelRefOffset.
     */
    void serialize(SkWStream*, EncodeBitmap encoder = NULL) const;

#ifdef SK_BUILD_FOR_ANDROID
    /** Signals that the caller is prematurely done replaying the drawing
        commands. This can be called from a canvas virtual while the picture
        is drawing. Has no effect if the picture is not drawing.
        @deprecated preserving for legacy purposes
    */
    void abortPlayback();
#endif

protected:
    // V2 : adds SkPixelRef's generation ID.
    // V3 : PictInfo tag at beginning, and EOF tag at the end
    // V4 : move SkPictInfo to be the header
    // V5 : don't read/write FunctionPtr on cross-process (we can detect that)
    // V6 : added serialization of SkPath's bounds (and packed its flags tighter)
    // V7 : changed drawBitmapRect(IRect) to drawBitmapRectToRect(Rect)
    // V8 : Add an option for encoding bitmaps
    // V9 : Allow the reader and writer of an SKP disagree on whether to support
    //      SK_SUPPORT_HINTING_SCALE_FACTOR
    // V10: add drawRRect, drawOval, clipRRect
    // V11: modify how readBitmap and writeBitmap store their info.
    // V12: add conics to SkPath, use new SkPathRef flattening
    // V13: add flag to drawBitmapRectToRect
    //      parameterize blurs by sigma rather than radius
    // V14: Add flags word to PathRef serialization
#ifndef DELETE_THIS_CODE_WHEN_SKPS_ARE_REBUILT_AT_V13_AND_ALL_OTHER_INSTANCES_TOO
    static const uint32_t PRIOR_PRIOR_PICTURE_VERSION = 12;  // TODO: remove when .skps regenerated
#endif
#ifndef DELETE_THIS_CODE_WHEN_SKPS_ARE_REBUILT_AT_V14_AND_ALL_OTHER_INSTANCES_TOO
    static const uint32_t PRIOR_PICTURE_VERSION2 = 13;  // TODO: remove when .skps regenerated
#endif
    static const uint32_t PICTURE_VERSION = 14;

    // fPlayback, fRecord, fWidth & fHeight are protected to allow derived classes to
    // install their own SkPicturePlayback-derived players,SkPictureRecord-derived
    // recorders and set the picture size
    SkPicturePlayback* fPlayback;
    SkPictureRecord* fRecord;
    int fWidth, fHeight;

    // Create a new SkPicture from an existing SkPicturePlayback. Ref count of
    // playback is unchanged.
    SkPicture(SkPicturePlayback*, int width, int height);

    // For testing. Derived classes may instantiate an alternate
    // SkBBoxHierarchy implementation
    virtual SkBBoxHierarchy* createBBoxHierarchy() const;

    // Return true if the SkStream represents a serialized picture, and fills out
    // SkPictInfo. After this function returns, the SkStream is not rewound; it
    // will be ready to be parsed to create an SkPicturePlayback.
    // If false is returned, SkPictInfo is unmodified.
    static bool StreamIsSKP(SkStream*, SkPictInfo*);
private:
    friend class SkFlatPicture;
    friend class SkPicturePlayback;

    typedef SkRefCnt INHERITED;
};

class SkAutoPictureRecord : SkNoncopyable {
public:
    SkAutoPictureRecord(SkPicture* pict, int width, int height,
                        uint32_t recordingFlags = 0) {
        fPicture = pict;
        fCanvas = pict->beginRecording(width, height, recordingFlags);
    }
    ~SkAutoPictureRecord() {
        fPicture->endRecording();
    }

    /** Return the canvas to draw into for recording into the picture.
    */
    SkCanvas* getRecordingCanvas() const { return fCanvas; }

private:
    SkPicture*  fPicture;
    SkCanvas*   fCanvas;
};

/**
 *  Subclasses of this can be passed to canvas.drawPicture. During the drawing
 *  of the picture, this callback will periodically be invoked. If its
 *  abortDrawing() 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 drawPicture call was made.
 */
class SK_API SkDrawPictureCallback {
public:
    SkDrawPictureCallback() {}
    virtual ~SkDrawPictureCallback() {}

    virtual bool abortDrawing() = 0;
};

#endif