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      1 /*
      2  * Copyright 2012 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef SkImage_DEFINED
      9 #define SkImage_DEFINED
     10 
     11 #include "SkImageInfo.h"
     12 #include "SkImageEncoder.h"
     13 #include "SkRefCnt.h"
     14 #include "SkScalar.h"
     15 
     16 class SkData;
     17 class SkCanvas;
     18 class SkPaint;
     19 class SkShader;
     20 class GrContext;
     21 class GrTexture;
     22 
     23 // need for TileMode
     24 #include "SkShader.h"
     25 
     26 /**
     27  *  SkImage is an abstraction for drawing a rectagle of pixels, though the
     28  *  particular type of image could be actually storing its data on the GPU, or
     29  *  as drawing commands (picture or PDF or otherwise), ready to be played back
     30  *  into another canvas.
     31  *
     32  *  The content of SkImage is always immutable, though the actual storage may
     33  *  change, if for example that image can be re-created via encoded data or
     34  *  other means.
     35  */
     36 class SK_API SkImage : public SkRefCnt {
     37 public:
     38     SK_DECLARE_INST_COUNT(SkImage)
     39 
     40     typedef SkImageInfo Info;
     41 
     42     static SkImage* NewRasterCopy(const Info&, const void* pixels, size_t rowBytes);
     43     static SkImage* NewRasterData(const Info&, SkData* pixels, size_t rowBytes);
     44     static SkImage* NewEncodedData(SkData*);
     45 
     46     /**
     47      * GrTexture is a more logical parameter for this factory, but its
     48      * interactions with scratch cache still has issues, so for now we take
     49      * SkBitmap instead. This will be changed in the future. skbug.com/1449
     50      */
     51     static SkImage* NewTexture(const SkBitmap&);
     52 
     53     int width() const { return fWidth; }
     54     int height() const { return fHeight; }
     55     uint32_t uniqueID() const { return fUniqueID; }
     56 
     57     /**
     58      * Return the GrTexture that stores the image pixels. Calling getTexture
     59      * does not affect the reference count of the GrTexture object.
     60      * Will return NULL if the image does not use a texture.
     61      */
     62     GrTexture* getTexture();
     63 
     64     SkShader*   newShaderClamp() const;
     65     SkShader*   newShader(SkShader::TileMode, SkShader::TileMode) const;
     66 
     67     void draw(SkCanvas*, SkScalar x, SkScalar y, const SkPaint*);
     68 
     69     /**
     70      *  Draw the image, cropped to the src rect, to the dst rect of a canvas.
     71      *  If src is larger than the bounds of the image, the rest of the image is
     72      *  filled with transparent black pixels.
     73      *
     74      *  See SkCanvas::drawBitmapRectToRect for similar behavior.
     75      */
     76     void draw(SkCanvas*, const SkRect* src, const SkRect& dst, const SkPaint*);
     77 
     78     /**
     79      *  If the image has direct access to its pixels (i.e. they are in local
     80      *  RAM) return the (const) address of those pixels, and if not null, return
     81      *  the ImageInfo and rowBytes. The returned address is only valid while
     82      *  the image object is in scope.
     83      *
     84      *  On failure, returns NULL and the info and rowBytes parameters are
     85      *  ignored.
     86      */
     87     const void* peekPixels(SkImageInfo* info, size_t* rowBytes) const;
     88 
     89     /**
     90      *  Encode the image's pixels and return the result as a new SkData, which
     91      *  the caller must manage (i.e. call unref() when they are done).
     92      *
     93      *  If the image type cannot be encoded, or the requested encoder type is
     94      *  not supported, this will return NULL.
     95      */
     96     SkData* encode(SkImageEncoder::Type t = SkImageEncoder::kPNG_Type,
     97                    int quality = 80) const;
     98 
     99 protected:
    100     SkImage(int width, int height) :
    101         fWidth(width),
    102         fHeight(height),
    103         fUniqueID(NextUniqueID()) {
    104 
    105         SkASSERT(width >= 0);
    106         SkASSERT(height >= 0);
    107     }
    108 
    109 private:
    110     const int       fWidth;
    111     const int       fHeight;
    112     const uint32_t  fUniqueID;
    113 
    114     static uint32_t NextUniqueID();
    115 
    116     typedef SkRefCnt INHERITED;
    117 
    118     /**
    119      *  Return a copy of the image's pixels, limiting them to the subset
    120      *  rectangle's intersection wit the image bounds. If subset is NULL, then
    121      *  the entire image will be considered.
    122      *
    123      *  If the bitmap's pixels have already been allocated, then readPixels()
    124      *  will succeed only if it can support converting the image's pixels into
    125      *  the bitmap's ColorType/AlphaType. Any pixels in the bitmap that do not
    126      *  intersect with the image's bounds and the subset (if not null) will be
    127      *  left untouched.
    128      *
    129      *  If the bitmap is initially empty/unallocated, then it will be allocated
    130      *  using the default allocator, and the ColorType/AlphaType will be chosen
    131      *  to most closely fit the image's configuration.
    132      *
    133      *  On failure, false will be returned, and bitmap will unmodified.
    134      */
    135     // On ice for now:
    136     // - should it respect the particular colortype/alphatype of the src
    137     // - should it have separate entrypoints for preallocated and not bitmaps?
    138     // - isn't it enough to allow the caller to draw() the image into a canvas?
    139     bool readPixels(SkBitmap* bitmap, const SkIRect* subset = NULL) const;
    140 };
    141 
    142 #endif
    143