text: /*
   * Copyright 2013 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #ifndef SkImageGenerator_DEFINED
  #define SkImageGenerator_DEFINED
  
  #include "SkBitmap.h"
  #include "SkColor.h"
  #include "SkImageInfo.h"
  
  class GrContext;
  class GrTexture;
  class GrTextureParams;
  class SkBitmap;
  class SkData;
  class SkImageGenerator;
  class SkMatrix;
  class SkPaint;
  class SkPicture;
  
  /**
   *  Takes ownership of SkImageGenerator.  If this method fails for
   *  whatever reason, it will return false and immediatetely delete
   *  the generator.  If it succeeds, it will modify destination
   *  bitmap.
   *
   *  If generator is NULL, will safely return false.
   *
   *  If this fails or when the SkDiscardablePixelRef that is
   *  installed into destination is destroyed, it will
   *  delete the generator.  Therefore, generator should be
   *  allocated with new.
   *
   *  @param destination Upon success, this bitmap will be
   *  configured and have a pixelref installed.
   *
   *  @return true iff successful.
   */
  SK_API bool SkDEPRECATED_InstallDiscardablePixelRef(SkImageGenerator*, SkBitmap* destination);
  
  /**
   *  On success, installs a discardable pixelref into destination, based on encoded data.
   *  Regardless of success or failure, the caller must still balance their ownership of encoded.
   */
  SK_API bool SkDEPRECATED_InstallDiscardablePixelRef(SkData* encoded, SkBitmap* destination);
  
  /**
   *  An interface that allows a purgeable PixelRef (such as a
   *  SkDiscardablePixelRef) to decode and re-decode an image as needed.
   */
  class SK_API SkImageGenerator : public SkNoncopyable {
  public:
      /**
       *  The PixelRef which takes ownership of this SkImageGenerator
       *  will call the image generator's destructor.
       */
      virtual ~SkImageGenerator() { }
  
      uint32_t uniqueID() const { return fUniqueID; }
  
      /**
       *  Return a ref to the encoded (i.e. compressed) representation,
       *  of this data.
       *
       *  If non-NULL is returned, the caller is responsible for calling
       *  unref() on the data when it is finished.
       */
      SkData* refEncodedData() { return this->onRefEncodedData(); }
  
      /**
       *  Return the ImageInfo associated with this generator.
       */
      const SkImageInfo& getInfo() const { return fInfo; }
  
      /**
       *  Decode into the given pixels, a block of memory of size at
       *  least (info.fHeight - 1) * rowBytes + (info.fWidth *
       *  bytesPerPixel)
       *
       *  Repeated calls to this function should give the same results,
       *  allowing the PixelRef to be immutable.
       *
       *  @param info A description of the format (config, size)
       *         expected by the caller.  This can simply be identical
       *         to the info returned by getInfo().
       *
       *         This contract also allows the caller to specify
       *         different output-configs, which the implementation can
       *         decide to support or not.
       *
       *         A size that does not match getInfo() implies a request
       *         to scale. If the generator cannot perform this scale,
       *         it will return kInvalidScale.
       *
       *  If info is kIndex8_SkColorType, then the caller must provide storage for up to 256
       *  SkPMColor values in ctable. On success the generator must copy N colors into that storage,
       *  (where N is the logical number of table entries) and set ctableCount to N.
       *
       *  If info is not kIndex8_SkColorType, then the last two parameters may be NULL. If ctableCount
       *  is not null, it will be set to 0.
       *
       *  @return true on success.
       */
      bool getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
                     SkPMColor ctable[], int* ctableCount);
  
      /**
       *  Simplified version of getPixels() that asserts that info is NOT kIndex8_SkColorType and
       *  uses the default Options.
       */
      bool getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes);
  
      /**
       *  If planes or rowBytes is NULL or if any entry in planes is NULL or if any entry in rowBytes
       *  is 0, this imagegenerator should output the sizes and return true if it can efficiently
       *  return YUV planar data. If it cannot, it should return false. Note that either planes and
       *  rowBytes are both fully defined and non NULL/non 0 or they are both NULL or have NULL or 0
       *  entries only. Having only partial planes/rowBytes information is not supported.
       *
       *  If all planes and rowBytes entries are non NULL or non 0, then it should copy the
       *  associated YUV data into those planes of memory supplied by the caller. It should validate
       *  that the sizes match what it expected. If the sizes do not match, it should return false.
       */
      bool getYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3],
                         SkYUVColorSpace* colorSpace);
  
      /**
       *  If the generator can natively/efficiently return its pixels as a GPU image (backed by a
       *  texture) this will return that image. If not, this will return NULL.
       *
       *  Regarding the GrContext parameter:
       *
       *  The caller may pass NULL for the context. In that case the generator may assume that its
       *  internal context is current. If it has no internal context, then it should just return
       *  null.
       *
       *  If the caller passes a non-null context, then the generator should only succeed if:
       *  - it has no intrinsic context, and will use the caller's
       *  - its internal context is the same
       *  - it can somehow convert its texture into one that is valid for the provided context.
       *
       *  Regarding the GrTextureParams parameter:
       *
       *  If the context (the provided one or the generator's intrinsic one) determines that to
       *  support the specified usage, it must return a different sized texture it may,
       *  so the caller must inspect the texture's width/height and compare them to the generator's
       *  getInfo() width/height. For readback usage use GrTextureParams::ClampNoFilter()
       */
      GrTexture* generateTexture(GrContext*, const SkIRect* subset = nullptr);
  
      struct SupportedSizes {
          SkISize fSizes[2];
      };
  
      /**
       *  Some generators can efficiently scale their contents. If this is supported, the generator
       *  may only support certain scaled dimensions. Call this with the desired scale factor,
       *  and it will return true if scaling is supported, and in supportedSizes[] it will return
       *  the nearest supported dimensions.
       *
       *  If no native scaling is supported, or scale is invalid (e.g. scale <= 0 || scale > 1)
       *  this will return false, and the supportedsizes will be undefined.
       */
      bool computeScaledDimensions(SkScalar scale, SupportedSizes*);
  
      /**
       *  Scale the generator's pixels to fit into scaledSize.
       *  This routine also support retrieving only a subset of the pixels. That subset is specified
       *  by the following rectangle (in the scaled space):
       *
       *      subset = SkIRect::MakeXYWH(subsetOrigin.x(), subsetOrigin.y(),
       *                                 subsetPixels.width(), subsetPixels.height())
       *
       *  If subset is not contained inside the scaledSize, this returns false.
       *
       *      whole = SkIRect::MakeWH(scaledSize.width(), scaledSize.height())
       *      if (!whole.contains(subset)) {
       *          return false;
       *      }
       *
       *  If the requested colortype/alphatype in pixels is not supported,
       *  or the requested scaledSize is not supported, or the generator encounters an error,
       *  this returns false.
       */
      bool generateScaledPixels(const SkISize& scaledSize, const SkIPoint& subsetOrigin,
                                const SkPixmap& subsetPixels);
  
      bool generateScaledPixels(const SkPixmap& scaledPixels) {
          return this->generateScaledPixels(SkISize::Make(scaledPixels.width(),
                                                          scaledPixels.height()),
                                            SkIPoint::Make(0, 0), scaledPixels);
      }
  
      /**
       *  If the default image decoder system can interpret the specified (encoded) data, then
       *  this returns a new ImageGenerator for it. Otherwise this returns NULL. Either way
       *  the caller is still responsible for managing their ownership of the data.
       */
      static SkImageGenerator* NewFromEncoded(SkData*);
  
      /** Return a new image generator backed by the specified picture.  If the size is empty or
       *  the picture is NULL, this returns NULL.
       *  The optional matrix and paint arguments are passed to drawPicture() at rasterization
       *  time.
       */
      static SkImageGenerator* NewFromPicture(const SkISize&, const SkPicture*, const SkMatrix*,
                                              const SkPaint*);
  
      bool tryGenerateBitmap(SkBitmap* bm) {
          return this->tryGenerateBitmap(bm, nullptr, nullptr);
      }
      bool tryGenerateBitmap(SkBitmap* bm, const SkImageInfo& info, SkBitmap::Allocator* allocator) {
          return this->tryGenerateBitmap(bm, &info, allocator);
      }
      void generateBitmap(SkBitmap* bm) {
          if (!this->tryGenerateBitmap(bm, nullptr, nullptr)) {
              sk_throw();
          }
      }
      void generateBitmap(SkBitmap* bm, const SkImageInfo& info) {
          if (!this->tryGenerateBitmap(bm, &info, nullptr)) {
              sk_throw();
          }
      }
  
  protected:
      SkImageGenerator(const SkImageInfo& info);
  
      virtual SkData* onRefEncodedData();
  
      virtual bool onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
                               SkPMColor ctable[], int* ctableCount);
      virtual bool onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3]);
      virtual bool onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3],
                                   SkYUVColorSpace* colorSpace);
  
      virtual GrTexture* onGenerateTexture(GrContext*, const SkIRect*) {
          return nullptr;
      }
  
      virtual bool onComputeScaledDimensions(SkScalar, SupportedSizes*) {
          return false;
      }
      virtual bool onGenerateScaledPixels(const SkISize&, const SkIPoint&, const SkPixmap&) {
          return false;
      }
  
      bool tryGenerateBitmap(SkBitmap* bm, const SkImageInfo* optionalInfo, SkBitmap::Allocator*);
  
  private:
      const SkImageInfo fInfo;
      const uint32_t fUniqueID;
  
      // This is our default impl, which may be different on different platforms.
      // It is called from NewFromEncoded() after it has checked for any runtime factory.
      // The SkData will never be NULL, as that will have been checked by NewFromEncoded.
      static SkImageGenerator* NewFromEncodedImpl(SkData*);
  };
  
  #endif  // SkImageGenerator_DEFINED
  