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/*
* 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 "SkColor.h"
#include "SkImageInfo.h"
class SkBitmap;
class SkData;
class SkImageGenerator;
//#define SK_SUPPORT_LEGACY_OPTIONLESS_GET_PIXELS
/**
* 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 call
* SkDELETE() on the generator. Therefore, generator should be
* allocated with SkNEW() or SkNEW_ARGS().
*
* @param destination Upon success, this bitmap will be
* configured and have a pixelref installed.
*
* @return true iff successful.
*/
SK_API bool SkInstallDiscardablePixelRef(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 SkInstallDiscardablePixelRef(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() { }
/**
* 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; }
/**
* Used to describe the result of a call to getPixels().
*
* Result is the union of possible results from subclasses.
*/
enum Result {
/**
* General return value for success.
*/
kSuccess,
/**
* The input is incomplete. A partial image was generated.
*/
kIncompleteInput,
/**
* The generator cannot convert to match the request, ignoring
* dimensions.
*/
kInvalidConversion,
/**
* The generator cannot scale to requested size.
*/
kInvalidScale,
/**
* Parameters (besides info) are invalid. e.g. NULL pixels, rowBytes
* too small, etc.
*/
kInvalidParameters,
/**
* The input did not contain a valid image.
*/
kInvalidInput,
/**
* Fulfilling this request requires rewinding the input, which is not
* supported for this input.
*/
kCouldNotRewind,
/**
* This method is not implemented by this generator.
*/
kUnimplemented,
};
/**
* Whether or not the memory passed to getPixels is zero initialized.
*/
enum ZeroInitialized {
/**
* The memory passed to getPixels is zero initialized. The SkCodec
* may take advantage of this by skipping writing zeroes.
*/
kYes_ZeroInitialized,
/**
* The memory passed to getPixels has not been initialized to zero,
* so the SkCodec must write all zeroes to memory.
*
* This is the default. It will be used if no Options struct is used.
*/
kNo_ZeroInitialized,
};
/**
* Additional options to pass to getPixels.
*/
struct Options {
Options()
: fZeroInitialized(kNo_ZeroInitialized) {}
ZeroInitialized fZeroInitialized;
};
/**
* 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 Result kSuccess, or another value explaining the type of failure.
*/
Result getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, const Options*,
SkPMColor ctable[], int* ctableCount);
/**
* Simplified version of getPixels() that asserts that info is NOT kIndex8_SkColorType and
* uses the default Options.
*/
Result 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 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* NewFromData(SkData*);
protected:
SkImageGenerator(const SkImageInfo& info) : fInfo(info) {}
virtual SkData* onRefEncodedData();
#ifdef SK_SUPPORT_LEGACY_OPTIONLESS_GET_PIXELS
virtual Result onGetPixels(const SkImageInfo& info,
void* pixels, size_t rowBytes,
SkPMColor ctable[], int* ctableCount);
#endif
virtual Result onGetPixels(const SkImageInfo& info,
void* pixels, size_t rowBytes, const Options&,
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);
private:
const SkImageInfo fInfo;
};
#endif // SkImageGenerator_DEFINED
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