skia2/include/core/SkImageGenerator.h
halcanary@google.com 3d50ea1b87 Add Options to SkDecodingImageGenerator, simplify API.
Motivation: We want to remove redundant classes from Skia.  To
that end we want to remove SkImageRef and its subclasses and
replace their uses with SkDiscardablePixelRef +
SkDecodingImageGenerator.  Since Android uses SkImageRef, we need
to make sure that SkDecodingImageGenerator allows all of the
settings that Android exposes in BitmapFactory.Options.

To that end, we have created an Options struct for the
SkDecodingImageGenerator which lets the client of the generator set
sample size, dithering, and bitmap config.

We have made the SkDecodingImageGenerator constructor private
and replaced the SkDecodingImageGenerator::Install functions
with a SkDecodingImageGenerator::Create functions (one for
SkData and one for SkStream) which now take a
SkDecodingImageGenerator::Options struct.

Also added a ImageDecoderOptions test which loops through a list
of sets of options and tries them on a set of 5 small encoded
images.

Also updated several users of SkDecodingImageGenerator::Install to
follow new call signature - gm/factory.cpp, LazyDecodeBitmap.cpp,
and PictureTest.cpp, CachedDecodingPixelRefTest.cpp.

We also added a new ImprovedBitmapFactory Test which simulates the
exact function that Android will need to modify to use this,
installPixelRef() in BitmapFactory.

R=reed@google.com, scroggo@google.com

Committed: https://code.google.com/p/skia/source/detail?r=12744

Review URL: https://codereview.chromium.org/93703004

git-svn-id: http://skia.googlecode.com/svn/trunk@12855 2bbb7eff-a529-9590-31e7-b0007b416f81
2014-01-02 13:15:13 +00:00

102 lines
3.2 KiB
C++

/*
* 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 "SkDiscardableMemory.h"
#include "SkImageInfo.h"
class SkBitmap;
class SkData;
class SkImageGenerator;
/**
* 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.
*
* @param factory If not NULL, this object will be used as a
* source of discardable memory when decoding. If NULL, then
* SkDiscardableMemory::Create() will be called.
*
* @return true iff successful.
*/
SK_API bool SkInstallDiscardablePixelRef(SkImageGenerator* generator,
SkBitmap* destination,
SkDiscardableMemory::Factory* factory = NULL);
/**
* 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:
/**
* 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.
*/
virtual SkData* refEncodedData() { return NULL; }
/**
* Return some information about the image, allowing the owner of
* this object to allocate pixels.
*
* Repeated calls to this function should give the same results,
* allowing the PixelRef to be immutable.
*
* @return false if anything goes wrong.
*/
virtual bool getInfo(SkImageInfo* info) = 0;
/**
* 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.
*
* @return false if anything goes wrong or if the image info is
* unsupported.
*/
virtual bool getPixels(const SkImageInfo& info,
void* pixels,
size_t rowBytes) = 0;
};
#endif // SkImageGenerator_DEFINED