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