skia2/include/core/SkImageGenerator.h
Brian Osman d85dd53e28 Shrink the SkImageGenerator API
generateBitmap was used in one test, so it's easily converted to
tryGenerateBitmap. Then, all calls to tryGenerateBitmap supplied
an image info, so we don't need it to be optional.

BUG=skia:

Change-Id: I19e8f9da7e442a2d37af68b029b5ec85228766f7
Reviewed-on: https://skia-review.googlesource.com/6149
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
2016-12-15 20:47:26 +00:00

294 lines
12 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 "SkBitmap.h"
#include "SkColor.h"
#include "SkImageInfo.h"
#include "SkYUVSizeInfo.h"
class GrContext;
class GrContextThreadSafeProxy;
class GrTexture;
class GrSamplerParams;
class SkBitmap;
class SkData;
class SkImage;
class SkImageGenerator;
class SkMatrix;
class SkPaint;
class SkPicture;
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 the GrContext is non-null, then the caller is only interested in
* gpu-specific formats, so the impl may return null even if they have encoded data,
* assuming they know it is not suitable for the gpu.
*
* If non-NULL is returned, the caller is responsible for calling
* unref() on the data when it is finished.
*/
SkData* refEncodedData(GrContext* ctx = nullptr) {
return this->onRefEncodedData(ctx);
}
/**
* 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 decoding to YUV is supported, this returns true. Otherwise, this
* returns false and does not modify any of the parameters.
*
* @param sizeInfo Output parameter indicating the sizes and required
* allocation widths of the Y, U, and V planes.
* @param colorSpace Output parameter.
*/
bool queryYUV8(SkYUVSizeInfo* sizeInfo, SkYUVColorSpace* colorSpace) const;
/**
* Returns true on success and false on failure.
* This always attempts to perform a full decode. If the client only
* wants size, it should call queryYUV8().
*
* @param sizeInfo Needs to exactly match the values returned by the
* query, except the WidthBytes may be larger than the
* recommendation (but not smaller).
* @param planes Memory for each of the Y, U, and V planes.
*/
bool getYUV8Planes(const SkYUVSizeInfo& sizeInfo, void* planes[3]);
/**
* 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.
*
* This routine also supports retrieving only a subset of the pixels. That subset is specified
* by the following rectangle:
*
* subset = SkIRect::MakeXYWH(origin.x(), origin.y(), info.width(), info.height())
*
* If subset is not contained inside the generator's bounds, this returns false.
*
* whole = SkIRect::MakeWH(getInfo().width(), getInfo().height())
* if (!whole.contains(subset)) {
* return false;
* }
*
* 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.
*/
GrTexture* generateTexture(GrContext*, const SkImageInfo& info, const SkIPoint& origin);
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);
}
/**
* External generator API: provides efficient access to externally-managed image data.
*
* Skia calls accessScaledPixels() during rasterization, to gain temporary access to
* the external pixel data. When done, the provided callback is invoked to release the
* associated resources.
*
* @param srcRect the source rect in use for the current draw
* @param totalMatrix full matrix in effect (mapping srcRect -> device space)
* @param quality the SkFilterQuality requested for rasterization.
* @param rec out param, expected to be set when the call succeeds:
*
* - fPixmap external pixel data
* - fSrcRect is an adjusted srcRect
* - fQuality is the adjusted filter quality
* - fReleaseProc pixmap release callback, same signature as the
* SkBitmap::installPixels() callback
* - fReleaseCtx opaque release context argument
*
* @return true on success, false otherwise (error or if this API is not supported;
* in this case Skia will fall back to its internal scaling and caching
* heuristics)
*
* Implementors can return pixmaps with a different size than requested, by adjusting the
* src rect. The contract is that Skia will observe the adjusted src rect, and will map it
* to the same dest as the original draw (the impl doesn't get to control the destination).
*
*/
struct ScaledImageRec {
SkPixmap fPixmap;
SkRect fSrcRect;
SkFilterQuality fQuality;
using ReleaseProcT = void (*)(void* pixels, void* releaseCtx);
ReleaseProcT fReleaseProc;
void* fReleaseCtx;
};
bool accessScaledImage(const SkRect& srcRect, const SkMatrix& totalMatrix,
SkFilterQuality quality, ScaledImageRec* rec);
/**
* 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, const SkImageInfo& info, SkBitmap::Allocator* allocator);
protected:
enum {
kNeedNewImageUniqueID = 0
};
SkImageGenerator(const SkImageInfo& info, uint32_t uniqueId = kNeedNewImageUniqueID);
virtual SkData* onRefEncodedData(GrContext* ctx);
virtual bool onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
SkPMColor ctable[], int* ctableCount);
virtual bool onQueryYUV8(SkYUVSizeInfo*, SkYUVColorSpace*) const {
return false;
}
virtual bool onGetYUV8Planes(const SkYUVSizeInfo&, void*[3] /*planes*/) {
return false;
}
virtual GrTexture* onGenerateTexture(GrContext*, const SkImageInfo&, const SkIPoint&) {
return nullptr;
}
virtual bool onComputeScaledDimensions(SkScalar, SupportedSizes*) {
return false;
}
virtual bool onGenerateScaledPixels(const SkISize&, const SkIPoint&, const SkPixmap&) {
return false;
}
virtual bool onAccessScaledImage(const SkRect&, const SkMatrix&, SkFilterQuality,
ScaledImageRec*) {
return false;
}
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