61 lines
2.7 KiB
C++
61 lines
2.7 KiB
C++
/*
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* Copyright 2022 Google LLC
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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 skgpu_graphite_ImageProvider_DEFINED
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#define skgpu_graphite_ImageProvider_DEFINED
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#include "include/core/SkImage.h"
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#include "include/core/SkRefCnt.h"
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namespace skgpu::graphite {
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class Recorder;
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/*
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* This class provides a centralized location for clients to perform any caching of images
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* they desire. Whenever Graphite encounters an SkImage which is not Graphite-backed
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* it will call ImageProvider::findOrCreate. The client's derived version of this class should
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* return a Graphite-backed version of the provided SkImage that meets the specified
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* requirements.
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*
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* Skia requires that 'findOrCreate' return a Graphite-backed image that preserves the dimensions,
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* number of channels and alpha type of the original image. The bit depth of the
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* individual channels can change (e.g., 4444 -> 8888 is allowed).
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* Wrt mipmapping, the returned image can have different mipmap settings than requested. If
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* mipmapping was requested but not returned, the sampling level will be reduced to linear.
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* If the requirements are not met by the returned image (modulo the flexibility wrt mipmapping)
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* Graphite will drop the draw.
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*
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* Note: by default, Graphite will not perform any caching of images
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*
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* Threading concerns:
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* If the same ImageProvider is given to multiple Recorders it is up to the
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* client to handle any required thread synchronization. This is not limited to just
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* restricting access to whatever map a derived class may have but extends to ensuring
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* that an image created on one Recorder has had its creation work submitted before it
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* is used by any work submitted by another Recording. Please note, this requirement
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* (re the submission of creation work and image usage on different threads) is common to all
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* graphite SkImages and isn't unique to SkImages returned by the ImageProvider.
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*
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* TODO(b/240996632): add documentation re shutdown order.
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* TODO(b/240997067): add unit tests
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*/
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class SK_API ImageProvider : public SkRefCnt {
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public:
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// If the client's derived class already has a Graphite-backed image that has the same
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// contents as 'image' and meets the requirements, then it can be returned.
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// makeTextureImage can always be called to create an acceptable Graphite-backed image
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// which could then be cached.
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virtual sk_sp<SkImage> findOrCreate(Recorder* recorder,
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const SkImage* image,
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SkImage::RequiredImageProperties) = 0;
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};
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} // namespace skgpu::graphite
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#endif // skgpu_graphite_ImageProvider_DEFINED
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