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/*
* Copyright 2022 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef skgpu_graphite_ImageProvider_DEFINED
#define skgpu_graphite_ImageProvider_DEFINED
#include "include/core/SkImage.h"
#include "include/core/SkRefCnt.h"
namespace skgpu::graphite {
class Recorder;
/*
* This class provides a centralized location for clients to perform any caching of images
* they desire. Whenever Graphite encounters an SkImage which is not Graphite-backed
* it will call ImageProvider::findOrCreate. The client's derived version of this class should
* return a Graphite-backed version of the provided SkImage that meets the specified
* requirements.
*
* Skia requires that 'findOrCreate' return a Graphite-backed image that preserves the
* dimensions and alpha type of the original image. The bit depth of the
* individual channels can change (e.g., 4444 -> 8888 is allowed) as well as the channels - as
* long as the returned image has a superset of the original image's channels
* (e.g., 565 -> 8888 opaque is allowed).
*
* Wrt mipmapping, the returned image can have different mipmap settings than requested. If
* mipmapping was requested but not returned, the sampling level will be reduced to linear.
* If the requirements are not met by the returned image (modulo the flexibility wrt mipmapping)
* Graphite will drop the draw.
*
* All returned images must be backed by textures that have a TopLeft origin. If Skia is used to
* create the texture (e.g. using makeTextureImage) then this is always guaranteed. If the client
* returns a texture they created themselves and wrapped in Skia, they must ensure that texture has
* a TopLeft origin.
*
* Note: by default, Graphite will not perform any caching of images
*
* Threading concerns:
* If the same ImageProvider is given to multiple Recorders it is up to the
* client to handle any required thread synchronization. This is not limited to just
* restricting access to whatever map a derived class may have but extends to ensuring
* that an image created on one Recorder has had its creation work submitted before it
* is used by any work submitted by another Recording. Please note, this requirement
* (re the submission of creation work and image usage on different threads) is common to all
* graphite SkImages and isn't unique to SkImages returned by the ImageProvider.
*
* TODO(b/240996632): add documentation re shutdown order.
* TODO(b/240997067): add unit tests
*/
class SK_API ImageProvider : public SkRefCnt {
public:
// If the client's derived class already has a Graphite-backed image that has the same
// contents as 'image' and meets the requirements, then it can be returned.
// makeTextureImage can always be called to create an acceptable Graphite-backed image
// which could then be cached.
virtual sk_sp<SkImage> findOrCreate(Recorder* recorder,
const SkImage* image,
SkImage::RequiredProperties) = 0;
};
} // namespace skgpu::graphite
#endif // skgpu_graphite_ImageProvider_DEFINED
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