chromium/third_party/skia/src/gpu/graphite/PaintParamsKey.h

/*
 * 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_PaintParamsKey_DEFINED
#define skgpu_graphite_PaintParamsKey_DEFINED

#include "include/core/SkSpan.h"
#include "include/core/SkTypes.h"
#include "include/private/base/SkMacros.h"
#include "include/private/base/SkTArray.h"
#include "src/core/SkChecksum.h"
#include "src/gpu/graphite/BuiltInCodeSnippetID.h"

#include <limits>
#include <cstring> // for memcmp

class SkArenaAlloc;
struct SkSamplingOptions;
enum class SkTileMode;

namespace skgpu::graphite {

class Caps;
class ShaderCodeDictionary;
class ShaderNode;
class TextureProxy;
class UniquePaintParamsID;

// This class is a compact representation of the shader needed to implement a given
// PaintParams. Its structure is a series of nodes where each node consists of:
//   4 bytes: code-snippet ID
//   N child nodes, where N is the constant number of children defined by the ShaderCodeDictionary
//     for the node's snippet ID.
//
// All children of a child node are stored in the key before the next child is encoded in the key,
// e.g. iterating the data in a key is a depth-first traversal of the node tree.
class PaintParamsKey { … };

// The PaintParamsKeyBuilder and the PaintParamsKeys snapped from it share the same
// underlying block of memory. When an PaintParamsKey is snapped from the builder it 'locks'
// the memory and 'unlocks' it in its destructor. Because of this relationship, the builder
// can only have one extant key and that key must be destroyed before the builder can be reused
// to create another one.
//
// This arrangement is intended to improve performance in the expected case, where a builder is
// being used in a tight loop to generate keys which can be recycled once they've been used to
// find the dictionary's matching uniqueID. We don't expect the cost of copying the key's memory
// into the dictionary to be prohibitive since that should be infrequent.
class PaintParamsKeyBuilder { … };

class AutoLockBuilderAsKey { … };

}  // namespace skgpu::graphite

#endif // skgpu_graphite_PaintParamsKey_DEFINED