1/*
2 * Copyright 2020 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef GrEagerVertexAllocator_DEFINED
9#define GrEagerVertexAllocator_DEFINED
10
11#include "src/gpu/ops/GrMeshDrawOp.h"
12
13// This interface is used to allocate and map GPU vertex data before the exact number of required
14// vertices is known. Usage pattern:
15//
16// 1. Call lock(eagerCount) with an upper bound on the number of required vertices.
17// 2. Compute and write vertex data to the returned pointer (if not null).
18// 3. Call unlock(actualCount) and provide the actual number of vertices written during step #2.
19//
20// On step #3, the implementation will attempt to shrink the underlying GPU memory slot to fit the
21// actual vertex count.
22class GrEagerVertexAllocator {
23public:
24 template<typename T> T* lock(int eagerCount) {
25 return static_cast<T*>(this->lock(sizeof(T), eagerCount));
26 }
27 virtual void* lock(size_t stride, int eagerCount) = 0;
28
29 virtual void unlock(int actualCount) = 0;
30
31 virtual ~GrEagerVertexAllocator() {}
32};
33
34// GrEagerVertexAllocator implementation that uses GrMeshDrawOp::Target::makeVertexSpace and
35// GrMeshDrawOp::Target::putBackVertices.
36class GrEagerDynamicVertexAllocator : public GrEagerVertexAllocator {
37public:
38 GrEagerDynamicVertexAllocator(GrMeshDrawOp::Target* target,
39 sk_sp<const GrBuffer>* vertexBuffer, int* baseVertex)
40 : fTarget(target)
41 , fVertexBuffer(vertexBuffer)
42 , fBaseVertex(baseVertex) {
43 }
44
45#ifdef SK_DEBUG
46 ~GrEagerDynamicVertexAllocator() override {
47 SkASSERT(!fLockCount);
48 }
49#endif
50
51 void* lock(size_t stride, int eagerCount) override {
52 SkASSERT(!fLockCount);
53 SkASSERT(eagerCount);
54 if (void* data = fTarget->makeVertexSpace(stride, eagerCount, fVertexBuffer, fBaseVertex)) {
55 fLockStride = stride;
56 fLockCount = eagerCount;
57 return data;
58 }
59 fVertexBuffer->reset();
60 *fBaseVertex = 0;
61 return nullptr;
62 }
63
64 void unlock(int actualCount) override {
65 SkASSERT(fLockCount);
66 SkASSERT(actualCount <= fLockCount);
67 fTarget->putBackVertices(fLockCount - actualCount, fLockStride);
68 if (!actualCount) {
69 fVertexBuffer->reset();
70 *fBaseVertex = 0;
71 }
72 fLockCount = 0;
73 }
74
75private:
76 GrMeshDrawOp::Target* const fTarget;
77 sk_sp<const GrBuffer>* const fVertexBuffer;
78 int* const fBaseVertex;
79
80 size_t fLockStride;
81 int fLockCount = 0;
82};
83
84#endif
85