GrDynamicAtlas.h

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/*
 * Copyright 2020 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
#ifndef GrDynamicAtlas_DEFINED
#define GrDynamicAtlas_DEFINED
 
#include "src/base/SkArenaAlloc.h"
#include "src/gpu/ganesh/GrTextureProxy.h"
 
class GrOnFlushResourceProvider;
class GrResourceProvider;
class GrSurfaceProxyView;
struct SkIPoint16;
struct SkIRect;
 
/**
 * This class implements a dynamic size skgpu::Rectanizer that grows until it reaches the
 * implementation-dependent max texture size. When finalized, it also creates and stores a
 * GrTextureProxy for the underlying atlas.
 */
class GrDynamicAtlas {
public:
    // As long as GrSurfaceOrigin exists, we just have to decide on one for the atlas texture.
    inline static constexpr GrSurfaceOrigin kTextureOrigin = kTopLeft_GrSurfaceOrigin;
    inline static constexpr int kPadding = 1;  // Amount of padding below and to the right of each
                                               // path.
 
    using LazyAtlasDesc = GrSurfaceProxy::LazySurfaceDesc;
    using LazyInstantiateAtlasCallback = GrSurfaceProxy::LazyInstantiateCallback;
 
    enum class InternalMultisample : bool {
        kNo = false,
        kYes = true
    };
 
    static sk_sp<GrTextureProxy> MakeLazyAtlasProxy(LazyInstantiateAtlasCallback&&,
                                                    GrColorType colorType,
                                                    InternalMultisample,
                                                    const GrCaps&,
                                                    GrSurfaceProxy::UseAllocator);
 
    enum class RectanizerAlgorithm {
        kSkyline,
        kPow2
    };
 
    GrDynamicAtlas(GrColorType colorType, InternalMultisample, SkISize initialSize,
                   int maxAtlasSize, const GrCaps&,
                   RectanizerAlgorithm = RectanizerAlgorithm::kSkyline);
    virtual ~GrDynamicAtlas();
 
    void reset(SkISize initialSize, const GrCaps& desc);
 
    GrColorType colorType() const { return fColorType; }
    int maxAtlasSize() const { return fMaxAtlasSize; }
    GrTextureProxy* textureProxy() const { return fTextureProxy.get(); }
    GrSurfaceProxyView readView(const GrCaps&) const;
    GrSurfaceProxyView writeView(const GrCaps&) const;
    bool isInstantiated() const { return fTextureProxy->isInstantiated(); }
 
    // Attempts to add a rect to the atlas. Returns true if successful, along with the rect's
    // top-left location in the atlas.
    bool addRect(int width, int height, SkIPoint16* location);
    const SkISize& drawBounds() { return fDrawBounds; }
 
    // Instantiates our texture proxy for the atlas. After this call, it is no longer valid to call
    // addRect(), setUserBatchID(), or this method again.
    //
    // 'backingTexture', if provided, is a renderable texture with which to instantiate our proxy.
    // If null then we will create a texture using the resource provider. The purpose of this param
    // is to provide a guaranteed way to recycle textures from previous atlases.
    [[nodiscard]] bool instantiate(GrOnFlushResourceProvider*,
                                   sk_sp<GrTexture> backingTexture = nullptr);
 
private:
    class Node;
 
    Node* makeNode(Node* previous, int l, int t, int r, int b);
    bool internalPlaceRect(int w, int h, SkIPoint16* loc);
 
    const GrColorType fColorType;
    const InternalMultisample fInternalMultisample;
    const int fMaxAtlasSize;
    const RectanizerAlgorithm fRectanizerAlgorithm;
    int fWidth;
    int fHeight;
    SkISize fDrawBounds;
 
    SkSTArenaAllocWithReset<512> fNodeAllocator;
    Node* fTopNode = nullptr;
 
    sk_sp<GrTextureProxy> fTextureProxy;
    sk_sp<GrTexture> fBackingTexture;
};
 
#endif