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      1 /*
      2  * Copyright 2011 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 GrRenderTarget_DEFINED
      9 #define GrRenderTarget_DEFINED
     10 
     11 #include "GrSurface.h"
     12 #include "SkRect.h"
     13 
     14 class GrCaps;
     15 class GrRenderTargetOpList;
     16 class GrRenderTargetPriv;
     17 class GrStencilAttachment;
     18 class GrBackendRenderTarget;
     19 
     20 /**
     21  * GrRenderTarget represents a 2D buffer of pixels that can be rendered to.
     22  * A context's render target is set by setRenderTarget(). Render targets are
     23  * created by a createTexture with the kRenderTarget_SurfaceFlag flag.
     24  * Additionally, GrContext provides methods for creating GrRenderTargets
     25  * that wrap externally created render targets.
     26  */
     27 class GrRenderTarget : virtual public GrSurface {
     28 public:
     29     virtual bool alwaysClearStencil() const { return false; }
     30 
     31     // GrSurface overrides
     32     GrRenderTarget* asRenderTarget() override { return this; }
     33     const GrRenderTarget* asRenderTarget() const  override { return this; }
     34 
     35     // GrRenderTarget
     36     bool isStencilBufferMultisampled() const { return fSampleCnt > 1; }
     37 
     38     GrFSAAType fsaaType() const {
     39         SkASSERT(fSampleCnt >= 1);
     40         if (fSampleCnt <= 1) {
     41             SkASSERT(!this->hasMixedSamples());
     42             return GrFSAAType::kNone;
     43         }
     44         return this->hasMixedSamples() ? GrFSAAType::kMixedSamples : GrFSAAType::kUnifiedMSAA;
     45     }
     46 
     47     /**
     48      * Returns the number of samples/pixel in the stencil buffer (One if non-MSAA).
     49      */
     50     int numStencilSamples() const { return fSampleCnt; }
     51 
     52     /**
     53      * Returns the number of samples/pixel in the color buffer (One if non-MSAA or mixed sampled).
     54      */
     55     int numColorSamples() const {
     56         return GrFSAAType::kMixedSamples == this->fsaaType() ? 1 : fSampleCnt;
     57     }
     58 
     59     /**
     60      * Call to indicate the multisample contents were modified such that the
     61      * render target needs to be resolved before it can be used as texture. Gr
     62      * tracks this for its own drawing and thus this only needs to be called
     63      * when the render target has been modified outside of Gr. This has no
     64      * effect on wrapped backend render targets.
     65      *
     66      * @param rect  a rect bounding the area needing resolve. NULL indicates
     67      *              the whole RT needs resolving.
     68      */
     69     void flagAsNeedingResolve(const SkIRect* rect = nullptr);
     70 
     71     /**
     72      * Call to override the region that needs to be resolved.
     73      */
     74     void overrideResolveRect(const SkIRect rect);
     75 
     76     /**
     77      * Call to indicate that GrRenderTarget was externally resolved. This may
     78      * allow Gr to skip a redundant resolve step.
     79      */
     80     void flagAsResolved();
     81 
     82     /**
     83      * @return true if the GrRenderTarget requires MSAA resolving
     84      */
     85     bool needsResolve() const { return !fResolveRect.isEmpty(); }
     86 
     87     /**
     88      * Returns a rect bounding the region needing resolving.
     89      */
     90     const SkIRect& getResolveRect() const { return fResolveRect; }
     91 
     92     // a MSAA RT may require explicit resolving , it may auto-resolve (e.g. FBO
     93     // 0 in GL), or be unresolvable because the client didn't give us the
     94     // resolve destination.
     95     enum ResolveType {
     96         kCanResolve_ResolveType,
     97         kAutoResolves_ResolveType,
     98         kCantResolve_ResolveType,
     99     };
    100     virtual ResolveType getResolveType() const = 0;
    101 
    102     virtual GrBackendRenderTarget getBackendRenderTarget() const = 0;
    103 
    104     // Checked when this object is asked to attach a stencil buffer.
    105     virtual bool canAttemptStencilAttachment() const = 0;
    106 
    107     // Provides access to functions that aren't part of the public API.
    108     GrRenderTargetPriv renderTargetPriv();
    109     const GrRenderTargetPriv renderTargetPriv() const;
    110 
    111 protected:
    112     GrRenderTarget(GrGpu*, const GrSurfaceDesc&, GrStencilAttachment* = nullptr);
    113     ~GrRenderTarget() override;
    114 
    115     // override of GrResource
    116     void onAbandon() override;
    117     void onRelease() override;
    118 
    119 private:
    120     // Allows the backends to perform any additional work that is required for attaching a
    121     // GrStencilAttachment. When this is called, the GrStencilAttachment has already been put onto
    122     // the GrRenderTarget. This function must return false if any failures occur when completing the
    123     // stencil attachment.
    124     virtual bool completeStencilAttachment() = 0;
    125 
    126     friend class GrRenderTargetPriv;
    127 
    128     int fSampleCnt;
    129     int fSamplePatternKey;
    130     sk_sp<GrStencilAttachment> fStencilAttachment;
    131     SkIRect fResolveRect;
    132 
    133     typedef GrSurface INHERITED;
    134 };
    135 
    136 #endif
    137