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      1 /*
      2  * Copyright 2019 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 GrVkSecondaryCBDrawContext_DEFINED
      9 #define GrVkSecondaryCBDrawContext_DEFINED
     10 
     11 #include "SkTypes.h"
     12 #include "SkRefCnt.h"
     13 #include "SkSurfaceProps.h"
     14 
     15 class GrBackendSemaphore;
     16 class GrContext;
     17 struct GrVkDrawableInfo;
     18 class SkCanvas;
     19 class SkDeferredDisplayList;
     20 class SkGpuDevice;
     21 struct SkImageInfo;
     22 class SkSurfaceCharacterization;
     23 class SkSurfaceProps;
     24 
     25 /**
     26  * This class is a private header that is intended to only be used inside of Chromium. This requires
     27  * Chromium to burrow in and include this specifically since it is not part of skia's public include
     28  * directory.
     29  */
     30 
     31 /**
     32  * This class is used to draw into an external Vulkan secondary command buffer that is imported
     33  * by the client. The secondary command buffer that gets imported must already have had begin called
     34  * on it with VK_COMMAND_BUFFER_USAGE_RENDER_PASS_CONTINUE_BIT. Thus any draws to the imported
     35  * command buffer cannot require changing the render pass. This requirement means that certain types
     36  * of draws will not be supported when using a GrVkSecondaryCBDrawContext. This includes:
     37  *     Draws that require a dst copy for blending will be dropped
     38  *     Text draws will be dropped (these may require intermediate uploads of text data)
     39  *     Read and Write pixels will not work
     40  *     Any other draw that requires a copy will fail (this includes using backdrop filter with save
     41  *         layer).
     42  *     Stenciling is also disabled, but that should not restrict any actual draws from working.
     43  *
     44  * While using a GrVkSecondaryCBDrawContext, the client can also draw into normal SkSurfaces and
     45  * then draw those SkSufaces (as SkImages) into the GrVkSecondaryCBDrawContext. If any of the
     46  * previously mentioned unsupported draws are needed by the client, they can draw them into an
     47  * offscreen surface, and then draw that into the GrVkSecondaryCBDrawContext.
     48  *
     49  * After all drawing to the GrVkSecondaryCBDrawContext has been done, the client must call flush()
     50  * on the GrVkSecondaryCBDrawContext to actually fill in the secondary VkCommandBuffer with the
     51  * draws.
     52  *
     53  * Additionally, the client must keep the GrVkSecondaryCBDrawContext alive until the secondary
     54  * VkCommandBuffer has been submitted and all work finished on the GPU. Before deleting the
     55  * GrVkSecondaryCBDrawContext, the client must call releaseResources() so that Skia can cleanup
     56  * any internal objects that were created for the draws into the secondary command buffer.
     57  */
     58 class SK_API GrVkSecondaryCBDrawContext : public SkRefCnt {
     59 public:
     60     static sk_sp<GrVkSecondaryCBDrawContext> Make(GrContext*, const SkImageInfo&,
     61                                                   const GrVkDrawableInfo&,
     62                                                   const SkSurfaceProps* props);
     63 
     64     ~GrVkSecondaryCBDrawContext() override;
     65 
     66     SkCanvas* getCanvas();
     67 
     68     // Records all the draws to the imported secondary command buffer and sets any dependent
     69     // offscreen draws to the GPU.
     70     void flush();
     71 
     72     /** Inserts a list of GPU semaphores that Skia will have the driver wait on before executing
     73         commands for this secondary CB. The wait semaphores will get added to the VkCommandBuffer
     74         owned by this GrContext when flush() is called, and not the command buffer which the
     75         Secondary CB is from. This will guarantee that the driver waits on the semaphores before
     76         the secondary command buffer gets executed. Skia will take ownership of the underlying
     77         semaphores and delete them once they have been signaled and waited on. If this call returns
     78         false, then the GPU back-end will not wait on any passed in semaphores, and the client will
     79         still own the semaphores.
     80 
     81         @param numSemaphores   size of waitSemaphores array
     82         @param waitSemaphores  array of semaphore containers
     83         @return                true if GPU is waiting on semaphores
     84     */
     85     bool wait(int numSemaphores, const GrBackendSemaphore waitSemaphores[]);
     86 
     87     // This call will release all resources held by the draw context. The client must call
     88     // releaseResources() before deleting the drawing context. However, the resources also include
     89     // any Vulkan resources that were created and used for draws. Therefore the client must only
     90     // call releaseResources() after submitting the secondary command buffer, and waiting for it to
     91     // finish on the GPU. If it is called earlier then some vulkan objects may be deleted while they
     92     // are still in use by the GPU.
     93     void releaseResources();
     94 
     95     const SkSurfaceProps& props() const { return fProps; }
     96 
     97     // TODO: Fill out these calls to support DDL
     98     bool characterize(SkSurfaceCharacterization* characterization) const;
     99     bool draw(SkDeferredDisplayList* deferredDisplayList);
    100 
    101 private:
    102     explicit GrVkSecondaryCBDrawContext(sk_sp<SkGpuDevice>, const SkSurfaceProps*);
    103 
    104     bool isCompatible(const SkSurfaceCharacterization& characterization) const;
    105 
    106     sk_sp<SkGpuDevice>        fDevice;
    107     std::unique_ptr<SkCanvas> fCachedCanvas;
    108     const SkSurfaceProps      fProps;
    109 
    110     typedef SkRefCnt INHERITED;
    111 };
    112 
    113 #endif
    114