GraphiteVulkanWindowContext.cpp

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/*
 * Copyright 2023 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
#include "tools/window/GraphiteVulkanWindowContext.h"
 
#include "include/core/SkSurface.h"
#include "include/gpu/MutableTextureState.h"
#include "include/gpu/graphite/BackendSemaphore.h"
#include "include/gpu/graphite/BackendTexture.h"
#include "include/gpu/graphite/Context.h"
#include "include/gpu/graphite/ContextOptions.h"
#include "include/gpu/graphite/GraphiteTypes.h"
#include "include/gpu/graphite/Recorder.h"
#include "include/gpu/graphite/Surface.h"
#include "include/gpu/graphite/TextureInfo.h"
#include "include/gpu/graphite/vk/VulkanGraphiteTypes.h"
#include "include/gpu/graphite/vk/VulkanGraphiteUtils.h"
#include "include/gpu/vk/VulkanExtensions.h"
#include "include/gpu/vk/VulkanMutableTextureState.h"
#include "include/gpu/vk/VulkanTypes.h"
#include "include/private/gpu/graphite/ContextOptionsPriv.h"
#include "src/base/SkAutoMalloc.h"
#include "src/gpu/graphite/vk/VulkanGraphiteUtilsPriv.h"
#include "src/gpu/vk/VulkanInterface.h"
#include "tools/GpuToolUtils.h"
#include "tools/ToolUtils.h"
 
#ifdef VK_USE_PLATFORM_WIN32_KHR
// windows wants to define this as CreateSemaphoreA or CreateSemaphoreW
#undef CreateSemaphore
#endif
 
#define GET_PROC(F) f ## F = \
    (PFN_vk ## F) backendContext.fGetProc("vk" #F, fInstance, VK_NULL_HANDLE)
#define GET_DEV_PROC(F) f ## F = \
    (PFN_vk ## F) backendContext.fGetProc("vk" #F, VK_NULL_HANDLE, fDevice)
 
namespace skwindow::internal {
 
GraphiteVulkanWindowContext::GraphiteVulkanWindowContext(const DisplayParams& params,
                                                         CreateVkSurfaceFn createVkSurface,
                                                         CanPresentFn canPresent,
                                                         PFN_vkGetInstanceProcAddr instProc)
    : WindowContext(params)
    , fCreateVkSurfaceFn(std::move(createVkSurface))
    , fCanPresentFn(std::move(canPresent))
    , fSurface(VK_NULL_HANDLE)
    , fSwapchain(VK_NULL_HANDLE)
    , fImages(nullptr)
    , fImageLayouts(nullptr)
    , fSurfaces(nullptr)
    , fBackbuffers(nullptr) {
    fGetInstanceProcAddr = instProc;
    this->initializeContext();
}
 
void GraphiteVulkanWindowContext::initializeContext() {
    SkASSERT(!fGraphiteContext && !fGraphiteRecorder);
    // any config code here (particularly for msaa)?
 
    PFN_vkGetInstanceProcAddr getInstanceProc = fGetInstanceProcAddr;
    skgpu::VulkanBackendContext backendContext;
    skgpu::VulkanExtensions extensions;
    VkPhysicalDeviceFeatures2 features;
    if (!sk_gpu_test::CreateVkBackendContext(getInstanceProc, &backendContext, &extensions,
                                             &features, &fDebugCallback, &fPresentQueueIndex,
                                             fCanPresentFn,
                                             fDisplayParams.fCreateProtectedNativeBackend)) {
        sk_gpu_test::FreeVulkanFeaturesStructs(&features);
        return;
    }
 
    if (!extensions.hasExtension(VK_KHR_SURFACE_EXTENSION_NAME, 25) ||
        !extensions.hasExtension(VK_KHR_SWAPCHAIN_EXTENSION_NAME, 68)) {
        sk_gpu_test::FreeVulkanFeaturesStructs(&features);
        return;
    }
 
    fInstance = backendContext.fInstance;
    fPhysicalDevice = backendContext.fPhysicalDevice;
    fDevice = backendContext.fDevice;
    fGraphicsQueueIndex = backendContext.fGraphicsQueueIndex;
    fGraphicsQueue = backendContext.fQueue;
 
    PFN_vkGetPhysicalDeviceProperties localGetPhysicalDeviceProperties =
            reinterpret_cast<PFN_vkGetPhysicalDeviceProperties>(
                    backendContext.fGetProc("vkGetPhysicalDeviceProperties",
                                            backendContext.fInstance,
                                            VK_NULL_HANDLE));
    if (!localGetPhysicalDeviceProperties) {
        sk_gpu_test::FreeVulkanFeaturesStructs(&features);
        return;
    }
    VkPhysicalDeviceProperties physDeviceProperties;
    localGetPhysicalDeviceProperties(backendContext.fPhysicalDevice, &physDeviceProperties);
    uint32_t physDevVersion = physDeviceProperties.apiVersion;
 
    fInterface.reset(new skgpu::VulkanInterface(backendContext.fGetProc, fInstance, fDevice,
                                                backendContext.fMaxAPIVersion, physDevVersion,
                                                &extensions));
 
    GET_PROC(DestroyInstance);
    if (fDebugCallback != VK_NULL_HANDLE) {
        GET_PROC(DestroyDebugReportCallbackEXT);
    }
    GET_PROC(DestroySurfaceKHR);
    GET_PROC(GetPhysicalDeviceSurfaceSupportKHR);
    GET_PROC(GetPhysicalDeviceSurfaceCapabilitiesKHR);
    GET_PROC(GetPhysicalDeviceSurfaceFormatsKHR);
    GET_PROC(GetPhysicalDeviceSurfacePresentModesKHR);
    GET_DEV_PROC(DeviceWaitIdle);
    GET_DEV_PROC(QueueWaitIdle);
    GET_DEV_PROC(DestroyDevice);
    GET_DEV_PROC(CreateSwapchainKHR);
    GET_DEV_PROC(DestroySwapchainKHR);
    GET_DEV_PROC(GetSwapchainImagesKHR);
    GET_DEV_PROC(AcquireNextImageKHR);
    GET_DEV_PROC(QueuePresentKHR);
    GET_DEV_PROC(GetDeviceQueue);
 
    skgpu::graphite::ContextOptions contextOptions;
    skgpu::graphite::ContextOptionsPriv contextOptionsPriv;
    // Needed to make synchronous readPixels work
    contextOptionsPriv.fStoreContextRefInRecorder = true;
    contextOptions.fOptionsPriv = &contextOptionsPriv;
    fGraphiteContext = skgpu::graphite::ContextFactory::MakeVulkan(backendContext, contextOptions);
    fGraphiteRecorder = fGraphiteContext->makeRecorder(ToolUtils::CreateTestingRecorderOptions());
 
    fSurface = fCreateVkSurfaceFn(fInstance);
    if (VK_NULL_HANDLE == fSurface) {
        this->destroyContext();
        sk_gpu_test::FreeVulkanFeaturesStructs(&features);
        return;
    }
 
    VkBool32 supported;
    VkResult res = fGetPhysicalDeviceSurfaceSupportKHR(fPhysicalDevice, fPresentQueueIndex,
                                                       fSurface, &supported);
    if (VK_SUCCESS != res) {
        this->destroyContext();
        sk_gpu_test::FreeVulkanFeaturesStructs(&features);
        return;
    }
 
    if (!this->createSwapchain(-1, -1, fDisplayParams)) {
        this->destroyContext();
        sk_gpu_test::FreeVulkanFeaturesStructs(&features);
        return;
    }
 
    // create presentQueue
    fGetDeviceQueue(fDevice, fPresentQueueIndex, 0, &fPresentQueue);
    sk_gpu_test::FreeVulkanFeaturesStructs(&features);
}
 
bool GraphiteVulkanWindowContext::createSwapchain(int width, int height,
                                                  const DisplayParams& params) {
    // check for capabilities
    VkSurfaceCapabilitiesKHR caps;
    VkResult res = fGetPhysicalDeviceSurfaceCapabilitiesKHR(fPhysicalDevice, fSurface, &caps);
    if (VK_SUCCESS != res) {
        return false;
    }
 
    uint32_t surfaceFormatCount;
    res = fGetPhysicalDeviceSurfaceFormatsKHR(fPhysicalDevice, fSurface, &surfaceFormatCount,
                                              nullptr);
    if (VK_SUCCESS != res) {
        return false;
    }
 
    SkAutoMalloc surfaceFormatAlloc(surfaceFormatCount * sizeof(VkSurfaceFormatKHR));
    VkSurfaceFormatKHR* surfaceFormats = (VkSurfaceFormatKHR*)surfaceFormatAlloc.get();
    res = fGetPhysicalDeviceSurfaceFormatsKHR(fPhysicalDevice, fSurface, &surfaceFormatCount,
                                              surfaceFormats);
    if (VK_SUCCESS != res) {
        return false;
    }
 
    uint32_t presentModeCount;
    res = fGetPhysicalDeviceSurfacePresentModesKHR(fPhysicalDevice, fSurface, &presentModeCount,
                                                   nullptr);
    if (VK_SUCCESS != res) {
        return false;
    }
 
    SkAutoMalloc presentModeAlloc(presentModeCount * sizeof(VkPresentModeKHR));
    VkPresentModeKHR* presentModes = (VkPresentModeKHR*)presentModeAlloc.get();
    res = fGetPhysicalDeviceSurfacePresentModesKHR(fPhysicalDevice, fSurface, &presentModeCount,
                                                   presentModes);
    if (VK_SUCCESS != res) {
        return false;
    }
 
    VkExtent2D extent = caps.currentExtent;
    // use the hints
    if (extent.width == (uint32_t)-1) {
        extent.width = width;
        extent.height = height;
    }
 
    // clamp width; to protect us from broken hints
    if (extent.width < caps.minImageExtent.width) {
        extent.width = caps.minImageExtent.width;
    } else if (extent.width > caps.maxImageExtent.width) {
        extent.width = caps.maxImageExtent.width;
    }
    // clamp height
    if (extent.height < caps.minImageExtent.height) {
        extent.height = caps.minImageExtent.height;
    } else if (extent.height > caps.maxImageExtent.height) {
        extent.height = caps.maxImageExtent.height;
    }
 
    fWidth = (int)extent.width;
    fHeight = (int)extent.height;
 
    uint32_t imageCount = caps.minImageCount + 2;
    if (caps.maxImageCount > 0 && imageCount > caps.maxImageCount) {
        // Application must settle for fewer images than desired:
        imageCount = caps.maxImageCount;
    }
 
    VkImageUsageFlags usageFlags = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT |
                                   VK_IMAGE_USAGE_TRANSFER_SRC_BIT |
                                   VK_IMAGE_USAGE_TRANSFER_DST_BIT;
    SkASSERT((caps.supportedUsageFlags & usageFlags) == usageFlags);
    if (caps.supportedUsageFlags & VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT) {
        usageFlags |= VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT;
    }
    if (caps.supportedUsageFlags & VK_IMAGE_USAGE_SAMPLED_BIT) {
        usageFlags |= VK_IMAGE_USAGE_SAMPLED_BIT;
    }
    SkASSERT(caps.supportedTransforms & caps.currentTransform);
    SkASSERT(caps.supportedCompositeAlpha & (VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR |
                                             VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR));
    VkCompositeAlphaFlagBitsKHR composite_alpha =
        (caps.supportedCompositeAlpha & VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR) ?
                                        VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR :
                                        VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
 
    // Pick our surface format.
    VkFormat surfaceFormat = VK_FORMAT_UNDEFINED;
    VkColorSpaceKHR colorSpace = VK_COLORSPACE_SRGB_NONLINEAR_KHR;
    for (uint32_t i = 0; i < surfaceFormatCount; ++i) {
        VkFormat localFormat = surfaceFormats[i].format;
        if (skgpu::graphite::vkFormatIsSupported(localFormat)) {
            surfaceFormat = localFormat;
            colorSpace = surfaceFormats[i].colorSpace;
            break;
        }
    }
    fDisplayParams = params;
    fSampleCount = std::max(1, params.fMSAASampleCount);
    fStencilBits = 8;
 
    if (VK_FORMAT_UNDEFINED == surfaceFormat) {
        return false;
    }
 
    SkColorType colorType;
    switch (surfaceFormat) {
        case VK_FORMAT_R8G8B8A8_UNORM: // fall through
        case VK_FORMAT_R8G8B8A8_SRGB:
            colorType = kRGBA_8888_SkColorType;
            break;
        case VK_FORMAT_B8G8R8A8_UNORM: // fall through
            colorType = kBGRA_8888_SkColorType;
            break;
        default:
            return false;
    }
 
    // If mailbox mode is available, use it, as it is the lowest-latency non-
    // tearing mode. If not, fall back to FIFO which is always available.
    VkPresentModeKHR mode = VK_PRESENT_MODE_FIFO_KHR;
    bool hasImmediate = false;
    for (uint32_t i = 0; i < presentModeCount; ++i) {
        // use mailbox
        if (VK_PRESENT_MODE_MAILBOX_KHR == presentModes[i]) {
            mode = VK_PRESENT_MODE_MAILBOX_KHR;
        }
        if (VK_PRESENT_MODE_IMMEDIATE_KHR == presentModes[i]) {
            hasImmediate = true;
        }
    }
    if (params.fDisableVsync && hasImmediate) {
        mode = VK_PRESENT_MODE_IMMEDIATE_KHR;
    }
 
    VkSwapchainCreateInfoKHR swapchainCreateInfo;
    memset(&swapchainCreateInfo, 0, sizeof(VkSwapchainCreateInfoKHR));
    swapchainCreateInfo.sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR;
    swapchainCreateInfo.flags = fDisplayParams.fCreateProtectedNativeBackend
                                ? VK_SWAPCHAIN_CREATE_PROTECTED_BIT_KHR
                                : 0;
    swapchainCreateInfo.surface = fSurface;
    swapchainCreateInfo.minImageCount = imageCount;
    swapchainCreateInfo.imageFormat = surfaceFormat;
    swapchainCreateInfo.imageColorSpace = colorSpace;
    swapchainCreateInfo.imageExtent = extent;
    swapchainCreateInfo.imageArrayLayers = 1;
    swapchainCreateInfo.imageUsage = usageFlags;
 
    uint32_t queueFamilies[] = { fGraphicsQueueIndex, fPresentQueueIndex };
    if (fGraphicsQueueIndex != fPresentQueueIndex) {
        swapchainCreateInfo.imageSharingMode = VK_SHARING_MODE_CONCURRENT;
        swapchainCreateInfo.queueFamilyIndexCount = 2;
        swapchainCreateInfo.pQueueFamilyIndices = queueFamilies;
    } else {
        swapchainCreateInfo.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;
        swapchainCreateInfo.queueFamilyIndexCount = 0;
        swapchainCreateInfo.pQueueFamilyIndices = nullptr;
    }
 
    swapchainCreateInfo.preTransform = VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR;
    swapchainCreateInfo.compositeAlpha = composite_alpha;
    swapchainCreateInfo.presentMode = mode;
    swapchainCreateInfo.clipped = true;
    swapchainCreateInfo.oldSwapchain = fSwapchain;
 
    res = fCreateSwapchainKHR(fDevice, &swapchainCreateInfo, nullptr, &fSwapchain);
    if (VK_SUCCESS != res) {
        return false;
    }
 
    // destroy the old swapchain
    if (swapchainCreateInfo.oldSwapchain != VK_NULL_HANDLE) {
        fDeviceWaitIdle(fDevice);
 
        this->destroyBuffers();
 
        fDestroySwapchainKHR(fDevice, swapchainCreateInfo.oldSwapchain, nullptr);
        swapchainCreateInfo.oldSwapchain = VK_NULL_HANDLE;
    }
 
    if (!this->createBuffers(swapchainCreateInfo.imageFormat, usageFlags, colorType,
                             swapchainCreateInfo.imageSharingMode)) {
        fDeviceWaitIdle(fDevice);
 
        this->destroyBuffers();
 
        fDestroySwapchainKHR(fDevice, swapchainCreateInfo.oldSwapchain, nullptr);
        swapchainCreateInfo.oldSwapchain = VK_NULL_HANDLE;
    }
 
    return true;
}
 
bool GraphiteVulkanWindowContext::createBuffers(VkFormat format,
                                                VkImageUsageFlags usageFlags,
                                                SkColorType colorType,
                                                VkSharingMode sharingMode) {
    fGetSwapchainImagesKHR(fDevice, fSwapchain, &fImageCount, nullptr);
    SkASSERT(fImageCount);
    fImages = new VkImage[fImageCount];
    fGetSwapchainImagesKHR(fDevice, fSwapchain, &fImageCount, fImages);
 
    // set up initial image layouts and create surfaces
    fImageLayouts = new VkImageLayout[fImageCount];
    fSurfaces = new sk_sp<SkSurface>[fImageCount];
    for (uint32_t i = 0; i < fImageCount; ++i) {
        fImageLayouts[i] = VK_IMAGE_LAYOUT_UNDEFINED;
 
        skgpu::graphite::VulkanTextureInfo info;
        info.fImageTiling = VK_IMAGE_TILING_OPTIMAL;
        info.fFormat = format;
        info.fImageUsageFlags = usageFlags;
        info.fSharingMode = sharingMode;
        info.fFlags = fDisplayParams.fCreateProtectedNativeBackend ? VK_IMAGE_CREATE_PROTECTED_BIT
                                                                   : 0;
 
        skgpu::graphite::BackendTexture backendTex(this->dimensions(),
                                                   info,
                                                   VK_IMAGE_LAYOUT_UNDEFINED,
                                                   fPresentQueueIndex,
                                                   fImages[i],
                                                   skgpu::VulkanAlloc());
 
        fSurfaces[i] = SkSurfaces::WrapBackendTexture(this->graphiteRecorder(),
                                                      backendTex,
                                                      colorType,
                                                      fDisplayParams.fColorSpace,
                                                      &fDisplayParams.fSurfaceProps);
 
        if (!fSurfaces[i]) {
            return false;
        }
    }
 
    // set up the backbuffers
    VkSemaphoreCreateInfo semaphoreInfo;
    memset(&semaphoreInfo, 0, sizeof(VkSemaphoreCreateInfo));
    semaphoreInfo.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;
    semaphoreInfo.pNext = nullptr;
    semaphoreInfo.flags = 0;
 
    // we create one additional backbuffer structure here, because we want to
    // give the command buffers they contain a chance to finish before we cycle back
    fBackbuffers = new BackbufferInfo[fImageCount + 1];
    for (uint32_t i = 0; i < fImageCount + 1; ++i) {
        fBackbuffers[i].fImageIndex = -1;
        VkResult result;
        VULKAN_CALL_RESULT_NOCHECK(
                fInterface,
                result,
                CreateSemaphore(
                        fDevice, &semaphoreInfo, nullptr, &fBackbuffers[i].fRenderSemaphore));
    }
    fCurrentBackbufferIndex = fImageCount;
 
    return true;
}
 
void GraphiteVulkanWindowContext::destroyBuffers() {
    if (fBackbuffers) {
        for (uint32_t i = 0; i < fImageCount + 1; ++i) {
            fBackbuffers[i].fImageIndex = -1;
            VULKAN_CALL(fInterface,
                        DestroySemaphore(fDevice,
                                         fBackbuffers[i].fRenderSemaphore,
                                         nullptr));
        }
    }
 
    delete[] fBackbuffers;
    fBackbuffers = nullptr;
 
    // Does this actually free the surfaces?
    delete[] fSurfaces;
    fSurfaces = nullptr;
    delete[] fImageLayouts;
    fImageLayouts = nullptr;
    delete[] fImages;
    fImages = nullptr;
}
 
GraphiteVulkanWindowContext::~GraphiteVulkanWindowContext() {
   this->destroyContext();
}
 
void GraphiteVulkanWindowContext::destroyContext() {
    if (this->isValid()) {
        fQueueWaitIdle(fPresentQueue);
        fDeviceWaitIdle(fDevice);
 
        if (fWaitSemaphore != VK_NULL_HANDLE) {
            VULKAN_CALL(fInterface, DestroySemaphore(fDevice, fWaitSemaphore, nullptr));
            fWaitSemaphore = VK_NULL_HANDLE;
        }
 
        this->destroyBuffers();
 
        if (fSwapchain != VK_NULL_HANDLE) {
            fDestroySwapchainKHR(fDevice, fSwapchain, nullptr);
            fSwapchain = VK_NULL_HANDLE;
        }
 
        if (fSurface != VK_NULL_HANDLE) {
            fDestroySurfaceKHR(fInstance, fSurface, nullptr);
            fSurface = VK_NULL_HANDLE;
        }
    }
 
    if (fGraphiteContext) {
        fGraphiteRecorder.reset();
        fGraphiteContext.reset();
    }
    fInterface.reset();
 
    if (fDevice != VK_NULL_HANDLE) {
        fDestroyDevice(fDevice, nullptr);
        fDevice = VK_NULL_HANDLE;
    }
 
#ifdef SK_ENABLE_VK_LAYERS
    if (fDebugCallback != VK_NULL_HANDLE) {
        fDestroyDebugReportCallbackEXT(fInstance, fDebugCallback, nullptr);
    }
#endif
 
    fPhysicalDevice = VK_NULL_HANDLE;
 
    if (fInstance != VK_NULL_HANDLE) {
        fDestroyInstance(fInstance, nullptr);
        fInstance = VK_NULL_HANDLE;
    }
}
 
GraphiteVulkanWindowContext::BackbufferInfo* GraphiteVulkanWindowContext::getAvailableBackbuffer() {
    SkASSERT(fBackbuffers);
 
    ++fCurrentBackbufferIndex;
    if (fCurrentBackbufferIndex > fImageCount) {
        fCurrentBackbufferIndex = 0;
    }
 
    BackbufferInfo* backbuffer = fBackbuffers + fCurrentBackbufferIndex;
    return backbuffer;
}
 
sk_sp<SkSurface> GraphiteVulkanWindowContext::getBackbufferSurface() {
    BackbufferInfo* backbuffer = this->getAvailableBackbuffer();
    SkASSERT(backbuffer);
 
    // semaphores should be in unsignaled state
    VkSemaphoreCreateInfo semaphoreInfo;
    memset(&semaphoreInfo, 0, sizeof(VkSemaphoreCreateInfo));
    semaphoreInfo.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;
    semaphoreInfo.pNext = nullptr;
    semaphoreInfo.flags = 0;
    VkResult result;
    VULKAN_CALL_RESULT_NOCHECK(
            fInterface, result, CreateSemaphore(fDevice, &semaphoreInfo, nullptr, &fWaitSemaphore));
 
    // acquire the image
    VkResult res = fAcquireNextImageKHR(fDevice, fSwapchain, UINT64_MAX,
                                        fWaitSemaphore, VK_NULL_HANDLE,
                                        &backbuffer->fImageIndex);
    if (VK_ERROR_SURFACE_LOST_KHR == res) {
        // TODO: Recreate fSurface using fCreateVkSurfaceFn, and then rebuild the swapchain
        VULKAN_CALL(fInterface, DestroySemaphore(fDevice, fWaitSemaphore, nullptr));
        return nullptr;
    }
    if (VK_ERROR_OUT_OF_DATE_KHR == res) {
        // tear swapchain down and try again
        if (!this->createSwapchain(-1, -1, fDisplayParams)) {
            VULKAN_CALL(fInterface, DestroySemaphore(fDevice, fWaitSemaphore, nullptr));
            return nullptr;
        }
        backbuffer = this->getAvailableBackbuffer();
 
        // acquire the image
        res = fAcquireNextImageKHR(fDevice, fSwapchain, UINT64_MAX,
                                   fWaitSemaphore, VK_NULL_HANDLE,
                                   &backbuffer->fImageIndex);
 
        if (VK_SUCCESS != res) {
            VULKAN_CALL(fInterface, DestroySemaphore(fDevice, fWaitSemaphore, nullptr));
            return nullptr;
        }
    }
 
    SkSurface* surface = fSurfaces[backbuffer->fImageIndex].get();
 
    return sk_ref_sp(surface);
}
 
void GraphiteVulkanWindowContext::onSwapBuffers() {
    if (!fGraphiteContext) {
        return;
    }
    SkASSERT(fGraphiteRecorder);
 
    BackbufferInfo* backbuffer = fBackbuffers + fCurrentBackbufferIndex;
 
    std::unique_ptr<skgpu::graphite::Recording> recording = fGraphiteRecorder->snap();
    if (recording) {
        skgpu::graphite::InsertRecordingInfo info;
        info.fRecording = recording.get();
 
        // set up surface for layout transition
        info.fTargetSurface = fSurfaces[backbuffer->fImageIndex].get();
        skgpu::MutableTextureState presentState = skgpu::MutableTextureStates::MakeVulkan(
                VK_IMAGE_LAYOUT_PRESENT_SRC_KHR, fPresentQueueIndex);
        info.fTargetTextureState = &presentState;
 
        SkASSERT(fWaitSemaphore != VK_NULL_HANDLE);
        skgpu::graphite::BackendSemaphore beWaitSemaphore(fWaitSemaphore);
        info.fNumWaitSemaphores = 1;
        info.fWaitSemaphores = &beWaitSemaphore;
        skgpu::graphite::BackendSemaphore beSignalSemaphore(backbuffer->fRenderSemaphore);
        info.fNumSignalSemaphores = 1;
        info.fSignalSemaphores = &beSignalSemaphore;
 
        // Insert finishedProc to delete waitSemaphore when done
        struct FinishContext {
            sk_sp<const skgpu::VulkanInterface> interface;
            VkDevice device;
            VkSemaphore waitSemaphore;
        };
        auto* finishContext = new FinishContext{fInterface, fDevice, fWaitSemaphore};
        skgpu::graphite::GpuFinishedProc finishCallback = [](skgpu::graphite::GpuFinishedContext c,
                                                                 skgpu::CallbackResult status) {
            // regardless of the status we need to destroy the semaphore
            const auto* context = reinterpret_cast<const FinishContext*>(c);
            VULKAN_CALL(context->interface,
                        DestroySemaphore(context->device, context->waitSemaphore, nullptr));
        };
        info.fFinishedContext = finishContext;
        info.fFinishedProc = finishCallback;
 
        fGraphiteContext->insertRecording(info);
        fGraphiteContext->submit(skgpu::graphite::SyncToCpu::kNo);
        fWaitSemaphore = VK_NULL_HANDLE; // FinishCallback will destroy this
    }
 
    // Submit present operation to present queue
    const VkPresentInfoKHR presentInfo =
    {
        VK_STRUCTURE_TYPE_PRESENT_INFO_KHR, // sType
        nullptr, // pNext
        1, // waitSemaphoreCount
        &backbuffer->fRenderSemaphore, // pWaitSemaphores
        1, // swapchainCount
        &fSwapchain, // pSwapchains
        &backbuffer->fImageIndex, // pImageIndices
        nullptr // pResults
    };
 
    fQueuePresentKHR(fPresentQueue, &presentInfo);
}
 
}   //namespace skwindow::internal