src/dawn/native/opengl/SwapChainEGL.cpp

// Copyright 2024 The Dawn & Tint Authors
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#include "dawn/native/opengl/SwapChainEGL.h"

#include <utility>

#include "dawn/native/Surface.h"
#include "dawn/native/opengl/ContextEGL.h"
#include "dawn/native/opengl/DeviceGL.h"
#include "dawn/native/opengl/DisplayEGL.h"
#include "dawn/native/opengl/PhysicalDeviceGL.h"
#include "dawn/native/opengl/TextureGL.h"
#include "dawn/native/opengl/UtilsEGL.h"

namespace dawn::native::opengl {

// static
ResultOrError<Ref<SwapChainEGL>> SwapChainEGL::Create(Device* device,
                                                      Surface* surface,
                                                      SwapChainBase* previousSwapChain,
                                                      const SurfaceConfiguration* config) {
    Ref<SwapChainEGL> swapchain = AcquireRef(new SwapChainEGL(device, surface, config));
    DAWN_TRY(swapchain->Initialize(previousSwapChain));
    return swapchain;
}

SwapChainEGL::SwapChainEGL(DeviceBase* dev, Surface* sur, const SurfaceConfiguration* config)
    : SwapChainBase(dev, sur, config) {}

SwapChainEGL::~SwapChainEGL() = default;

MaybeError SwapChainEGL::Initialize(SwapChainBase* previousSwapChain) {
    const Device* device = ToBackend(GetDevice());

    if (previousSwapChain != nullptr) {
        // TODO(crbug.com/dawn/269): figure out what should happen when surfaces are used by
        // multiple backends one after the other. It probably needs to block until the backend
        // and GPU are completely finished with the previous swapchain.
        DAWN_INVALID_IF(previousSwapChain->GetBackendType() != GetBackendType(),
                        "OpenGL SwapChain cannot switch backend types from %s to %s.",
                        previousSwapChain->GetBackendType(), GetBackendType());

        // TODO(crbug.com/dawn/269): figure out what should happen when surfaces are used by
        // a different EGL display. We probably need to block until the GPU is completely
        // finished with the previous work, and then a bit more.
        DAWN_INVALID_IF(
            previousSwapChain->GetDevice()->GetPhysicalDevice() != device->GetPhysicalDevice(),
            "OpenGL SwapChain cannot switch between contexts for %s and %s.",
            previousSwapChain->GetDevice(), device);

        // The EGLSurface created depends on the format; only reuse it if we have the same one.
        if (previousSwapChain->GetFormat() == GetFormat()) {
            SwapChainEGL* previousEGLSwapChain =
                reinterpret_cast<SwapChainEGL*>(ToBackend(previousSwapChain));
            std::swap(previousEGLSwapChain->mEGLSurface, mEGLSurface);
        }

        previousSwapChain->DetachFromSurface();
    }

    const DisplayEGL* display = ToBackend(device->GetPhysicalDevice())->GetDisplay();

    // Create the EGLSurface if needed.
    if (mEGLSurface == EGL_NO_SURFACE) {
        DAWN_TRY(CreateEGLSurface(display));
    }

    EGLint swapInterval = GetPresentMode() == wgpu::PresentMode::Immediate ? 0 : 1;
    display->egl.SwapInterval(display->GetDisplay(), swapInterval);

    return {};
}

MaybeError SwapChainEGL::PresentImpl() {
    Device* device = ToBackend(GetDevice());
    EGLDisplay display = device->GetEGLDisplay();
    const EGLFunctions& egl = device->GetEGL(false);

    // Do the reverse-Y blit from the fake surface texture to the default framebuffer.
    {
        auto surfaceCurrent = device->GetContext()->MakeSurfaceCurrentScope(mEGLSurface);
        EGLint surfaceWidth;
        EGLint surfaceHeight;
        DAWN_TRY(CheckEGL(egl, egl.QuerySurface(display, mEGLSurface, EGL_WIDTH, &surfaceWidth),
                          "getting surface width"));
        DAWN_TRY(CheckEGL(egl, egl.QuerySurface(display, mEGLSurface, EGL_HEIGHT, &surfaceHeight),
                          "getting surface height"));

        const OpenGLFunctions& gl = device->GetGL();

        GLuint readFbo = 0;
        gl.GenFramebuffers(1, &readFbo);
        gl.BindFramebuffer(GL_READ_FRAMEBUFFER, readFbo);
        mTextureView->BindToFramebuffer(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0);

        gl.BindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
        gl.Scissor(0, 0, surfaceWidth, surfaceHeight);
        gl.BlitFramebuffer(0, 0, mTexture->GetWidth(Aspect::Color),
                           mTexture->GetHeight(Aspect::Color), 0, surfaceHeight, surfaceWidth, 0,
                           GL_COLOR_BUFFER_BIT, GL_LINEAR);

        gl.DeleteFramebuffers(1, &readFbo);
    }

    egl.SwapBuffers(display, mEGLSurface);

    mTexture->APIDestroy();
    mTexture = nullptr;

    return {};
}

ResultOrError<SwapChainTextureInfo> SwapChainEGL::GetCurrentTextureImpl() {
    // Create the fake surface texture that we'll blit from.
    TextureDescriptor desc = GetSwapChainBaseTextureDescriptor(this);
    Ref<TextureBase> texture;
    Ref<TextureViewBase> view;
    DAWN_TRY_ASSIGN(texture, GetDevice()->CreateTexture(&desc));
    DAWN_TRY_ASSIGN(view, GetDevice()->CreateTextureView(texture.Get()));

    mTexture = std::move(ToBackend(texture));
    mTextureView = std::move(ToBackend(view));

    SwapChainTextureInfo info;
    info.texture = mTexture;
    info.status = wgpu::SurfaceGetCurrentTextureStatus::Success;
    // TODO(dawn:2320): Check for optimality
    info.suboptimal = false;
    return info;
}

void SwapChainEGL::DetachFromSurfaceImpl() {
    if (mEGLSurface != EGL_NO_SURFACE) {
        Device* device = ToBackend(GetDevice());
        device->GetEGL(false).DestroySurface(device->GetEGLDisplay(), mEGLSurface);
        mEGLSurface = EGL_NO_SURFACE;
    }

    if (mTexture != nullptr) {
        mTexture->APIDestroy();
        mTexture = nullptr;
        mTextureView = nullptr;
    }
}

MaybeError SwapChainEGL::CreateEGLSurface(const DisplayEGL* display) {
    DAWN_ASSERT(mEGLSurface == EGL_NO_SURFACE);

    EGLConfig config = display->ChooseConfig(EGL_WINDOW_BIT, GetFormat());
    if (config == kNoConfig) {
        return DAWN_FORMAT_INTERNAL_ERROR("Couldn't find an EGLConfig for %s on %s.", GetFormat(),
                                          GetSurface());
    }

    // [[maybe_unused]] to prevent unused variable warnings when platform code is disabled.
    [[maybe_unused]] const EGLFunctions& egl = display->egl;
    [[maybe_unused]] EGLDisplay eglDisplay = display->GetDisplay();
    Surface* surface = GetSurface();

    absl::InlinedVector<EGLint, 3> attribs;
    auto AddAttrib = [&](EGLint attrib, EGLint value) {
        attribs.push_back(attrib);
        attribs.push_back(value);
    };

    if (GetFormat() == wgpu::TextureFormat::RGBA8UnormSrgb) {
        DAWN_ASSERT(egl.HasExt(EGLExt::GLColorspace));
        AddAttrib(EGL_GL_COLORSPACE_KHR, EGL_GL_COLORSPACE_SRGB_KHR);
    }

    attribs.push_back(EGL_NONE);

    // Note that we cannot use ResultOrError<EGLSurface> as it might not have the required alignment
    // constraints.
    auto TryCreateSurface = [&]() -> MaybeError {
        switch (surface->GetType()) {
#if DAWN_PLATFORM_IS(ANDROID)
            case Surface::Type::AndroidWindow:
                mEGLSurface = egl.CreateWindowSurface(
                    eglDisplay, config,
                    static_cast<ANativeWindow*>(surface->GetAndroidNativeWindow()), attribs.data());
                return {};
#endif  // DAWN_PLATFORM_IS(ANDROID)
#if defined(DAWN_ENABLE_BACKEND_METAL)
            case Surface::Type::MetalLayer:
                mEGLSurface = egl.CreateWindowSurface(eglDisplay, config, surface->GetMetalLayer(),
                                                      attribs.data());
                return {};
#endif  // defined(DAWN_ENABLE_BACKEND_METAL)
#if DAWN_PLATFORM_IS(WIN32)
            case Surface::Type::WindowsHWND:
                mEGLSurface = egl.CreateWindowSurface(
                    eglDisplay, config, static_cast<HWND>(surface->GetHWND()), attribs.data());
                return {};
#endif  // DAWN_PLATFORM_IS(WIN32)
#if defined(DAWN_USE_X11)
            case Surface::Type::XlibWindow:
                mEGLSurface = egl.CreateWindowSurface(eglDisplay, config, surface->GetXWindow(),
                                                      attribs.data());
                return {};
#endif  // defined(DAWN_USE_X11)

            // TODO(344814083): Add support for creating surfaces using EGL_KHR_platform_base and
            // friends.
            case Surface::Type::WaylandSurface:

            default:
                return DAWN_FORMAT_INTERNAL_ERROR("%s cannot be supported on EGL.", surface);
        }
    };

    DAWN_TRY(TryCreateSurface());
    if (mEGLSurface == EGL_NO_SURFACE) {
        return DAWN_FORMAT_INTERNAL_ERROR("Couldn't create an EGLSurface for %s.", surface);
    }
    return {};
}

}  // namespace dawn::native::opengl