shiny/driver/gldriver/win32.go - exp - Git at Google

 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 //go:build windows
 // +build windows

 package gldriver

 import (
 	"errors"
 	"fmt"
 	"runtime"
 	"syscall"
 	"unsafe"

 	"golang.org/x/exp/shiny/driver/internal/win32"
 	"golang.org/x/exp/shiny/screen"
 	"golang.org/x/mobile/event/key"
 	"golang.org/x/mobile/event/lifecycle"
 	"golang.org/x/mobile/event/mouse"
 	"golang.org/x/mobile/event/paint"
 	"golang.org/x/mobile/event/size"
 	"golang.org/x/mobile/gl"
 )

 // TODO: change this to true, after manual testing on Win32.
 const useLifecycler = false

 // TODO: change this to true, after manual testing on Win32.
 const handleSizeEventsAtChannelReceive = false

 func main(f func(screen.Screen)) error {
 	return win32.Main(func() { f(theScreen) })
 }

 var (
 	eglGetPlatformDisplayEXT = gl.LibEGL.NewProc("eglGetPlatformDisplayEXT")
 	eglInitialize            = gl.LibEGL.NewProc("eglInitialize")
 	eglChooseConfig          = gl.LibEGL.NewProc("eglChooseConfig")
 	eglGetError              = gl.LibEGL.NewProc("eglGetError")
 	eglBindAPI               = gl.LibEGL.NewProc("eglBindAPI")
 	eglCreateWindowSurface   = gl.LibEGL.NewProc("eglCreateWindowSurface")
 	eglCreateContext         = gl.LibEGL.NewProc("eglCreateContext")
 	eglMakeCurrent           = gl.LibEGL.NewProc("eglMakeCurrent")
 	eglSwapInterval          = gl.LibEGL.NewProc("eglSwapInterval")
 	eglDestroySurface        = gl.LibEGL.NewProc("eglDestroySurface")
 	eglSwapBuffers           = gl.LibEGL.NewProc("eglSwapBuffers")
 )

 type eglConfig uintptr // void*

 type eglInt int32

 var rgb888 = [...]eglInt{
 	_EGL_RENDERABLE_TYPE, _EGL_OPENGL_ES2_BIT,
 	_EGL_SURFACE_TYPE, _EGL_WINDOW_BIT,
 	_EGL_BLUE_SIZE, 8,
 	_EGL_GREEN_SIZE, 8,
 	_EGL_RED_SIZE, 8,
 	_EGL_DEPTH_SIZE, 16,
 	_EGL_STENCIL_SIZE, 8,
 	_EGL_NONE,
 }

 type ctxWin32 struct {
 	ctx     uintptr
 	display uintptr // EGLDisplay
 	surface uintptr // EGLSurface
 }

 func newWindow(opts *screen.NewWindowOptions) (uintptr, error) {
 	w, err := win32.NewWindow(opts)
 	if err != nil {
 		return 0, err
 	}
 	return uintptr(w), nil
 }

 func initWindow(w *windowImpl) {
 	w.glctx, w.worker = gl.NewContext()
 }

 func showWindow(w *windowImpl) {
 	// Show makes an initial call to sizeEvent (via win32.SizeEvent), where
 	// we setup the EGL surface and GL context.
 	win32.Show(syscall.Handle(w.id))
 }

 func closeWindow(id uintptr) {} // TODO

 func drawLoop(w *windowImpl) {
 	runtime.LockOSThread()

 	display := w.ctx.(ctxWin32).display
 	surface := w.ctx.(ctxWin32).surface
 	ctx := w.ctx.(ctxWin32).ctx

 	if ret, _, _ := eglMakeCurrent.Call(display, surface, surface, ctx); ret == 0 {
 		panic(fmt.Sprintf("eglMakeCurrent failed: %v", eglErr()))
 	}

 	// TODO(crawshaw): exit this goroutine on Release.
 	workAvailable := w.worker.WorkAvailable()
 	for {
 		select {
 		case <-workAvailable:
 			w.worker.DoWork()
 		case <-w.publish:
 		loop:
 			for {
 				select {
 				case <-workAvailable:
 					w.worker.DoWork()
 				default:
 					break loop
 				}
 			}
 			if ret, _, _ := eglSwapBuffers.Call(display, surface); ret == 0 {
 				panic(fmt.Sprintf("eglSwapBuffers failed: %v", eglErr()))
 			}
 			w.publishDone <- screen.PublishResult{}
 		}
 	}
 }

 func init() {
 	win32.SizeEvent = sizeEvent
 	win32.PaintEvent = paintEvent
 	win32.MouseEvent = mouseEvent
 	win32.KeyEvent = keyEvent
 	win32.LifecycleEvent = lifecycleEvent
 }

 func lifecycleEvent(hwnd syscall.Handle, to lifecycle.Stage) {
 	theScreen.mu.Lock()
 	w := theScreen.windows[uintptr(hwnd)]
 	theScreen.mu.Unlock()

 	if w.lifecycleStage == to {
 		return
 	}
 	w.Send(lifecycle.Event{
 		From:        w.lifecycleStage,
 		To:          to,
 		DrawContext: w.glctx,
 	})
 	w.lifecycleStage = to
 }

 func mouseEvent(hwnd syscall.Handle, e mouse.Event) {
 	theScreen.mu.Lock()
 	w := theScreen.windows[uintptr(hwnd)]
 	theScreen.mu.Unlock()

 	w.Send(e)
 }

 func keyEvent(hwnd syscall.Handle, e key.Event) {
 	theScreen.mu.Lock()
 	w := theScreen.windows[uintptr(hwnd)]
 	theScreen.mu.Unlock()

 	w.Send(e)
 }

 func paintEvent(hwnd syscall.Handle, e paint.Event) {
 	theScreen.mu.Lock()
 	w := theScreen.windows[uintptr(hwnd)]
 	theScreen.mu.Unlock()

 	if w.ctx == nil {
 		// Sometimes a paint event comes in before initial
 		// window size is set. Ignore it.
 		return
 	}

 	// TODO: the paint.Event should have External: true.
 	w.Send(paint.Event{})
 }

 func sizeEvent(hwnd syscall.Handle, e size.Event) {
 	theScreen.mu.Lock()
 	w := theScreen.windows[uintptr(hwnd)]
 	theScreen.mu.Unlock()

 	if w.ctx == nil {
 		// This is the initial size event on window creation.
 		// Create an EGL surface and spin up a GL context.
 		if err := createEGLSurface(hwnd, w); err != nil {
 			panic(err)
 		}
 		go drawLoop(w)
 	}

 	if !handleSizeEventsAtChannelReceive {
 		w.szMu.Lock()
 		w.sz = e
 		w.szMu.Unlock()
 	}

 	w.Send(e)

 	if handleSizeEventsAtChannelReceive {
 		return
 	}

 	// Screen is dirty, generate a paint event.
 	//
 	// The sizeEvent function is called on the goroutine responsible for
 	// calling the GL worker.DoWork. When compiling with -tags gldebug,
 	// these GL calls are blocking (so we can read the error message), so
 	// to make progress they need to happen on another goroutine.
 	go func() {
 		// TODO: this call to Viewport is not right, but is very hard to
 		// do correctly with our async events channel model. We want
 		// the call to Viewport to be made the instant before the
 		// paint.Event is received.
 		w.glctxMu.Lock()
 		w.glctx.Viewport(0, 0, e.WidthPx, e.HeightPx)
 		w.glctx.ClearColor(0, 0, 0, 1)
 		w.glctx.Clear(gl.COLOR_BUFFER_BIT)
 		w.glctxMu.Unlock()

 		w.Send(paint.Event{})
 	}()
 }

 func eglErr() error {
 	if ret, _, _ := eglGetError.Call(); ret != _EGL_SUCCESS {
 		return errors.New(eglErrString(ret))
 	}
 	return nil
 }

 func createEGLSurface(hwnd syscall.Handle, w *windowImpl) error {
 	var displayAttribPlatforms = [][]eglInt{
 		// Default
 		[]eglInt{
 			_EGL_PLATFORM_ANGLE_TYPE_ANGLE,
 			_EGL_PLATFORM_ANGLE_TYPE_DEFAULT_ANGLE,
 			_EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, _EGL_DONT_CARE,
 			_EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, _EGL_DONT_CARE,
 			_EGL_NONE,
 		},
 		// Direct3D 11
 		[]eglInt{
 			_EGL_PLATFORM_ANGLE_TYPE_ANGLE,
 			_EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,
 			_EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, _EGL_DONT_CARE,
 			_EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, _EGL_DONT_CARE,
 			_EGL_NONE,
 		},
 		// Direct3D 9
 		[]eglInt{
 			_EGL_PLATFORM_ANGLE_TYPE_ANGLE,
 			_EGL_PLATFORM_ANGLE_TYPE_D3D9_ANGLE,
 			_EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, _EGL_DONT_CARE,
 			_EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, _EGL_DONT_CARE,
 			_EGL_NONE,
 		},
 		// Direct3D 11 with WARP
 		//   https://msdn.microsoft.com/en-us/library/windows/desktop/gg615082.aspx
 		[]eglInt{
 			_EGL_PLATFORM_ANGLE_TYPE_ANGLE,
 			_EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,
 			_EGL_PLATFORM_ANGLE_DEVICE_TYPE_ANGLE,
 			_EGL_PLATFORM_ANGLE_DEVICE_TYPE_WARP_ANGLE,
 			_EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, _EGL_DONT_CARE,
 			_EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, _EGL_DONT_CARE,
 			_EGL_NONE,
 		},
 	}

 	dc, err := win32.GetDC(hwnd)
 	if err != nil {
 		return fmt.Errorf("win32.GetDC failed: %v", err)
 	}

 	var display uintptr = _EGL_NO_DISPLAY
 	for i, displayAttrib := range displayAttribPlatforms {
 		lastTry := i == len(displayAttribPlatforms)-1

 		display, _, _ = eglGetPlatformDisplayEXT.Call(
 			_EGL_PLATFORM_ANGLE_ANGLE,
 			uintptr(dc),
 			uintptr(unsafe.Pointer(&displayAttrib[0])),
 		)

 		if display == _EGL_NO_DISPLAY {
 			if !lastTry {
 				continue
 			}
 			return fmt.Errorf("eglGetPlatformDisplayEXT failed: %v", eglErr())
 		}

 		if ret, _, _ := eglInitialize.Call(display, 0, 0); ret == 0 {
 			if !lastTry {
 				continue
 			}
 			return fmt.Errorf("eglInitialize failed: %v", eglErr())
 		}
 	}

 	eglBindAPI.Call(_EGL_OPENGL_ES_API)
 	if err := eglErr(); err != nil {
 		return err
 	}

 	var numConfigs eglInt
 	var config eglConfig
 	ret, _, _ := eglChooseConfig.Call(
 		display,
 		uintptr(unsafe.Pointer(&rgb888[0])),
 		uintptr(unsafe.Pointer(&config)),
 		1,
 		uintptr(unsafe.Pointer(&numConfigs)),
 	)
 	if ret == 0 {
 		return fmt.Errorf("eglChooseConfig failed: %v", eglErr())
 	}
 	if numConfigs <= 0 {
 		return errors.New("eglChooseConfig found no valid config")
 	}

 	surface, _, _ := eglCreateWindowSurface.Call(display, uintptr(config), uintptr(hwnd), 0, 0)
 	if surface == _EGL_NO_SURFACE {
 		return fmt.Errorf("eglCreateWindowSurface failed: %v", eglErr())
 	}

 	contextAttribs := [...]eglInt{
 		_EGL_CONTEXT_CLIENT_VERSION, 2,
 		_EGL_NONE,
 	}
 	context, _, _ := eglCreateContext.Call(
 		display,
 		uintptr(config),
 		_EGL_NO_CONTEXT,
 		uintptr(unsafe.Pointer(&contextAttribs[0])),
 	)
 	if context == _EGL_NO_CONTEXT {
 		return fmt.Errorf("eglCreateContext failed: %v", eglErr())
 	}

 	eglSwapInterval.Call(display, 1)

 	w.ctx = ctxWin32{
 		ctx:     context,
 		display: display,
 		surface: surface,
 	}

 	return nil
 }

 func surfaceCreate() error {
 	return errors.New("gldriver: surface creation not implemented on windows")
 }
	// Copyright 2015 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	//go:build windows
	// +build windows

	package gldriver

	import (
	"errors"
	"fmt"
	"runtime"
	"syscall"
	"unsafe"

	"golang.org/x/exp/shiny/driver/internal/win32"
	"golang.org/x/exp/shiny/screen"
	"golang.org/x/mobile/event/key"
	"golang.org/x/mobile/event/lifecycle"
	"golang.org/x/mobile/event/mouse"
	"golang.org/x/mobile/event/paint"
	"golang.org/x/mobile/event/size"
	"golang.org/x/mobile/gl"
	)

	// TODO: change this to true, after manual testing on Win32.
	const useLifecycler = false

	// TODO: change this to true, after manual testing on Win32.
	const handleSizeEventsAtChannelReceive = false

	func main(f func(screen.Screen)) error {
	return win32.Main(func() { f(theScreen) })
	}

	var (
	eglGetPlatformDisplayEXT = gl.LibEGL.NewProc("eglGetPlatformDisplayEXT")
	eglInitialize = gl.LibEGL.NewProc("eglInitialize")
	eglChooseConfig = gl.LibEGL.NewProc("eglChooseConfig")
	eglGetError = gl.LibEGL.NewProc("eglGetError")
	eglBindAPI = gl.LibEGL.NewProc("eglBindAPI")
	eglCreateWindowSurface = gl.LibEGL.NewProc("eglCreateWindowSurface")
	eglCreateContext = gl.LibEGL.NewProc("eglCreateContext")
	eglMakeCurrent = gl.LibEGL.NewProc("eglMakeCurrent")
	eglSwapInterval = gl.LibEGL.NewProc("eglSwapInterval")
	eglDestroySurface = gl.LibEGL.NewProc("eglDestroySurface")
	eglSwapBuffers = gl.LibEGL.NewProc("eglSwapBuffers")
	)

	type eglConfig uintptr // void*

	type eglInt int32

	var rgb888 = [...]eglInt{
	_EGL_RENDERABLE_TYPE, _EGL_OPENGL_ES2_BIT,
	_EGL_SURFACE_TYPE, _EGL_WINDOW_BIT,
	_EGL_BLUE_SIZE, 8,
	_EGL_GREEN_SIZE, 8,
	_EGL_RED_SIZE, 8,
	_EGL_DEPTH_SIZE, 16,
	_EGL_STENCIL_SIZE, 8,
	_EGL_NONE,
	}

	type ctxWin32 struct {
	ctx uintptr
	display uintptr // EGLDisplay
	surface uintptr // EGLSurface
	}

	func newWindow(opts *screen.NewWindowOptions) (uintptr, error) {
	w, err := win32.NewWindow(opts)
	if err != nil {
	return 0, err
	}
	return uintptr(w), nil
	}

	func initWindow(w *windowImpl) {
	w.glctx, w.worker = gl.NewContext()
	}

	func showWindow(w *windowImpl) {
	// Show makes an initial call to sizeEvent (via win32.SizeEvent), where
	// we setup the EGL surface and GL context.
	win32.Show(syscall.Handle(w.id))
	}

	func closeWindow(id uintptr) {} // TODO

	func drawLoop(w *windowImpl) {
	runtime.LockOSThread()

	display := w.ctx.(ctxWin32).display
	surface := w.ctx.(ctxWin32).surface
	ctx := w.ctx.(ctxWin32).ctx

	if ret, _, _ := eglMakeCurrent.Call(display, surface, surface, ctx); ret == 0 {
	panic(fmt.Sprintf("eglMakeCurrent failed: %v", eglErr()))
	}

	// TODO(crawshaw): exit this goroutine on Release.
	workAvailable := w.worker.WorkAvailable()
	for {
	select {
	case <-workAvailable:
	w.worker.DoWork()
	case <-w.publish:
	loop:
	for {
	select {
	case <-workAvailable:
	w.worker.DoWork()
	default:
	break loop
	}
	}
	if ret, _, _ := eglSwapBuffers.Call(display, surface); ret == 0 {
	panic(fmt.Sprintf("eglSwapBuffers failed: %v", eglErr()))
	}
	w.publishDone <- screen.PublishResult{}
	}
	}
	}

	func init() {
	win32.SizeEvent = sizeEvent
	win32.PaintEvent = paintEvent
	win32.MouseEvent = mouseEvent
	win32.KeyEvent = keyEvent
	win32.LifecycleEvent = lifecycleEvent
	}

	func lifecycleEvent(hwnd syscall.Handle, to lifecycle.Stage) {
	theScreen.mu.Lock()
	w := theScreen.windows[uintptr(hwnd)]
	theScreen.mu.Unlock()

	if w.lifecycleStage == to {
	return
	}
	w.Send(lifecycle.Event{
	From: w.lifecycleStage,
	To: to,
	DrawContext: w.glctx,
	})
	w.lifecycleStage = to
	}

	func mouseEvent(hwnd syscall.Handle, e mouse.Event) {
	theScreen.mu.Lock()
	w := theScreen.windows[uintptr(hwnd)]
	theScreen.mu.Unlock()

	w.Send(e)
	}

	func keyEvent(hwnd syscall.Handle, e key.Event) {
	theScreen.mu.Lock()
	w := theScreen.windows[uintptr(hwnd)]
	theScreen.mu.Unlock()

	w.Send(e)
	}

	func paintEvent(hwnd syscall.Handle, e paint.Event) {
	theScreen.mu.Lock()
	w := theScreen.windows[uintptr(hwnd)]
	theScreen.mu.Unlock()

	if w.ctx == nil {
	// Sometimes a paint event comes in before initial
	// window size is set. Ignore it.
	return
	}

	// TODO: the paint.Event should have External: true.
	w.Send(paint.Event{})
	}

	func sizeEvent(hwnd syscall.Handle, e size.Event) {
	theScreen.mu.Lock()
	w := theScreen.windows[uintptr(hwnd)]
	theScreen.mu.Unlock()

	if w.ctx == nil {
	// This is the initial size event on window creation.
	// Create an EGL surface and spin up a GL context.
	if err := createEGLSurface(hwnd, w); err != nil {
	panic(err)
	}
	go drawLoop(w)
	}

	if !handleSizeEventsAtChannelReceive {
	w.szMu.Lock()
	w.sz = e
	w.szMu.Unlock()
	}

	w.Send(e)

	if handleSizeEventsAtChannelReceive {
	return
	}

	// Screen is dirty, generate a paint event.
	//
	// The sizeEvent function is called on the goroutine responsible for
	// calling the GL worker.DoWork. When compiling with -tags gldebug,
	// these GL calls are blocking (so we can read the error message), so
	// to make progress they need to happen on another goroutine.
	go func() {
	// TODO: this call to Viewport is not right, but is very hard to
	// do correctly with our async events channel model. We want
	// the call to Viewport to be made the instant before the
	// paint.Event is received.
	w.glctxMu.Lock()
	w.glctx.Viewport(0, 0, e.WidthPx, e.HeightPx)
	w.glctx.ClearColor(0, 0, 0, 1)
	w.glctx.Clear(gl.COLOR_BUFFER_BIT)
	w.glctxMu.Unlock()

	w.Send(paint.Event{})
	}()
	}

	func eglErr() error {
	if ret, _, _ := eglGetError.Call(); ret != _EGL_SUCCESS {
	return errors.New(eglErrString(ret))
	}
	return nil
	}

	func createEGLSurface(hwnd syscall.Handle, w *windowImpl) error {
	var displayAttribPlatforms = [][]eglInt{
	// Default
	[]eglInt{
	_EGL_PLATFORM_ANGLE_TYPE_ANGLE,
	_EGL_PLATFORM_ANGLE_TYPE_DEFAULT_ANGLE,
	_EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, _EGL_DONT_CARE,
	_EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, _EGL_DONT_CARE,
	_EGL_NONE,
	},
	// Direct3D 11
	[]eglInt{
	_EGL_PLATFORM_ANGLE_TYPE_ANGLE,
	_EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,
	_EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, _EGL_DONT_CARE,
	_EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, _EGL_DONT_CARE,
	_EGL_NONE,
	},
	// Direct3D 9
	[]eglInt{
	_EGL_PLATFORM_ANGLE_TYPE_ANGLE,
	_EGL_PLATFORM_ANGLE_TYPE_D3D9_ANGLE,
	_EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, _EGL_DONT_CARE,
	_EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, _EGL_DONT_CARE,
	_EGL_NONE,
	},
	// Direct3D 11 with WARP
	// https://msdn.microsoft.com/en-us/library/windows/desktop/gg615082.aspx
	[]eglInt{
	_EGL_PLATFORM_ANGLE_TYPE_ANGLE,
	_EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,
	_EGL_PLATFORM_ANGLE_DEVICE_TYPE_ANGLE,
	_EGL_PLATFORM_ANGLE_DEVICE_TYPE_WARP_ANGLE,
	_EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, _EGL_DONT_CARE,
	_EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, _EGL_DONT_CARE,
	_EGL_NONE,
	},
	}

	dc, err := win32.GetDC(hwnd)
	if err != nil {
	return fmt.Errorf("win32.GetDC failed: %v", err)
	}

	var display uintptr = _EGL_NO_DISPLAY
	for i, displayAttrib := range displayAttribPlatforms {
	lastTry := i == len(displayAttribPlatforms)-1

	display, _, _ = eglGetPlatformDisplayEXT.Call(
	_EGL_PLATFORM_ANGLE_ANGLE,
	uintptr(dc),
	uintptr(unsafe.Pointer(&displayAttrib[0])),
	)

	if display == _EGL_NO_DISPLAY {
	if !lastTry {
	continue
	}
	return fmt.Errorf("eglGetPlatformDisplayEXT failed: %v", eglErr())
	}

	if ret, _, _ := eglInitialize.Call(display, 0, 0); ret == 0 {
	if !lastTry {
	continue
	}
	return fmt.Errorf("eglInitialize failed: %v", eglErr())
	}
	}

	eglBindAPI.Call(_EGL_OPENGL_ES_API)
	if err := eglErr(); err != nil {
	return err
	}

	var numConfigs eglInt
	var config eglConfig
	ret, _, _ := eglChooseConfig.Call(
	display,
	uintptr(unsafe.Pointer(&rgb888[0])),
	uintptr(unsafe.Pointer(&config)),
	1,
	uintptr(unsafe.Pointer(&numConfigs)),
	)
	if ret == 0 {
	return fmt.Errorf("eglChooseConfig failed: %v", eglErr())
	}
	if numConfigs <= 0 {
	return errors.New("eglChooseConfig found no valid config")
	}

	surface, _, _ := eglCreateWindowSurface.Call(display, uintptr(config), uintptr(hwnd), 0, 0)
	if surface == _EGL_NO_SURFACE {
	return fmt.Errorf("eglCreateWindowSurface failed: %v", eglErr())
	}

	contextAttribs := [...]eglInt{
	_EGL_CONTEXT_CLIENT_VERSION, 2,
	_EGL_NONE,
	}
	context, _, _ := eglCreateContext.Call(
	display,
	uintptr(config),
	_EGL_NO_CONTEXT,
	uintptr(unsafe.Pointer(&contextAttribs[0])),
	)
	if context == _EGL_NO_CONTEXT {
	return fmt.Errorf("eglCreateContext failed: %v", eglErr())
	}

	eglSwapInterval.Call(display, 1)

	w.ctx = ctxWin32{
	ctx: context,
	display: display,
	surface: surface,
	}

	return nil
	}

	func surfaceCreate() error {
	return errors.New("gldriver: surface creation not implemented on windows")
	}