fixup

Signed-off-by: Elias Naur <mail@eliasnaur.com>

go.mod

@@ -3,22 +3,22 @@ module gioui.org/cmd
 go 1.17
 
 require (
-	gioui.org v0.0.0-20220328154813-a3f147541fd0
+	gioui.org v0.0.0-20220628163331-e21c665e70ae
 	github.com/akavel/rsrc v0.10.1
 	github.com/chromedp/cdproto v0.0.0-20191114225735-6626966fbae4
 	github.com/chromedp/chromedp v0.5.2
 	golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d
 	golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9
-	golang.org/x/text v0.3.6
+	golang.org/x/text v0.3.7
 	golang.org/x/tools v0.1.0
 )
 
 require (
 	gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2 // indirect
 	gioui.org/shader v1.0.6 // indirect
-	github.com/benoitkugler/textlayout v0.0.10 // indirect
+	github.com/benoitkugler/textlayout v0.1.1 // indirect
 	github.com/gioui/uax v0.2.1-0.20220325163150-e3d987515a12 // indirect
-	github.com/go-text/typesetting v0.0.0-20220112121102-58fe93c84506 // indirect
+	github.com/go-text/typesetting v0.0.0-20220411150340-35994bc27a7b // indirect
 	github.com/gobwas/httphead v0.0.0-20180130184737-2c6c146eadee // indirect
 	github.com/gobwas/pool v0.2.0 // indirect
 	github.com/gobwas/ws v1.0.2 // indirect

go.sum

@@ -1,5 +1,6 @@
-gioui.org v0.0.0-20220328154813-a3f147541fd0 h1:n4FUiCT6P4a2wF6hwX4a5R8TpjAhu/d+3nhwZW16MAI=
+eliasnaur.com/font v0.0.0-20220124212145-832bb8fc08c3 h1:djFprmHZgrSepsHAIRMp5UJn3PzsoTg9drI+BDmif5Q=
-gioui.org v0.0.0-20220328154813-a3f147541fd0/go.mod h1:b8vBukexG6eYuXZa14asjLAWJ+JjbZ/ophEnS2FjYUg=
+gioui.org v0.0.0-20220628163331-e21c665e70ae h1:s8Erm0/zVvi3Fbq0ijjPkRT04XxcGZWTxkxDwUBsxuQ=
+gioui.org v0.0.0-20220628163331-e21c665e70ae/go.mod h1:WHoHbUjH91BJS2xkfps2AhKxji+9o3xwfsphGsCBfnM=
 gioui.org/cpu v0.0.0-20210808092351-bfe733dd3334/go.mod h1:A8M0Cn5o+vY5LTMlnRoK3O5kG+rH0kWfJjeKd9QpBmQ=
 gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2 h1:AGDDxsJE1RpcXTAxPG2B4jrwVUJGFDjINIPi1jtO6pc=
 gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2/go.mod h1:A8M0Cn5o+vY5LTMlnRoK3O5kG+rH0kWfJjeKd9QpBmQ=
@@ -9,8 +10,9 @@ github.com/akavel/rsrc v0.10.1 h1:hCCPImjmFKVNGpeLZyTDRHEFC283DzyTXTo0cO0Rq9o=
 github.com/akavel/rsrc v0.10.1/go.mod h1:uLoCtb9J+EyAqh+26kdrTgmzRBFPGOolLWKpdxkKq+c=
 github.com/benoitkugler/pstokenizer v1.0.0/go.mod h1:l1G2Voirz0q/jj0TQfabNxVsa8HZXh/VMxFSRALWTiE=
 github.com/benoitkugler/textlayout v0.0.5/go.mod h1:puH4v13Uz7uIhIH0XMk5jgc8U3MXcn5r3VlV9K8n0D8=
-github.com/benoitkugler/textlayout v0.0.10 h1:uIaQgH4pBFw1LQ0tPkfjgxo94WYcckzzQaB41L2X84w=
+github.com/benoitkugler/textlayout v0.1.1 h1:hizE/085xAeY8q7gwV00uHR2Q27KYB2g1HW+UacXl68=
-github.com/benoitkugler/textlayout v0.0.10/go.mod h1:puH4v13Uz7uIhIH0XMk5jgc8U3MXcn5r3VlV9K8n0D8=
+github.com/benoitkugler/textlayout v0.1.1/go.mod h1:o+1hFV+JSHBC9qNLIuwVoLedERU7sBPgEFcuSgfvi/w=
+github.com/benoitkugler/textlayout-testdata v0.1.1 h1:AvFxBxpfrQd8v55qH59mZOJOQjtD6K2SFe9/HvnIbJk=
 github.com/chromedp/cdproto v0.0.0-20191114225735-6626966fbae4 h1:QD3KxSJ59L2lxG6MXBjNHxiQO2RmxTQ3XcK+wO44WOg=
 github.com/chromedp/cdproto v0.0.0-20191114225735-6626966fbae4/go.mod h1:PfAWWKJqjlGFYJEidUM6aVIWPr0EpobeyVWEEmplX7g=
 github.com/chromedp/chromedp v0.5.2 h1:W8xBXQuUnd2dZK0SN/lyVwsQM7KgW+kY5HGnntms194=
@@ -20,8 +22,8 @@ github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMo
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/gioui/uax v0.2.1-0.20220325163150-e3d987515a12 h1:1bjaB/5IIicfKpP4k0s30T2WEw//Kh00zULa8DQ0cxA=
 github.com/gioui/uax v0.2.1-0.20220325163150-e3d987515a12/go.mod h1:kDhBRTA/i3H46PVdhqcw26TdGSIj42TOKNWKY+Kipnw=
-github.com/go-text/typesetting v0.0.0-20220112121102-58fe93c84506 h1:1TPz/Gn/MsXwJ6bEtI9wdkPcQYr2X3V9I+wz4wPYUdY=
+github.com/go-text/typesetting v0.0.0-20220411150340-35994bc27a7b h1:WINlj3ANt+CVrO2B4NGDHRlPvEWZPxjhb7z+JKypwXI=
-github.com/go-text/typesetting v0.0.0-20220112121102-58fe93c84506/go.mod h1:R0mlTNeyszZ/tKQhbZA7SRGjx+OHsmNzgN2jTV7yZcs=
+github.com/go-text/typesetting v0.0.0-20220411150340-35994bc27a7b/go.mod h1:ZNYu5saGoMOqtkVH5T8onTwhzenDUVszI+5WFHJRaxQ=
 github.com/gobwas/httphead v0.0.0-20180130184737-2c6c146eadee h1:s+21KNqlpePfkah2I+gwHF8xmJWRjooY+5248k6m4A0=
 github.com/gobwas/httphead v0.0.0-20180130184737-2c6c146eadee/go.mod h1:L0fX3K22YWvt/FAX9NnzrNzcI4wNYi9Yku4O0LKYflo=
 github.com/gobwas/pool v0.2.0 h1:QEmUOlnSjWtnpRGHF3SauEiOsy82Cup83Vf2LcMlnc8=
@@ -60,7 +62,6 @@ golang.org/x/image v0.0.0-20210504121937-7319ad40d33e/go.mod h1:FeLwcggjj3mMvU+o
 golang.org/x/image v0.0.0-20210607152325-775e3b0c77b9/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
 golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d h1:RNPAfi2nHY7C2srAV8A49jpsYr0ADedCk1wq6fTMTvs=
 golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
-golang.org/x/mod v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.2 h1:Gz96sIWK3OalVv/I/qNygP42zyoKp3xptRVCWRFEBvo=
 golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
@@ -93,8 +94,9 @@ golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20201224043029-2b0845dc783e/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=

gogio/e2e_test.go

@@ -13,6 +13,7 @@ import (
 	"io/ioutil"
 	"os"
 	"os/exec"
+	"runtime"
 	"strings"
 	"testing"
 	"time"
@@ -69,27 +70,33 @@ func TestEndToEnd(t *testing.T) {
 	t.Parallel()
 
 	const (
-		testdataWithGoImportPkgPath = "gioui.org/cmd/gogio/testdata"
+		testdataWithGoImportPkgPath             = "gioui.org/cmd/gogio/internal/normal"
-		testdataWithRelativePkgPath = "testdata/testdata.go"
+		testdataWithRelativePkgPath             = "internal/normal/testdata.go"
+		customRenderTestdataWithRelativePkgPath = "internal/custom/testdata.go"
 	)
 	// Keep this list local, to not reuse TestDriver objects.
 	subtests := []struct {
-		name    string
+		name      string
-		driver  TestDriver
+		driver    TestDriver
-		pkgPath string
+		pkgPath   string
+		skipGeese string
 	}{
-		{"X11 using go import path", &X11TestDriver{}, testdataWithGoImportPkgPath},
+		{"X11 using go import path", &X11TestDriver{}, testdataWithGoImportPkgPath, ""},
-		{"X11", &X11TestDriver{}, testdataWithRelativePkgPath},
+		{"X11", &X11TestDriver{}, testdataWithRelativePkgPath, ""},
+		{"X11 with custom rendering", &X11TestDriver{}, customRenderTestdataWithRelativePkgPath, "openbsd"},
 		// Doesn't work on the builders.
 		//{"Wayland", &WaylandTestDriver{}, testdataWithRelativePkgPath},
-		{"JS", &JSTestDriver{}, testdataWithRelativePkgPath},
+		{"JS", &JSTestDriver{}, testdataWithRelativePkgPath, ""},
-		{"Android", &AndroidTestDriver{}, testdataWithRelativePkgPath},
+		{"Android", &AndroidTestDriver{}, testdataWithRelativePkgPath, ""},
-		{"Windows", &WineTestDriver{}, testdataWithRelativePkgPath},
+		{"Windows", &WineTestDriver{}, testdataWithRelativePkgPath, ""},
 	}
 
 	for _, subtest := range subtests {
 		t.Run(subtest.name, func(t *testing.T) {
 			subtest := subtest // copy the changing loop variable
+			if strings.Contains(subtest.skipGeese, runtime.GOOS) {
+				t.Skipf("not supported on %s", runtime.GOOS)
+			}
 			t.Parallel()
 			runEndToEndTest(t, subtest.driver, subtest.pkgPath)
 		})

gogio/internal/custom/testdata.go

@@ -0,0 +1,367 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+//go:build linux
+// +build linux
+
+// This program demonstrates the use of a custom OpenGL ES context with
+// app.Window.
+package main
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	"image/color"
+	"log"
+	"os"
+	"runtime"
+	"strings"
+	"unsafe"
+
+	"gioui.org/app"
+	"gioui.org/gpu"
+	"gioui.org/io/pointer"
+	"gioui.org/io/system"
+	"gioui.org/layout"
+	"gioui.org/op"
+	"gioui.org/op/clip"
+	"gioui.org/op/paint"
+)
+
+/*
+#cgo linux pkg-config: egl wayland-egl
+#cgo freebsd openbsd CFLAGS: -I/usr/local/include
+#cgo openbsd CFLAGS: -I/usr/X11R6/include
+#cgo freebsd LDFLAGS: -L/usr/local/lib
+#cgo openbsd LDFLAGS: -L/usr/X11R6/lib
+#cgo freebsd openbsd LDFLAGS: -lwayland-egl
+#cgo CFLAGS: -DEGL_NO_X11
+#cgo LDFLAGS: -lEGL -lGLESv2
+
+#include <EGL/egl.h>
+#include <wayland-client.h>
+#include <wayland-egl.h>
+#include <GLES3/gl3.h>
+#define EGL_EGLEXT_PROTOTYPES
+#include <EGL/eglext.h>
+
+*/
+import "C"
+
+func getDisplay(ve app.ViewEvent) C.EGLDisplay {
+	switch ve := ve.(type) {
+	case app.X11ViewEvent:
+		return C.eglGetDisplay(C.EGLNativeDisplayType(ve.Display))
+	case app.WaylandViewEvent:
+		return C.eglGetDisplay(C.EGLNativeDisplayType(ve.Display))
+	}
+	panic("no display available")
+}
+
+func nativeViewFor(e app.ViewEvent, size image.Point) (C.EGLNativeWindowType, func()) {
+	switch e := e.(type) {
+	case app.X11ViewEvent:
+		return C.EGLNativeWindowType(uintptr(e.Window)), func() {}
+	case app.WaylandViewEvent:
+		eglWin := C.wl_egl_window_create((*C.struct_wl_surface)(e.Surface), C.int(size.X), C.int(size.Y))
+		return C.EGLNativeWindowType(uintptr(unsafe.Pointer(eglWin))), func() {
+			C.wl_egl_window_destroy(eglWin)
+		}
+	}
+	panic("no native view available")
+}
+
+type (
+	C = layout.Context
+	D = layout.Dimensions
+)
+
+type notifyFrame int
+
+const (
+	notifyNone notifyFrame = iota
+	notifyInvalidate
+	notifyPrint
+)
+
+// notify keeps track of whether we want to print to stdout to notify the user
+// when a frame is ready. Initially we want to notify about the first frame.
+var notify = notifyInvalidate
+
+type eglContext struct {
+	disp    C.EGLDisplay
+	ctx     C.EGLContext
+	surf    C.EGLSurface
+	cleanup func()
+}
+
+func main() {
+	go func() {
+		// Set CustomRenderer so we can provide our own rendering context.
+		w := app.NewWindow(app.CustomRenderer(true))
+		if err := loop(w); err != nil {
+			log.Fatal(err)
+		}
+		os.Exit(0)
+	}()
+	app.Main()
+}
+
+func loop(w *app.Window) error {
+	var ops op.Ops
+	var (
+		ctx    *eglContext
+		gioCtx gpu.GPU
+		ve     app.ViewEvent
+		init   bool
+		size   image.Point
+	)
+
+	recreateContext := func() {
+		w.Run(func() {
+			if gioCtx != nil {
+				gioCtx.Release()
+				gioCtx = nil
+			}
+			if ctx != nil {
+				C.eglMakeCurrent(ctx.disp, nil, nil, nil)
+				ctx.Release()
+				ctx = nil
+			}
+			c, err := createContext(ve, size)
+			if err != nil {
+				log.Fatal(err)
+			}
+			ctx = c
+		})
+		if ok := C.eglMakeCurrent(ctx.disp, ctx.surf, ctx.surf, ctx.ctx); ok != C.EGL_TRUE {
+			err := fmt.Errorf("eglMakeCurrent failed (%#x)", C.eglGetError())
+			log.Fatal(err)
+		}
+		glGetString := func(e C.GLenum) string {
+			return C.GoString((*C.char)(unsafe.Pointer(C.glGetString(e))))
+		}
+		fmt.Printf("GL_VERSION: %s\nGL_RENDERER: %s\n", glGetString(C.GL_VERSION), glGetString(C.GL_RENDERER))
+		var err error
+		gioCtx, err = gpu.New(gpu.OpenGL{ES: true, Shared: true})
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+
+	topLeft := quarterWidget{
+		color: color.NRGBA{R: 0xde, G: 0xad, B: 0xbe, A: 0xff},
+	}
+	topRight := quarterWidget{
+		color: color.NRGBA{R: 0xff, G: 0xff, B: 0xff, A: 0xff},
+	}
+	botLeft := quarterWidget{
+		color: color.NRGBA{R: 0x00, G: 0x00, B: 0x00, A: 0xff},
+	}
+	botRight := quarterWidget{
+		color: color.NRGBA{R: 0x00, G: 0x00, B: 0x00, A: 0x80},
+	}
+
+	// eglMakeCurrent binds a context to an operating system thread. Prevent Go from switching thread.
+	runtime.LockOSThread()
+	for e := range w.Events() {
+		switch e := e.(type) {
+		case app.ViewEvent:
+			ve = e
+			init = true
+			if size != (image.Point{}) {
+				recreateContext()
+			}
+		case system.DestroyEvent:
+			return e.Err
+		case system.FrameEvent:
+			if init && size != e.Size {
+				size = e.Size
+				recreateContext()
+			}
+			if gioCtx == nil || !init {
+				break
+			}
+			// Build ops.
+			gtx := layout.NewContext(&ops, e)
+
+			// Clear background to white, even on embedded platforms such as webassembly.
+			paint.Fill(gtx.Ops, color.NRGBA{A: 0xff, R: 0xff, G: 0xff, B: 0xff})
+			layout.Flex{Axis: layout.Vertical}.Layout(gtx,
+				layout.Flexed(1, func(gtx C) D {
+					return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
+						// r1c1
+						layout.Flexed(1, func(gtx C) D { return topLeft.Layout(gtx) }),
+						// r1c2
+						layout.Flexed(1, func(gtx C) D { return topRight.Layout(gtx) }),
+					)
+				}),
+				layout.Flexed(1, func(gtx C) D {
+					return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
+						// r2c1
+						layout.Flexed(1, func(gtx C) D { return botLeft.Layout(gtx) }),
+						// r2c2
+						layout.Flexed(1, func(gtx C) D { return botRight.Layout(gtx) }),
+					)
+				}),
+			)
+			op.InvalidateOp{}.Add(gtx.Ops)
+			log.Println("frame")
+
+			// Trigger window resize detection in ANGLE.
+			C.eglWaitClient()
+			// Draw custom OpenGL content.
+			drawGL()
+
+			// Render drawing ops.
+			if err := gioCtx.Frame(gtx.Ops, gpu.OpenGLRenderTarget{}, e.Size); err != nil {
+				log.Fatal(fmt.Errorf("render failed: %v", err))
+			}
+
+			// Process non-drawing ops.
+			e.Frame(gtx.Ops)
+			switch notify {
+			case notifyInvalidate:
+				notify = notifyPrint
+				w.Invalidate()
+			case notifyPrint:
+				notify = notifyNone
+				fmt.Println("gio frame ready")
+			}
+
+			if ok := C.eglSwapBuffers(ctx.disp, ctx.surf); ok != C.EGL_TRUE {
+				log.Fatal(fmt.Errorf("swap failed: %v", C.eglGetError()))
+			}
+
+		}
+	}
+	return nil
+}
+
+func drawGL() {
+	C.glClearColor(0, 0, 0, 1)
+	C.glClear(C.GL_COLOR_BUFFER_BIT | C.GL_DEPTH_BUFFER_BIT)
+}
+
+func createContext(ve app.ViewEvent, size image.Point) (*eglContext, error) {
+	view, cleanup := nativeViewFor(ve, size)
+	var nilv C.EGLNativeWindowType
+	if view == nilv {
+		return nil, fmt.Errorf("failed creating native view")
+	}
+	disp := getDisplay(ve)
+	if disp == 0 {
+		return nil, fmt.Errorf("eglGetPlatformDisplay failed: 0x%x", C.eglGetError())
+	}
+	var major, minor C.EGLint
+	if ok := C.eglInitialize(disp, &major, &minor); ok != C.EGL_TRUE {
+		return nil, fmt.Errorf("eglInitialize failed: 0x%x", C.eglGetError())
+	}
+	exts := strings.Split(C.GoString(C.eglQueryString(disp, C.EGL_EXTENSIONS)), " ")
+	srgb := hasExtension(exts, "EGL_KHR_gl_colorspace")
+	attribs := []C.EGLint{
+		C.EGL_RENDERABLE_TYPE, C.EGL_OPENGL_ES2_BIT,
+		C.EGL_SURFACE_TYPE, C.EGL_WINDOW_BIT,
+		C.EGL_BLUE_SIZE, 8,
+		C.EGL_GREEN_SIZE, 8,
+		C.EGL_RED_SIZE, 8,
+		C.EGL_CONFIG_CAVEAT, C.EGL_NONE,
+	}
+	if srgb {
+		// Some drivers need alpha for sRGB framebuffers to work.
+		attribs = append(attribs, C.EGL_ALPHA_SIZE, 8)
+	}
+	attribs = append(attribs, C.EGL_NONE)
+	var (
+		cfg     C.EGLConfig
+		numCfgs C.EGLint
+	)
+	if ok := C.eglChooseConfig(disp, &attribs[0], &cfg, 1, &numCfgs); ok != C.EGL_TRUE {
+		return nil, fmt.Errorf("eglChooseConfig failed: 0x%x", C.eglGetError())
+	}
+	if numCfgs == 0 {
+		supportsNoCfg := hasExtension(exts, "EGL_KHR_no_config_context")
+		if !supportsNoCfg {
+			return nil, errors.New("eglChooseConfig returned no configs")
+		}
+	}
+	ctxAttribs := []C.EGLint{
+		C.EGL_CONTEXT_CLIENT_VERSION, 3,
+		C.EGL_NONE,
+	}
+	ctx := C.eglCreateContext(disp, cfg, nil, &ctxAttribs[0])
+	if ctx == nil {
+		return nil, fmt.Errorf("eglCreateContext failed: 0x%x", C.eglGetError())
+	}
+	var surfAttribs []C.EGLint
+	if srgb {
+		surfAttribs = append(surfAttribs, C.EGL_GL_COLORSPACE, C.EGL_GL_COLORSPACE_SRGB)
+	}
+	surfAttribs = append(surfAttribs, C.EGL_NONE)
+	surf := C.eglCreateWindowSurface(disp, cfg, view, &surfAttribs[0])
+	if surf == nil {
+		return nil, fmt.Errorf("eglCreateWindowSurface failed (0x%x)", C.eglGetError())
+	}
+	return &eglContext{disp: disp, ctx: ctx, surf: surf, cleanup: cleanup}, nil
+}
+
+func (c *eglContext) Release() {
+	if c.ctx != nil {
+		C.eglDestroyContext(c.disp, c.ctx)
+	}
+	if c.surf != nil {
+		C.eglDestroySurface(c.disp, c.surf)
+	}
+	if c.cleanup != nil {
+		c.cleanup()
+	}
+	*c = eglContext{}
+}
+
+func hasExtension(exts []string, ext string) bool {
+	for _, e := range exts {
+		if ext == e {
+			return true
+		}
+	}
+	return false
+}
+
+// quarterWidget paints a quarter of the screen with one color. When clicked, it
+// turns red, going back to its normal color when clicked again.
+type quarterWidget struct {
+	color color.NRGBA
+
+	clicked bool
+}
+
+var red = color.NRGBA{R: 0xff, G: 0x00, B: 0x00, A: 0xff}
+
+func (w *quarterWidget) Layout(gtx layout.Context) layout.Dimensions {
+	var color color.NRGBA
+	if w.clicked {
+		color = red
+	} else {
+		color = w.color
+	}
+
+	r := image.Rectangle{Max: gtx.Constraints.Max}
+	paint.FillShape(gtx.Ops, color, clip.Rect(r).Op())
+
+	defer clip.Rect(image.Rectangle{
+		Max: image.Pt(gtx.Constraints.Max.X, gtx.Constraints.Max.Y),
+	}).Push(gtx.Ops).Pop()
+	pointer.InputOp{
+		Tag:   w,
+		Types: pointer.Press,
+	}.Add(gtx.Ops)
+
+	for _, e := range gtx.Events(w) {
+		if e, ok := e.(pointer.Event); ok && e.Type == pointer.Press {
+			w.clicked = !w.clicked
+			// notify when we're done updating the frame.
+			notify = notifyInvalidate
+		}
+	}
+	return layout.Dimensions{Size: gtx.Constraints.Max}
+}