Add sensors example.

.gitignore

@@ -1 +1,2 @@
 *.ast
+*.apk

examples/sensors/android.go

@@ -0,0 +1,73 @@
+//+build android
+
+package main
+
+import "C"
+
+import (
+	"fmt"
+	"log"
+	"os"
+
+	ndk "git.wow.st/gmp/android-go/android27"
+	"gioui.org/ui/app"
+)
+
+var (
+	tag *ndk.Char
+)
+
+func mkHomeDir() {
+	msg := ndk.CharWithGoString("getting datadir")
+	ndk.AndroidLogWrite(ndk.ANDROID_LOG_WARN, tag, msg)
+	msg.Free()
+
+	godir,_ := app.DataDir()
+	labchan <- fmt.Sprintf("DataDir is %s", godir)
+
+	msg = ndk.CharWithGoString("ok. calling mkdir")
+	ndk.AndroidLogWrite(ndk.ANDROID_LOG_WARN, tag, msg)
+	msg.Free()
+
+	if _, err := os.Stat(godir); !os.IsNotExist(err) {
+		labchan <- "already exists"
+		return
+	}
+	if err := os.MkdirAll(godir, 0700); err != nil {
+		fmt.Sprintf("Error creating directory: %s", err)
+		labchan <- fmt.Sprintf("Error creating directory: %s", err)
+	} else {
+		labchan <- "created"
+	}
+}
+
+func apiLevel() {
+	msg := ndk.CharWithGoString("hello log world")
+	ndk.AndroidLogWrite(ndk.ANDROID_LOG_WARN, tag, msg)
+	msg.Free()
+	apilevel := ndk.AndroidGetDeviceApiLevel()
+	message := fmt.Sprintf("API level is %d", apilevel)
+	labchan <- message
+	msg = ndk.CharWithGoString(message)
+	ndk.AndroidLogWrite(ndk.ANDROID_LOG_WARN, tag, msg)
+	msg.Free()
+}
+
+func getSensors() {
+	pkg := ndk.CharWithGoString("st.wow.git.jni")
+	sm := ndk.ASensorManagerGetInstanceForPackage(pkg)
+	pkg.Free()
+	sens := ndk.ASensorManagerGetDefaultSensor(sm, ndk.ASENSOR_TYPE_ACCELEROMETER)
+	stp := ndk.ASensorGetStringType(sens)
+	labchan <- "sensor" + stp.String()
+}
+
+func init() {
+	tag = ndk.CharWithGoString("gio")
+	log.Print("Android starting")
+	go func() {
+		apiLevel()
+		mkHomeDir()
+		getSensors()
+	}()
+}

examples/sensors/main.go

@@ -0,0 +1,96 @@
+// +build darwin linux
+
+package main
+
+import (
+	"log"
+	"image/color"
+
+	"gioui.org/ui"
+	"gioui.org/ui/app"
+	"gioui.org/ui/layout"
+	"gioui.org/ui/measure"
+	"gioui.org/ui/text"
+
+	"golang.org/x/image/font/sfnt"
+	"golang.org/x/image/font/gofont/goregular"
+)
+
+var (
+	face text.Face
+	white = color.RGBA{A: 0xff, R: 0xff, G: 0xff, B: 0xff}
+	gray = color.RGBA{A: 0xff, R: 0xb0, G: 0xb0, B: 0xb0}
+	black = color.RGBA{A: 0xff, R: 0x00, G: 0x00, B: 0x00}
+
+	labchan chan string
+)
+
+func main() {
+	labchan = make(chan string)
+	log.Print("Staring event loop")
+	go eventloop()
+	app.Main()
+	log.Print("App closed")
+}
+
+func diffInsets(x, y app.Insets) bool {
+	return  x.Top != y.Top ||
+		x.Bottom != y.Bottom ||
+		x.Left != y.Left ||
+		x.Right != y.Right
+}
+
+func eventloop() {
+	w := app.NewWindow(
+		app.WithWidth(ui.Dp(400)),
+		app.WithHeight(ui.Dp(400)),
+		app.WithTitle("Hello"))
+	q := w.Queue()
+	var c ui.Config
+	ops := new(ui.Ops)
+	//var dims layout.Dimensions
+	var cs layout.Constraints
+	var faces measure.Faces
+
+	regular, err := sfnt.Parse(goregular.TTF)
+	if err != nil { log.Fatal("Cannot parse font.") }
+	face = faces.For(regular, ui.Sp(16))
+
+	sysinset := &layout.Inset{}
+	margin := layout.UniformInset(ui.Dp(10))
+	labels := []*text.Label{}
+	list := &layout.List{Axis: layout.Vertical}
+
+	resetSysinset := func(x app.Insets) {
+		sysinset.Top = x.Top
+		sysinset.Bottom = x.Bottom
+		sysinset.Left = x.Left
+		sysinset.Right = x.Right
+	}
+
+	for {
+		select {
+		case x := <-labchan:
+			labels = append(labels,&text.Label{Face: face, Text: x})
+		case e := <-w.Events():
+			switch e := e.(type) {
+			case app.DestroyEvent:
+				return
+			case app.UpdateEvent:
+				c = &e.Config
+				ops.Reset()
+				faces.Reset(c)
+				resetSysinset(e.Insets)
+				cs = layout.RigidConstraints(e.Size)
+				cs = sysinset.Begin(c, ops, cs)
+				cs = margin.Begin(c, ops, cs)
+				for list.Init(c, q, ops, cs, len(labels)); list.More(); list.Next() {
+					list.End(labels[list.Index()].Layout(ops, list.Constraints()))
+				}
+				sysinset.End(margin.End(list.Layout()))
+				w.Update(ops)
+			}
+		}
+	}
+}
+