io: give event packages a common prefix

Packages that provide support for external events such as pointer, key and
system are only the beginning. Future packages are expected for clipboard
access, drag and drop, gps positions and so on.

To keep the number of top-level packages under control, move such I/O packages
to the new `io` directory.

The `system` package name was the previous solution to keeping the number of
top-level packages under control: I named it `system` instead of the narrower
`profile` because I expected to put all the less common events into it, turning
`system` into a "package util" smell.

With `io`, package system can be renamed to `profile`.

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

app/internal/input/key.go

@@ -3,10 +3,10 @@
 package input
 
 import (
-	"gioui.org/ui"
 	"gioui.org/internal/opconst"
 	"gioui.org/internal/ops"
-	"gioui.org/key"
+	"gioui.org/io/key"
+	"gioui.org/ui"
 )
 
 type TextInputState uint8

app/internal/input/pointer.go

@@ -6,11 +6,11 @@ import (
 	"encoding/binary"
 	"image"
 
-	"gioui.org/ui"
 	"gioui.org/f32"
 	"gioui.org/internal/opconst"
 	"gioui.org/internal/ops"
-	"gioui.org/pointer"
+	"gioui.org/io/pointer"
+	"gioui.org/ui"
 )
 
 type pointerQueue struct {

app/internal/input/router.go

@@ -6,12 +6,12 @@ import (
 	"encoding/binary"
 	"time"
 
-	"gioui.org/ui"
 	"gioui.org/internal/opconst"
 	"gioui.org/internal/ops"
-	"gioui.org/key"
-	"gioui.org/pointer"
-	"gioui.org/system"
+	"gioui.org/io/key"
+	"gioui.org/io/pointer"
+	"gioui.org/io/profile"
+	"gioui.org/ui"
 )
 
 // Router is a Queue implementation that routes events from
@@ -98,7 +98,7 @@ func (q *Router) collect() {
 	}
 }
 
-func (q *Router) AddProfile(e system.ProfileEvent) {
+func (q *Router) AddProfile(e profile.Event) {
 	for _, h := range q.profHandlers {
 		q.handlers.Add(h, e)
 	}
@@ -150,11 +150,11 @@ func (h *handlerEvents) Clear() {
 	}
 }
 
-func decodeProfileOp(d []byte, refs []interface{}) system.ProfileOp {
+func decodeProfileOp(d []byte, refs []interface{}) profile.Op {
 	if opconst.OpType(d[0]) != opconst.TypeProfile {
 		panic("invalid op")
 	}
-	return system.ProfileOp{
+	return profile.Op{
 		Key: refs[0].(ui.Key),
 	}
 }

app/os_android.go

@@ -24,10 +24,10 @@ import (
 	"time"
 	"unsafe"
 
-	"gioui.org/ui"
 	"gioui.org/f32"
-	"gioui.org/key"
-	"gioui.org/pointer"
+	"gioui.org/io/key"
+	"gioui.org/io/pointer"
+	"gioui.org/ui"
 )
 
 type window struct {

app/os_ios.go

@@ -22,10 +22,10 @@ import (
 	"sync/atomic"
 	"time"
 
-	"gioui.org/ui"
 	"gioui.org/f32"
-	"gioui.org/key"
-	"gioui.org/pointer"
+	"gioui.org/io/key"
+	"gioui.org/io/pointer"
+	"gioui.org/ui"
 )
 
 type window struct {

app/os_js.go

@@ -9,8 +9,8 @@ import (
 	"time"
 
 	"gioui.org/f32"
-	"gioui.org/key"
-	"gioui.org/pointer"
+	"gioui.org/io/key"
+	"gioui.org/io/pointer"
 )
 
 type window struct {

app/os_macos.go

@@ -20,8 +20,8 @@ import (
 	"unsafe"
 
 	"gioui.org/f32"
-	"gioui.org/key"
-	"gioui.org/pointer"
+	"gioui.org/io/key"
+	"gioui.org/io/pointer"
 )
 
 func init() {

app/os_wayland.go

@@ -18,8 +18,8 @@ import (
 
 	"gioui.org/f32"
 	"gioui.org/internal/fling"
-	"gioui.org/key"
-	"gioui.org/pointer"
+	"gioui.org/io/key"
+	"gioui.org/io/pointer"
 	syscall "golang.org/x/sys/unix"
 )
 

app/os_windows.go

@@ -15,8 +15,8 @@ import (
 	syscall "golang.org/x/sys/windows"
 
 	"gioui.org/f32"
-	"gioui.org/key"
-	"gioui.org/pointer"
+	"gioui.org/io/key"
+	"gioui.org/io/pointer"
 )
 
 var winMap = make(map[syscall.Handle]*window)

app/window.go

@@ -8,10 +8,10 @@ import (
 	"image"
 	"time"
 
-	"gioui.org/ui"
 	"gioui.org/app/internal/gpu"
 	"gioui.org/app/internal/input"
-	"gioui.org/system"
+	"gioui.org/io/profile"
+	"gioui.org/ui"
 )
 
 // WindowOption configures a Window.
@@ -144,7 +144,7 @@ func (w *Window) draw(size image.Point, frame *ui.Ops) {
 	if w.queue.q.Profiling() {
 		q := 100 * time.Microsecond
 		timings := fmt.Sprintf("tot:%7s cpu:%7s %s", frameDur.Round(q), drawDur.Round(q), w.gpu.Timings())
-		w.queue.q.AddProfile(system.ProfileEvent{Timings: timings})
+		w.queue.q.AddProfile(profile.Event{Timings: timings})
 		w.setNextFrame(time.Time{})
 	}
 	if t, ok := w.queue.q.WakeupTime(); ok {

app/xkb_linux.go

@@ -22,7 +22,7 @@ import (
 	"unicode/utf8"
 	"unsafe"
 
-	"gioui.org/key"
+	"gioui.org/io/key"
 )
 
 type xkb struct {