inpututil: Add AppendJustConnectedGamepadIDs

Updates hajimehoshi#1705
RiXelanya · Jul 10, 2021 · e8ea404 · e8ea404
1 parent a79c287
commit e8ea404
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Showing 2 changed files with 23 additions and 11 deletions.
diff --git a/examples/gamepad/main.go b/examples/gamepad/main.go
@@ -35,6 +35,7 @@ const (
 )
 
 type Game struct {
+	gamepadIDsBuf  []ebiten.GamepadID
 	gamepadIDs     map[ebiten.GamepadID]struct{}
 	axes           map[ebiten.GamepadID][]string
 	pressedButtons map[ebiten.GamepadID][]string
@@ -46,7 +47,8 @@ func (g *Game) Update() error {
 	}
 
 	// Log the gamepad connection events.
-	for _, id := range inpututil.JustConnectedGamepadIDs() {
+	g.gamepadIDsBuf = inpututil.AppendJustConnectedGamepadIDs(g.gamepadIDsBuf[:0])
+	for _, id := range g.gamepadIDsBuf {
 		log.Printf("gamepad connected: id: %d", id)
 		g.gamepadIDs[id] = struct{}{}
 	}

diff --git a/inpututil/inpututil.go b/inpututil/inpututil.go
@@ -185,7 +185,7 @@ func AppendPressedKeys(keys []ebiten.Key) []ebiten.Key {
 
 // PressedKeys returns a set of currently pressed keyboard keys.
 //
-// Deprecated: as of v2.2.0. Use AppendPressedKeys instead.
+// Deprecated: as of v2.2. Use AppendPressedKeys instead.
 func PressedKeys() []ebiten.Key {
 	return AppendPressedKeys(nil)
 }
@@ -249,24 +249,34 @@ func MouseButtonPressDuration(button ebiten.MouseButton) int {
 	return s
 }
 
-// JustConnectedGamepadIDs returns gamepad IDs that are connected just in the current frame.
+// AppendJustConnectedGamepadIDs appends gamepad IDs that are connected just in the current frame to gamepadIDs,
+// and returns the extended buffer.
+// Giving a slice that already has enough capacity works efficiently.
 //
-// JustConnectedGamepadIDs might return nil when there is no connected gamepad.
+// AppendJustConnectedGamepadIDs might append nothing when there is no connected gamepad.
 //
-// JustConnectedGamepadIDs is concurrent safe.
-func JustConnectedGamepadIDs() []ebiten.GamepadID {
-	var ids []ebiten.GamepadID
+// AppendJustConnectedGamepadIDs is concurrent safe.
+func AppendJustConnectedGamepadIDs(gamepadIDs []ebiten.GamepadID) []ebiten.GamepadID {
+	origLen := len(gamepadIDs)
 	theInputState.m.RLock()
 	for id := range theInputState.gamepadIDs {
 		if _, ok := theInputState.prevGamepadIDs[id]; !ok {
-			ids = append(ids, id)
+			gamepadIDs = append(gamepadIDs, id)
 		}
 	}
 	theInputState.m.RUnlock()
-	sort.Slice(ids, func(a, b int) bool {
-		return ids[a] < ids[b]
+	s := gamepadIDs[origLen:]
+	sort.Slice(s, func(a, b int) bool {
+		return s[a] < s[b]
 	})
-	return ids
+	return gamepadIDs
+}
+
+// JustConnectedGamepadIDs returns gamepad IDs that are connected just in the current frame.
+//
+// Deprecated: as of v2.2. Use AppendJustConnectedGamepadIDs instead.
+func JustConnectedGamepadIDs() []ebiten.GamepadID {
+	return AppendJustConnectedGamepadIDs(nil)
 }
 
 // IsGamepadJustDisconnected returns a boolean value indicating