From ba86d37ce8fd362e2a0896d285e01c8686f7a7f2 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Tue, 27 Jun 2017 00:36:38 +0900
Subject: [PATCH] examples/2048: Add mouse/touch feature (#370)

---
 examples/2048/2048/input.go | 130 ++++++++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)

diff --git a/examples/2048/2048/input.go b/examples/2048/2048/input.go
index 6473e7381..3de49c0ca 100644
--- a/examples/2048/2048/input.go
+++ b/examples/2048/2048/input.go
@@ -30,6 +30,24 @@ const (
 	DirLeft
 )
 
+type mouseState int
+
+const (
+	mouseStateNone mouseState = iota
+	mouseStatePressing
+	mouseStateSettled
+)
+
+type touchState int
+
+const (
+	touchStateNone touchState = iota
+	touchStatePressing
+	touchStateSettled
+	touchStateInvalid
+	n
+)
+
 // String returns a string representing the direction.
 func (d Dir) String() string {
 	switch d {
@@ -63,6 +81,19 @@ func (d Dir) Vector() (x, y int) {
 // Input represents the current key states.
 type Input struct {
 	keyState map[ebiten.Key]int
+
+	mouseState    mouseState
+	mouseInitPosX int
+	mouseInitPosY int
+	mouseDir      Dir
+
+	touchState    touchState
+	touchID       int
+	touchInitPosX int
+	touchInitPosY int
+	touchLastPosX int
+	touchLastPosY int
+	touchDir      Dir
 }
 
 // NewInput generates a new Input object.
@@ -81,6 +112,30 @@ var (
 	}
 )
 
+func abs(x int) int {
+	if x < 0 {
+		return -x
+	}
+	return x
+}
+
+func vecToDir(dx, dy int) (Dir, bool) {
+	if abs(dx) < 4 && abs(dy) < 4 {
+		return 0, false
+	}
+	if abs(dx) < abs(dy) {
+		if dy < 0 {
+			return DirUp, true
+		}
+		return DirDown, true
+	} else {
+		if dx < 0 {
+			return DirLeft, true
+		}
+		return DirRight, true
+	}
+}
+
 // Update updates the current input states.
 func (i *Input) Update() {
 	for k := range dirKeys {
@@ -90,6 +145,75 @@ func (i *Input) Update() {
 			i.keyState[k] = 0
 		}
 	}
+	switch i.mouseState {
+	case mouseStateNone:
+		if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
+			x, y := ebiten.CursorPosition()
+			i.mouseInitPosX = x
+			i.mouseInitPosY = y
+			i.mouseState = mouseStatePressing
+		}
+	case mouseStatePressing:
+		if !ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
+			x, y := ebiten.CursorPosition()
+			dx := x - i.mouseInitPosX
+			dy := y - i.mouseInitPosY
+			d, ok := vecToDir(dx, dy)
+			if !ok {
+				i.mouseState = mouseStateNone
+				break
+			}
+			i.mouseDir = d
+			i.mouseState = mouseStateSettled
+		}
+	case mouseStateSettled:
+		i.mouseState = mouseStateNone
+	}
+	switch i.touchState {
+	case touchStateNone:
+		ts := ebiten.Touches()
+		if len(ts) == 1 {
+			i.touchID = ts[0].ID()
+			x, y := ts[0].Position()
+			i.touchInitPosX = x
+			i.touchInitPosY = y
+			i.touchLastPosX = x
+			i.touchLastPosX = y
+			i.touchState = touchStatePressing
+		}
+	case touchStatePressing:
+		ts := ebiten.Touches()
+		if len(ts) >= 2 {
+			break
+		}
+		if len(ts) == 1 {
+			if ts[0].ID() != i.touchID {
+				i.touchState = touchStateInvalid
+			} else {
+				x, y := ts[0].Position()
+				i.touchLastPosX = x
+				i.touchLastPosY = y
+			}
+			break
+		}
+		if len(ts) == 0 {
+			dx := i.touchLastPosX - i.touchInitPosX
+			dy := i.touchLastPosY - i.touchInitPosY
+			d, ok := vecToDir(dx, dy)
+			if !ok {
+				i.touchState = touchStateNone
+				break
+			}
+			i.touchDir = d
+			i.touchState = touchStateSettled
+		}
+	case touchStateSettled:
+		i.touchState = touchStateNone
+	case touchStateInvalid:
+		if len(ebiten.Touches()) == 0 {
+			i.touchState = touchStateNone
+		}
+	}
 }
 
 // Dir returns a currenly pressed direction.
@@ -100,5 +224,11 @@ func (i *Input) Dir() (Dir, bool) {
 			return d, true
 		}
 	}
+	if i.mouseState == mouseStateSettled {
+		return i.mouseDir, true
+	}
+	if i.touchState == touchStateSettled {
+		return i.touchDir, true
+	}
 	return 0, false
 }