fix(tui): mouse wheel ansi codes leaking into editor

packages/tui/input/mouse.go

@@ -0,0 +1,292 @@
+package input
+
+import (
+	"fmt"
+
+	"github.com/charmbracelet/x/ansi"
+)
+
+// MouseButton represents the button that was pressed during a mouse message.
+type MouseButton = ansi.MouseButton
+
+// Mouse event buttons
+//
+// This is based on X11 mouse button codes.
+//
+//	1 = left button
+//	2 = middle button (pressing the scroll wheel)
+//	3 = right button
+//	4 = turn scroll wheel up
+//	5 = turn scroll wheel down
+//	6 = push scroll wheel left
+//	7 = push scroll wheel right
+//	8 = 4th button (aka browser backward button)
+//	9 = 5th button (aka browser forward button)
+//	10
+//	11
+//
+// Other buttons are not supported.
+const (
+	MouseNone       = ansi.MouseNone
+	MouseLeft       = ansi.MouseLeft
+	MouseMiddle     = ansi.MouseMiddle
+	MouseRight      = ansi.MouseRight
+	MouseWheelUp    = ansi.MouseWheelUp
+	MouseWheelDown  = ansi.MouseWheelDown
+	MouseWheelLeft  = ansi.MouseWheelLeft
+	MouseWheelRight = ansi.MouseWheelRight
+	MouseBackward   = ansi.MouseBackward
+	MouseForward    = ansi.MouseForward
+	MouseButton10   = ansi.MouseButton10
+	MouseButton11   = ansi.MouseButton11
+)
+
+// MouseEvent represents a mouse message. This is a generic mouse message that
+// can represent any kind of mouse event.
+type MouseEvent interface {
+	fmt.Stringer
+
+	// Mouse returns the underlying mouse event.
+	Mouse() Mouse
+}
+
+// Mouse represents a Mouse message. Use [MouseEvent] to represent all mouse
+// messages.
+//
+// The X and Y coordinates are zero-based, with (0,0) being the upper left
+// corner of the terminal.
+//
+//	// Catch all mouse events
+//	switch Event := Event.(type) {
+//	case MouseEvent:
+//	    m := Event.Mouse()
+//	    fmt.Println("Mouse event:", m.X, m.Y, m)
+//	}
+//
+//	// Only catch mouse click events
+//	switch Event := Event.(type) {
+//	case MouseClickEvent:
+//	    fmt.Println("Mouse click event:", Event.X, Event.Y, Event)
+//	}
+type Mouse struct {
+	X, Y   int
+	Button MouseButton
+	Mod    KeyMod
+}
+
+// String returns a string representation of the mouse message.
+func (m Mouse) String() (s string) {
+	if m.Mod.Contains(ModCtrl) {
+		s += "ctrl+"
+	}
+	if m.Mod.Contains(ModAlt) {
+		s += "alt+"
+	}
+	if m.Mod.Contains(ModShift) {
+		s += "shift+"
+	}
+
+	str := m.Button.String()
+	if str == "" {
+		s += "unknown"
+	} else if str != "none" { // motion events don't have a button
+		s += str
+	}
+
+	return s
+}
+
+// MouseClickEvent represents a mouse button click event.
+type MouseClickEvent Mouse
+
+// String returns a string representation of the mouse click event.
+func (e MouseClickEvent) String() string {
+	return Mouse(e).String()
+}
+
+// Mouse returns the underlying mouse event. This is a convenience method and
+// syntactic sugar to satisfy the [MouseEvent] interface, and cast the mouse
+// event to [Mouse].
+func (e MouseClickEvent) Mouse() Mouse {
+	return Mouse(e)
+}
+
+// MouseReleaseEvent represents a mouse button release event.
+type MouseReleaseEvent Mouse
+
+// String returns a string representation of the mouse release event.
+func (e MouseReleaseEvent) String() string {
+	return Mouse(e).String()
+}
+
+// Mouse returns the underlying mouse event. This is a convenience method and
+// syntactic sugar to satisfy the [MouseEvent] interface, and cast the mouse
+// event to [Mouse].
+func (e MouseReleaseEvent) Mouse() Mouse {
+	return Mouse(e)
+}
+
+// MouseWheelEvent represents a mouse wheel message event.
+type MouseWheelEvent Mouse
+
+// String returns a string representation of the mouse wheel event.
+func (e MouseWheelEvent) String() string {
+	return Mouse(e).String()
+}
+
+// Mouse returns the underlying mouse event. This is a convenience method and
+// syntactic sugar to satisfy the [MouseEvent] interface, and cast the mouse
+// event to [Mouse].
+func (e MouseWheelEvent) Mouse() Mouse {
+	return Mouse(e)
+}
+
+// MouseMotionEvent represents a mouse motion event.
+type MouseMotionEvent Mouse
+
+// String returns a string representation of the mouse motion event.
+func (e MouseMotionEvent) String() string {
+	m := Mouse(e)
+	if m.Button != 0 {
+		return m.String() + "+motion"
+	}
+	return m.String() + "motion"
+}
+
+// Mouse returns the underlying mouse event. This is a convenience method and
+// syntactic sugar to satisfy the [MouseEvent] interface, and cast the mouse
+// event to [Mouse].
+func (e MouseMotionEvent) Mouse() Mouse {
+	return Mouse(e)
+}
+
+// Parse SGR-encoded mouse events; SGR extended mouse events. SGR mouse events
+// look like:
+//
+//	ESC [ < Cb ; Cx ; Cy (M or m)
+//
+// where:
+//
+//	Cb is the encoded button code
+//	Cx is the x-coordinate of the mouse
+//	Cy is the y-coordinate of the mouse
+//	M is for button press, m is for button release
+//
+// https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Extended-coordinates
+func parseSGRMouseEvent(cmd ansi.Cmd, params ansi.Params) Event {
+	x, _, ok := params.Param(1, 1)
+	if !ok {
+		x = 1
+	}
+	y, _, ok := params.Param(2, 1)
+	if !ok {
+		y = 1
+	}
+	release := cmd.Final() == 'm'
+	b, _, _ := params.Param(0, 0)
+	mod, btn, _, isMotion := parseMouseButton(b)
+
+	// (1,1) is the upper left. We subtract 1 to normalize it to (0,0).
+	x--
+	y--
+
+	m := Mouse{X: x, Y: y, Button: btn, Mod: mod}
+
+	// Wheel buttons don't have release events
+	// Motion can be reported as a release event in some terminals (Windows Terminal)
+	if isWheel(m.Button) {
+		return MouseWheelEvent(m)
+	} else if !isMotion && release {
+		return MouseReleaseEvent(m)
+	} else if isMotion {
+		return MouseMotionEvent(m)
+	}
+	return MouseClickEvent(m)
+}
+
+const x10MouseByteOffset = 32
+
+// Parse X10-encoded mouse events; the simplest kind. The last release of X10
+// was December 1986, by the way. The original X10 mouse protocol limits the Cx
+// and Cy coordinates to 223 (=255-032).
+//
+// X10 mouse events look like:
+//
+//	ESC [M Cb Cx Cy
+//
+// See: http://www.xfree86.org/current/ctlseqs.html#Mouse%20Tracking
+func parseX10MouseEvent(buf []byte) Event {
+	v := buf[3:6]
+	b := int(v[0])
+	if b >= x10MouseByteOffset {
+		// XXX: b < 32 should be impossible, but we're being defensive.
+		b -= x10MouseByteOffset
+	}
+
+	mod, btn, isRelease, isMotion := parseMouseButton(b)
+
+	// (1,1) is the upper left. We subtract 1 to normalize it to (0,0).
+	x := int(v[1]) - x10MouseByteOffset - 1
+	y := int(v[2]) - x10MouseByteOffset - 1
+
+	m := Mouse{X: x, Y: y, Button: btn, Mod: mod}
+	if isWheel(m.Button) {
+		return MouseWheelEvent(m)
+	} else if isMotion {
+		return MouseMotionEvent(m)
+	} else if isRelease {
+		return MouseReleaseEvent(m)
+	}
+	return MouseClickEvent(m)
+}
+
+// See: https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Extended-coordinates
+func parseMouseButton(b int) (mod KeyMod, btn MouseButton, isRelease bool, isMotion bool) {
+	// mouse bit shifts
+	const (
+		bitShift  = 0b0000_0100
+		bitAlt    = 0b0000_1000
+		bitCtrl   = 0b0001_0000
+		bitMotion = 0b0010_0000
+		bitWheel  = 0b0100_0000
+		bitAdd    = 0b1000_0000 // additional buttons 8-11
+
+		bitsMask = 0b0000_0011
+	)
+
+	// Modifiers
+	if b&bitAlt != 0 {
+		mod |= ModAlt
+	}
+	if b&bitCtrl != 0 {
+		mod |= ModCtrl
+	}
+	if b&bitShift != 0 {
+		mod |= ModShift
+	}
+
+	if b&bitAdd != 0 {
+		btn = MouseBackward + MouseButton(b&bitsMask)
+	} else if b&bitWheel != 0 {
+		btn = MouseWheelUp + MouseButton(b&bitsMask)
+	} else {
+		btn = MouseLeft + MouseButton(b&bitsMask)
+		// X10 reports a button release as 0b0000_0011 (3)
+		if b&bitsMask == bitsMask {
+			btn = MouseNone
+			isRelease = true
+		}
+	}
+
+	// Motion bit doesn't get reported for wheel events.
+	if b&bitMotion != 0 && !isWheel(btn) {
+		isMotion = true
+	}
+
+	return //nolint:nakedret
+}
+
+// isWheel returns true if the mouse event is a wheel event.
+func isWheel(btn MouseButton) bool {
+	return btn >= MouseWheelUp && btn <= MouseWheelRight
+}