Add functionality for binding mouse buttons

This commit enables users to bind the mouse buttons (left, middle,
right buttons and the scroll wheel).

The default bindings now include the mouse bindings:

    "MouseWheelUp":   "ScrollUp",
    "MouseWheelDown": "ScrollDown",
    "MouseLeft":      "MousePress",
    "MouseMiddle":    "PastePrimary",

Mouse buttons can now also be bound to normal actions. For example:

    "MouseLeft": "Backspace"

This also means that plugins can access mouse event callbacks in the
standard way ('onAction').

More documentation for this will be coming soon.

Fixes #542

cmd/micro/bindings.go

@@ -10,8 +10,13 @@ import (
 )
 
 var bindings map[Key][]func(*View, bool) bool
+var mouseBindings map[Key][]func(*View, bool, *tcell.EventMouse) bool
 var helpBinding string
 
+var mouseBindingActions = map[string]func(*View, bool, *tcell.EventMouse) bool{
+	"MousePress": (*View).MousePress,
+}
+
 var bindingActions = map[string]func(*View, bool) bool{
 	"CursorUp":            (*View).CursorUp,
 	"CursorDown":          (*View).CursorDown,
@@ -91,11 +96,23 @@ var bindingActions = map[string]func(*View, bool) bool{
 	"ToggleMacro":         (*View).ToggleMacro,
 	"PlayMacro":           (*View).PlayMacro,
 	"Suspend":             (*View).Suspend,
+	"ScrollUp":            (*View).ScrollUpAction,
+	"ScrollDown":          (*View).ScrollDownAction,
 
 	// This was changed to InsertNewline but I don't want to break backwards compatibility
 	"InsertEnter": (*View).InsertNewline,
 }
 
+var bindingMouse = map[string]tcell.ButtonMask{
+	"MouseLeft":       tcell.Button1,
+	"MouseMiddle":     tcell.Button2,
+	"MouseRight":      tcell.Button3,
+	"MouseWheelUp":    tcell.WheelUp,
+	"MouseWheelDown":  tcell.WheelDown,
+	"MouseWheelLeft":  tcell.WheelLeft,
+	"MouseWheelRight": tcell.WheelRight,
+}
+
 var bindingKeys = map[string]tcell.Key{
 	"Up":             tcell.KeyUp,
 	"Down":           tcell.KeyDown,
@@ -230,12 +247,14 @@ var bindingKeys = map[string]tcell.Key{
 type Key struct {
 	keyCode   tcell.Key
 	modifiers tcell.ModMask
+	buttons   tcell.ButtonMask
 	r         rune
 }
 
 // InitBindings initializes the keybindings for micro
 func InitBindings() {
 	bindings = make(map[Key][]func(*View, bool) bool)
+	mouseBindings = make(map[Key][]func(*View, bool, *tcell.EventMouse) bool)
 
 	var parsed map[string]string
 	defaults := DefaultBindings()
@@ -301,6 +320,7 @@ modSearch:
 			return Key{
 				keyCode:   code,
 				modifiers: modifiers,
+				buttons:   -1,
 				r:         0,
 			}, true
 		}
@@ -311,6 +331,16 @@ modSearch:
 		return Key{
 			keyCode:   code,
 			modifiers: modifiers,
+			buttons:   -1,
+			r:         0,
+		}, true
+	}
+
+	// See if we can find the key in bindingMouse
+	if code, ok := bindingMouse[k]; ok {
+		return Key{
+			modifiers: modifiers,
+			buttons:   code,
 			r:         0,
 		}, true
 	}
@@ -320,12 +350,13 @@ modSearch:
 		return Key{
 			keyCode:   tcell.KeyRune,
 			modifiers: modifiers,
+			buttons:   -1,
 			r:         rune(k[0]),
 		}, true
 	}
 
 	// We don't know what happened.
-	return Key{}, false
+	return Key{buttons: -1}, false
 }
 
 // findAction will find 'action' using string 'v'
@@ -339,6 +370,16 @@ func findAction(v string) (action func(*View, bool) bool) {
 	return action
 }
 
+func findMouseAction(v string) func(*View, bool, *tcell.EventMouse) bool {
+	action, ok := mouseBindingActions[v]
+	if !ok {
+		// If the user seems to be binding a function that doesn't exist
+		// We hope that it's a lua function that exists and bind it to that
+		action = LuaFunctionMouseBinding(v)
+	}
+	return action
+}
+
 // BindKey takes a key and an action and binds the two together
 func BindKey(k, v string) {
 	key, ok := findKey(k)
@@ -356,18 +397,31 @@ func BindKey(k, v string) {
 	actionNames := strings.Split(v, ",")
 	if actionNames[0] == "UnbindKey" {
 		delete(bindings, key)
+		delete(mouseBindings, key)
 		if len(actionNames) == 1 {
-			actionNames = make([]string, 0, 0)
-		} else {
-			actionNames = append(actionNames[:0], actionNames[1:]...)
+			return
 		}
+		actionNames = append(actionNames[:0], actionNames[1:]...)
 	}
 	actions := make([]func(*View, bool) bool, 0, len(actionNames))
+	mouseActions := make([]func(*View, bool, *tcell.EventMouse) bool, 0, len(actionNames))
 	for _, actionName := range actionNames {
-		actions = append(actions, findAction(actionName))
+		if strings.HasPrefix(actionName, "Mouse") {
+			mouseActions = append(mouseActions, findMouseAction(actionName))
+		} else {
+			actions = append(actions, findAction(actionName))
+		}
 	}
 
-	bindings[key] = actions
+	if len(actions) > 0 {
+		// Can't have a binding be both mouse and normal
+		delete(mouseBindings, key)
+		bindings[key] = actions
+	} else if len(mouseActions) > 0 {
+		// Can't have a binding be both mouse and normal
+		delete(bindings, key)
+		mouseBindings[key] = mouseActions
+	}
 }
 
 // DefaultBindings returns a map containing micro's default keybindings
@@ -453,5 +507,11 @@ func DefaultBindings() map[string]string {
 		"F7":  "Find",
 		"F10": "Quit",
 		"Esc": "Escape",
+
+		// Mouse bindings
+		"MouseWheelUp":   "ScrollUp",
+		"MouseWheelDown": "ScrollDown",
+		"MouseLeft":      "MousePress",
+		"MouseMiddle":    "PastePrimary",
 	}
 }