From 840caf5fd5e86d26551802de74971b8fc8b10a7c Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Mon, 27 Mar 2023 17:06:56 +0530
Subject: [PATCH] Start work on mouse handling in diff kitten

---
 kittens/diff/main.go |  2 ++
 kittens/diff/ui.go   | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/kittens/diff/main.go b/kittens/diff/main.go
index 4107a4ac5..d5ca9798b 100644
--- a/kittens/diff/main.go
+++ b/kittens/diff/main.go
@@ -133,6 +133,7 @@ func main(_ *cli.Command, opts_ *Options, args []string) (rc int, err error) {
 		return 1, fmt.Errorf("%s does not exist", right)
 	}
 	lp, err = loop.New()
+	loop.MouseTrackingMode(lp, loop.BUTTONS_AND_DRAG_MOUSE_TRACKING)
 	if err != nil {
 		return 1, err
 	}
@@ -155,6 +156,7 @@ func main(_ *cli.Command, opts_ *Options, args []string) (rc int, err error) {
 	lp.OnResize = h.on_resize
 	lp.OnKeyEvent = h.on_key_event
 	lp.OnText = h.on_text
+	lp.OnMouseEvent = h.on_mouse_event
 	err = lp.Run()
 	if err != nil {
 		return 1, err
diff --git a/kittens/diff/ui.go b/kittens/diff/ui.go
index 30562400a..feb9108c3 100644
--- a/kittens/diff/ui.go
+++ b/kittens/diff/ui.go
@@ -627,3 +627,21 @@ func (self *Handler) dispatch_action(name, args string) error {
 	}
 	return nil
 }
+
+func (self *Handler) handle_wheel_event(up bool) {
+	if self.logical_lines != nil {
+		amt := 2
+		if up {
+			amt *= -1
+		}
+		self.dispatch_action(`scroll_by`, strconv.Itoa(amt))
+	}
+}
+
+func (self *Handler) on_mouse_event(ev *loop.MouseEvent) error {
+	if ev.Event_type == loop.MOUSE_PRESS && ev.Buttons&(loop.MOUSE_WHEEL_UP|loop.MOUSE_WHEEL_DOWN) != 0 {
+		self.handle_wheel_event(ev.Buttons&(loop.MOUSE_WHEEL_UP) != 0)
+		return nil
+	}
+	return nil
+}