From 0ff885461b0474b58f08d7c3f48992a0e1eafee0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vlastimil=20Ov=C4=8D=C3=A1=C4=8D=C3=ADk?=
 <vovcacik@github.ovcacik.org>
Date: Tue, 21 Sep 2021 17:52:39 +0200
Subject: [PATCH] Add mouse support to the FullscreenRenderer

---
 src/tui/tcell.go | 42 ++++++++++++++++++++++++++++++++++++++----
 src/tui/tui.go   | 24 ++++++++++++++----------
 2 files changed, 52 insertions(+), 14 deletions(-)

diff --git a/src/tui/tcell.go b/src/tui/tcell.go
index dd0581b..054c550 100644
--- a/src/tui/tcell.go
+++ b/src/tui/tcell.go
@@ -185,14 +185,48 @@ func (r *FullscreenRenderer) GetChar() Event {
 
 	// process mouse events:
 	case *tcell.EventMouse:
+		// mouse down events have zeroed buttons, so we can't use them
+		// mouse up event consists of two events, 1. (main) event with modifier and other metadata, 2. event with zeroed buttons
+		// so mouse click is three consecutive events, but the first and last are indistinguishable from movement events (with released buttons)
+		// dragging has same structure, it only repeats the middle (main) event appropriately
 		x, y := ev.Position()
-		button := ev.Buttons()
 		mod := ev.Modifiers() != 0
-		if button&tcell.WheelDown != 0 {
+
+		// since we dont have mouse down events (unlike LightRenderer), we need to track state in prevButton
+		prevButton, button := r.prevMouseButton, ev.Buttons()
+		r.prevMouseButton = button
+		drag := prevButton == button
+
+		switch {
+		case button&tcell.WheelDown != 0:
 			return Event{Mouse, 0, &MouseEvent{y, x, -1, false, false, false, mod}}
-		} else if button&tcell.WheelUp != 0 {
+		case button&tcell.WheelUp != 0:
 			return Event{Mouse, 0, &MouseEvent{y, x, +1, false, false, false, mod}}
-		} else if runtime.GOOS != "windows" {
+		case button&tcell.Button1 != 0 && !drag:
+			// all potential double click events put their 'line' coordinate in the clickY array
+			// double click event has two conditions, temporal and spatial, the first is checked here
+			now := time.Now()
+			if now.Sub(r.prevDownTime) < doubleClickDuration {
+				r.clickY = append(r.clickY, y)
+			} else {
+				r.clickY = []int{y}
+			}
+			r.prevDownTime = now
+
+			// detect double clicks (also check for spatial condition)
+			n := len(r.clickY)
+			double := n > 1 && r.clickY[n-2] == r.clickY[n-1]
+			if double {
+				// make sure two consecutive double clicks require four clicks
+				r.clickY = []int{}
+			}
+
+			// fire single or double click event
+			return Event{Mouse, 0, &MouseEvent{y, x, 0, true, !double, double, mod}}
+		case button&tcell.Button2 != 0 && !drag:
+			return Event{Mouse, 0, &MouseEvent{y, x, 0, false, true, false, mod}}
+		case runtime.GOOS != "windows":
+
 			// double and single taps on Windows don't quite work due to
 			// the console acting on the events and not allowing us
 			// to consume them.
diff --git a/src/tui/tui.go b/src/tui/tui.go
index eb09da4..12359c6 100644
--- a/src/tui/tui.go
+++ b/src/tui/tui.go
@@ -5,6 +5,8 @@ import (
 	"os"
 	"strconv"
 	"time"
+
+	"github.com/gdamore/tcell"
 )
 
 // Types of user action
@@ -397,20 +399,22 @@ type Window interface {
 }
 
 type FullscreenRenderer struct {
-	theme        *ColorTheme
-	mouse        bool
-	forceBlack   bool
-	prevDownTime time.Time
-	clickY       []int
+	theme           *ColorTheme
+	mouse           bool
+	forceBlack      bool
+	prevDownTime    time.Time
+	prevMouseButton tcell.ButtonMask
+	clickY          []int
 }
 
 func NewFullscreenRenderer(theme *ColorTheme, forceBlack bool, mouse bool) Renderer {
 	r := &FullscreenRenderer{
-		theme:        theme,
-		mouse:        mouse,
-		forceBlack:   forceBlack,
-		prevDownTime: time.Unix(0, 0),
-		clickY:       []int{}}
+		theme:           theme,
+		mouse:           mouse,
+		forceBlack:      forceBlack,
+		prevDownTime:    time.Unix(0, 0),
+		prevMouseButton: tcell.ButtonNone,
+		clickY:          []int{}}
 	return r
 }