From 28e366bbce51860dab27f22ffd4acdc3ef3a11a3 Mon Sep 17 00:00:00 2001
From: Trevor Slocum <trevor@rocketnine.space>
Date: Wed, 21 Oct 2020 09:36:23 -0700
Subject: [PATCH] Display TextView scroll bar automatically by default

---
 CHANGELOG                      |  1 +
 demos/presentation/cover.go    |  2 +-
 demos/presentation/textview.go |  4 ++--
 demos/presentation/treeview.go |  2 +-
 doc.go                         |  3 +--
 textview.go                    | 38 ++++++++++++++++++++--------------
 6 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 32419be..79dcb7d 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -12,6 +12,7 @@ v1.5.1 (WIP)
 - Allow modification of scroll bar render text
 - Allow scrolling List horizontally
 - Clarify that Table rows must each have the same number of columns
+- Display TextView scroll bar automatically by default
 - Generalize tag stripping as StripTags
 - Make printWithStyle public and rename as PrintStyle
 - Optimize TextView (writing is 90% faster, drawing is 50% faster)
diff --git a/demos/presentation/cover.go b/demos/presentation/cover.go
index ecb39dc..952429d 100644
--- a/demos/presentation/cover.go
+++ b/demos/presentation/cover.go
@@ -11,7 +11,7 @@ import (
 const logo = `
  ======= ===  === === ======== ===  ===  ===
 ===      ===  === === ===      ===  ===  ===
-===      ===  === === ======   ===  ===  ===
+===      ===  === === ======   ===  ===  ===	
 ===       ======  === ===       ===========
  =======    ==    === ========   ==== ====
 `
diff --git a/demos/presentation/textview.go b/demos/presentation/textview.go
index 601836b..dfdbd50 100644
--- a/demos/presentation/textview.go
+++ b/demos/presentation/textview.go
@@ -33,7 +33,6 @@ const textView1 = `[green]func[white] [yellow]main[white]() {
 func TextView1(nextSlide func()) (title string, content cview.Primitive) {
 	textView := cview.NewTextView()
 	textView.SetTextColor(tcell.ColorYellow.TrueColor())
-	textView.SetScrollable(false)
 	textView.SetDoneFunc(func(key tcell.Key) {
 		nextSlide()
 	})
@@ -52,7 +51,7 @@ func TextView1(nextSlide func()) (title string, content cview.Primitive) {
 			}
 
 			fmt.Fprintf(textView, "%d ", n)
-			time.Sleep(200 * time.Millisecond)
+			time.Sleep(75 * time.Millisecond)
 		}
 	}()
 	textView.SetBorder(true)
@@ -153,6 +152,7 @@ func TextView2(nextSlide func()) (title string, content cview.Primitive) {
 	fmt.Fprint(textView, textView2)
 	textView.SetBorder(true)
 	textView.SetTitle("TextView output")
+	textView.SetScrollBarVisibility(cview.ScrollBarAuto)
 
 	flex := cview.NewFlex()
 	flex.AddItem(textView, 0, 1, true)
diff --git a/demos/presentation/treeview.go b/demos/presentation/treeview.go
index c998d89..0f71572 100644
--- a/demos/presentation/treeview.go
+++ b/demos/presentation/treeview.go
@@ -161,5 +161,5 @@ func TreeView(nextSlide func()) (title string, content cview.Primitive) {
 	flex.AddItem(tree, 0, 1, true)
 	flex.AddItem(treeCode, codeWidth, 1, false)
 
-	return "Tree", flex
+	return "TreeView", flex
 }
diff --git a/doc.go b/doc.go
index 62368aa..a4db83c 100644
--- a/doc.go
+++ b/doc.go
@@ -180,8 +180,7 @@ Scroll Bars
 
 Scroll bars are supported by the following widgets: List, Table, TextView and
 TreeView. Each widget will display scroll bars automatically when there are
-additional items offscreen, except TextView. See Widget.SetScrollBarColor and
-Widget.SetScrollBarVisibility.
+additional items offscreen. See SetScrollBarColor and SetScrollBarVisibility.
 
 Hello World
 
diff --git a/textview.go b/textview.go
index 98e2b03..2e62a58 100644
--- a/textview.go
+++ b/textview.go
@@ -206,15 +206,16 @@ type TextView struct {
 // NewTextView returns a new text view.
 func NewTextView() *TextView {
 	return &TextView{
-		Box:            NewBox(),
-		highlights:     make(map[string]struct{}),
-		lineOffset:     -1,
-		reindex:        true,
-		scrollable:     true,
-		align:          AlignLeft,
-		wrap:           true,
-		textColor:      Styles.PrimaryTextColor,
-		scrollBarColor: Styles.ScrollBarColor,
+		Box:                 NewBox(),
+		highlights:          make(map[string]struct{}),
+		lineOffset:          -1,
+		reindex:             true,
+		scrollable:          true,
+		scrollBarVisibility: ScrollBarAuto,
+		scrollBarColor:      Styles.ScrollBarColor,
+		align:               AlignLeft,
+		wrap:                true,
+		textColor:           Styles.PrimaryTextColor,
 	}
 }
 
@@ -964,10 +965,13 @@ func (t *TextView) Draw(screen tcell.Screen) {
 
 	// Get the available size.
 	x, y, width, height := t.GetInnerRect()
+	if height == 0 {
+		return
+	}
 	t.pageSize = height
 
 	t.reindexBuffer(width)
-	showVerticalScrollBar := t.scrollBarVisibility == ScrollBarAlways || (t.scrollBarVisibility == ScrollBarAuto && len(t.index) >= height)
+	showVerticalScrollBar := t.scrollBarVisibility == ScrollBarAlways || (t.scrollBarVisibility == ScrollBarAuto && len(t.index) > height)
 	if showVerticalScrollBar {
 		width-- // Subtract space for scroll bar.
 		if t.wrap {
@@ -1285,12 +1289,16 @@ func (t *TextView) MouseHandler() func(action MouseAction, event *tcell.EventMou
 			consumed = true
 			setFocus(t)
 		case MouseScrollUp:
-			t.trackEnd = false
-			t.lineOffset--
-			consumed = true
+			if t.scrollable {
+				t.trackEnd = false
+				t.lineOffset--
+				consumed = true
+			}
 		case MouseScrollDown:
-			t.lineOffset++
-			consumed = true
+			if t.scrollable {
+				t.lineOffset++
+				consumed = true
+			}
 		}
 
 		return