From 3e8523f37a03c3ae6ff74d5c97ef016b8fdfc2f6 Mon Sep 17 00:00:00 2001
From: Sasha Koshka <sashakoshka@tebibyte.media>
Date: Fri, 20 Jan 2023 23:40:59 -0500
Subject: [PATCH] TextBox contstrains scroll positions to max

---
 elements/basic/textbox.go  | 13 +++++++++++--
 elements/testing/artist.go |  2 +-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/elements/basic/textbox.go b/elements/basic/textbox.go
index f3d3854..4323a85 100644
--- a/elements/basic/textbox.go
+++ b/elements/basic/textbox.go
@@ -249,16 +249,25 @@ func (element *TextBox) ScrollViewportBounds () (bounds image.Rectangle) {
 	return image.Rect (
 		element.scroll,
 		0,
-		element.scroll + element.Bounds().Inset(theme.Padding()).Dx(),
+		element.scroll + element.scrollViewportWidth(),
 		0)
 }
 
+func (element *TextBox) scrollViewportWidth () (width int) {
+	return element.Bounds().Inset(theme.Padding()).Dx()
+}
+
 // ScrollTo scrolls the viewport to the specified point relative to
 // ScrollBounds.
 func (element *TextBox) ScrollTo (position image.Point) {
+	// constrain to minimum
 	element.scroll = position.X
 	if element.scroll < 0 { element.scroll = 0 }
-	// TODO: constrain to max
+	
+	// constrain to maximum
+	contentBounds := element.ScrollContentBounds()
+	maxPosition   := contentBounds.Max.X - element.scrollViewportWidth()
+	if element.scroll > maxPosition { element.scroll = maxPosition }
 
 	if element.core.HasImage () {
 		element.draw()
diff --git a/elements/testing/artist.go b/elements/testing/artist.go
index 84c88b4..220a236 100644
--- a/elements/testing/artist.go
+++ b/elements/testing/artist.go
@@ -131,7 +131,7 @@ func (element *Artist) Resize (width, height int) {
 }
 
 func (element *Artist) lines (weight int, bounds image.Rectangle) {
-	bounds = bounds.Inset(8)
+	bounds = bounds.Inset(4)
 	c := uhex(0xFFFFFFFF)
 	artist.Line(element, c, weight, bounds.Min, bounds.Max)
 	artist.Line (