From e45e391f6d50ee8446ef2382738f1c3b034e10e2 Mon Sep 17 00:00:00 2001
From: Sasha Koshka <sashakoshka@tebibyte.media>
Date: Fri, 15 Sep 2023 01:47:58 -0400
Subject: [PATCH] Added ScrollContainer

---
 scrollbar.go       |   8 ++-
 scrollcontainer.go | 167 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 174 insertions(+), 1 deletion(-)
 create mode 100644 scrollcontainer.go

diff --git a/scrollbar.go b/scrollbar.go
index 2f71248..826837f 100644
--- a/scrollbar.go
+++ b/scrollbar.go
@@ -278,7 +278,13 @@ func (this scrollbarLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
 	// calculate handle length
 	handleLength := gutterLength * this.viewportContentRatio()
 	if handleLength < handleMin { handleLength = handleMin }
-	if handleLength > gutterLength { handleLength = gutterLength }
+	if handleLength >= gutterLength {
+		// just hide the handle if it isn't needed.
+		// TODO: we need a way to hide and show boxes, this is janky as
+		// fuck
+		boxes[0].SetBounds(image.Rect(-16, -16, 0, 0))
+		return
+	}
 	if this.vertical {
 		handle.Max.Y = int(handleLength)
 	} else {
diff --git a/scrollcontainer.go b/scrollcontainer.go
new file mode 100644
index 0000000..4255f61
--- /dev/null
+++ b/scrollcontainer.go
@@ -0,0 +1,167 @@
+package objects
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/tomo/theme"
+
+// ScrollSide determines which Scrollbars are active in a ScrollContainer.
+type ScrollSide int; const (
+	ScrollVertical ScrollSide = 1 << iota
+	ScrollHorizontal
+	ScrollBoth = ScrollVertical | ScrollHorizontal
+)
+
+// Horizontal returns true if the side includes a horizontal bar.
+func (sides ScrollSide) Horizontal () bool {
+	return sides & ScrollHorizontal > 0
+}
+
+// Vertical returns true if the side includes a vertical bar.
+func (sides ScrollSide) Vertical () bool {
+	return sides & ScrollVertical > 0
+}
+
+// String returns one of:
+//   - both
+//   - horizontal
+//   - vertical
+//   - none
+func (sides ScrollSide) String () string {
+	switch {
+	case sides.Horizontal() && sides.Vertical(): return "both"
+	case sides.Horizontal():                     return "horizontal"
+	case sides.Vertical():                       return "vertical"
+	default:                                     return "none"
+	}
+}
+
+// ScrollContainer couples a ContentBox with one or two Scrollbars.
+type ScrollContainer struct {
+	tomo.ContainerBox
+	layout *scrollContainerLayout
+
+	horizontalCookie event.Cookie
+	verticalCookie   event.Cookie
+}
+
+// NewScrollContainer creates a new scroll container.
+func NewScrollContainer (sides ScrollSide) *ScrollContainer {
+	this := &ScrollContainer {
+		ContainerBox: tomo.NewContainerBox(),
+		layout:       &scrollContainerLayout { },
+	}
+	if sides.Vertical() {
+		this.layout.vertical = NewVerticalScrollbar()
+		this.Add(this.layout.vertical)
+	}
+	if sides.Horizontal() {
+		this.layout.horizontal = NewHorizontalScrollbar()
+		this.Add(this.layout.horizontal)
+	}
+	this.CaptureScroll(true)
+	this.OnScroll(this.handleScroll)
+	theme.Apply(this, theme.R("objects", "ScrollContainer", sides.String()))
+	this.SetLayout(this.layout)
+	return this
+}
+
+// SetRoot sets the root child of the ScrollContainer. There can only be one at
+// a time, and setting it will remove and unlink the current child if there is
+// one.
+func (this *ScrollContainer) SetRoot (root tomo.ContentBox) {
+	if this.layout.root != nil {
+		// delete root and close cookies
+		this.Delete(this.layout.root)
+		if this.horizontalCookie != nil {
+			this.horizontalCookie.Close()
+			this.horizontalCookie = nil
+		}
+		if this.verticalCookie != nil {
+			this.verticalCookie.Close()
+			this.verticalCookie = nil
+		}
+	}
+	this.layout.root = root
+	if root != nil {
+		// insert root at the beginning (for keynav)
+		switch {
+		case this.layout.vertical != nil:
+			this.Insert(root, this.layout.vertical)
+		case this.layout.horizontal != nil:
+			this.Insert(root, this.layout.horizontal)
+		default:
+			this.Add(root)
+		}
+		
+		// link root and remember cookies
+		if this.layout.horizontal != nil {
+			this.horizontalCookie = this.layout.horizontal.Link(root)
+		}
+		if this.layout.vertical != nil {
+			this.verticalCookie =  this.layout.vertical.Link(root)
+		}
+	}
+}
+
+func (this *ScrollContainer) handleScroll (x, y float64) {
+	if this.layout.root == nil { return }
+	this.layout.root.ScrollTo (
+		this.layout.root.ContentBounds().Min.
+		Add(image.Pt(int(x), int(y))))
+}
+
+type scrollContainerLayout struct {
+	root       tomo.ContentBox
+	horizontal *Scrollbar
+	vertical   *Scrollbar
+}
+
+func (this *scrollContainerLayout) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	var minimum image.Point; if this.root != nil {
+		minimum = this.root.MinimumSize()
+	}
+	if this.horizontal != nil {
+		minimum.Y += this.horizontal.MinimumSize().Y
+	}
+	if this.vertical != nil {
+		minimum.X += this.vertical.MinimumSize().X
+		minimum.Y = max(minimum.Y, this.vertical.MinimumSize().Y)
+	}
+	if this.horizontal != nil {
+		minimum.X = max(minimum.X, this.horizontal.MinimumSize().X)
+	}
+	return minimum
+}
+
+func (this *scrollContainerLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	rootBounds := hints.Bounds
+	if this.horizontal != nil {
+		rootBounds.Max.Y -= this.horizontal.MinimumSize().Y
+	}
+	if this.vertical != nil {
+		rootBounds.Max.X -= this.vertical.MinimumSize().X
+	}
+	if this.root != nil {
+		this.root.SetBounds(rootBounds)
+	}
+	if this.horizontal != nil {
+		this.horizontal.SetBounds(image.Rect (
+			hints.Bounds.Min.X,
+			rootBounds.Max.Y,
+			rootBounds.Max.X,
+			hints.Bounds.Max.Y))
+	}
+	if this.vertical != nil {
+		this.vertical.SetBounds(image.Rect (
+			rootBounds.Max.X,
+			hints.Bounds.Min.Y,
+			hints.Bounds.Max.X,
+			rootBounds.Max.Y))
+	}
+}
+
+func max (x, y int) int {
+	if x > y { return x }
+	return y
+}