From 992c242ba2124675281364bf36aca89481972bc6 Mon Sep 17 00:00:00 2001
From: Sasha Koshka <sashakoshka@tebibyte.media>
Date: Sat, 12 Aug 2023 01:02:48 -0400
Subject: [PATCH] Add slider

---
 slider.go | 184 +++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 176 insertions(+), 8 deletions(-)

diff --git a/slider.go b/slider.go
index fdb3488..0b1ad23 100644
--- a/slider.go
+++ b/slider.go
@@ -1,38 +1,206 @@
 package objects
 
+import "image"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/theme"
+import "git.tebibyte.media/tomo/tomo/input"
+import "git.tebibyte.media/tomo/tomo/event"
 
+// UNDER CONSTRUCTION!
 
 type Slider struct {
 	tomo.ContainerBox
-	handle *SliderHandle
-	vertical bool
+	handle     *SliderHandle
+	layout     sliderLayout
+	dragging   bool
+	dragOffset image.Point
+	
+	on struct {
+		valueChange event.FuncBroadcaster
+	}
 }
 
 type SliderHandle struct {
 	tomo.Box
 }
 
-func newSlider (orient string) *Slider {
+func newSlider (orient string, value float64) *Slider {
 	this := &Slider {
 		ContainerBox: tomo.NewContainerBox(),
 		handle: &SliderHandle {
 			Box: tomo.NewBox(),
 		},
-		vertical: orient == "vertical",
+		layout: sliderLayout {
+			vertical: orient == "vertical",
+		},
 	}
 	
 	this.Add(this.handle)
+	this.SetFocusable(true)
+	this.SetPropagateEvents(false)
+	this.SetValue(value)
+	this.OnKeyDown(this.handleKeyDown)
+	this.OnMouseDown(this.handleMouseDown)
+	this.OnMouseUp(this.handleMouseUp)
+	this.OnMouseMove(this.handleMouseMove)
 	theme.Apply(this.handle, theme.R("objects", "SliderHandle", orient))
 	theme.Apply(this,        theme.R("objects", "Slider", orient))
 	return this
 }
 
-func NewVerticalSlider () *Slider {
-	return newSlider("vertical")
+func NewVerticalSlider (value float64) *Slider {
+	return newSlider("vertical", value)
 }
 
-func NewHorizontalSlider () *Slider {
-	return newSlider("horizontal")
+func NewHorizontalSlider (value float64) *Slider {
+	return newSlider("horizontal", value)
+}
+
+func (this *Slider) SetValue (value float64) {
+	if value < 0 { value = 0 }
+	if value > 1 { value = 1 }
+	if value == this.layout.value { return }
+	this.layout.value = value
+	this.SetLayout(this.layout)
+	this.on.valueChange.Broadcast()
+}
+
+func (this *Slider) Value () float64 {
+	return this.layout.value
+}
+
+func (this *Slider) OnValueChange (callback func ()) event.Cookie {
+	return this.on.valueChange.Connect(callback)
+}
+
+func (this *Slider) handleKeyDown (key input.Key, numpad bool) {
+	switch key {
+	case input.KeyUp, input.KeyLeft:
+		if this.Modifiers().Alt {
+			this.SetValue(0)
+		} else {
+			this.SetValue(this.Value() - 0.05)		
+		}
+	case input.KeyDown, input.KeyRight:
+		if this.Modifiers().Alt {
+			this.SetValue(1)
+		} else {
+			this.SetValue(this.Value() + 0.05)		
+		}
+	case input.KeyHome:
+		this.SetValue(0)
+	case input.KeyEnd:
+		this.SetValue(1)
+	}
+}
+
+func (this *Slider) handleMouseDown (button input.Button) {
+	pointer := this.MousePosition()
+	handle  := this.handle.Bounds()
+	var above, within bool
+	
+	if pointer.In(handle) {
+		within = true
+	} else if this.layout.vertical {
+		above = pointer.Y < handle.Min.Y
+	} else {
+		above = pointer.X < handle.Min.X
+	}
+	
+	switch button {
+	case input.ButtonLeft:
+		if within {
+			this.dragging   = true
+			this.dragOffset =
+				pointer.Sub(this.handle.Bounds().Min).
+				Add(this.InnerBounds().Min)
+			this.drag()
+		} else {
+			this.dragOffset = this.fallbackDragOffset()
+			this.dragging   = true
+			this.drag()
+		}
+	case input.ButtonMiddle:
+		if above {
+			this.SetValue(0)
+		} else {
+			this.SetValue(1)
+		}
+	case input.ButtonRight:
+		if above {
+			this.SetValue(this.Value() - 0.05)
+		} else {
+			this.SetValue(this.Value() + 0.05)
+		}
+	}
+}
+
+func (this *Slider) handleMouseUp (button input.Button) {
+	if button != input.ButtonLeft || !this.dragging { return }
+	this.dragging = false
+}
+
+func (this *Slider) handleMouseMove () {
+	if !this.dragging { return }
+	this.drag()
+}
+
+func (this *Slider) drag () {
+	pointer := this.MousePosition().Sub(this.dragOffset)
+	gutter  := this.InnerBounds()
+	handle  := this.handle.Bounds()
+
+	if this.layout.vertical {
+		this.SetValue (
+			float64(pointer.Y) /
+			float64(gutter.Dy() - handle.Dy()))
+	} else {
+		this.SetValue (
+			float64(pointer.X) /
+			float64(gutter.Dx() - handle.Dx()))
+	}
+}
+
+func (this *Slider) fallbackDragOffset () image.Point {
+	if this.layout.vertical {
+		return this.InnerBounds().Min.
+			Add(image.Pt(0, this.handle.Bounds().Dy() / 2))
+	} else {
+		return this.InnerBounds().Min.
+			Add(image.Pt(this.handle.Bounds().Dx() / 2, 0))
+	}
+}
+
+type sliderLayout struct {
+	vertical bool
+	value    float64
+}
+
+func (sliderLayout) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	if len(boxes) != 1 { return image.Pt(0, 0) }
+	return boxes[0].MinimumSize()
+}
+
+func (this sliderLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	if len(boxes) != 1 { return }
+	handle := image.Rectangle { Max: boxes[0].MinimumSize() }
+	gutter := hints.Bounds
+	
+	if this.vertical {
+		height := gutter.Dy() - handle.Dy()
+		offset := int(float64(height) * this.value)
+		gutter.Max.X = handle.Max.X
+		boxes[0].SetBounds (
+			handle.
+			Add(image.Pt(0, offset)).
+			Add(gutter.Min))
+	} else {
+		width  := gutter.Dx() - handle.Dx()
+		offset := int(float64(width) * this.value)
+		gutter.Max.Y = handle.Max.Y
+		boxes[0].SetBounds (
+			handle.
+			Add(image.Pt(offset, 0)).
+			Add(gutter.Min))
+	}
 }