From 0b7e5392f413cc43cc7569b8aa91e7b03a39aeac Mon Sep 17 00:00:00 2001
From: "sashakoshka@tebibyte.media" <sashakoshka@tebibyte.media>
Date: Sat, 22 Jun 2024 15:44:24 -0400
Subject: [PATCH] Add color picker

---
 colorpicker.go | 156 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 colorpicker.go

diff --git a/colorpicker.go b/colorpicker.go
new file mode 100644
index 0000000..26f1273
--- /dev/null
+++ b/colorpicker.go
@@ -0,0 +1,156 @@
+package objects
+
+import "image/color"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/input"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/objects/layouts"
+import "git.tebibyte.media/tomo/objects/internal"
+
+// ColorPicker allows the user to pick a color by controlling its HSBA
+// parameters.
+type ColorPicker struct {
+	tomo.ContainerBox
+	value internal.HSVA
+	
+	pickerMap   *colorPickerMap
+	hueSlider   *Slider
+	alphaSlider *Slider
+	
+	on struct {
+		valueChange event.FuncBroadcaster
+	}
+}
+
+// NewColorPicker creates a new color picker with the specified color.
+func NewColorPicker (value color.Color) *ColorPicker {
+	picker := &ColorPicker {
+		ContainerBox: tomo.NewContainerBox(),
+	}
+	picker.SetRole(tomo.R("objects", "ColorPicker", ""))
+	picker.SetLayout(layouts.Row { true, false, false })
+	picker.pickerMap = newColorPickerMap(picker)
+	picker.Add(picker.pickerMap)
+	
+	picker.hueSlider = NewVerticalSlider(0.0)
+	picker.Add(picker.hueSlider)
+	picker.hueSlider.OnSlide(func () {
+		picker.value.H = picker.hueSlider.Value()
+		picker.on.valueChange.Broadcast()
+		picker.pickerMap.Invalidate()
+	})
+	
+	picker.alphaSlider = NewVerticalSlider(0.0)
+	picker.Add(picker.alphaSlider)
+	picker.alphaSlider.OnSlide(func () {
+		picker.value.A = uint8(picker.alphaSlider.Value() * 255)
+		picker.on.valueChange.Broadcast()
+		picker.pickerMap.Invalidate()
+	})
+	
+	if value == nil { value = color.Transparent }
+	picker.SetValue(value)
+	return picker
+}
+
+// SetValue sets the color of the picker.
+func (this *ColorPicker) SetValue (value color.Color) {
+	if value == nil { value = color.Transparent }
+	this.value = internal.RGBAToHSVA(value.RGBA())
+	this.hueSlider.SetValue(this.value.H)
+	this.alphaSlider.SetValue(float64(this.value.A) / 255)
+}
+
+// Value returns the color of the picker.
+func (this *ColorPicker) Value () color.Color {
+	return this.value
+}
+
+// RGBA satisfies the color.Color interface
+func (this *ColorPicker) RGBA () (r, g, b, a uint32) {
+	return this.value.RGBA()
+}
+
+// OnValueChange specifies a function to be called when the swatch's color
+// changes.
+func (this *ColorPicker) OnValueChange (callback func ()) event.Cookie {
+	return this.on.valueChange.Connect(callback)
+}
+
+type colorPickerMap struct {
+	tomo.CanvasBox
+	dragging bool
+	parent *ColorPicker
+}
+
+func newColorPickerMap (parent *ColorPicker) *colorPickerMap {
+	picker := &colorPickerMap {
+		CanvasBox: tomo.NewCanvasBox(),
+		parent: parent,
+	}
+	picker.SetDrawer(picker)
+	picker.SetRole(tomo.R("objects", "ColorPickerMap", ""))
+	picker.OnMouseUp(picker.handleMouseUp)
+	picker.OnMouseDown(picker.handleMouseDown)
+	picker.OnMouseMove(picker.handleMouseMove)
+	return picker
+}
+
+func (this *colorPickerMap) handleMouseDown (button input.Button) {
+	if button != input.ButtonLeft { return }
+	this.dragging = true
+	this.drag()
+}
+
+func (this *colorPickerMap) handleMouseUp (button input.Button) {
+	if button != input.ButtonLeft || !this.dragging { return }
+	this.dragging = false
+}
+
+func (this *colorPickerMap) handleMouseMove () {
+	if !this.dragging { return }
+	this.drag()
+}
+
+func (this *colorPickerMap) drag () {
+	pointer := this.MousePosition()
+	bounds  := this.InnerBounds()
+	this.parent.value.S =     float64(pointer.X - bounds.Min.X) / float64(bounds.Dx())
+	this.parent.value.V = 1 - float64(pointer.Y - bounds.Min.Y) / float64(bounds.Dy())
+	this.parent.value = this.parent.value.Canon()
+	this.parent.on.valueChange.Broadcast()
+	this.Invalidate()
+}
+
+func (this *colorPickerMap) Draw (can canvas.Canvas) {
+	bounds := can.Bounds()
+	for y := bounds.Min.Y; y < bounds.Max.Y; y ++ {
+	for x := bounds.Min.X; x < bounds.Max.X; x ++ {
+		xx := x - bounds.Min.X
+		yy := y - bounds.Min.Y
+		
+		pixel := internal.HSVA {
+			H: this.parent.value.H,
+			S:     float64(xx) / float64(bounds.Dx()),
+			V: 1 - float64(yy) / float64(bounds.Dy()),
+			A: 255,
+		}
+		
+		sPos := int(     this.parent.value.S  * float64(bounds.Dx()))
+		vPos := int((1 - this.parent.value.V) * float64(bounds.Dy()))
+		sDist := sPos - xx
+		vDist := vPos - yy
+		crosshair :=
+			(sDist == 0 || vDist == 0) &&
+			-8 < sDist && sDist < 8 &&
+			-8 < vDist && vDist < 8
+		if crosshair {
+			pixel.S = 1 - pixel.S
+			pixel.V = 1 - pixel.V
+		}
+		
+		can.Set(x, y, pixel)
+	}}
+}
+