Made this crazy selection system

elements/entry.go

@@ -0,0 +1,142 @@
+package elements
+
+import "git.tebibyte.media/sashakoshka/tomo"
+import "git.tebibyte.media/sashakoshka/tomo/canvas"
+import "git.tebibyte.media/sashakoshka/tomo/artist"
+import "git.tebibyte.media/sashakoshka/tomo/default/theme"
+
+type cellEntity interface {
+	tomo.ContainerEntity
+	tomo.SelectableEntity
+}
+
+// Cell is a single-element container that satisfies tomo.Selectable. It
+// provides styling based on whether or not it is selected.
+type Cell struct {
+	entity   cellEntity
+	child    tomo.Element
+	enabled  bool
+	padding  bool
+	theme    theme.Wrapped
+}
+
+// NewCell creates a new cell element. If padding is true, the cell will have
+// padding on all sides. Child can be nil and added later with the Adopt()
+// method.
+func NewCell (child tomo.Element, padding bool) (element *Cell) {
+	element = &Cell { padding: padding }
+	element.theme.Case = tomo.C("tomo", "cell")
+	element.entity = tomo.NewEntity(element).(cellEntity)
+	element.Adopt(child)
+	return
+}
+
+// Entity returns this element's entity.
+func (element *Cell) Entity () tomo.Entity {
+	return element.entity
+}
+
+// Draw causes the element to draw to the specified destination canvas.
+func (element *Cell) Draw (destination canvas.Canvas) {
+	bounds  := element.entity.Bounds()
+	pattern := element.theme.Pattern(tomo.PatternTableCell, element.state())
+	if element.child == nil {
+		pattern.Draw(destination, bounds)
+	} else if element.padding {
+		artist.DrawShatter (
+			destination, pattern, bounds,
+			element.child.Entity().Bounds())
+	}
+}
+
+// Draw causes the element to perform a layout operation.
+func (element *Cell) Layout () {
+	if element.child == nil { return }
+	
+	bounds := element.entity.Bounds()
+	if element.padding {
+		bounds = element.theme.Padding(tomo.PatternTableCell).Apply(bounds)
+	}
+
+	element.entity.PlaceChild(0, bounds)
+}
+
+// DrawBackground draws this element's background pattern to the specified
+// destination canvas.
+func (element *Cell) DrawBackground (destination canvas.Canvas) {
+	element.theme.Pattern(tomo.PatternTableCell, element.state()).
+		Draw(destination, element.entity.Bounds())
+}
+
+// Adopt sets this element's child. If nil is passed, any child is removed.
+func (element *Cell) Adopt (child tomo.Element) {
+	if element.child != nil {
+		element.entity.Disown(element.entity.IndexOf(element.child))
+	}
+	if child != nil {
+		element.entity.Adopt(child)
+	}
+	element.child = child
+
+	element.updateMinimumSize()
+	element.entity.Invalidate()
+	element.entity.InvalidateLayout()
+}
+
+// Enabled returns whether this cell is enabled or not.
+func (element *Cell) Enabled () bool {
+	return element.enabled
+}
+
+// SetEnabled sets whether this cell can be selected or not.
+func (element *Cell) SetEnabled (enabled bool) {
+	if element.enabled == enabled { return }
+	element.enabled = enabled
+	element.entity.Invalidate()
+	if child, ok := element.child.(tomo.Enableable); ok {
+		child.SetEnabled(enabled)
+	}
+}
+
+// SetTheme sets this element's theme.
+func (element *Cell) SetTheme (theme tomo.Theme) {
+	if theme == element.theme.Theme { return }
+	element.theme.Theme = theme
+	element.updateMinimumSize()
+	element.entity.Invalidate()
+	element.entity.InvalidateLayout()
+}
+
+func (element *Cell) HandleSelectionChange () {
+	element.entity.Invalidate()
+}
+
+func (element *Cell) HandleChildMinimumSizeChange (tomo.Element) {
+	element.updateMinimumSize()
+	element.entity.Invalidate()
+	element.entity.InvalidateLayout()
+}
+
+func (element *Cell) state () tomo.State {
+	return tomo.State {
+		Disabled: !element.enabled,
+		On:       element.entity.Selected(),
+	}
+}
+
+func (element *Cell) updateMinimumSize () {
+	width, height := 0, 0
+
+	if element.child != nil {
+		childWidth, childHeight := element.entity.ChildMinimumSize(0)
+		width  += childWidth
+		height += childHeight
+	}
+	if element.padding {
+		padding := element.theme.Padding(tomo.PatternTableCell)
+		width  += padding.Horizontal()
+		height += padding.Vertical()
+	}
+	
+	element.entity.SetMinimumSize(width, height)
+}