objects/layouts/layouts.go

package layouts

import "image"
import "git.tebibyte.media/tomo/tomo"

// Contract is a layout that arranges boxes in a simple row or column according
// to their minimum sizes.
type Contract bool

// ContractVertical is a vertical contracted layout.
const ContractVertical Contract = true

// ContractHorizontal is a horizontal contracted layout.
const ContractHorizontal Contract = false

func (contract Contract) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
	if contract.v() {
		dot := image.Point { }
		for _, box := range boxes {
			minimum := box.MinimumSize()
			dot.Y += minimum.Y
			if dot.X < minimum.X {
				dot.X = minimum.X
			}
		}
		dot.Y += hints.Gap.Y * (len(boxes) - 1)
		return dot
	} else {
		dot := image.Point { }
		for _, box := range boxes {
			minimum := box.MinimumSize()
			dot.X += minimum.X
			if dot.Y < minimum.Y {
				dot.Y = minimum.Y
			}
		}
		dot.X += hints.Gap.X * (len(boxes) - 1)
		return dot
	}
}

func (contract Contract) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
	if contract.v() {
		dot := hints.Bounds.Min
		for index, box := range boxes {
			if index > 0 { dot.Y += hints.Gap.Y }
			minimum := box.MinimumSize()
			box.SetBounds(image.Rectangle {
				Min: dot,
				Max: dot.Add(image.Pt(hints.Bounds.Dx(), minimum.Y)),
			})
			dot.Y += minimum.Y
		}
		
		height := dot.Y - hints.Bounds.Min.Y
		offset := 0
		
		switch hints.AlignY {
		case tomo.AlignMiddle:
			offset = (hints.Bounds.Dy() - height) / 2
		case tomo.AlignEnd:
			offset = hints.Bounds.Dy() - height
		}
		for _, box := range boxes {
			box.SetBounds(box.Bounds().Add(image.Pt(0, offset)))
		}
	} else {
		dot := hints.Bounds.Min
		for index, box := range boxes {
			if index > 0 { dot.X += hints.Gap.X }
			minimum := box.MinimumSize()
			box.SetBounds(image.Rectangle {
				Min: dot,
				Max: dot.Add(image.Pt(minimum.X, hints.Bounds.Dy())),
			})
			dot.X += minimum.X
		}

		width  := dot.X - hints.Bounds.Min.X
		offset := 0
		
		switch hints.AlignX {
		case tomo.AlignMiddle:
			offset = (hints.Bounds.Dx() - width) / 2
		case tomo.AlignEnd:
			offset = hints.Bounds.Dx() - width
		}
		for _, box := range boxes {
			box.SetBounds(box.Bounds().Add(image.Pt(offset, 0)))
		}
	}
}

func (contract Contract) v () bool { return contract == ContractVertical   }
func (contract Contract) h () bool { return contract == ContractHorizontal }