objects/layouts/grid.go

126 lines
3.5 KiB
Go

package layouts
import "math"
import "image"
import "git.tebibyte.media/tomo/tomo"
var _ tomo.Layout = new(Grid)
// Grid is a layout that arranges boxes in a grid formation with distinct rows
// and columns. It is great for creating forms.
type Grid struct {
xExpand []bool
yExpand []bool
}
// NewGrid creates a new grid layout. Rows and columns are specified as slices
// of booleans, where true means a row or column will expand and false means it
// will contract. Boxes are laid out left to right, then top to bottom. Boxes
// that go beyond the lengh of rows will be laid out according to columns, but
// they will not expand vertically.
//
// If you aren't sure how to use this constructor, here is an example:
//
// X0 X1 X2 Y0 Y1 Y2
// NewGrid(true, false, true)(false, true, true)
func NewGrid (columns ...bool) func (rows ...bool) *Grid {
return func (rows ...bool) *Grid {
return &Grid {
xExpand: columns,
yExpand: rows,
}
}
}
func (this *Grid) MinimumSize (hints tomo.LayoutHints, boxes tomo.BoxQuerier) image.Point {
cols, rows := this.minimums(boxes)
size := image.Pt (
(len(cols) - 1) * hints.Gap.X,
(len(rows) - 1) * hints.Gap.Y)
for _, width := range cols { size.X += width }
for _, height := range rows { size.Y += height }
return size
}
func (this *Grid) Arrange (hints tomo.LayoutHints, boxes tomo.BoxArranger) {
xExpand := func (index int) bool {
return this.xExpand[index]
}
yExpand := func (index int) bool {
if index < len(this.yExpand) { return this.yExpand[index] }
return false
}
cols, rows := this.minimums(boxes)
expand(hints, cols, hints.Bounds.Dx(), xExpand)
expand(hints, rows, hints.Bounds.Dy(), yExpand)
position := hints.Bounds.Min
for index := 0; index < boxes.Len(); index ++ {
col, row := index % len(cols), index / len(cols)
boxes.SetBounds(index, image.Rectangle {
Min: position,
Max: position.Add(image.Pt(cols[col], rows[row])),
})
if col == len(cols) - 1 {
position.X = hints.Bounds.Min.X
position.Y += rows[row] + hints.Gap.Y
} else {
position.X += cols[col] + hints.Gap.X
}
}
}
func (this *Grid) minimums (boxes tomo.BoxQuerier) ([]int, []int) {
nCols, nRows := this.dimensions(boxes)
cols, rows := make([]int, nCols), make([]int, nRows)
for index := 0; index < boxes.Len(); index ++ {
col, row := index % len(cols), index / len(cols)
minimum := boxes.MinimumSize(index)
if cols[col] < minimum.X {
cols[col] = minimum.X
}
if rows[row] < minimum.Y {
rows[row] = minimum.Y
}
}
return cols, rows
}
func (this *Grid) dimensions (boxes tomo.BoxQuerier) (int, int) {
return len(this.xExpand), ceilDiv(boxes.Len(), len(this.xExpand))
}
func expand (hints tomo.LayoutHints, sizes []int, space int, expands func (int) bool) {
gaps := len(sizes) - 1
freeSpace := float64(space - hints.Gap.Y * gaps)
nExpanding := 0; for index, minimum := range sizes {
if expands(index) {
nExpanding ++
} else {
freeSpace -= float64(minimum)
}
}
expandingSize := freeSpace / float64(nExpanding)
for index := range sizes {
if expands(index) {
sizes[index] = int(expandingSize)
}
}
}
func ceilDiv (x, y int) int {
if y == 0 { return 0 }
return int(math.Ceil(float64(x) / float64(y)))
}
func (this *Grid) RecommendedHeight (hints tomo.LayoutHints, boxes tomo.BoxQuerier, width int) int {
return this.MinimumSize(hints, boxes).Y
}
func (this *Grid) RecommendedWidth (hints tomo.LayoutHints, boxes tomo.BoxQuerier, height int) int {
return this.MinimumSize(hints, boxes).X
}