Files
8bitMyGoUI/layout/masonry.go
T

68 lines
1.6 KiB
Go

package layout
import (
"fmt"
"github.com/egoist/mygo/ui"
"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
)
type MasonryOptions struct {
// Columns is zero for 3.
Columns int
// Gap is zero for 4.
Gap int
}
// Masonry puts each item into the shortest column.
func Masonry(c *ui.Context, heights []int, o MasonryOptions, item func(i int)) *ui.Element {
k := pixel.K(c)
gap := pixel.Or("Masonry Gap", o.Gap, 4)
n := pixel.Or("Masonry Columns", o.Columns, 3)
cols := lanes(heights, n, gap)
row := ui.Row(c).FillWidth().Gap(k.D(gap)).AlignItems(ui.Start)
w, check := pixel.WrapWidth(c, row)
widths := shares(w-gap*(n-1), n)
return row.Draw(func(p *ui.Painter, r ui.Rect) { check(r) }).Children(func() {
for j, lane := range cols {
ui.Column(c).Width(k.D(widths[j])).Gap(k.D(gap)).Children(func() {
for _, i := range lane {
ui.Box(c).FillWidth().Height(k.D(heights[i])).Clip().Children(func() { item(i) })
}
})
}
})
}
// shares splits total into n whole parts, the first larger.
func shares(total, n int) []int {
out := make([]int, n)
for i := range out {
out[i] = max(0, total/n)
if i < total%n {
out[i]++
}
}
return out
}
// lanes deals items into n columns, shortest first.
func lanes(heights []int, n, gap int) [][]int {
out, tall := make([][]int, n), make([]int, n)
for i, h := range heights {
if h <= 0 {
panic(fmt.Sprintf("layout: Masonry height %d at %d", h, i))
}
j := 0
for k := range tall {
if tall[k] < tall[j] {
j = k
}
}
out[j] = append(out[j], i)
tall[j] += h + gap
}
return out
}