forked from joejulian/gio
Elias Naur
119 lines
2.0 KiB
Go
119 lines
2.0 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
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package layout
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import (
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"image"
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"gioui.org/ui"
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)
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type Stack struct {
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Alignment Direction
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cs Constraints
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children []stackChild
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maxSZ image.Point
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baseline int
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ccache [10]stackChild
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opCache [10]ui.Op
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}
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type stackChild struct {
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op ui.Op
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dims Dimens
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}
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type Direction uint8
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const (
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NW Direction = iota
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N
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NE
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E
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SE
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S
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SW
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W
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)
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func (s *Stack) Init(cs Constraints) *Stack {
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if s.children == nil {
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s.children = s.ccache[:0]
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}
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s.children = s.children[:0]
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s.maxSZ = image.Point{}
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s.baseline = 0
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s.cs = cs
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return s
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}
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func (s *Stack) Rigid(w Widget) *Stack {
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op, dims := w.Layout(s.cs)
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if w := dims.Size.X; w > s.maxSZ.X {
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s.maxSZ.X = w
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}
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if h := dims.Size.Y; h > s.maxSZ.Y {
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s.maxSZ.Y = h
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}
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s.add(op, dims)
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return s
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}
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func (s *Stack) Expand(idx int, w Widget) *Stack {
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cs := Constraints{
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Width: Constraint{Min: s.maxSZ.X, Max: s.maxSZ.X},
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Height: Constraint{Min: s.maxSZ.Y, Max: s.maxSZ.Y},
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}
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s.add(w.Layout(cs))
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if idx < 0 {
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idx += len(s.children)
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}
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s.children[idx], s.children[len(s.children)-1] = s.children[len(s.children)-1], s.children[idx]
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return s
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}
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func (s *Stack) add(op ui.Op, dims Dimens) {
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s.children = append(s.children, stackChild{op, dims})
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if s.baseline == 0 {
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if b := dims.Baseline; b != dims.Size.Y {
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s.baseline = b
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}
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}
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}
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func (s *Stack) Layout() (ui.Op, Dimens) {
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var ops ui.Ops
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if len(s.children) > len(s.opCache) {
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ops = make([]ui.Op, len(s.children))
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} else {
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ops = s.opCache[:len(s.children)]
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}
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for i, ch := range s.children {
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sz := ch.dims.Size
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var p image.Point
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switch s.Alignment {
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case N, S, Center:
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p.X = (s.maxSZ.X - sz.X) / 2
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case NE, SE, E:
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p.X = s.maxSZ.X - sz.X
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}
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switch s.Alignment {
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case W, Center, E:
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p.Y = (s.maxSZ.Y - sz.Y) / 2
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case SW, S, SE:
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p.Y = s.maxSZ.Y - sz.Y
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}
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ops[i] = ui.OpLayer{Op: ui.OpTransform{Transform: ui.Offset(toPointF(p)), Op: ch.op}}
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}
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b := s.baseline
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if b == 0 {
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b = s.maxSZ.Y
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}
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return ops, Dimens{
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Size: s.maxSZ,
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Baseline: b,
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}
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}
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