~eliasnaur/gio

ref: 2a0b0077da6f4065b5ec1e0989e07975ec1614bc gio/ui/layout/flex.go -rw-r--r-- 4.9 KiB
2a0b0077Elias Naur ui/app: (wasm) add checks for required extensions 1 year, 10 months ago
                                                                                
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
// SPDX-License-Identifier: Unlicense OR MIT

package layout

import (
	"image"

	"gioui.org/ui"
	"gioui.org/ui/f32"
)

type Flex struct {
	Axis               Axis
	MainAxisAlignment  MainAxisAlignment
	CrossAxisAlignment CrossAxisAlignment

	macro       ui.MacroOp
	ops         *ui.Ops
	cs          Constraints
	mode        flexMode
	size        int
	rigidSize   int
	maxCross    int
	maxBaseline int
}

type FlexChild struct {
	macro ui.MacroOp
	dims  Dimens
}

type MainAxisAlignment uint8
type CrossAxisAlignment uint8

type flexMode uint8

const (
	Start = 100 + iota
	End
	Center

	SpaceAround MainAxisAlignment = iota
	SpaceBetween
	SpaceEvenly

	Baseline CrossAxisAlignment = iota
)

const (
	modeNone flexMode = iota
	modeBegun
	modeRigid
	modeFlex
)

func (f *Flex) Init(ops *ui.Ops, cs Constraints) *Flex {
	if f.mode > modeBegun {
		panic("must End the current child before calling Init again")
	}
	f.mode = modeBegun
	f.ops = ops
	f.cs = cs
	f.size = 0
	f.rigidSize = 0
	f.maxCross = 0
	f.maxBaseline = 0
	return f
}

func (f *Flex) begin(mode flexMode) {
	switch {
	case f.mode == modeNone:
		panic("must Init before adding a child")
	case f.mode > modeBegun:
		panic("must End before adding a child")
	}
	f.mode = mode
	f.macro.Record(f.ops)
}

func (f *Flex) Rigid() Constraints {
	f.begin(modeRigid)
	mainc := axisMainConstraint(f.Axis, f.cs)
	mainMax := mainc.Max - f.size
	if mainMax < 0 {
		mainMax = 0
	}
	return axisConstraints(f.Axis, Constraint{Max: mainMax}, axisCrossConstraint(f.Axis, f.cs))
}

func (f *Flex) Flexible(weight float32) Constraints {
	f.begin(modeFlex)
	mainc := axisMainConstraint(f.Axis, f.cs)
	var flexSize int
	if mainc.Max > f.size {
		maxSize := mainc.Max - f.size
		flexSize = mainc.Max - f.rigidSize
		flexSize = int(float32(flexSize)*weight + .5)
		if flexSize > maxSize {
			flexSize = maxSize
		}
	}
	submainc := Constraint{Max: flexSize}
	return axisConstraints(f.Axis, submainc, axisCrossConstraint(f.Axis, f.cs))
}

func (f *Flex) End(dims Dimens) FlexChild {
	if f.mode <= modeBegun {
		panic("End called without an active child")
	}
	f.macro.Stop()
	sz := axisMain(f.Axis, dims.Size)
	f.size += sz
	if f.mode == modeRigid {
		f.rigidSize += sz
	}
	f.mode = modeBegun
	if c := axisCross(f.Axis, dims.Size); c > f.maxCross {
		f.maxCross = c
	}
	if b := dims.Baseline; b > f.maxBaseline {
		f.maxBaseline = b
	}
	return FlexChild{f.macro, dims}
}

func (f *Flex) Layout(children ...FlexChild) Dimens {
	mainc := axisMainConstraint(f.Axis, f.cs)
	crossSize := axisCrossConstraint(f.Axis, f.cs).Constrain(f.maxCross)
	var space int
	if mainc.Min > f.size {
		space = mainc.Min - f.size
	}
	var mainSize int
	var baseline int
	switch f.MainAxisAlignment {
	case Center:
		mainSize += space / 2
	case End:
		mainSize += space
	case SpaceEvenly:
		mainSize += space / (1 + len(children))
	case SpaceAround:
		mainSize += space / (len(children) * 2)
	}
	for i, child := range children {
		dims := child.dims
		b := dims.Baseline
		var cross int
		switch f.CrossAxisAlignment {
		case End:
			cross = crossSize - axisCross(f.Axis, dims.Size)
		case Center:
			cross = (crossSize - axisCross(f.Axis, dims.Size)) / 2
		case Baseline:
			if f.Axis == Horizontal {
				cross = f.maxBaseline - b
			}
		}
		var stack ui.StackOp
		stack.Push(f.ops)
		ui.TransformOp{}.Offset(toPointF(axisPoint(f.Axis, mainSize, cross))).Add(f.ops)
		child.macro.Add(f.ops)
		stack.Pop()
		mainSize += axisMain(f.Axis, dims.Size)
		if i < len(children)-1 {
			switch f.MainAxisAlignment {
			case SpaceEvenly:
				mainSize += space / (1 + len(children))
			case SpaceAround:
				mainSize += space / len(children)
			case SpaceBetween:
				mainSize += space / (len(children) - 1)
			}
		}
		if b != dims.Size.Y {
			baseline = b
		}
	}
	switch f.MainAxisAlignment {
	case Center:
		mainSize += space / 2
	case Start:
		mainSize += space
	case SpaceEvenly:
		mainSize += space / (1 + len(children))
	case SpaceAround:
		mainSize += space / (len(children) * 2)
	}
	sz := axisPoint(f.Axis, mainSize, crossSize)
	if baseline == 0 {
		baseline = sz.Y
	}
	return Dimens{Size: sz, Baseline: baseline}
}

func axisPoint(a Axis, main, cross int) image.Point {
	if a == Horizontal {
		return image.Point{main, cross}
	} else {
		return image.Point{cross, main}
	}
}

func axisMain(a Axis, sz image.Point) int {
	if a == Horizontal {
		return sz.X
	} else {
		return sz.Y
	}
}

func axisCross(a Axis, sz image.Point) int {
	if a == Horizontal {
		return sz.Y
	} else {
		return sz.X
	}
}

func axisMainConstraint(a Axis, cs Constraints) Constraint {
	if a == Horizontal {
		return cs.Width
	} else {
		return cs.Height
	}
}

func axisCrossConstraint(a Axis, cs Constraints) Constraint {
	if a == Horizontal {
		return cs.Height
	} else {
		return cs.Width
	}
}

func axisConstraints(a Axis, mainc, crossc Constraint) Constraints {
	if a == Horizontal {
		return Constraints{mainc, crossc}
	} else {
		return Constraints{crossc, mainc}
	}
}

func toPointF(p image.Point) f32.Point {
	return f32.Point{X: float32(p.X), Y: float32(p.Y)}
}