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
|
package ui
import (
"fmt"
"math"
)
type Grid struct {
Rows []DimSpec
rowLayout []dimLayout
Columns []DimSpec
columnLayout []dimLayout
Cells []*GridCell
onInvalidate func(d Drawable)
invalid bool
}
const (
SIZE_EXACT = iota
SIZE_WEIGHT = iota
)
// Specifies the layout of a single row or column
type DimSpec struct {
// One of SIZE_EXACT or SIZE_WEIGHT
Strategy int
// If Strategy = SIZE_EXACT, this is the number of cells this dim shall
// occupy. If SIZE_WEIGHT, the space left after all exact dims are measured
// is distributed amonst the remaining dims weighted by this value.
Size int
}
// Used to cache layout of each row/column
type dimLayout struct {
Offset int
Size int
}
type GridCell struct {
Row int
Column int
RowSpan int
ColSpan int
Content Drawable
invalid bool
}
func NewGrid() *Grid {
return &Grid{invalid: true}
}
func (cell *GridCell) At(row, col int) *GridCell {
cell.Row = row
cell.Column = col
return cell
}
func (cell *GridCell) Span(rows, cols int) *GridCell {
cell.RowSpan = rows
cell.ColSpan = cols
return cell
}
func (grid *Grid) Draw(ctx *Context) {
invalid := grid.invalid
if invalid {
grid.reflow(ctx)
}
for _, cell := range grid.Cells {
if !cell.invalid && !invalid {
continue
}
rows := grid.rowLayout[cell.Row : cell.Row+cell.RowSpan]
cols := grid.columnLayout[cell.Column : cell.Column+cell.ColSpan]
x := cols[0].Offset
y := rows[0].Offset
width := 0
height := 0
for _, col := range cols {
width += col.Size
}
for _, row := range rows {
height += row.Size
}
subctx := ctx.Subcontext(x, y, width, height)
cell.Content.Draw(subctx)
}
}
func (grid *Grid) reflow(ctx *Context) {
grid.rowLayout = nil
grid.columnLayout = nil
flow := func(specs *[]DimSpec, layouts *[]dimLayout, extent int) {
exact := 0
weight := 0
nweights := 0
for _, dim := range *specs {
if dim.Strategy == SIZE_EXACT {
exact += dim.Size
} else if dim.Strategy == SIZE_WEIGHT {
nweights += 1
weight += dim.Size
}
}
offset := 0
for _, dim := range *specs {
layout := dimLayout{Offset: offset}
if dim.Strategy == SIZE_EXACT {
layout.Size = dim.Size
} else if dim.Strategy == SIZE_WEIGHT {
size := float64(dim.Size) / float64(weight)
size *= float64(extent - exact)
layout.Size = int(math.Floor(size))
}
offset += layout.Size
*layouts = append(*layouts, layout)
}
}
flow(&grid.Rows, &grid.rowLayout, ctx.Height())
flow(&grid.Columns, &grid.columnLayout, ctx.Width())
grid.invalid = false
}
func (grid *Grid) invalidateLayout() {
grid.invalid = true
if grid.onInvalidate != nil {
grid.onInvalidate(grid)
}
}
func (grid *Grid) Invalidate() {
grid.invalidateLayout()
for _, cell := range grid.Cells {
cell.Content.Invalidate()
}
}
func (grid *Grid) OnInvalidate(onInvalidate func(d Drawable)) {
grid.onInvalidate = onInvalidate
}
func (grid *Grid) AddChild(content Drawable) *GridCell {
cell := &GridCell{
RowSpan: 1,
ColSpan: 1,
Content: content,
invalid: true,
}
grid.Cells = append(grid.Cells, cell)
cell.Content.OnInvalidate(grid.cellInvalidated)
cell.invalid = true
grid.invalidateLayout()
return cell
}
func (grid *Grid) RemoveChild(cell *GridCell) {
for i, _cell := range grid.Cells {
if _cell == cell {
grid.Cells = append(grid.Cells[:i], grid.Cells[i+1:]...)
break
}
}
grid.invalidateLayout()
}
func (grid *Grid) cellInvalidated(drawable Drawable) {
var cell *GridCell
for _, cell = range grid.Cells {
if cell.Content == drawable {
break
}
cell = nil
}
if cell == nil {
panic(fmt.Errorf("Attempted to invalidate unknown cell"))
}
cell.invalid = true
if grid.onInvalidate != nil {
grid.onInvalidate(grid)
}
}
|