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shiny/widget: let a Flow shrink as well as expand. 

This will be needed for scrollable Sheets, where the parent (the Sheet)
should be laid out at a smaller size than its child.

Change-Id: Iacf69c90f263f24f9fd149f3864d23737c1593a8
Reviewed-on: https://go-review.googlesource.com/28345
Reviewed-by: David Crawshaw <crawshaw@golang.org>
This commit is contained in:
Nigel Tao 2016-09-01 16:06:57 +10:00
Родитель da927ba5e2
Коммит 14f0c66cee
4 изменённых файлов: 109 добавлений и 50 удалений
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6
shiny/example/layout/main.go
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@ -46,17 +46,17 @@ func main() {
widget.NewLabel("Cyan:"),
widget.WithLayoutData(
colorPatch(color.RGBA{0x00, 0x7f, 0x7f, 0xff}, px(0), px(20)),
widget.FlowLayoutData{ExpandAlongWeight: 1},
widget.FlowLayoutData{AlongWeight: 1, ExpandAlong: true},
),
widget.NewLabel("Magenta:"),
widget.WithLayoutData(
colorPatch(color.RGBA{0x7f, 0x00, 0x7f, 0xff}, px(0), px(30)),
widget.FlowLayoutData{ExpandAlongWeight: 2},
widget.FlowLayoutData{AlongWeight: 2, ExpandAlong: true},
),
widget.NewLabel("Yellow:"),
widget.WithLayoutData(
colorPatch(color.RGBA{0x7f, 0x7f, 0x00, 0xff}, px(0), px(40)),
widget.FlowLayoutData{ExpandAlongWeight: 3},
widget.FlowLayoutData{AlongWeight: 3, ExpandAlong: true},
),
)

17
shiny/example/textedit/main.go
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@ -25,10 +25,13 @@ import (
"golang.org/x/exp/shiny/widget/theme"
)
func expand(n node.Node, expandAlongWeight int) node.Node {
func stretch(n node.Node, alongWeight int) node.Node {
return widget.WithLayoutData(n, widget.FlowLayoutData{
ExpandAcross: true,
ExpandAlongWeight: expandAlongWeight,
AlongWeight: alongWeight,
ExpandAlong: true,
ShrinkAlong: true,
ExpandAcross: true,
ShrinkAcross: true,
})
}
@ -39,7 +42,7 @@ func main() {
widget.NewPadder(widget.AxisBoth, unit.Ems(0.5),
widget.NewFlow(widget.AxisHorizontal,
widget.NewLabel("TODO: status"),
expand(widget.NewSpace(), 1),
stretch(widget.NewSpace(), 1),
widget.NewLabel("TODO: Menu"),
),
),
@ -50,10 +53,10 @@ func main() {
body := widget.NewText(prideAndPrejudice)
w := widget.NewFlow(widget.AxisVertical,
expand(widget.NewSheet(header), 0),
expand(widget.NewSheet(divider), 0),
stretch(widget.NewSheet(header), 0),
stretch(widget.NewSheet(divider), 0),
// TODO: make the body's sheet scrollable.
expand(widget.NewSheet(body), 1),
stretch(widget.NewSheet(body), 1),
)
if err := widget.RunWindow(s, w, nil); err != nil {

129
shiny/widget/flow.go
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@ -71,46 +71,73 @@ func (w *Flow) Layout(t *theme.Theme) {
return
}
eaExtra, eaWeight := 0, 0
extra, totalExpandWeight, totalShrinkWeight := 0, 0, 0
if w.Axis == AxisHorizontal {
eaExtra = w.Rect.Dx()
extra = w.Rect.Dx()
} else {
eaExtra = w.Rect.Dy()
extra = w.Rect.Dy()
}
for c := w.FirstChild; c != nil; c = c.NextSibling {
if d, ok := c.LayoutData.(FlowLayoutData); ok && d.ExpandAlongWeight > 0 {
eaWeight += d.ExpandAlongWeight
if d, ok := c.LayoutData.(FlowLayoutData); ok && d.AlongWeight > 0 {
if d.AlongWeight <= 0 {
continue
}
if d.ExpandAlong {
totalExpandWeight += d.AlongWeight
}
if d.ShrinkAlong {
totalShrinkWeight += d.AlongWeight
}
}
if w.Axis == AxisHorizontal {
eaExtra -= c.MeasuredSize.X
extra -= c.MeasuredSize.X
} else {
eaExtra -= c.MeasuredSize.Y
extra -= c.MeasuredSize.Y
}
}
if eaExtra < 0 {
eaExtra = 0
expand, shrink, totalWeight := extra > 0, extra < 0, 0
if expand {
if totalExpandWeight == 0 {
expand = false
} else {
totalWeight = totalExpandWeight
}
}
if shrink {
if totalShrinkWeight == 0 {
shrink = false
} else {
totalWeight = totalShrinkWeight
}
}
p := image.Point{}
for c := w.FirstChild; c != nil; c = c.NextSibling {
q := p.Add(c.MeasuredSize)
if d, ok := c.LayoutData.(FlowLayoutData); ok {
if d.ExpandAlongWeight > 0 {
delta := eaExtra * d.ExpandAlongWeight / eaWeight
eaExtra -= delta
eaWeight -= d.ExpandAlongWeight
if w.Axis == AxisHorizontal {
q.X += delta
} else {
q.Y += delta
if d.AlongWeight > 0 {
if (expand && d.ExpandAlong) || (shrink && d.ShrinkAlong) {
delta := extra * d.AlongWeight / totalWeight
extra -= delta
totalWeight -= d.AlongWeight
if w.Axis == AxisHorizontal {
q.X += delta
if q.X < p.X {
q.X = p.X
}
} else {
q.Y += delta
if q.Y < p.Y {
q.Y = p.Y
}
}
}
}
if d.ExpandAcross {
if w.Axis == AxisHorizontal {
q.Y = max(q.Y, w.Rect.Dy())
} else {
q.X = max(q.X, w.Rect.Dx())
}
if w.Axis == AxisHorizontal {
q.Y = stretchAcross(q.Y, w.Rect.Dy(), d.ExpandAcross, d.ShrinkAcross)
} else {
q.X = stretchAcross(q.X, w.Rect.Dx(), d.ExpandAcross, d.ShrinkAcross)
}
}
c.Rect = image.Rectangle{
@ -126,19 +153,55 @@ func (w *Flow) Layout(t *theme.Theme) {
}
}
func stretchAcross(child, parent int, expand, shrink bool) int {
if (expand && child < parent) || (shrink && child > parent) {
return parent
}
return child
}
// FlowLayoutData is the node LayoutData type for a Flow's children.
type FlowLayoutData struct {
// ExpandAlongWeight is the relative weight for distributing any excess
// space along the Flow's axis. For example, if an AxisHorizontal Flow's
// AlongWeight is the relative weight for distributing any space surplus or
// deficit along the Flow's axis. For example, if an AxisHorizontal Flow's
// Rect width was 100 pixels greater than the sum of its children's natural
// widths, and three children had non-zero FlowLayoutData.ExpandAlongWeight
// values 6, 3 and 1, then those children's laid out widths would be larger
// than their natural widths by 60, 30 and 10 pixels.
ExpandAlongWeight int
// widths, and three children had non-zero FlowLayoutData.AlongWeight
// values 6, 3 and 1 (and their FlowLayoutData.ExpandAlong values were
// true) then those children's laid out widths would be larger than their
// natural widths by 60, 30 and 10 pixels.
//
// A negative AlongWeight is equivalent to zero.
AlongWeight int
// ExpandAcross is whether the child's laid out size should expand to fill
// the Flow's cross-axis. For example, if an AxisHorizontal Flow's Rect
// height was 80 pixels, any child whose FlowLayoutData.ExpandAcross was
// true would also be laid out with at least an 80 pixel height.
// ExpandAlong is whether the child's laid out size should increase along
// the Flow's axis, based on AlongWeight, if there is a space surplus (the
// children's measured size total less than the parent's size). To allow
// size decreases as well as increases, set ShrinkAlong.
ExpandAlong bool
// ShrinkAlong is whether the child's laid out size should decrease along
// the Flow's axis, based on AlongWeight, if there is a space deficit (the
// children's measured size total more than the parent's size). To allow
// size increases as well as decreases, set ExpandAlong.
ShrinkAlong bool
// ExpandAcross is whether the child's laid out size should increase along
// the Flow's cross-axis if there is a space surplus (the child's measured
// size is less than the parent's size). To allow size decreases as well as
// increases, set ShrinkAcross.
//
// For example, if an AxisHorizontal Flow's Rect height was 80 pixels, any
// child whose FlowLayoutData.ExpandAcross was true would also be laid out
// with at least an 80 pixel height.
ExpandAcross bool
// ShrinkAcross is whether the child's laid out size should decrease along
// the Flow's cross-axis if there is a space deficit (the child's measured
// size is more than the parent's size). To allow size increases as well as
// decreases, set ExpandAcross.
//
// For example, if an AxisHorizontal Flow's Rect height was 80 pixels, any
// child whose FlowLayoutData.ShrinkAcross was true would also be laid out
// with at most an 80 pixel height.
ShrinkAcross bool
}

7
shiny/widget/widget.go
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@ -22,13 +22,6 @@ import (
"golang.org/x/mobile/event/size"
)
func max(x, y int) int {
if x > y {
return x
}
return y
}
// Axis is zero, one or both of the horizontal and vertical axes. For example,
// a widget may be scrollable in one of the four AxisXxx values.
type Axis uint8