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ui/layout: add common state to Context

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Almost every layout and widget need the ui.Config for its environment,
an ui.Ops to store operations. Stateful widgets need an input.Queue
for events.

Add all these common objects to Context, greatly simplifying the
function signatures for Gio programs.

Fixes gio#33

Signed-off-by: Elias Naur <mail@eliasnaur.com>
This commit is contained in:
Elias Naur
2019-09-24 21:10:35 +02:00
parent b928ee65f7
commit 2782436ffc
9 changed files with 157 additions and 156 deletions
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ui/layout/layout.go
+36 -18
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@@ -6,6 +6,7 @@ import (
"image"
"gioui.org/ui"
"gioui.org/ui/input"
)
// Constraints represent a set of acceptable ranges for
@@ -41,11 +42,18 @@ type Direction uint8
// computing dimensions for a user interface element.
type Widget func()
// Context tracks the current constraints and dimensions during
// layout.
// Context carry the state needed by almost all layouts and widgets.
type Context struct {
// Constraints track the constraints for the active widget or
// layout.
Constraints Constraints
Dimensions Dimensions
// Dimensions track the result of the most recent layout
// operation.
Dimensions Dimensions
ui.Config
input.Queue
*ui.Ops
}
const (
@@ -83,6 +91,16 @@ func (s *Context) Layout(cs Constraints, w Widget) Dimensions {
return s.Dimensions
}
// Reset the context.
func (c *Context) Reset(cfg ui.Config, cs Constraints) {
c.Constraints = cs
c.Config = cfg
if c.Ops == nil {
c.Ops = new(ui.Ops)
}
c.Ops.Reset()
}
// Constrain a value to the range [Min; Max].
func (c Constraint) Constrain(v int) int {
if v < c.Min {
@@ -116,12 +134,12 @@ type Inset struct {
type Align Direction
// Layout a widget.
func (in Inset) Layout(c ui.Config, ops *ui.Ops, ctx *Context, w Widget) {
func (in Inset) Layout(c *Context, w Widget) {
top := c.Px(in.Top)
right := c.Px(in.Right)
bottom := c.Px(in.Bottom)
left := c.Px(in.Left)
mcs := ctx.Constraints
mcs := c.Constraints
mcs.Width.Min -= left + right
mcs.Width.Max -= left + right
if mcs.Width.Min < 0 {
@@ -139,12 +157,12 @@ func (in Inset) Layout(c ui.Config, ops *ui.Ops, ctx *Context, w Widget) {
mcs.Height.Max = mcs.Height.Min
}
var stack ui.StackOp
stack.Push(ops)
ui.TransformOp{}.Offset(toPointF(image.Point{X: left, Y: top})).Add(ops)
dims := ctx.Layout(mcs, w)
stack.Push(c.Ops)
ui.TransformOp{}.Offset(toPointF(image.Point{X: left, Y: top})).Add(c.Ops)
dims := c.Layout(mcs, w)
stack.Pop()
ctx.Dimensions = Dimensions{
Size: ctx.Constraints.Constrain(dims.Size.Add(image.Point{X: right + left, Y: top + bottom})),
c.Dimensions = Dimensions{
Size: c.Constraints.Constrain(dims.Size.Add(image.Point{X: right + left, Y: top + bottom})),
Baseline: dims.Baseline + top,
}
}
@@ -156,14 +174,14 @@ func UniformInset(v ui.Value) Inset {
}
// Layout a widget.
func (a Align) Layout(ops *ui.Ops, st *Context, w Widget) {
func (a Align) Layout(c *Context, w Widget) {
var macro ui.MacroOp
macro.Record(ops)
cs := st.Constraints
macro.Record(c.Ops)
cs := c.Constraints
mcs := cs
mcs.Width.Min = 0
mcs.Height.Min = 0
dims := st.Layout(mcs, w)
dims := c.Layout(mcs, w)
macro.Stop()
sz := dims.Size
if sz.X < cs.Width.Min {
@@ -186,11 +204,11 @@ func (a Align) Layout(ops *ui.Ops, st *Context, w Widget) {
p.Y = sz.Y - dims.Size.Y
}
var stack ui.StackOp
stack.Push(ops)
ui.TransformOp{}.Offset(toPointF(p)).Add(ops)
macro.Add(ops)
stack.Push(c.Ops)
ui.TransformOp{}.Offset(toPointF(p)).Add(c.Ops)
macro.Add(c.Ops)
stack.Pop()
st.Dimensions = Dimensions{
c.Dimensions = Dimensions{
Size: sz,
Baseline: dims.Baseline,
}