Change the definition of Widget from the implicit
type Widget func()
to the explicit functional
type Widget func(gtx layout.Context) layout.Dimensions
The advantages are numerous:
- Clearer connection between the incoming context and the output dimensions.
- Returning the Dimensions are impossible to omit.
- Contexts passed by value, so its fields can be exported
and freely mutated by the program.
The only disadvantage is the longer function literals and the many "returns".
What tipped the scales in favour of the explicit Widget variant is that type
aliases can dramatically shorten the literals:
type (
C = layout.Context
D = layout.Dimensions
)
widget := func(gtx C) D {
...
}
Note that the aliases are not part of the Gio API and it is up to each user
whether they want to use them.
Finally the Go proposal for lightweight function literals,
https://github.com/golang/go/issues/21498, may remove the disadvantage
completely in future.
Context becomes a plain struct with only public fields, and its Reset is
replaced by a NewContext convenience constructor.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Instead of
type Contraints struct {
Width, Height Constraint
}
use
type Constraints struct {
Min, Max image.Point
}
which leads to simpler use. For example, the Min method is trivally replaced by
the field, and the RigidConstraints constructor is no longer a net win.
API Change. Rewrites:
gofmt -r 'gtx.Constraints.Min() -> gtx.Constraints.Min'
gofmt -r 'gtx.Constraints.Width.Min -> gtx.Constraints.Min.X'
gofmt -r 'gtx.Constraints.Height.Min -> gtx.Constraints.Min.Y'
gofmt -r 'gtx.Constraints.Height.Max -> gtx.Constraints.Max.Y'
gofmt -r 'gtx.Constraints.Width.Max -> gtx.Constraints.Max.X'
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Similar to what a previous commit did for Flex, this change simplifies
Stack to just one Layout call:
layout.Stack{}.Layout(gtx,
layout.Stacked(func() {...}),
layout.Expanded(func() {...}),
)
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The ability to invoke other operation lists belongs in the new CallOp.
While we're here, make MacroOp.Add use a pointer receiver to match the
other methods.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Overlapping layouts such as
outer := layout.Flex{}
inner := layout.Stack{}
child := inner.Rigid(gtx, ...)
outerChild := outer.Rigid(gtx, func() {
inner.Layout(gtx, child)
})
outer.Layout(gtx, outerChild)
runs but result in a wrong layout.
This change use empty StackOps to ensure that the Stack and Flex
child layout methods are called in the same scope as their Layout
methods:
outer := layout.Flex{}
inner := layout.Stack{}
outerChild := outer.Rigid(gtx, func() {
child := inner.Rigid(gtx, ...)
inner.Layout(gtx, child)
})
outer.Layout(gtx, outerChild)
Signed-off-by: Elias Naur <mail@eliasnaur.com>
With Context containing all the necessary information, separate
Init methods no longer makes much sense. Delete them and thereby
remove a source of runtime panics.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Elias Naur