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>
We're about to reduce the scope of the Window.Queue by moving it
to FrameEvent. As a consequence, Context can no longer rely on a
Queue constant over its lifetime.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
It's one less type (Align) and shorter:
Before:
layout.Align(layout.Center).Layout(...)
After
layout.Center.Layout(...)
It is also safer: since `layout.Align(...)` was a casting operation,
the Go compiler would not complain about an incompatible constant.
For example, the widget/material package contained a wrong cast:
layout.Align(layout.Start)
which should have been
layout.Align(layout.W)
After this change, attempting `layout.Start.Layout(...)` result
in a compile error.
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>
With the simplification of MacroOp, it is now possible to simplify
the Flex API to just a single Layout method, similar to List:
layout.Flex{}.Layout(gtx,
layout.Rigid(func() { ... }),
layout.Flexed(0.5, func() { ... }),
)
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Elias Naur