forked from joejulian/gio
Elias Naur
3d37491342
The unit.Value is a struct and thus more inconvenient to use than its
underlying float32 type. In addition, most uses don't need a general
value, but rather a specific unit given by the context. This change
replaces unit.Value with two float32 units, Dp and Sp. It also changes
variables and parameters of unit.Value to a specific unit type matching
the context. That is, unit.Dp everywhere except for text sizes which are
in Sp.
Switching to typed float32s has multiple advantages
- They can be constants:
const touchSlop = unit.Dp(16)
- Casting untyped constants is no longer necessary:
insets := layout.UniformInset(16)
- Calculation with values is natural:
func (s ScrollbarStyle) Width() unit.Dp {
return s.Indicator.MinorWidth + s.Track.MinorPadding + s.Track.MinorPadding
}
The main API change is that calls to gtx.Px must be replaced with either
gtx.Dp or gtx.Sp depending on the unit.
Idea by Christophe Meessen.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
103 lines
2.3 KiB
Go
103 lines
2.3 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
|
|
|
|
package layout
|
|
|
|
import (
|
|
"image"
|
|
"time"
|
|
|
|
"gioui.org/io/event"
|
|
"gioui.org/io/system"
|
|
"gioui.org/op"
|
|
"gioui.org/unit"
|
|
)
|
|
|
|
// Context carries the state needed by almost all layouts and widgets.
|
|
// A zero value Context never returns events, map units to pixels
|
|
// with a scale of 1.0, and returns the zero time from Now.
|
|
type Context struct {
|
|
// Constraints track the constraints for the active widget or
|
|
// layout.
|
|
Constraints Constraints
|
|
|
|
Metric unit.Metric
|
|
// By convention, a nil Queue is a signal to widgets to draw themselves
|
|
// in a disabled state.
|
|
Queue event.Queue
|
|
// Now is the animation time.
|
|
Now time.Time
|
|
|
|
// Locale provides information on the system's language preferences.
|
|
// BUG(whereswaldon): this field is not currently populated automatically.
|
|
// Interested users must look up and populate these values manually.
|
|
Locale system.Locale
|
|
|
|
*op.Ops
|
|
}
|
|
|
|
// NewContext is a shorthand for
|
|
//
|
|
// Context{
|
|
// Ops: ops,
|
|
// Now: e.Now,
|
|
// Queue: e.Queue,
|
|
// Config: e.Config,
|
|
// Constraints: Exact(e.Size),
|
|
// }
|
|
//
|
|
// NewContext calls ops.Reset and adjusts ops for e.Insets.
|
|
func NewContext(ops *op.Ops, e system.FrameEvent) Context {
|
|
ops.Reset()
|
|
|
|
size := e.Size
|
|
|
|
if e.Insets != (system.Insets{}) {
|
|
left := e.Metric.Dp(e.Insets.Left)
|
|
top := e.Metric.Dp(e.Insets.Top)
|
|
op.Offset(image.Point{
|
|
X: left,
|
|
Y: top,
|
|
}).Add(ops)
|
|
|
|
size.X -= left + e.Metric.Dp(e.Insets.Right)
|
|
size.Y -= top + e.Metric.Dp(e.Insets.Bottom)
|
|
}
|
|
|
|
return Context{
|
|
Ops: ops,
|
|
Now: e.Now,
|
|
Queue: e.Queue,
|
|
Metric: e.Metric,
|
|
Constraints: Exact(size),
|
|
}
|
|
}
|
|
|
|
// Dp converts v to pixels.
|
|
func (c Context) Dp(v unit.Dp) int {
|
|
return c.Metric.Dp(v)
|
|
}
|
|
|
|
// Sp converts v to pixels.
|
|
func (c Context) Sp(v unit.Sp) int {
|
|
return c.Metric.Sp(v)
|
|
}
|
|
|
|
// Events returns the events available for the key. If no
|
|
// queue is configured, Events returns nil.
|
|
func (c Context) Events(k event.Tag) []event.Event {
|
|
if c.Queue == nil {
|
|
return nil
|
|
}
|
|
return c.Queue.Events(k)
|
|
}
|
|
|
|
// Disabled returns a copy of this context with a nil Queue,
|
|
// blocking events to widgets using it.
|
|
//
|
|
// By convention, a nil Queue is a signal to widgets to draw themselves
|
|
// in a disabled state.
|
|
func (c Context) Disabled() Context {
|
|
c.Queue = nil
|
|
return c
|
|
}
|