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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>
83 lines
2.0 KiB
Go
83 lines
2.0 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
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// Package system contains events usually handled at the top-level
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// program level.
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package system
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import (
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"image"
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"time"
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"gioui.org/io/event"
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"gioui.org/op"
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"gioui.org/unit"
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)
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// A FrameEvent requests a new frame in the form of a list of
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// operations that describes what to display and how to handle
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// input.
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type FrameEvent struct {
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// Now is the current animation. Use Now instead of time.Now to
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// synchronize animation and to avoid the time.Now call overhead.
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Now time.Time
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// Metric converts device independent dp and sp to device pixels.
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Metric unit.Metric
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// Size is the dimensions of the window.
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Size image.Point
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// Insets represent the space occupied by system decorations and controls.
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Insets Insets
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// Frame completes the FrameEvent by drawing the graphical operations
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// from ops into the window.
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Frame func(frame *op.Ops)
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// Queue supplies the events for event handlers.
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Queue event.Queue
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}
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// DestroyEvent is the last event sent through
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// a window event channel.
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type DestroyEvent struct {
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// Err is nil for normal window closures. If a
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// window is prematurely closed, Err is the cause.
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Err error
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}
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// Insets is the space taken up by
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// system decoration such as translucent
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// system bars and software keyboards.
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type Insets struct {
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// Values are in pixels.
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Top, Bottom, Left, Right unit.Dp
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}
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// A StageEvent is generated whenever the stage of a
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// Window changes.
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type StageEvent struct {
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Stage Stage
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}
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// Stage of a Window.
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type Stage uint8
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const (
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// StagePaused is the Stage for inactive Windows.
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// Inactive Windows don't receive FrameEvents.
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StagePaused Stage = iota
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// StateRunning is for active Windows.
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StageRunning
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)
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func (l Stage) String() string {
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switch l {
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case StagePaused:
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return "StagePaused"
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case StageRunning:
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return "StageRunning"
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default:
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panic("unexpected Stage value")
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}
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}
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func (FrameEvent) ImplementsEvent() {}
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func (StageEvent) ImplementsEvent() {}
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func (DestroyEvent) ImplementsEvent() {}
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