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77 lines
1.6 KiB
Go
77 lines
1.6 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
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package layout
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import (
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"time"
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"gioui.org/io/event"
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"gioui.org/io/system"
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"gioui.org/op"
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"gioui.org/unit"
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)
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// Context carries the state needed by almost all layouts and widgets.
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// A zero value Context never returns events, map units to pixels
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// with a scale of 1.0, and returns the zero time from Now.
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type Context struct {
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// Constraints track the constraints for the active widget or
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// layout.
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Constraints Constraints
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Metric unit.Metric
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// By convention, a nil Queue is a signal to widgets to draw themselves
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// in a disabled state.
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Queue event.Queue
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// Now is the animation time.
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Now time.Time
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*op.Ops
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}
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// NewContext is a shorthand for
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//
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// Context{
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// Ops: ops,
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// Now: e.Now,
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// Queue: e.Queue,
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// Config: e.Config,
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// Constraints: Exact(e.Size),
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// }
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//
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// NewContext calls ops.Reset.
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func NewContext(ops *op.Ops, e system.FrameEvent) Context {
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ops.Reset()
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return Context{
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Ops: ops,
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Now: e.Now,
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Queue: e.Queue,
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Metric: e.Metric,
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Constraints: Exact(e.Size),
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}
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}
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// Px maps the value to pixels.
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func (c Context) Px(v unit.Value) int {
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return c.Metric.Px(v)
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}
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// Events returns the events available for the key. If no
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// queue is configured, Events returns nil.
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func (c Context) Events(k event.Tag) []event.Event {
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if c.Queue == nil {
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return nil
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}
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return c.Queue.Events(k)
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}
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// Disabled returns a copy of this context with a nil Queue,
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// blocking events to widgets using it.
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//
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// By convention, a nil Queue is a signal to widgets to draw themselves
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// in a disabled state.
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func (c Context) Disabled() Context {
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c.Queue = nil
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return c
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}
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