context

Documentation

Index

• type Context
  • func NewContext(ops *op.Ops, e system.FrameEvent) Context
  • func (c Context) Disabled() Context
  • func (c Context) Events(k event.Tag) []event.Event
  • func (c Context) Px(v unit.Value) int

Types

type Context

type Context struct {
	// Constraints track the constraints for the active widget or
	// layout.
	Constraints 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

	*op.Ops
}

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.

func NewContext

func NewContext(ops *op.Ops, e system.FrameEvent) Context

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 (Context) Disabled

func (c Context) Disabled() Context

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 (Context) Events

func (c Context) Events(k event.Tag) []event.Event

Events return the events available for the key. If no queue is configured, Events returns nil.

func (Context) Px

func (c Context) Px(v unit.Value) int

Px maps the value to pixels.