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layers.go
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layers.go
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package screen
import (
"context"
"github.com/cfoust/cy/pkg/geom"
"github.com/cfoust/cy/pkg/geom/image"
"github.com/cfoust/cy/pkg/geom/tty"
"github.com/cfoust/cy/pkg/mux"
"github.com/sasha-s/go-deadlock"
)
type Layer struct {
Screen
isInteractive bool
isOpaque bool
}
// Layers allows you to stack several Screens on top of one another. The
// topmost layer with isInteractive set to true receives all key presses.
type Layers struct {
deadlock.RWMutex
*mux.UpdatePublisher
size geom.Vec2
layers []*Layer
}
var _ Screen = (*Layers)(nil)
type RenderLayer struct {
state *tty.State
layer *Layer
}
func (l *Layers) State() *tty.State {
l.RLock()
defer l.RUnlock()
state := tty.New(l.size)
states := make([]RenderLayer, 0)
// We don't want to invoke State() separately in two different passes
for _, layer := range l.layers {
states = append(states, RenderLayer{
state: layer.State(),
layer: layer,
})
}
// In the first pass we layer the states on top of each other
for _, layer := range states {
if layer.layer.isOpaque {
image.Copy(geom.Vec2{}, state.Image, layer.state.Image)
} else {
image.Compose(geom.Vec2{}, state.Image, layer.state.Image)
}
}
// Then we find the topmost cursor state for interactivity
foundCursor := false
for i := len(states) - 1; i >= 0; i-- {
layer := states[i]
if !foundCursor && layer.layer.isInteractive {
foundCursor = true
state.Cursor = layer.state.Cursor
state.CursorVisible = layer.state.CursorVisible
}
}
if !foundCursor {
state.CursorVisible = false
}
return state
}
func (l *Layers) rerender() {
l.Notify()
}
func (l *Layers) NumLayers() int {
l.RLock()
defer l.RUnlock()
return len(l.layers)
}
type LayerOption func(*Layer)
func WithInteractive(layer *Layer) {
layer.isInteractive = true
}
func WithOpaque(layer *Layer) {
layer.isOpaque = true
}
type Position int
const (
PositionTop Position = iota
PositionBottom
)
func (l *Layers) NewLayer(ctx context.Context, screen Screen, pos Position, options ...LayerOption) *Layer {
layer := &Layer{
Screen: screen,
}
for _, option := range options {
option(layer)
}
l.Lock()
if pos == PositionTop {
l.layers = append(l.layers, layer)
} else {
l.layers = append([]*Layer{layer}, l.layers...)
}
l.Unlock()
go func() {
updates := layer.Subscribe(ctx)
for {
select {
case event := <-updates.Recv():
l.Publish(event)
case <-ctx.Done():
return
}
}
}()
go func() {
<-ctx.Done()
l.Lock()
newLayers := make([]*Layer, 0)
for _, other := range l.layers {
if layer == other {
continue
}
newLayers = append(newLayers, other)
}
l.layers = newLayers
l.Unlock()
l.rerender()
}()
layer.Resize(l.size)
return layer
}
func (l *Layers) Send(msg mux.Msg) {
l.RLock()
layers := l.layers
l.RUnlock()
for i := len(layers) - 1; i >= 0; i-- {
layer := layers[i]
if !layer.isInteractive {
continue
}
layer.Send(msg)
return
}
}
func (l *Layers) Resize(size Size) error {
l.Lock()
l.size = size
l.Unlock()
for _, layer := range l.layers {
layer.Resize(size)
}
return nil
}
func NewLayers() *Layers {
return &Layers{
UpdatePublisher: mux.NewPublisher(),
size: geom.DEFAULT_SIZE,
}
}