79 lines
2.3 KiB
Go
79 lines
2.3 KiB
Go
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package numeter
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import (
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"sync"
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"fyne.io/fyne/v2/data/binding"
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)
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// basicBinder stores a DataItem and a function to be called when it changes.
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// It provides a convenient way to replace data and callback independently.
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type basicBinder struct {
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callbackLock sync.RWMutex
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callback func(binding.DataItem) // access guarded by callbackLock
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dataListenerPairLock sync.RWMutex
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dataListenerPair annotatedListener // access guarded by dataListenerPairLock
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}
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// Bind replaces the data item whose changes are tracked by the callback function.
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func (binder *basicBinder) Bind(data binding.DataItem) {
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listener := binding.NewDataListener(func() { // NB: listener captures `data` but always calls the up-to-date callback
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binder.callbackLock.RLock()
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f := binder.callback
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binder.callbackLock.RUnlock()
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if f != nil {
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f(data)
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}
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})
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data.AddListener(listener)
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listenerInfo := annotatedListener{
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data: data,
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listener: listener,
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}
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binder.dataListenerPairLock.Lock()
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binder.unbindLocked()
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binder.dataListenerPair = listenerInfo
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binder.dataListenerPairLock.Unlock()
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}
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// CallWithData passes the currently bound data item as an argument to the
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// provided function.
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func (binder *basicBinder) CallWithData(f func(data binding.DataItem)) {
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binder.dataListenerPairLock.RLock()
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data := binder.dataListenerPair.data
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binder.dataListenerPairLock.RUnlock()
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f(data)
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}
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// SetCallback replaces the function to be called when the data changes.
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func (binder *basicBinder) SetCallback(f func(data binding.DataItem)) {
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binder.callbackLock.Lock()
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binder.callback = f
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binder.callbackLock.Unlock()
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}
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// Unbind requests the callback to be no longer called when the previously bound
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// data item changes.
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func (binder *basicBinder) Unbind() {
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binder.dataListenerPairLock.Lock()
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binder.unbindLocked()
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binder.dataListenerPairLock.Unlock()
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}
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// unbindLocked expects the caller to hold dataListenerPairLock.
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func (binder *basicBinder) unbindLocked() {
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previousListener := binder.dataListenerPair
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binder.dataListenerPair = annotatedListener{nil, nil}
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if previousListener.listener == nil || previousListener.data == nil {
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return
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}
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previousListener.data.RemoveListener(previousListener.listener)
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}
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type annotatedListener struct {
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data binding.DataItem
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listener binding.DataListener
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}
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