55 lines
1.7 KiB
Go
55 lines
1.7 KiB
Go
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package tomo
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import "errors"
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// Backend represents a connection to a display server, or something similar.
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// It is capable of managing an event loop, and creating windows.
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type Backend interface {
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// Run runs the backend's event loop. It must block until the backend
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// experiences a fatal error, or Stop() is called.
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Run () (err error)
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// Stop stops the backend's event loop.
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Stop ()
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// Do executes the specified callback within the main thread as soon as
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// possible. This method must be safe to call from other threads.
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Do (callback func ())
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// NewWindow creates a new window with the specified width and height,
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// and returns a struct representing it that fulfills the Window
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// interface.
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NewWindow (width, height int) (window Window, err error)
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}
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// BackendFactory represents a function capable of constructing a backend
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// struct. Any connections should be initialized within this function. If there
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// any errors encountered during this process, the function should immediately
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// stop, clean up any resources, and return an error.
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type BackendFactory func () (backend Backend, err error)
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// RegisterBackend registers a backend factory. When an application calls
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// tomo.Run(), the first registered backend that does not throw an error will be
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// used.
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func RegisterBackend (factory BackendFactory) {
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factories = append(factories, factory)
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}
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var factories []BackendFactory
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func instantiateBackend () (backend Backend, err error) {
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// find a suitable backend
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for _, factory := range factories {
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backend, err = factory()
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if err == nil && backend != nil { return }
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}
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// if none were found, but there was no error produced, produce an
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// error
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if err == nil {
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err = errors.New("no available backends")
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}
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return
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}
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