declarations/webmidi/webmidi.d.ts

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// Type definitions for Web MIDI API
// Project: http://www.w3.org/TR/webmidi/
// Definitions by: six a <https://github.com/lostfictions>
// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped

interface Navigator {
  /**
   * When invoked, returns a Promise object representing a request for access to MIDI
   * devices on the user's system.
   */
  requestMIDIAccess(options?: WebMidi.MIDIOptions) : Promise<WebMidi.MIDIAccess>;
}

declare namespace WebMidi {
  export interface MIDIOptions {
    /**
     * This member informs the system whether the ability to send and receive system
     * exclusive messages is requested or allowed on a given MIDIAccess object.
     */
    sysex : boolean;
  }

  /**
   * This is a maplike interface whose value is a MIDIInput instance and key is its
   * ID.
   */
  export type MIDIInputMap = Map<string, MIDIInput>;

  /**
   * This is a maplike interface whose value is a MIDIOutput instance and key is its
   * ID.
   */
  export type MIDIOutputMap = Map<string, MIDIOutput>;

  export interface MIDIAccess extends EventTarget {
    /**
     * The MIDI input ports available to the system.
     */
    inputs : MIDIInputMap;

    /**
     * The MIDI output ports available to the system.
     */
    outputs : MIDIOutputMap;

    /**
     * The handler called when a new port is connected or an existing port changes the
     * state attribute.
     */
    onstatechange : (e : MIDIConnectionEvent) => void;

    /**
     * This attribute informs the user whether system exclusive support is enabled on
     * this MIDIAccess.
     */
    sysexEnabled : boolean;
  }

  export type MIDIPortType = "input" | "output";

  export type MIDIPortDeviceState = "disconnected" | "connected";

  export type MIDIPortConnectionState = "open" | "closed" | "pending";

  export interface MIDIPort extends EventTarget {
    /**
     * A unique ID of the port. This can be used by developers to remember ports the
     * user has chosen for their application.
     */
    id : string;

    /**
     * The manufacturer of the port.
     */
    manufacturer? : string;

    /**
     * The system name of the port.
     */
    name? : string;

    /**
     * A descriptor property to distinguish whether the port is an input or an output
     * port.
     */
    type : MIDIPortType;

    /**
     * The version of the port.
     */
    version? : string;

    /**
     * The state of the device.
     */
    state : MIDIPortDeviceState;

    /**
     * The state of the connection to the device.
     */
    connection : MIDIPortConnectionState;

    /**
     * The handler called when an existing port changes its state or connection
     * attributes.
     */
    onstatechange : (e : MIDIConnectionEvent) => void;

    /**
     * Makes the MIDI device corresponding to the MIDIPort explicitly available. Note
     * that this call is NOT required in order to use the MIDIPort - calling send() on
     * a MIDIOutput or attaching a MIDIMessageEvent handler on a MIDIInputPort will
     * cause an implicit open().
     *
     * When invoked, this method returns a Promise object representing a request for
     * access to the given MIDI port on the user's system.
     */
    open() : Promise<MIDIPort>;

    /**
     * Makes the MIDI device corresponding to the MIDIPort
     * explicitly unavailable (subsequently changing the state from "open" to
     * "connected"). Note that successful invocation of this method will result in MIDI
     * messages no longer being delivered to MIDIMessageEvent handlers on a
     * MIDIInputPort (although setting a new handler will cause an implicit open()).
     *
     * When invoked, this method returns a Promise object representing a request for
     * access to the given MIDI port on the user's system. When the port has been
     * closed (and therefore, in exclusive access systems, the port is available to
     * other applications), the vended Promise is resolved. If the port is
     * disconnected, the Promise is rejected.
     */
    close() : Promise<MIDIPort>;
  }

  export interface MIDIInput extends MIDIPort {
    onmidimessage : (e : MIDIMessageEvent) => void;
  }

  export interface MIDIOutput extends MIDIPort {
    /**
     * Enqueues the message to be sent to the corresponding MIDI port.
     * @param data The data to be enqueued, with each sequence entry representing a single byte of data.
     * @param timestamp The time at which to begin sending the data to the port. If timestamp is set
     * to zero (or another time in the past), the data is to be sent as soon as
     * possible.
     */
    send(data : number[], timestamp? : number) : void;

    /**
     * Clears any pending send data that has not yet been sent from the MIDIOutput 's
     * queue. The implementation will need to ensure the MIDI stream is left in a good
     * state, so if the output port is in the middle of a sysex message, a sysex
     * termination byte (0xf7) should be sent.
     */
    clear() : void;
  }

  export interface MIDIMessageEvent extends Event {
    /**
     * A timestamp specifying when the event occurred.
     */
    receivedTime : number;

    /**
     * A Uint8Array containing the MIDI data bytes of a single MIDI message.
     */
    data : Uint8Array;
  }

  export interface MIDIMessageEventInit extends EventInit {
    /**
     * A timestamp specifying when the event occurred.
     */
    receivedTime : number;

    /**
     * A Uint8Array containing the MIDI data bytes of a single MIDI message.
     */
    data : Uint8Array;
  }

  export interface MIDIConnectionEvent extends Event {
    /**
     * The port that has been connected or disconnected.
     */
    port : MIDIPort;
  }

  export interface MIDIConnectionEventInit extends EventInit {
    /**
     * The port that has been connected or disconnected.
     */
    port : MIDIPort;
  }
}