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      1 // Copyright 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef DEVICE_NFC_NFC_TAG_H_
      6 #define DEVICE_NFC_NFC_TAG_H_
      7 
      8 #include "device/nfc/nfc_tag_technology.h"
      9 
     10 namespace device {
     11 
     12 // NfcTag represents a remote NFC tag. An NFC tag is a passive NFC device,
     13 // powered by the NFC field of the local adapter while it is in range. Tags
     14 // can come in many forms, such as stickers, key fobs, or even embedded in a
     15 // more sofisticated device.
     16 //
     17 // Tags can have a wide range of capabilities. Simple tags just offer
     18 // read/write semantics, and contain some one time programmable areas to make
     19 // read-only. More complex tags offer math operations and per-sector access
     20 // control and authentication. The most sophisticated tags contain operating
     21 // environments allowing complex interactions with the code executing on the
     22 // tag.
     23 //
     24 // The NfcTag class facilitates possible interactions with a tag. The most
     25 // common usage of a tag is to exchange NDEF messages, but different kinds of
     26 // I/O can be performed using the NfcTagTechnology classes.
     27 class NfcTag {
     28  public:
     29   // NFC tag types.
     30   enum TagType {
     31     kTagType1,
     32     kTagType2,
     33     kTagType3,
     34     kTagType4,
     35     kTagTypeUnknown,
     36   };
     37 
     38   // NFC protocols that a tag can support. A tag will usually support only one
     39   // of these.
     40   enum Protocol {
     41     kProtocolFelica,
     42     kProtocolIsoDep,
     43     kProtocolJewel,
     44     kProtocolMifare,
     45     kProtocolNfcDep,
     46     kProtocolUnknown
     47   };
     48 
     49   // Interface for observing changes from NFC tags.
     50   class Observer {
     51    public:
     52     virtual ~Observer() {}
     53 
     54     // Called when the tag type has been determined.
     55     virtual void TagTypeChanged(NfcTag* tag, TagType type) {}
     56 
     57     // Called when the write access to the tag has been determined or changed.
     58     virtual void TagWritePermissionChanged(NfcTag* tag, bool read_only) {}
     59 
     60     // Called when the underlying NFC protocol has been determined.
     61     virtual void TagSupportedProtocolChanged(NfcTag* tag, Protocol protocol) {}
     62 
     63     // Called when all initial values of the tag properties have been received
     64     // from the remote tag and |tag| is ready to use.
     65     virtual void TagReady(NfcTag* tag) {}
     66   };
     67 
     68   virtual ~NfcTag();
     69 
     70   // Adds and removes observers for events on this NFC tag. If monitoring
     71   // multiple tags, check the |tag| parameter of observer methods to determine
     72   // which tag is issuing the event.
     73   virtual void AddObserver(Observer* observer) = 0;
     74   virtual void RemoveObserver(Observer* observer) = 0;
     75 
     76   // Returns the unique identifier assigned to this tag.
     77   virtual std::string GetIdentifier() const = 0;
     78 
     79   // Returns the current tag's NFC forum specified "type".
     80   virtual TagType GetType() const = 0;
     81 
     82   // Returns true, if this tag is read-only and cannot be written to.
     83   virtual bool IsReadOnly() const = 0;
     84 
     85   // Returns the current tag's supported NFC protocol.
     86   virtual Protocol GetSupportedProtocol() const = 0;
     87 
     88   // Returns a bitmask of the tag I/O technologies supported by this tag.
     89   virtual NfcTagTechnology::TechnologyTypeMask
     90       GetSupportedTechnologies() const = 0;
     91 
     92   // Returns true, if all tag properties have been received from the remote tag
     93   // and this object is ready to use.
     94   virtual bool IsReady() const = 0;
     95 
     96   // Returns a pointer to the NDEF technology object that allows I/O on NDEF
     97   // records. If NDEF is not supported by this tag, operations that are
     98   // performed on the returned instance may not succeed. Users can determine
     99   // support by calling NfcTagTechnology::IsSupportedByTag. The returned
    100   // instance is owned by this tag.
    101   virtual NfcNdefTagTechnology* GetNdefTagTechnology() = 0;
    102 
    103  protected:
    104   NfcTag();
    105 
    106  private:
    107   DISALLOW_COPY_AND_ASSIGN(NfcTag);
    108 };
    109 
    110 }  // namespace device
    111 
    112 #endif  // DEVICE_NFC_NFC_TAG_H_
    113