device/nfc/nfc_tag.h

   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_