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_TECHNOLOGY_H_ 6 #define DEVICE_NFC_NFC_TAG_TECHNOLOGY_H_ 7 8 #include "base/callback.h" 9 #include "device/nfc/nfc_ndef_record.h" 10 11 namespace device { 12 13 class NfcTag; 14 15 // NfcTagTechnology represents an NFC technology that allows a certain type of 16 // I/O operation on an NFC tag. NFC tags can support a wide array of protocols. 17 // The NfcTagTechnology hierarchy allows both raw and high-level I/O operations 18 // on NFC tags. Do not create instances of these objects directly. Instead, 19 // obtain a handle directly from an NfcTag object. 20 class NfcTagTechnology { 21 public: 22 // The various I/O technologies that an NFC tag can support. 23 enum TechnologyType { 24 kTechnologyTypeNfcA = 1 << 0, 25 kTechnologyTypeNfcB = 1 << 1, 26 kTechnologyTypeNfcF = 1 << 2, 27 kTechnologyTypeNfcV = 1 << 3, 28 kTechnologyTypeIsoDep = 1 << 4, 29 kTechnologyTypeNdef = 1 << 5 30 }; 31 typedef uint32 TechnologyTypeMask; 32 33 virtual ~NfcTagTechnology(); 34 35 // Returns true, if the underlying tag supports the NFC tag technology that 36 // this instance represents. 37 virtual bool IsSupportedByTag() const = 0; 38 39 // Returns a pointer to the associated NfcTag instance. tag()40 NfcTag* tag() const { return tag_; } 41 42 protected: 43 // Constructs a technology instance, where |tag| is the NFC tag that this 44 // instance will operate on. Clients aren't allowed to instantiate classes 45 // directly. They should use the static "Create" methods defined in each 46 // subclass to obtain the platform specific implementation. 47 explicit NfcTagTechnology(NfcTag* tag); 48 49 private: 50 NfcTagTechnology(); 51 52 // The underlying NfcTag instance that data exchange operations through this 53 // instance are performed on. 54 NfcTag* tag_; 55 56 DISALLOW_COPY_AND_ASSIGN(NfcTagTechnology); 57 }; 58 59 // NfcNdefTagTechnology allows reading and writing NDEF messages to a tag. This 60 // is the most commonly used data exchange format in NFC. NDEF is a data 61 // exchange format and is the top most layer of the protocol stack. NDEF itself 62 // is not a protocol; data is typically formatted in a way that is defined by 63 // the NDEF format and then transmitted via one of the underlying protocols. 64 // Hence all tags are capable of NDEF data exchange, however, all tags don't 65 // necessarily use NDEF to operate (e.g. a tag may contain a smart chip that 66 // does data processing on ISO-DEP based APDUs and ignores NDEF). This is why, 67 // even if a tag inherently supports NDEF, operations done via this class may 68 // not necessarily succeed. 69 class NfcNdefTagTechnology : public NfcTagTechnology { 70 public: 71 // The ErrorCallback is used by methods to asynchronously report errors. 72 typedef base::Closure ErrorCallback; 73 74 virtual ~NfcNdefTagTechnology(); 75 76 // Interface for observing changes from NFC tags related to NDEF records. 77 class Observer { 78 public: ~Observer()79 virtual ~Observer() {} 80 81 // This method will be called when an NDEF record |record|, stored on the 82 // NFC tag |tag| has been read. This method will be called multiple times 83 // as records are read from the tag or when the tag's records change (e.g. 84 // when the tag has been rewritten). All received records can be accessed by 85 // calling GetNdefMessage(). RecordReceived(NfcTag * tag,const NfcNdefRecord * record)86 virtual void RecordReceived(NfcTag* tag, const NfcNdefRecord* record) {} 87 }; 88 89 // Adds and removes observers for events on this NFC tag. If monitoring 90 // multiple tags, check the |tag| parameter of observer methods to determine 91 // which tag is issuing the event. 92 virtual void AddObserver(Observer* observer) = 0; 93 virtual void RemoveObserver(Observer* observer) = 0; 94 95 // NfcTagTechnology override. 96 virtual bool IsSupportedByTag() const OVERRIDE; 97 98 // Returns all NDEF records that were received from the tag in the form of an 99 // NDEF message. If the returned NDEF message contains no records, this only 100 // means that no records have yet been received from the tag. Users should 101 // use this method in conjunction with the NfcTag::Observer::RecordsReceived 102 // method to be notified when the records are ready. 103 virtual const NfcNdefMessage& GetNdefMessage() const = 0; 104 105 // Writes the given NDEF message to the underlying tag, overwriting any 106 // existing NDEF message on it. On success, |callback| will be invoked. On 107 // failure, |error_callback| will be invoked. This method can fail, if the 108 // underlying tag does not support NDEF as a technology. 109 virtual void WriteNdef(const NfcNdefMessage& message, 110 const base::Closure& callback, 111 const ErrorCallback& error_callback) = 0; 112 113 protected: 114 // Constructs a technology instance, where |tag| is the NFC tag that this 115 // instance will operate on. 116 explicit NfcNdefTagTechnology(NfcTag* tag); 117 118 DISALLOW_COPY_AND_ASSIGN(NfcNdefTagTechnology); 119 }; 120 121 } // namespace device 122 123 #endif // DEVICE_NFC_NFC_TAG_TECHNOLOGY_H_ 124