Bug 1094669 - Add a size attribute for MozNDEFRecord. r=smaug, dimi

From 2f518e162998b4ac911b3e10f8a7f8177fe03f59 Mon Sep 17 00:00:00 2001
---
 dom/nfc/MozNDEFRecord.cpp       | 7 +++++++
 dom/nfc/MozNDEFRecord.h         | 6 ++++++
 dom/webidl/MozNDEFRecord.webidl | 6 ++++++
 3 files changed, 19 insertions(+)

dom/nfc/MozNDEFRecord.cpp

@@ -131,23 +131,30 @@ MozNDEFRecord::MozNDEFRecord(JSContext* aCx, nsPIDOMWindow* aWindow,
   mWindow = aWindow; // For GetParentObject()
 
   mTnf = aOptions.mTnf;
+  mSize = 3; // 1(flags) + 1(type_length) + 1(payload_length)
 
   if (aOptions.mType.WasPassed()) {
     const Uint8Array& type = aOptions.mType.Value();
     type.ComputeLengthAndData();
     mType = Uint8Array::Create(aCx, this, type.Length(), type.Data());
+    mSize += type.Length();
   }
 
   if (aOptions.mId.WasPassed()) {
     const Uint8Array& id = aOptions.mId.Value();
     id.ComputeLengthAndData();
     mId = Uint8Array::Create(aCx, this, id.Length(), id.Data());
+    mSize += 1 /* id_length */ + id.Length();
   }
 
   if (aOptions.mPayload.WasPassed()) {
     const Uint8Array& payload = aOptions.mPayload.Value();
     payload.ComputeLengthAndData();
     mPayload = Uint8Array::Create(aCx, this, payload.Length(), payload.Data());
+    if (payload.Length() > 0xff) {
+      mSize += 3;
+    }
+    mSize += payload.Length();
   }
 
   HoldData();

dom/nfc/MozNDEFRecord.h

@@ -83,6 +83,11 @@ public:
     retval.set(mPayload);
   }
 
+  uint32_t Size() const
+  {
+    return mSize;
+  }
+
 private:
   MozNDEFRecord() MOZ_DELETE;
   nsRefPtr<nsPIDOMWindow> mWindow;
@@ -96,6 +101,7 @@ private:
   JS::Heap<JSObject*> mType;
   JS::Heap<JSObject*> mId;
   JS::Heap<JSObject*> mPayload;
+  uint32_t mSize;
 };
 
 } // namespace dom

dom/webidl/MozNDEFRecord.webidl

@@ -42,6 +42,12 @@ interface MozNDEFRecord
    */
   [Constant]
   readonly attribute Uint8Array? payload;
+
+  /**
+   * Get the size of this NDEF Record.
+   */
+  [Constant]
+  readonly attribute unsigned long size;
 };
 
 dictionary MozNDEFRecordOptions {