Add NFC checkbox to Settings app.

Based on Trusted_NFC_Device_Host_AA03.01e02_google.zip code drop (23-Sep-2010)

Heavily modified to remove dead code.

Change-Id: I9e5f0bf2d32105feff4d68f03adebe87d2e9d900

src/com/android/settings/nfc/NfcEnabler.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.nfc;
+
+import com.android.settings.R;
+import com.trustedlogic.trustednfc.android.NfcException;
+import com.trustedlogic.trustednfc.android.NfcManager;
+import android.content.Context;
+import android.preference.Preference;
+import android.preference.CheckBoxPreference;
+import android.provider.Settings;
+import android.util.Log;
+
+/**
+ * NfcEnabler is a helper to manage the Nfc on/off checkbox preference. It is
+ * turns on/off Nfc and ensures the summary of the preference reflects the
+ * current state.
+ */
+public class NfcEnabler implements Preference.OnPreferenceChangeListener {
+    private static final String TAG = "NfcEnabler";
+
+    private final Context mContext;
+    private final CheckBoxPreference mCheckbox;
+    private final NfcManager mNfcManager;
+
+    private boolean mNfcState;
+
+    public NfcEnabler(Context context, CheckBoxPreference checkBoxPreference) {
+        mContext = context;
+        mCheckbox = checkBoxPreference;
+        mNfcManager = (NfcManager) context.getSystemService(Context.NFC_SERVICE);
+
+        if (mNfcManager == null) {
+            // NFC is not supported
+            mCheckbox.setEnabled(false);
+        }
+    }
+
+    public void resume() {
+        if (mNfcManager == null) {
+            return;
+        }
+		mCheckbox.setOnPreferenceChangeListener(this);
+		mNfcState = Settings.System.getInt(mContext.getContentResolver(),
+		        Settings.System.NFC_ON, 0) != 0;
+		updateUi();
+    }
+
+    public void pause() {
+        if (mNfcManager == null) {
+            return;
+        }
+        mCheckbox.setOnPreferenceChangeListener(null);
+    }
+
+    public boolean onPreferenceChange(Preference preference, Object value) {
+        // Turn on/off Nfc
+        mNfcState = (Boolean) value;
+        setEnabled();
+
+        return false;
+    }
+
+    private void setEnabled() {
+        if (mNfcState) {
+            try {
+                mNfcManager.enable();
+            } catch (NfcException e) {
+                Log.w(TAG, "NFC enabling failed: " + e.getMessage());
+				mNfcState = false;
+            }
+
+        } else {
+            try {
+                mNfcManager.disable();
+            } catch (NfcException e) {
+                Log.w(TAG, "NFC disabling failed: " + e.getMessage());
+				mNfcState = true;
+            }
+        }
+		updateUi();
+	}
+
+    private void updateUi() {
+        mCheckbox.setChecked(mNfcState);
+        if (mNfcState) {
+            mCheckbox.setSummary(R.string.nfc_quick_toggle_summary);
+        } else {
+            mCheckbox.setSummary("");
+        }
+    }
+}