Added a button to switch the identity in MessageCompose

Originally I wanted to use a Spinner, but it doesn't support multiple
view types (see [1]). Those are necessary because we use different
layouts for accounts (section headers) and identities (selectable list
items).
Removed the ChooseAccount activity because it's now unused.

res/layout/choose_account.xml

@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<ExpandableListView
-    xmlns:android="http://schemas.android.com/apk/res/android"
-    android:id="@android:id/list"
-    android:layout_width="fill_parent"
-    android:layout_height="fill_parent"
-    android:divider="?android:attr/listDivider"
-    android:childDivider="?android:attr/listDivider"
-    android:indicatorLeft="14dip" />

res/layout/choose_account_item.xml

@@ -3,37 +3,21 @@
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
-    android:minHeight="?android:attr/listPreferredItemHeight"
     android:orientation="horizontal"
-    android:paddingRight="6dip"
+    android:background="#cccccc"
-    android:paddingBottom="2dip"
+    android:gravity="left|center_vertical">
-    android:descendantFocusability="blocksDescendants"
-    android:gravity="center_vertical" >
-
-    <View
-        android:id="@+id/chip"
-        android:layout_width="6dip"
-        android:layout_height="fill_parent"
-        android:layout_centerVertical="true"
-        android:layout_alignParentLeft="true" />
-
-    <LinearLayout
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_weight="1"
-        android:orientation="vertical"
-        android:gravity="center_vertical"
-        android:paddingLeft="?android:attr/expandableListPreferredItemPaddingLeft" >
 
     <TextView
-            android:id="@+id/description"
+        android:id="@+id/name"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:singleLine="true"
         android:ellipsize="end"
+        android:paddingTop="2dp"
+        android:paddingLeft="18dp"
+        android:paddingRight="4dp"
+        android:paddingBottom="2dp"
         android:textColor="?android:attr/textColorPrimary"
-            android:textAppearance="?android:attr/textAppearanceMedium" />
+        android:textAppearance="?android:attr/textAppearanceSmall"/>
-
-    </LinearLayout>
 
 </LinearLayout>

res/layout/choose_identity_item.xml

@@ -5,25 +5,20 @@
     android:layout_height="wrap_content"
     android:minHeight="?android:attr/listPreferredItemHeight"
     android:orientation="horizontal"
-    android:paddingRight="6dip"
+    android:gravity="center_vertical">
-    android:paddingBottom="2dip"
-    android:descendantFocusability="blocksDescendants"
-    android:gravity="center_vertical" >
 
     <View
         android:id="@+id/chip"
-        android:layout_width="6dip"
         android:layout_height="fill_parent"
-        android:layout_centerVertical="true"
+        android:layout_width="6dp"/>
-        android:layout_alignParentLeft="true" />
 
     <LinearLayout
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_weight="1"
         android:orientation="vertical"
         android:gravity="center_vertical"
-        android:paddingLeft="?android:attr/expandableListPreferredItemPaddingLeft" >
+        android:paddingLeft="12dp"
+        android:paddingRight="4dp">
 
         <TextView
             android:id="@+id/name"
@@ -32,7 +27,7 @@
             android:singleLine="true"
             android:ellipsize="end"
             android:textColor="?android:attr/textColorPrimary"
-            android:textAppearance="?android:attr/textAppearanceMedium" />
+            android:textAppearance="?android:attr/textAppearanceMedium"/>
 
         <TextView
             android:id="@+id/description"
@@ -41,7 +36,7 @@
             android:singleLine="true"
             android:ellipsize="end"
             android:textColor="?android:attr/textColorSecondary"
-            android:textAppearance="?android:attr/textAppearanceSmall" />
+            android:textAppearance="?android:attr/textAppearanceSmall"/>
 
     </LinearLayout>
 

res/layout/message_compose.xml

@@ -20,17 +20,34 @@
             <LinearLayout
                 android:layout_width="fill_parent"
                 android:layout_height="wrap_content"
+                android:paddingTop="6dp"
                 android:orientation="vertical"
                 android:background="#ededed" >
 
-                <TextView
+                <LinearLayout
-                    android:id="@+id/from"
+                    android:id="@+id/identity_container"
                     android:layout_width="fill_parent"
                     android:layout_height="wrap_content"
+                    android:orientation="horizontal">
+
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
                         android:layout_marginLeft="6dip"
                         android:layout_marginRight="6dip"
+                        android:text="@string/send_as"
                         android:textColor="@android:color/primary_text_light"
-                    android:textAppearance="?android:attr/textAppearanceMedium" />
+                        android:textAppearance="?android:attr/textAppearanceMedium"/>
+
+                    <Button
+                        android:id="@+id/identity"
+                        android:layout_width="fill_parent"
+                        android:layout_height="wrap_content"
+                        android:layout_marginLeft="6dip"
+                        android:layout_marginRight="6dip"/>
+
+                </LinearLayout>
+
                 <LinearLayout
                     android:id="@+id/to_wrapper"
                     android:layout_height="wrap_content"

res/menu/message_compose_option.xml

@@ -30,12 +30,6 @@
 		android:title="@string/discard_action"
 		android:icon="@drawable/ic_menu_close_clear_cancel"
 	/>
-	<item
-		android:id="@+id/choose_identity"
-        android:alphabeticShortcut="i"
-		android:title="@string/send_as"
-		android:icon="@drawable/ic_menu_identity"
-	/>
 	<item
 		android:id="@+id/read_receipt"
 	android:alphabeticShortcut="r"

src/com/fsck/k9/activity/ChooseAccount.java

@@ -1,243 +0,0 @@
-package com.fsck.k9.activity;
-
-import android.content.Context;
-import android.content.Intent;
-import android.os.Bundle;
-import android.util.Log;
-import android.util.TypedValue;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.view.Window;
-import android.widget.BaseExpandableListAdapter;
-import android.widget.ExpandableListAdapter;
-import android.widget.ExpandableListView;
-import android.widget.TextView;
-
-import com.fsck.k9.Account;
-import com.fsck.k9.Identity;
-import com.fsck.k9.K9;
-import com.fsck.k9.Preferences;
-import com.fsck.k9.R;
-
-import java.util.List;
-
-/**
- * Activity displaying list of accounts/identity for user choice
- *
- * @see K9ExpandableListActivity
- */
-public class ChooseAccount extends K9ExpandableListActivity {
-    private static final Account[] EMPTY_ACCOUNT_ARRAY = new Account[0];
-
-    /**
-     * {@link Intent} extended data name for storing {@link Account#getUuid()
-     * account UUID}
-     */
-    public static final String EXTRA_ACCOUNT = ChooseAccount.class.getName() + "_account";
-
-    /**
-     * {@link Intent} extended data name for storing serialized {@link Identity}
-     */
-    public static final String EXTRA_IDENTITY = ChooseAccount.class.getName() + "_identity";
-
-    @Override
-    protected void onCreate(final Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-
-        requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
-        setContentView(R.layout.choose_account);
-
-        final ExpandableListView expandableListView = getExpandableListView();
-        expandableListView.setItemsCanFocus(false);
-
-        final IdentitiesAdapter adapter = createAdapter();
-        setListAdapter(adapter);
-
-        expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
-            @Override
-            public boolean onChildClick(ExpandableListView parent, View v, int groupPosition,
-            int childPosition, long id) {
-                final Identity identity = (Identity) adapter.getChild(groupPosition, childPosition);
-                final Account account = (Account) adapter.getGroup(groupPosition);
-
-                if (!account.isAvailable(v.getContext())) {
-                    Log.i(K9.LOG_TAG, "Refusing selection of unavailable account");
-                    return true;
-                }
-                final Intent intent = new Intent();
-                intent.putExtra(EXTRA_ACCOUNT, account.getUuid());
-                intent.putExtra(EXTRA_IDENTITY, identity);
-                setResult(RESULT_OK, intent);
-
-                finish();
-                return true;
-            }
-        });
-
-        final Bundle extras = getIntent().getExtras();
-        final String uuid = extras.getString(EXTRA_ACCOUNT);
-        if (uuid != null) {
-            final Account[] accounts = adapter.getAccounts();
-            final int length = accounts.length;
-            for (int i = 0; i < length; i++) {
-                final Account account = accounts[i];
-                if (uuid.equals(account.getUuid())) {
-                    // setSelectedChild() doesn't seem to obey the
-                    // shouldExpandGroup parameter (2.1), manually expanding
-                    // group
-                    expandableListView.expandGroup(i);
-
-                    final List<Identity> identities = account.getIdentities();
-                    final Identity identity = (Identity) extras.getSerializable(EXTRA_IDENTITY);
-                    if (identity == null) {
-                        expandableListView.setSelectedChild(i, 0, true);
-                        break;
-                    }
-                    for (int j = 0; j < identities.size(); j++) {
-                        final Identity loopIdentity = identities.get(j);
-                        if (identity.equals(loopIdentity)) {
-                            expandableListView.setSelectedChild(i, j, true);
-                            break;
-                        }
-                    }
-                    break;
-                }
-            }
-        }
-    }
-
-    private IdentitiesAdapter createAdapter() {
-        return new IdentitiesAdapter(this, getLayoutInflater());
-    }
-
-    /**
-     * Dynamically provides accounts/identities data for
-     * {@link ExpandableListView#setAdapter(ExpandableListAdapter)}:
-     *
-     * <ul>
-     * <li>Groups represent {@link Account accounts}</li>
-     * <li>Children represent {@link Identity identities} of the parent account</li>
-     * </ul>
-     */
-    public static class IdentitiesAdapter extends BaseExpandableListAdapter {
-
-        private Context mContext;
-        private LayoutInflater mLayoutInflater;
-        private Account[] mAccounts;
-
-        public IdentitiesAdapter(final Context context, final LayoutInflater layoutInflater) {
-            mContext = context;
-            mLayoutInflater = layoutInflater;
-            Preferences prefs = Preferences.getPreferences(mContext);
-            mAccounts = prefs.getAvailableAccounts().toArray(EMPTY_ACCOUNT_ARRAY);
-        }
-
-        @Override
-        public Object getChild(int groupPosition, int childPosition) {
-            return getAccounts()[groupPosition].getIdentity(childPosition);
-        }
-
-        @Override
-        public long getChildId(int groupPosition, int childPosition) {
-            return Integer.valueOf(childPosition).longValue();
-        }
-
-        @Override
-        public int getChildrenCount(int groupPosition) {
-            return getAccounts()[groupPosition].getIdentities().size();
-        }
-
-        @Override
-        public Object getGroup(int groupPosition) {
-            return getAccounts()[groupPosition];
-        }
-
-        @Override
-        public int getGroupCount() {
-            return getAccounts().length;
-        }
-
-        @Override
-        public long getGroupId(int groupPosition) {
-            return Integer.valueOf(groupPosition).longValue();
-        }
-
-        @Override
-        public View getGroupView(int groupPosition, boolean isExpanded, View convertView,
-                                 ViewGroup parent) {
-            final View v;
-            if (convertView == null) {
-                v = mLayoutInflater.inflate(R.layout.choose_account_item, parent, false);
-            } else {
-                v = convertView;
-            }
-
-            final TextView description = (TextView) v.findViewById(R.id.description);
-            final Account account = getAccounts()[groupPosition];
-            description.setText(account.getDescription());
-            description.setTextSize(TypedValue.COMPLEX_UNIT_SP, K9.getFontSizes().getAccountName());
-
-            // display unavailable accounts translucent
-            /*
-             * 20101030/fiouzy: NullPointerException on null getBackground()
-             *
-                        if (account.isAvailable(parent.getContext()))
-                        {
-                            description.getBackground().setAlpha(255);
-                            description.getBackground().setAlpha(255);
-                        }
-                        else
-                        {
-                            description.getBackground().setAlpha(127);
-                            description.getBackground().setAlpha(127);
-                        }
-            */
-
-            v.findViewById(R.id.chip).setBackgroundColor(account.getChipColor());
-
-            return v;
-        }
-
-        @Override
-        public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
-                                 View convertView, ViewGroup parent) {
-            final Account account = getAccounts()[groupPosition];
-            final Identity identity = account.getIdentity(childPosition);
-
-            final View v;
-            if (convertView == null) {
-                v = mLayoutInflater.inflate(R.layout.choose_identity_item, parent, false);
-            } else {
-                v = convertView;
-            }
-
-            final TextView name = (TextView) v.findViewById(R.id.name);
-            final TextView description = (TextView) v.findViewById(R.id.description);
-            name.setTextSize(TypedValue.COMPLEX_UNIT_SP, K9.getFontSizes().getAccountName());
-            description.setTextSize(TypedValue.COMPLEX_UNIT_SP, K9.getFontSizes().getAccountDescription());
-
-            name.setText(identity.getDescription());
-            description.setText(String.format("%s <%s>", identity.getName(), identity.getEmail()));
-
-            v.findViewById(R.id.chip).setBackgroundColor(account.getChipColor());
-
-            return v;
-        }
-
-        @Override
-        public boolean hasStableIds() {
-            // returning false since accounts/identities are mutable
-            return false;
-        }
-
-        @Override
-        public boolean isChildSelectable(int groupPosition, int childPosition) {
-            return true;
-        }
-
-        private Account[] getAccounts() {
-            return mAccounts;
-        }
-    }
-}

src/com/fsck/k9/activity/K9ExpandableListActivity.java

@@ -1,18 +0,0 @@
-package com.fsck.k9.activity;
-
-import android.app.ExpandableListActivity;
-import android.os.Bundle;
-
-import com.fsck.k9.K9;
-
-/**
- * @see ExpandableListActivity
- */
-public class K9ExpandableListActivity extends ExpandableListActivity {
-
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        setTheme(K9.getK9Theme());
-        super.onCreate(savedInstanceState);
-    }
-}

src/com/fsck/k9/activity/MessageCompose.java

@@ -15,6 +15,7 @@ import com.fsck.k9.mail.*;
 import com.fsck.k9.view.MessageWebView;
 import org.apache.james.mime4j.codec.EncoderUtil;
 import android.app.AlertDialog;
+import android.app.AlertDialog.Builder;
 import android.app.Dialog;
 import android.content.ContentResolver;
 import android.content.Context;
@@ -31,14 +32,17 @@ import android.provider.OpenableColumns;
 import android.text.util.Rfc822Tokenizer;
 import android.util.Log;
 import android.util.TypedValue;
+import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.view.View.OnFocusChangeListener;
+import android.view.ViewGroup;
 import android.view.Window;
 import android.webkit.WebView;
 import android.widget.AutoCompleteTextView.Validator;
+import android.widget.BaseAdapter;
 import android.widget.Button;
 import android.widget.CheckBox;
 import android.widget.EditText;
@@ -84,6 +88,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
     private static final int DIALOG_REFUSE_TO_SAVE_DRAFT_MARKED_ENCRYPTED = 2;
     private static final int DIALOG_CONTINUE_WITHOUT_PUBLIC_KEY = 3;
     private static final int DIALOG_CONFIRM_DISCARD_ON_BACK = 4;
+    private static final int DIALOG_CHOOSE_IDENTITY = 5;
 
     private static final long INVALID_DRAFT_ID = MessagingController.INVALID_MESSAGE_ID;
 
@@ -128,12 +133,11 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
     private static final int MSG_DISCARDED_DRAFT = 6;
 
     private static final int ACTIVITY_REQUEST_PICK_ATTACHMENT = 1;
-    private static final int ACTIVITY_CHOOSE_IDENTITY = 2;
+    private static final int CONTACT_PICKER_TO = 2;
-    private static final int ACTIVITY_CHOOSE_ACCOUNT = 3;
+    private static final int CONTACT_PICKER_CC = 3;
-    private static final int CONTACT_PICKER_TO = 4;
+    private static final int CONTACT_PICKER_BCC = 4;
-    private static final int CONTACT_PICKER_CC = 5;
-    private static final int CONTACT_PICKER_BCC = 6;
 
+    private static final Account[] EMPTY_ACCOUNT_ARRAY = new Account[0];
 
     /**
      * Regular expression to remove the first localized "Re:" prefix in subjects.
@@ -186,7 +190,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
 
     private QuotedTextMode mQuotedTextMode = QuotedTextMode.NONE;
 
-    private TextView mFromView;
+    private Button mChooseIdentityButton;
     private LinearLayout mCcWrapper;
     private LinearLayout mBccWrapper;
     private MultiAutoCompleteTextView mToView;
@@ -410,7 +414,14 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         mAddressAdapter = EmailAddressAdapter.getInstance(this);
         mAddressValidator = new EmailAddressValidator();
 
-        mFromView = (TextView) findViewById(R.id.from);
+        mChooseIdentityButton = (Button) findViewById(R.id.identity);
+        mChooseIdentityButton.setOnClickListener(this);
+
+        if (mAccount.getIdentities().size() == 1 &&
+                Preferences.getPreferences(this).getAvailableAccounts().size() == 1) {
+            findViewById(R.id.identity_container).setVisibility(View.GONE);
+        }
+
         mToView = (MultiAutoCompleteTextView) findViewById(R.id.to);
         mCcView = (MultiAutoCompleteTextView) findViewById(R.id.cc);
         mBccView = (MultiAutoCompleteTextView) findViewById(R.id.bcc);
@@ -548,8 +559,6 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         mQuotedTextEdit.setOnClickListener(this);
         mQuotedTextDelete.setOnClickListener(this);
 
-        mFromView.setVisibility(View.GONE);
-
         mToView.setAdapter(mAddressAdapter);
         mToView.setTokenizer(new Rfc822Tokenizer());
         mToView.setValidator(mAddressValidator);
@@ -607,8 +616,9 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         mReadReceipt = mAccount.isMessageReadReceiptAlways();
         mQuoteStyle = mAccount.getQuoteStyle();
 
-        if (!mSourceMessageProcessed) {
         updateFrom();
+
+        if (!mSourceMessageProcessed) {
             updateSignature();
 
             if (ACTION_REPLY.equals(action) ||
@@ -1776,12 +1786,6 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
             addAttachment(data.getData());
             mDraftNeedsSaving = true;
             break;
-        case ACTIVITY_CHOOSE_IDENTITY:
-            onIdentityChosen(data);
-            break;
-        case ACTIVITY_CHOOSE_ACCOUNT:
-            onAccountChosen(data);
-            break;
         case CONTACT_PICKER_TO:
         case CONTACT_PICKER_CC:
         case CONTACT_PICKER_BCC:
@@ -1811,15 +1815,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         startActivityForResult(mContacts.contactPickerIntent(), resultId);
     }
 
-
+    private void onAccountChosen(Account account, Identity identity) {
-
-    private void onAccountChosen(final Intent intent) {
-        final Bundle extras = intent.getExtras();
-        final String uuid = extras.getString(ChooseAccount.EXTRA_ACCOUNT);
-        final Identity identity = (Identity) extras.getSerializable(ChooseAccount.EXTRA_IDENTITY);
-
-        final Account account = Preferences.getPreferences(this).getAccount(uuid);
-
         if (!mAccount.equals(account)) {
             if (K9.DEBUG) {
                 Log.v(K9.LOG_TAG, "Switching account from " + mAccount + " to " + account);
@@ -1863,11 +1859,6 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         switchToIdentity(identity);
     }
 
-    private void onIdentityChosen(Intent intent) {
-        Bundle bundle = intent.getExtras();
-        switchToIdentity((Identity) bundle.getSerializable(ChooseIdentity.EXTRA_IDENTITY));
-    }
-
     private void switchToIdentity(Identity identity) {
         mIdentity = identity;
         mIdentityChanged = true;
@@ -1877,10 +1868,7 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
     }
 
     private void updateFrom() {
-        if (mIdentityChanged) {
+        mChooseIdentityButton.setText(getIdentityDescription(mIdentity));
-            mFromView.setVisibility(View.VISIBLE);
-        }
-        mFromView.setText(getString(R.string.message_view_from_format, mIdentity.getName(), mIdentity.getEmail()));
     }
 
     private void updateSignature() {
@@ -1923,6 +1911,9 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
                 MessagingController.getInstance(getApplication()).loadMessageForView(account, folderName, sourceMessageUid, null);
             }
             break;
+        case R.id.identity:
+            showDialog(DIALOG_CHOOSE_IDENTITY);
+            break;
         }
     }
 
@@ -1989,9 +1980,6 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         case R.id.add_attachment_video:
             onAddAttachment2("video/*");
             break;
-        case R.id.choose_identity:
-            onChooseIdentity();
-            break;
         case R.id.read_receipt:
             onReadReceipt();
         default:
@@ -2000,25 +1988,6 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         return true;
     }
 
-    private void onChooseIdentity() {
-        // keep things simple: trigger account choice only if there are more
-        // than 1 account
-        mIgnoreOnPause = true;
-        if (Preferences.getPreferences(this).getAvailableAccounts().size() > 1) {
-            final Intent intent = new Intent(this, ChooseAccount.class);
-            intent.putExtra(ChooseAccount.EXTRA_ACCOUNT, mAccount.getUuid());
-            intent.putExtra(ChooseAccount.EXTRA_IDENTITY, mIdentity);
-            startActivityForResult(intent, ACTIVITY_CHOOSE_ACCOUNT);
-        } else if (mAccount.getIdentities().size() > 1) {
-            Intent intent = new Intent(this, ChooseIdentity.class);
-            intent.putExtra(ChooseIdentity.EXTRA_ACCOUNT, mAccount.getUuid());
-            startActivityForResult(intent, ACTIVITY_CHOOSE_IDENTITY);
-        } else {
-            Toast.makeText(this, getString(R.string.no_identities),
-                           Toast.LENGTH_LONG).show();
-        }
-    }
-
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         super.onCreateOptionsMenu(menu);
@@ -2148,6 +2117,19 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
                 }
             })
             .create();
+        case DIALOG_CHOOSE_IDENTITY:
+            Builder builder = new AlertDialog.Builder(this);
+            builder.setTitle(R.string.send_as);
+            final IdentityAdapter adapter = new IdentityAdapter(this, getLayoutInflater());
+            builder.setAdapter(adapter, new DialogInterface.OnClickListener() {
+                @Override
+                public void onClick(DialogInterface dialog, int which) {
+                    IdentityContainer container = (IdentityContainer) adapter.getItem(which);
+                    onAccountChosen(container.account, container.identity);
+                }
+            });
+
+            return builder.create();
         }
         return super.onCreateDialog(id);
     }
@@ -3184,4 +3166,137 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
 
         return insertable;
     }
+
+    /**
+     * Used to store an {@link Identity} instance together with the {@link Account} it belongs to.
+     *
+     * @see IdentityAdapter
+     */
+    static class IdentityContainer {
+        public final Identity identity;
+        public final Account account;
+
+        IdentityContainer(Identity identity, Account account) {
+            this.identity = identity;
+            this.account = account;
+        }
+    }
+
+    /**
+     * Adapter for the <em>Choose identity</em> list view.
+     *
+     * <p>
+     * Account names are displayed as section headers, identities as selectable list items.
+     * </p>
+     */
+    static class IdentityAdapter extends BaseAdapter {
+        private LayoutInflater mLayoutInflater;
+        private List<Object> mItems;
+        private FontSizes mFontSizes;
+
+        public IdentityAdapter(Context context, LayoutInflater layoutInflater) {
+            mLayoutInflater = layoutInflater;
+            mFontSizes = K9.getFontSizes();
+
+            List<Object> items = new ArrayList<Object>();
+            Preferences prefs = Preferences.getPreferences(context.getApplicationContext());
+            Account[] accounts = prefs.getAvailableAccounts().toArray(EMPTY_ACCOUNT_ARRAY);
+            for (Account account : accounts) {
+                items.add(account);
+                List<Identity> identities = account.getIdentities();
+                for (Identity identity : identities) {
+                    items.add(new IdentityContainer(identity, account));
+                }
+            }
+            mItems = items;
+        }
+
+        @Override
+        public int getCount() {
+            return mItems.size();
+        }
+
+        @Override
+        public int getViewTypeCount() {
+            return 2;
+        }
+
+        @Override
+        public int getItemViewType(int position) {
+            return (mItems.get(position) instanceof Account) ? 0 : 1;
+        }
+
+        @Override
+        public boolean isEnabled(int position) {
+            return (mItems.get(position) instanceof IdentityContainer);
+        }
+
+        @Override
+        public Object getItem(int position) {
+            return mItems.get(position);
+        }
+
+        @Override
+        public long getItemId(int position) {
+            return position;
+        }
+
+        @Override
+        public boolean hasStableIds() {
+            return false;
+        }
+
+        @Override
+        public View getView(int position, View convertView, ViewGroup parent) {
+            Object item = mItems.get(position);
+
+            View view = null;
+            if (item instanceof Account) {
+                if (convertView != null && convertView.getTag() instanceof TextView) {
+                    view = convertView;
+                } else {
+                    view = mLayoutInflater.inflate(R.layout.choose_account_item, parent, false);
+                    TextView name = (TextView) view.findViewById(R.id.name);
+                    view.setTag(name);
+                }
+
+                Account account = (Account) item;
+                TextView name = (TextView) view.getTag();
+                name.setText(account.getDescription());
+            } else if (item instanceof IdentityContainer) {
+                if (convertView != null && convertView.getTag() instanceof IdentityHolder) {
+                    view = convertView;
+                } else {
+                    view = mLayoutInflater.inflate(R.layout.choose_identity_item, parent, false);
+                    IdentityHolder holder = new IdentityHolder();
+                    holder.name = (TextView) view.findViewById(R.id.name);
+                    holder.name.setTextSize(TypedValue.COMPLEX_UNIT_SP, mFontSizes.getAccountName());
+                    holder.description = (TextView) view.findViewById(R.id.description);
+                    holder.description.setTextSize(TypedValue.COMPLEX_UNIT_SP, mFontSizes.getAccountDescription());
+                    holder.chip = view.findViewById(R.id.chip);
+                    view.setTag(holder);
+                }
+
+                IdentityContainer identityContainer = (IdentityContainer) item;
+                Identity identity = identityContainer.identity;
+                Account account = identityContainer.account;
+                IdentityHolder holder = (IdentityHolder) view.getTag();
+                holder.name.setText(identity.getDescription());
+                holder.description.setText(getIdentityDescription(identity));
+                holder.chip.setBackgroundColor(account.getChipColor());
+            }
+
+            return view;
+        }
+
+        static class IdentityHolder {
+            public TextView name;
+            public TextView description;
+            public View chip;
+        }
+    }
+
+    private static String getIdentityDescription(Identity identity) {
+        return String.format("%s <%s>", identity.getName(), identity.getEmail());
+    }
 }