Added MultiSelectListPreference

Added set support to XmlUtils; added Set<String> functions to SharedPreferences.

MultiSelectListPreference allows multiple selection and persistence of
string preferences. Addresses bug 2575634.

Change-Id: Icd56022d444b0ce43cccf819cd7d600fdb00e88a

2 files changed, 334 insertions, 3 deletions

diff --git a/core/java/android/preference/MultiSelectListPreference.java b/core/java/android/preference/MultiSelectListPreference.java
new file mode 100644
index 0000000..42d555c
--- /dev/null
+++ b/core/java/android/preference/MultiSelectListPreference.java
@@ -0,0 +1,274 @@
+/*
+ * 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 android.preference;
+
+import android.app.AlertDialog.Builder;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.res.TypedArray;
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.util.AttributeSet;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * A {@link Preference} that displays a list of entries as
+ * a dialog.
+ * <p>
+ * This preference will store a set of strings into the SharedPreferences.
+ * This set will contain one or more values from the
+ * {@link #setEntryValues(CharSequence[])} array.
+ * 
+ * @attr ref android.R.styleable#MultiSelectListPreference_entries
+ * @attr ref android.R.styleable#MultiSelectListPreference_entryValues
+ */
+public class MultiSelectListPreference extends DialogPreference {
+    private CharSequence[] mEntries;
+    private CharSequence[] mEntryValues;
+    private Set<String> mValues = new HashSet<String>();
+    private Set<String> mNewValues = new HashSet<String>();
+    private boolean mPreferenceChanged;
+    
+    public MultiSelectListPreference(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        
+        TypedArray a = context.obtainStyledAttributes(attrs,
+                com.android.internal.R.styleable.MultiSelectListPreference, 0, 0);
+        mEntries = a.getTextArray(com.android.internal.R.styleable.MultiSelectListPreference_entries);
+        mEntryValues = a.getTextArray(com.android.internal.R.styleable.MultiSelectListPreference_entryValues);
+        a.recycle();
+    }
+    
+    public MultiSelectListPreference(Context context) {
+        this(context, null);
+    }
+    
+    /**
+     * Sets the human-readable entries to be shown in the list. This will be
+     * shown in subsequent dialogs.
+     * <p>
+     * Each entry must have a corresponding index in
+     * {@link #setEntryValues(CharSequence[])}.
+     * 
+     * @param entries The entries.
+     * @see #setEntryValues(CharSequence[])
+     */
+    public void setEntries(CharSequence[] entries) {
+        mEntries = entries;
+    }
+    
+    /**
+     * @see #setEntries(CharSequence[])
+     * @param entriesResId The entries array as a resource.
+     */
+    public void setEntries(int entriesResId) {
+        setEntries(getContext().getResources().getTextArray(entriesResId));
+    }
+    
+    /**
+     * The list of entries to be shown in the list in subsequent dialogs.
+     * 
+     * @return The list as an array.
+     */
+    public CharSequence[] getEntries() {
+        return mEntries;
+    }
+    
+    /**
+     * The array to find the value to save for a preference when an entry from
+     * entries is selected. If a user clicks on the second item in entries, the
+     * second item in this array will be saved to the preference.
+     * 
+     * @param entryValues The array to be used as values to save for the preference.
+     */
+    public void setEntryValues(CharSequence[] entryValues) {
+        mEntryValues = entryValues;
+    }
+
+    /**
+     * @see #setEntryValues(CharSequence[])
+     * @param entryValuesResId The entry values array as a resource.
+     */
+    public void setEntryValues(int entryValuesResId) {
+        setEntryValues(getContext().getResources().getTextArray(entryValuesResId));
+    }
+    
+    /**
+     * Returns the array of values to be saved for the preference.
+     * 
+     * @return The array of values.
+     */
+    public CharSequence[] getEntryValues() {
+        return mEntryValues;
+    }
+    
+    /**
+     * Sets the value of the key. This should contain entries in
+     * {@link #getEntryValues()}.
+     * 
+     * @param values The values to set for the key.
+     */
+    public void setValues(Set<String> values) {
+        mValues = values;
+        
+        persistStringSet(values);
+    }
+    
+    /**
+     * Retrieves the current value of the key.
+     */
+    public Set<String> getValues() {
+        return mValues;
+    }
+    
+    /**
+     * Returns the index of the given value (in the entry values array).
+     * 
+     * @param value The value whose index should be returned.
+     * @return The index of the value, or -1 if not found.
+     */
+    public int findIndexOfValue(String value) {
+        if (value != null && mEntryValues != null) {
+            for (int i = mEntryValues.length - 1; i >= 0; i--) {
+                if (mEntryValues[i].equals(value)) {
+                    return i;
+                }
+            }
+        }
+        return -1;
+    }
+    
+    @Override
+    protected void onPrepareDialogBuilder(Builder builder) {
+        super.onPrepareDialogBuilder(builder);
+        
+        if (mEntries == null || mEntryValues == null) {
+            throw new IllegalStateException(
+                    "MultiSelectListPreference requires an entries array and " +
+                    "an entryValues array.");
+        }
+        
+        boolean[] checkedItems = getSelectedItems();
+        builder.setMultiChoiceItems(mEntries, checkedItems,
+                new DialogInterface.OnMultiChoiceClickListener() {
+                    public void onClick(DialogInterface dialog, int which, boolean isChecked) {
+                        if (isChecked) {
+                            mPreferenceChanged |= mNewValues.add(mEntries[which].toString());
+                        } else {
+                            mPreferenceChanged |= mNewValues.remove(mEntries[which].toString());
+                        }
+                    }
+                });
+        mNewValues.clear();
+        mNewValues.addAll(mValues);
+    }
+    
+    private boolean[] getSelectedItems() {
+        final CharSequence[] entries = mEntries;
+        final int entryCount = entries.length;
+        final Set<String> values = mValues;
+        boolean[] result = new boolean[entryCount];
+        
+        for (int i = 0; i < entryCount; i++) {
+            result[i] = values.contains(entries[i].toString());
+        }
+        
+        return result;
+    }
+    
+    @Override
+    protected void onDialogClosed(boolean positiveResult) {
+        super.onDialogClosed(positiveResult);
+        
+        if (positiveResult && mPreferenceChanged) {
+            final Set<String> values = mNewValues;
+            if (callChangeListener(values)) {
+                setValues(values);
+            }
+        }
+        mPreferenceChanged = false;
+    }
+    
+    @Override
+    protected Object onGetDefaultValue(TypedArray a, int index) {
+        final CharSequence[] defaultValues = a.getTextArray(index);
+        final int valueCount = defaultValues.length;
+        final Set<String> result = new HashSet<String>();
+        
+        for (int i = 0; i < valueCount; i++) {
+            result.add(defaultValues[i].toString());
+        }
+        
+        return result;
+    }
+    
+    @Override
+    protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
+        setValues(restoreValue ? getPersistedStringSet(mValues) : (Set<String>) defaultValue);
+    }
+    
+    @Override
+    protected Parcelable onSaveInstanceState() {
+        final Parcelable superState = super.onSaveInstanceState();
+        if (isPersistent()) {
+            // No need to save instance state
+            return superState;
+        }
+        
+        final SavedState myState = new SavedState(superState);
+        myState.values = getValues();
+        return myState;
+    }
+    
+    private static class SavedState extends BaseSavedState {
+        Set<String> values;
+        
+        public SavedState(Parcel source) {
+            super(source);
+            values = new HashSet<String>();
+            String[] strings = source.readStringArray();
+            
+            final int stringCount = strings.length;
+            for (int i = 0; i < stringCount; i++) {
+                values.add(strings[i]);
+            }
+        }
+        
+        public SavedState(Parcelable superState) {
+            super(superState);
+        }
+        
+        @Override
+        public void writeToParcel(Parcel dest, int flags) {
+            super.writeToParcel(dest, flags);
+            dest.writeStringArray(values.toArray(new String[0]));
+        }
+        
+        public static final Parcelable.Creator<SavedState> CREATOR =
+                new Parcelable.Creator<SavedState>() {
+            public SavedState createFromParcel(Parcel in) {
+                return new SavedState(in);
+            }
+            
+            public SavedState[] newArray(int size) {
+                return new SavedState[size];
+            }
+        };
+    }
+}
diff --git a/core/java/android/preference/Preference.java b/core/java/android/preference/Preference.java
index 197d976..381f794 100644
--- a/core/java/android/preference/Preference.java
+++ b/core/java/android/preference/Preference.java
@@ -16,8 +16,7 @@
 
 package android.preference;
 
-import java.util.ArrayList;
-import java.util.List;
+import com.android.internal.util.CharSequences;
 
 import android.content.Context;
 import android.content.Intent;
@@ -28,7 +27,6 @@ import android.os.Parcel;
 import android.os.Parcelable;
 import android.text.TextUtils;
 import android.util.AttributeSet;
-import com.android.internal.util.CharSequences;
 import android.view.AbsSavedState;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -36,6 +34,10 @@ import android.view.ViewGroup;
 import android.widget.ListView;
 import android.widget.TextView;
 
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
 /**
  * Represents the basic Preference UI building
  * block displayed by a {@link PreferenceActivity} in the form of a
@@ -1250,6 +1252,61 @@ public class Preference implements Comparable<Preference>, OnDependencyChangeLis
     }
     
     /**
+     * Attempts to persist a set of Strings to the {@link android.content.SharedPreferences}.
+     * <p>
+     * This will check if this Preference is persistent, get an editor from
+     * the {@link PreferenceManager}, put in the strings, and check if we should commit (and
+     * commit if so).
+     * 
+     * @param values The values to persist.
+     * @return True if the Preference is persistent. (This is not whether the
+     *         value was persisted, since we may not necessarily commit if there
+     *         will be a batch commit later.)
+     * @see #getPersistedString(Set)
+     * 
+     * @hide Pending API approval
+     */
+    protected boolean persistStringSet(Set<String> values) {
+        if (shouldPersist()) {
+            // Shouldn't store null
+            if (values.equals(getPersistedStringSet(null))) {
+                // It's already there, so the same as persisting
+                return true;
+            }
+            
+            SharedPreferences.Editor editor = mPreferenceManager.getEditor();
+            editor.putStringSet(mKey, values);
+            tryCommit(editor);
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Attempts to get a persisted set of Strings from the
+     * {@link android.content.SharedPreferences}.
+     * <p>
+     * This will check if this Preference is persistent, get the SharedPreferences
+     * from the {@link PreferenceManager}, and get the value.
+     * 
+     * @param defaultReturnValue The default value to return if either the
+     *            Preference is not persistent or the Preference is not in the
+     *            shared preferences.
+     * @return The value from the SharedPreferences or the default return
+     *         value.
+     * @see #persistStringSet(Set)
+     * 
+     * @hide Pending API approval
+     */
+    protected Set<String> getPersistedStringSet(Set<String> defaultReturnValue) {
+        if (!shouldPersist()) {
+            return defaultReturnValue;
+        }
+        
+        return mPreferenceManager.getSharedPreferences().getStringSet(mKey, defaultReturnValue);
+    }
+    
+    /**
      * Attempts to persist an int to the {@link android.content.SharedPreferences}.
      * 
      * @param value The value to persist.