Adding settings screen for font size. Also factored out common

components from screen magnification settings screen.

Change-Id: I1828c7c0246f14493903172f2da7419fdc8e5f09

src/com/android/settings/accessibility/ToggleFontSizePreferenceFragment.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2015 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.accessibility;
+
+import com.android.settings.InstrumentedFragment;
+import com.android.settings.R;
+import com.android.settings.PreviewSeekBarPreferenceFragment;
+
+import android.annotation.Nullable;
+import android.app.ActivityManagerNative;
+import android.content.res.Configuration;
+import android.content.res.Resources;
+import android.os.Bundle;
+import android.os.RemoteException;
+import android.util.Log;
+
+/**
+ * Preference fragment used to control font size.
+ */
+public class ToggleFontSizePreferenceFragment extends PreviewSeekBarPreferenceFragment {
+    private static final String LOG_TAG = "ToggleFontSizePreferenceFragment";
+
+    private float[] mValues;
+
+    @Override
+    public void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        mActivityLayoutResId = R.layout.font_size_activity;
+        mPreviewSampleResId = R.layout.font_size_preview;
+
+        Resources res = getContext().getResources();
+        // Mark the appropriate item in the preferences list.
+        final Configuration origConfig = res.getConfiguration();
+        mEntries = res.getStringArray(R.array.entries_font_size);
+        final String[] strEntryValues = res.getStringArray(R.array.entryvalues_font_size);
+        mInitialIndex = floatToIndex(origConfig.fontScale, strEntryValues);
+        mValues = new float[strEntryValues.length];
+        for (int i = 0; i < strEntryValues.length; ++i) {
+            mValues[i] = Float.parseFloat(strEntryValues[i]);
+        }
+    }
+
+    @Override
+    protected Configuration createConfig(Configuration origConfig, int index) {
+        // Populate the sample layouts.
+        final Configuration config = new Configuration(origConfig);
+        config.fontScale = mValues[index];
+        return config;
+    }
+
+    /**
+     * Persists the selected font size and sends a configuration change.
+     */
+    @Override
+    protected void commit() {
+        Configuration config = getContext().getResources().getConfiguration();
+        config.fontScale = mValues[mCurrentIndex];
+        try {
+            ActivityManagerNative.getDefault().updatePersistentConfiguration(config);
+        } catch (RemoteException e) {
+            Log.w(LOG_TAG, "Unable to save font size setting");
+        }
+    }
+
+    @Override
+    protected int getMetricsCategory() {
+        return InstrumentedFragment.ACCESSIBILITY_FONT_SIZE;
+    }
+
+    private int floatToIndex(float val, String[] indices) {
+        float lastVal = Float.parseFloat(indices[0]);
+        for (int i=1; i<indices.length; i++) {
+            float thisVal = Float.parseFloat(indices[i]);
+            if (val < (lastVal + (thisVal-lastVal)*.5f)) {
+                return i-1;
+            }
+            lastVal = thisVal;
+        }
+        return indices.length-1;
+    }
+
+}