Introduce set/getFontVariationSettings.

This CL enables developers to specify axis values to the underlying
font collection. The specification of the font variation settings is
the same as the CSS font-variation-settings attribute in CSS working
draft as of 2016-11-30.

Code example: Here is an example to set width 100 and weight 1.5.

  TextView tv = (TextView) findViewById(R.id.textView);
  tv.setFontVariationSettings("'wdth' 100, 'wght' 1.5");

Bug: 33062398
Test: Manually done. Ran FrameworksGraphicsTests, CtsGraphicsTestCases
      and CtsWidgetTestCases
Change-Id: I249d464f8cdaa56017a987588b94ed685aadeb58

graphics/java/android/graphics/FontListParser.java

@@ -21,6 +21,7 @@ import android.util.Xml;
 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;
 
+import android.annotation.Nullable;
 import com.android.internal.annotations.VisibleForTesting;
 
 import java.io.IOException;
@@ -104,9 +105,12 @@ public class FontListParser {
     // Note that a well-formed variation contains a four-character tag and a float as styleValue,
     // with spacers in between. The tag is enclosd either by double quotes or single quotes.
     @VisibleForTesting
-    public static Axis[] parseFontVariationSettings(String settings) {
-        String[] settingList = settings.split(",");
+    public static ArrayList<Axis> parseFontVariationSettings(@Nullable String settings) {
         ArrayList<Axis> axisList = new ArrayList<>();
+        if (settings == null) {
+            return axisList;
+        }
+        String[] settingList = settings.split(",");
         settingLoop:
         for (String setting : settingList) {
             int pos = 0;
@@ -150,7 +154,7 @@ public class FontListParser {
                     tagString.charAt(3));
             axisList.add(new Axis(tag, styleValue));
         }
-        return axisList.toArray(new Axis[axisList.size()]);
+        return axisList;
     }
 
     @VisibleForTesting

graphics/java/android/graphics/Paint.java

@@ -71,6 +71,7 @@ public class Paint {
 
     private LocaleList  mLocales;
     private String      mFontFeatureSettings;
+    private String      mFontVariationSettings;
 
     private static final Object sCacheLock = new Object();
 
@@ -1493,6 +1494,37 @@ public class Paint {
         nSetFontFeatureSettings(mNativePaint, settings);
     }
 
+    /**
+     * Returns the font variation settings.
+     *
+     * @return the paint's currently set font variation settings. Default is null.
+     *
+     * @see #setFontVariationSettings(String)
+     */
+    public String getFontVariationSettings() {
+        return mFontVariationSettings;
+    }
+
+    /**
+     * Set font variation settings.
+     *
+     * @param settings font variation settings, e.g. "'wdth' 300, 'wght' 1.8"
+     *
+     * @see #getFontVariationSettings()
+     *
+     * @param settings the font variation settings. You can pass null or empty string as no
+     *                 variation settings.
+     */
+    public void setFontVariationSettings(String settings) {
+        settings = TextUtils.nullIfEmpty(settings);
+        if (settings == mFontVariationSettings
+                || (settings != null && settings.equals(mFontVariationSettings))) {
+            return;
+        }
+        mFontVariationSettings = settings;
+        setTypeface(Typeface.createFromTypefaceWithVariation(mTypeface, settings));
+    }
+
     /**
      * Get the current value of hyphen edit.
      *

graphics/java/android/graphics/Typeface.java

@@ -21,6 +21,7 @@ import android.util.Log;
 import android.util.LongSparseArray;
 import android.util.LruCache;
 import android.util.SparseArray;
+import android.graphics.FontListParser;
 
 import org.xmlpull.v1.XmlPullParserException;
 
@@ -171,6 +172,15 @@ public class Typeface {
         return typeface;
     }
 
+    /** @hide */
+    public static Typeface createFromTypefaceWithVariation(Typeface family,
+            String fontVariationSettings) {
+        final long ni = family == null ? 0 : family.native_instance;
+        ArrayList<FontListParser.Axis> axes =
+                FontListParser.parseFontVariationSettings(fontVariationSettings);
+        return new Typeface(nativeCreateFromTypefaceWithVariation(ni, axes));
+    }
+
     /**
      * Returns one of the default typeface objects, based on the specified style
      *
@@ -443,6 +453,8 @@ public class Typeface {
     }
 
     private static native long nativeCreateFromTypeface(long native_instance, int style);
+    private static native long nativeCreateFromTypefaceWithVariation(
+            long native_instance, List<FontListParser.Axis> axes);
     private static native long nativeCreateWeightAlias(long native_instance, int weight);
     private static native void nativeUnref(long native_instance);
     private static native int  nativeGetStyle(long native_instance);