Enable {ANTI_ALIAS,DITHER}_FLAG by default (1/2)

Test: atest android.graphics.cts.PaintTest
Bug: 186644628
Change-Id: I5d5d03e430af380e23016c6deba5eca46067a22b
diff --git a/graphics/java/android/graphics/Paint.java b/graphics/java/android/graphics/Paint.java
index e222570..51bf6d53 100644
--- a/graphics/java/android/graphics/Paint.java
+++ b/graphics/java/android/graphics/Paint.java
@@ -255,6 +255,12 @@
             | FILTER_BITMAP_FLAG;
 
     /**
+     * These flags are always set on a reset paint or a new paint instantiated using
+     * {@link #Paint()}.
+     */
+    private static final int DEFAULT_PAINT_FLAGS = ANTI_ALIAS_FLAG | DITHER_FLAG;
+
+    /**
      * Font hinter option that disables font hinting.
      *
      * @see #setHinting(int)
@@ -570,10 +576,13 @@
      * accelerated drawing always acts as if {@link #FILTER_BITMAP_FLAG} is set.
      * On devices running {@link Build.VERSION_CODES#Q} and above,
      * {@code FILTER_BITMAP_FLAG} is set by this constructor, and it can be
-     * cleared with {@link #setFlags} or {@link #setFilterBitmap}.</p>
+     * cleared with {@link #setFlags} or {@link #setFilterBitmap}.
+     * On devices running {@link Build.VERSION_CODES#S} and above, {@code ANTI_ALIAS_FLAG} and
+     * {@code DITHER_FLAG} are set by this constructor, and they can be cleared with
+     * {@link #setFlags} or {@link #setAntiAlias} and {@link #setDither}, respectively.</p>
      */
     public Paint() {
-        this(0);
+        this(DEFAULT_PAINT_FLAGS);
     }
 
     /**
@@ -618,7 +627,7 @@
     /** Restores the paint to its default settings. */
     public void reset() {
         nReset(mNativePaint);
-        setFlags(HIDDEN_DEFAULT_PAINT_FLAGS);
+        setFlags(HIDDEN_DEFAULT_PAINT_FLAGS | DEFAULT_PAINT_FLAGS);
 
         // TODO: Turning off hinting has undesirable side effects, we need to
         //       revisit hinting once we add support for subpixel positioning