Add elegantTextHeight text appearance attribute

This patch adds an elegantTextHeight text appearance attribute and
plumbs it through to the paint. This attribute selects the elegant
variant of fonts (when appropriate, which is typically Arabic and indic
scripts), and also specifies larger vertical metrics, to avoid clipping.

The intent is for this to be the default for quantum themes, but this
patch doesn't change any default behavior, just adds the attribute.

The larger vertical metrics are applied to top and bottom, but should
not affect line spacing in the common case. Also, with the setting,
metrics are no longer dependent on the font, so setting a custom font
will preserve layout and spacing.

Change-Id: If3b7d41f141deff50ca078f479ca90c2aa07829a

1 files changed, 17 insertions, 0 deletions

diff --git a/graphics/java/android/graphics/Paint.java b/graphics/java/android/graphics/Paint.java
index 916cb5a..1e1128e 100644
--- a/graphics/java/android/graphics/Paint.java
+++ b/graphics/java/android/graphics/Paint.java
@@ -500,6 +500,7 @@ public class Paint {
 
         mBidiFlags = BIDI_DEFAULT_LTR;
         setTextLocale(Locale.getDefault());
+        setElegantTextHeight(false);
     }
     
     /**
@@ -1221,6 +1222,22 @@ public class Paint {
     }
 
     /**
+     * Get the elegant metrics flag.
+     *
+     * @return true if elegant metrics are enabled for text drawing.
+     */
+    public native boolean isElegantTextHeight();
+
+    /**
+     * Set the paint's elegant height metrics flag. This setting selects font
+     * variants that have not been compacted to fit Latin-based vertical
+     * metrics, and also increases top and bottom bounds to provide more space.
+     *
+     * @param elegant set the paint's elegant metrics flag for drawing text.
+     */
+    public native void setElegantTextHeight(boolean elegant);
+
+    /**
      * Return the paint's text size.
      *
      * @return the paint's text size.