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, 26 insertions, 0 deletions

diff --git a/core/java/android/widget/TextView.java b/core/java/android/widget/TextView.java
index a7278dae4497..b91111d5e336 100644
--- a/core/java/android/widget/TextView.java
+++ b/core/java/android/widget/TextView.java
@@ -652,6 +652,7 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
         boolean allCaps = false;
         int shadowcolor = 0;
         float dx = 0, dy = 0, r = 0;
+        boolean elegant = false;
 
         final Resources.Theme theme = context.getTheme();
 
@@ -728,6 +729,10 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
                 case com.android.internal.R.styleable.TextAppearance_shadowRadius:
                     r = appearance.getFloat(attr, 0);
                     break;
+
+                case com.android.internal.R.styleable.TextAppearance_elegantTextHeight:
+                    elegant = appearance.getBoolean(attr, false);
+                    break;
                 }
             }
 
@@ -1065,6 +1070,10 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
             case com.android.internal.R.styleable.TextView_textAllCaps:
                 allCaps = a.getBoolean(attr, false);
                 break;
+
+            case com.android.internal.R.styleable.TextView_elegantTextHeight:
+                elegant = a.getBoolean(attr, false);
+                break;
             }
         }
         a.recycle();
@@ -1245,6 +1254,7 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
             setHighlightColor(textColorHighlight);
         }
         setRawTextSize(textSize);
+        setElegantTextHeight(elegant);
 
         if (allCaps) {
             setTransformationMethod(new AllCapsTransformationMethod(getContext()));
@@ -2468,6 +2478,11 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
             setTransformationMethod(new AllCapsTransformationMethod(getContext()));
         }
 
+        if (appearance.hasValue(com.android.internal.R.styleable.TextAppearance_elegantTextHeight)) {
+            setElegantTextHeight(appearance.getBoolean(
+                com.android.internal.R.styleable.TextAppearance_elegantTextHeight, false));
+        }
+
         appearance.recycle();
     }
 
@@ -2615,6 +2630,17 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
     }
 
     /**
+     * Set the TextView'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.
+     */
+    public void setElegantTextHeight(boolean elegant) {
+        mTextPaint.setElegantTextHeight(elegant);
+    }
+
+    /**
      * Sets the text color for all the states (normal, selected,
      * focused) to be this color.
      *