Fix border-rendering in APIs < 18

Summary:
`Canvas.clipPath` isn't supported with hardware acceleration in APIs below 18. The rounded border rendering logic for Android relies on this method. Therefore, rounded borders do not render correctly on such devices.

**Screenshot of Nexus 5 running API 17 (Before these changes):**
https://pxl.cl/9rsf

**The fix**: If the API version is less than 18 and we're rendering rounded borders, I disable hardware acceleration. Otherwise, I enable it. I'm going to check to see if this has perf regressions by running a CT-Scan.

With this change, rounded borders render correctly on Android devices running versions of Android between Honeycomb to JellyBean MR2.

**Screenshot of Nexus 5 running API 17 (After these changes):**
https://pxl.cl/9rrk

Reviewed By: xiphirx

Differential Revision: D6153087

fbshipit-source-id: 16e35be096051ac817c8b8bcdd132ecff3b4b167

ReactAndroid/src/main/java/com/facebook/react/views/view/ReactViewBackgroundDrawable.java

@@ -129,16 +129,29 @@ public class ReactViewBackgroundDrawable extends Drawable {
   @Override
   public void draw(Canvas canvas) {
     updatePathEffect();
-    boolean roundedBorders = mBorderCornerRadii != null ||
+    if (!hasRoundedBorders()) {
-        (!YogaConstants.isUndefined(mBorderRadius) && mBorderRadius > 0);
-
-    if (!roundedBorders) {
       drawRectangularBackgroundWithBorders(canvas);
     } else {
       drawRoundedBackgroundWithBorders(canvas);
     }
   }
 
+  public boolean hasRoundedBorders() {
+    if (!YogaConstants.isUndefined(mBorderRadius) && mBorderRadius > 0) {
+      return true;
+    }
+
+    if (mBorderCornerRadii != null) {
+      for (final float borderRadii : mBorderCornerRadii) {
+        if (!YogaConstants.isUndefined(borderRadii) && borderRadii > 0) {
+          return true;
+        }
+      }
+    }
+
+    return false;
+  }
+
   @Override
   protected void onBoundsChange(Rect bounds) {
     super.onBoundsChange(bounds);
@@ -620,23 +633,29 @@ public class ReactViewBackgroundDrawable extends Drawable {
      * border of V will render inside O.
      *
      * <p>Let BorderWidth = (borderTop, borderLeft, borderBottom, borderRight).
+     *
      * <p>Let I (for inner) = O - BorderWidth.
      *
      * <p>Then, remembering that O and I are rectangles and that I is inside O, O - I gives us the
      * border of V. Therefore, we can use canvas.clipPath to draw V's border.
      *
      * <p>canvas.clipPath(O, Region.OP.INTERSECT);
+     *
      * <p>canvas.clipPath(I, Region.OP.DIFFERENCE);
+     *
      * <p>canvas.drawRect(O, paint);
      *
      * <p>This lets us draw non-rounded single-color borders.
      *
      * <p>To extend this algorithm to rounded single-color borders, we:
+     *
      * <p>1. Curve the corners of O by the (border radii of V) using Path#addRoundRect.
+     *
      * <p>2. Curve the corners of I by (border radii of V - border widths of V) using
      * Path#addRoundRect.
      *
      * <p>Let O' = curve(O, border radii of V).
+     *
      * <p>Let I' = curve(I, border radii of V - border widths of V)
      *
      * <p>The rationale behind this decision is the (first sentence of the) following section in the
@@ -647,7 +666,9 @@ public class ReactViewBackgroundDrawable extends Drawable {
      * render curved single-color borders:
      *
      * <p>canvas.clipPath(O, Region.OP.INTERSECT);
+     *
      * <p>canvas.clipPath(I, Region.OP.DIFFERENCE);
+     *
      * <p>canvas.drawRect(O, paint);
      *
      * <p>To extend this algorithm to rendering multi-colored rounded borders, we render each side
@@ -655,8 +676,11 @@ public class ReactViewBackgroundDrawable extends Drawable {
      * border radii are 0. Then, the four quadrilaterals would be:
      *
      * <p>Left: (O.left, O.top), (I.left, I.top), (I.left, I.bottom), (O.left, O.bottom)
+     *
      * <p>Top: (O.left, O.top), (I.left, I.top), (I.right, I.top), (O.right, O.top)
+     *
      * <p>Right: (O.right, O.top), (I.right, I.top), (I.right, I.bottom), (O.right, O.bottom)
+     *
      * <p>Bottom: (O.right, O.bottom), (I.right, I.bottom), (I.left, I.bottom), (O.left, O.bottom)
      *
      * <p>Now, lets consider what happens when we render a rounded border (radii != 0). For the sake

ReactAndroid/src/main/java/com/facebook/react/views/view/ReactViewGroup.java

@@ -233,7 +233,20 @@ public class ReactViewGroup extends ViewGroup implements
   }
 
   public void setBorderRadius(float borderRadius, int position) {
-    getOrCreateReactViewBackground().setRadius(borderRadius, position);
+    ReactViewBackgroundDrawable backgroundDrawable = getOrCreateReactViewBackground();
+    backgroundDrawable.setRadius(borderRadius, position);
+
+    if (Build.VERSION_CODES.HONEYCOMB < Build.VERSION.SDK_INT
+        && Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR2) {
+      final int UPDATED_LAYER_TYPE =
+          backgroundDrawable.hasRoundedBorders()
+              ? View.LAYER_TYPE_SOFTWARE
+              : View.LAYER_TYPE_HARDWARE;
+
+      if (UPDATED_LAYER_TYPE != getLayerType()) {
+        setLayerType(UPDATED_LAYER_TYPE, null);
+      }
+    }
   }
 
   public void setBorderStyle(@Nullable String style) {