Allow setting shimmer to null

Summary: This lets callers remove the shimmer effect entirely more easily.

Reviewed By: sjkirby

Differential Revision: D10035902

fbshipit-source-id: 098c34bf7fcb106d27146d31bb5e4a5d98effed8

Author: xiphirx

shimmer/src/main/java/com/facebook/shimmer/ShimmerDrawable.java

@@ -44,14 +44,13 @@ public ShimmerDrawable() {
     mShimmerPaint.setAntiAlias(true);
   }
 
-  public void setShimmer(Shimmer shimmer) {
-    if (shimmer == null) {
-      throw new IllegalArgumentException("Given null shimmer");
-    }
+  public void setShimmer(@Nullable Shimmer shimmer) {
     mShimmer = shimmer;
-    mShimmerPaint.setXfermode(
-        new PorterDuffXfermode(
-            mShimmer.alphaShimmer ? PorterDuff.Mode.DST_IN : PorterDuff.Mode.SRC_IN));
+    if (mShimmer != null) {
+      mShimmerPaint.setXfermode(
+          new PorterDuffXfermode(
+              mShimmer.alphaShimmer ? PorterDuff.Mode.DST_IN : PorterDuff.Mode.SRC_IN));
+    }
     updateShader();
     updateValueAnimator();
     invalidateSelf();

shimmer/src/main/java/com/facebook/shimmer/ShimmerFrameLayout.java

@@ -74,13 +74,9 @@ private void init(Context context, @Nullable AttributeSet attrs) {
     }
   }
 
-  public ShimmerFrameLayout setShimmer(Shimmer shimmer) {
-    if (shimmer == null) {
-      throw new IllegalArgumentException("Given null shimmer");
-    }
-
+  public ShimmerFrameLayout setShimmer(@Nullable Shimmer shimmer) {
     mShimmerDrawable.setShimmer(shimmer);
-    if (shimmer.clipToChildren) {
+    if (shimmer != null && shimmer.clipToChildren) {
       setLayerType(LAYER_TYPE_HARDWARE, mContentPaint);
     } else {
       setLayerType(LAYER_TYPE_NONE, null);