Colorpicker: Fix possible NPE

Change-Id: I06628e6fc3ef7651e06b4c03acb048a9bb3e6540
diff --git a/src/com/bliss/support/colorpicker/AlphaPatternDrawable.java b/src/com/bliss/support/colorpicker/AlphaPatternDrawable.java
index 288c124..3649b5f 100644
--- a/src/com/bliss/support/colorpicker/AlphaPatternDrawable.java
+++ b/src/com/bliss/support/colorpicker/AlphaPatternDrawable.java
@@ -54,7 +54,9 @@
 
     @Override
     public void draw(Canvas canvas) {
-        canvas.drawBitmap(mBitmap, null, getBounds(), mPaint);
+        if (mBitmap != null) {
+            canvas.drawBitmap(mBitmap, null, getBounds(), mPaint);
+        }
     }
 
     @Override
diff --git a/src/com/bliss/support/colorpicker/ColorPickerPanelView.java b/src/com/bliss/support/colorpicker/ColorPickerPanelView.java
index a6185d1..aa6311d 100644
--- a/src/com/bliss/support/colorpicker/ColorPickerPanelView.java
+++ b/src/com/bliss/support/colorpicker/ColorPickerPanelView.java
@@ -39,7 +39,7 @@
      */
     private final static float    BORDER_WIDTH_PX = 1;
 
-    private float mDensity = 1f;
+    private static float mDensity = 1f;
 
     private int         mBorderColor = 0xff6E6E6E;
     private int         mColor = 0xff000000;