涂鸦礼物NPE fix

app/src/main/java/com/yizhuan/erban/ui/widget/drawgift/DrawGiftHelper.java

@@ -47,7 +47,9 @@ public class DrawGiftHelper {
                 .into(new CustomTarget<Bitmap>() {
                     @Override
                     public void onResourceReady(@NonNull Bitmap resource, @Nullable Transition<? super Bitmap> transition) {
-                        drawGiftView.setCurrentGift(giftId, obtainThumbBitmap(giftId, resource), giftPrice);
+                        if (drawGiftView!=null){
+                            drawGiftView.setCurrentGift(giftId, obtainThumbBitmap(giftId, resource), giftPrice);
+                        }
                     }
 
                     @Override

app/src/main/java/com/yizhuan/erban/ui/widget/drawgift/DrawGiftPlayView.java

@@ -24,13 +24,13 @@ public class DrawGiftPlayView extends View {
     private DrawAnimationListener onDrawAnimationListener;
 
     //为了体现最后的消失动画效果，才引入了这个Paint
-    private Paint mPaint;
+    private final Paint mPaint = new Paint();;
 
     private static final int DRAW_ONE_GIFT = 0;
 
-    private Handler mHandler;
+    private final Handler mHandler;
 
-    private Handler.Callback mCallback = new Handler.Callback() {
+    private final Handler.Callback mCallback = new Handler.Callback() {
         @Override
         public boolean handleMessage(Message msg) {
             switch (msg.what) {
@@ -193,7 +193,6 @@ public class DrawGiftPlayView extends View {
     @Override
     public void onAttachedToWindow(){
         super.onAttachedToWindow();
-        mPaint = new Paint();
     }
 
     @Override