[bug/crash] MaskedView makes application crash on Android

Hi,

I’m experiencing an app crash on Android devices when using MaskedView. It occurs when leaving the screen (react navigation) with rendered MaskedView component and started happening after upgrading to RN 0.64.0.

Deps: “@react-native-masked-view/masked-view”: “0.2.3”, “react-native”: “0.64.0”,

P.s. iOS is working fine.

Logcat fragment:

021-04-13 12:31:49.611 15339-15339/[app] E/unknown:ReactNative: Exception thrown when executing ReactViewGroup.dispatchDraw method on ReactViewGroup[2999]
    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setVisibility(int)' on a null object reference
        at org.reactnative.maskedview.RNCMaskedView.updateBitmapMask(RNCMaskedView.java:81)
        at org.reactnative.maskedview.RNCMaskedView.dispatchDraw(RNCMaskedView.java:35)
        at android.view.View.buildDrawingCacheImpl(View.java:20689)
        at android.view.View.buildDrawingCache(View.java:20555)
        at android.view.View.draw(View.java:21145)
        at android.view.ViewGroup.drawChild(ViewGroup.java:4388)
        at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4173)
        at com.facebook.react.views.view.ReactViewGroup.dispatchDraw(ReactViewGroup.java:710)

[k-ibr]

@DanielMarkiel I looked into this and it seems like MaskedView is trying to “modify” elements that no longer exist due to RN removing them from memory (by switching screens). So a quick fix for this is to check for null object on the view inside RNCMaskedView.java. You can try this by replacing the following functions by this code.

private void updateBitmapMask() {
    if (this.mBitmapMask != null) {
      this.mBitmapMask.recycle();
    }

    View maskView = getChildAt(0);
    if (maskView != null) {
      maskView.setVisibility(View.VISIBLE);
      this.mBitmapMask = getBitmapFromView(maskView);
      maskView.setVisibility(View.INVISIBLE);
    } else{
      this.mBitmapMask = null;
    }
  }

public void onDescendantInvalidated(View child, View target) {
    super.onDescendantInvalidated(child, target);

    if (!mBitmapMaskInvalidated) {
      View maskView = getChildAt(0);
      if (maskView != null) {
        if (maskView.equals(child)) {
          mBitmapMaskInvalidated = true;
        }
      }
    }
  }

this solves the crashing, but perhaps someone from the MaskedView team could look further into it because I am not 100% sure this is a clean solution. Could someone more experienced also look into this? @Naturalclar @FonDorn

[khorark]

The fix has been released here: https://github.com/react-native-masked-view/masked-view/releases/tag/v0.2.5