First implementation.

plugin.xml

@@ -12,7 +12,7 @@
         <source-file src="src/android/SafeInsets.java" target-dir="src/org/apache/cordova/safeinsets" />
         <config-file target="res/xml/config.xml" parent="/*">
             <feature name="SafeInsets">
-                <param name="android-package" value="org.apache.cordova.statusbar.SafeInsets" />
+                <param name="android-package" value="org.apache.cordova.safeinsets.SafeInsets" />
                 <param name="onload" value="true" />
             </feature>
         </config-file>

src/android/SafeInsets.java

@@ -0,0 +1,117 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+package org.apache.cordova.safeinsets;
+
+import android.app.Activity;
+import android.os.Build;
+import android.view.DisplayCutout;
+import android.view.View;
+import android.view.Window;
+import android.view.WindowInsets;
+
+import org.apache.cordova.CallbackContext;
+import org.apache.cordova.CordovaArgs;
+import org.apache.cordova.CordovaInterface;
+import org.apache.cordova.CordovaPlugin;
+import org.apache.cordova.CordovaWebView;
+import org.apache.cordova.LOG;
+import org.apache.cordova.PluginResult;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+public class SafeInsets extends CordovaPlugin {
+
+    private static final String TAG = "SafeInsets";
+
+    private CallbackContext callbackContext;
+
+    private final JSONObject insetsJSON = new JSONObject();
+
+    private float density;
+
+    @Override
+    public void initialize(CordovaInterface cordova, CordovaWebView webView) {
+        super.initialize(cordova, webView);
+
+        if (Build.VERSION.SDK_INT >= 20) {
+            final Activity activity = cordova.getActivity();
+            final Window window = activity.getWindow();
+            final View rootView = window.getDecorView().getRootView();
+
+            density = activity.getResources().getDisplayMetrics().density;
+
+            rootView.setOnApplyWindowInsetsListener(new View.OnApplyWindowInsetsListener() {
+                @Override
+                public WindowInsets onApplyWindowInsets(View view, WindowInsets insets) {
+                    if (Build.VERSION.SDK_INT < 28) {
+                        updateInsets(
+                                insets.getSystemWindowInsetTop(),
+                                insets.getSystemWindowInsetRight(),
+                                insets.getSystemWindowInsetBottom(),
+                                insets.getStableInsetLeft()
+                        );
+                    } else {
+                        DisplayCutout cutout = insets.getDisplayCutout();
+                        updateInsets(
+                                cutout.getSafeInsetTop(),
+                                cutout.getSafeInsetRight(),
+                                cutout.getSafeInsetBottom(),
+                                cutout.getSafeInsetLeft()
+                        );
+                    }
+                    rootView.onApplyWindowInsets(insets);
+                    return insets;
+                }
+            });
+        } else {
+            LOG.v(TAG, "Required API level 20");
+        }
+    }
+
+    @Override
+    public boolean execute(final String action, final CordovaArgs args, final CallbackContext callbackContext) {
+        if ("check".equals(action)) {
+            PluginResult result = new PluginResult(PluginResult.Status.OK, insetsJSON);
+            result.setKeepCallback(true);
+            this.callbackContext = callbackContext;
+            callbackContext.sendPluginResult(result);
+            return true;
+        }
+        return false;
+    }
+
+    private void updateInsets(int top, int right, int bottom, int left) {
+        try {
+            insetsJSON.put("top", top / density);
+            insetsJSON.put("bottom", bottom / density);
+            insetsJSON.put("left", left / density);
+            insetsJSON.put("right", right / density);
+        } catch (JSONException ex) {}
+        if (callbackContext != null) {
+            sendInsets();
+        }
+    }
+
+    private void sendInsets() {
+        PluginResult pluginResult = new PluginResult(PluginResult.Status.OK, insetsJSON);
+        pluginResult.setKeepCallback(true);
+        callbackContext.sendPluginResult(pluginResult);
+    }
+}

src/plugin.js

@@ -1,37 +1,26 @@
 var exec = require('cordova/exec');
 
-// var _ready = false;
-//
-// var _callbacks = [];
-
 var SafeInsets = {
-
-    // ready: function(callback) {
-    //     if (callback) {
-    //         _ready ? callback() : _callbacks.push(callback);
-    //     }
-    //     return _ready;
-    // },
-
     top: 0,
-
     right: 0,
-
     bottom: 0,
-
     left: 0
-
 };
 
-window.setTimeout(function () {
-    exec(function (insets) {
-        SafeInsets.top = insets.top;
-        SafeInsets.right = insets.right;
-        SafeInsets.bottom = insets.bottom;
-        SafeInsets.left = insets.left;
-    }, function (error) {
-        console.log('[SafeInsets] Error: ' + error);
-    }, "SafeInsets", "check");
-}, 0);
+exec(function (insets) {
+    SafeInsets.top = insets.top;
+    SafeInsets.right = insets.right;
+    SafeInsets.bottom = insets.bottom;
+    SafeInsets.left = insets.left;
+
+    var style = document.documentElement.style;
+    style.setProperty('--safe-inset-top', insets.top + 'px');
+    style.setProperty('--safe-inset-right', insets.right + 'px');
+    style.setProperty('--safe-inset-bottom', insets.bottom + 'px');
+    style.setProperty('--safe-inset-left', insets.left + 'px');
+
+}, function (error) {
+    console.log('[SafeInsets] Error: ' + error);
+}, "SafeInsets", "check");
 
 module.exports = SafeInsets;