Not using magic constants for navbar height

Change-Id: I6783b8a2ebb059ce35748d8c3e818cbe732ff40d
diff --git a/src/com/android/launcher3/ResourceUtils.java b/src/com/android/launcher3/ResourceUtils.java
new file mode 100644
index 0000000..8df3290
--- /dev/null
+++ b/src/com/android/launcher3/ResourceUtils.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed 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 com.android.launcher3;
+
+import android.content.res.Resources;
+import android.util.DisplayMetrics;
+import android.util.TypedValue;
+
+public class ResourceUtils {
+    public static final String NAVBAR_VERTICAL_SIZE = "navigation_bar_frame_height";
+    public static final String NAVBAR_HORIZONTAL_SIZE = "navigation_bar_width";
+
+    public static int getNavbarSize(String resName, Resources res) {
+        return getDimenByName(resName, res, 48);
+    }
+
+    private static int getDimenByName(String resName, Resources res, int defaultValue) {
+        final int frameSize;
+        final int frameSizeResID = res.getIdentifier(resName, "dimen", "android");
+        if (frameSizeResID != 0) {
+            frameSize = res.getDimensionPixelSize(frameSizeResID);
+        } else {
+            frameSize = pxFromDp(defaultValue, res.getDisplayMetrics());
+        }
+        return frameSize;
+    }
+
+    public static int pxFromDp(float size, DisplayMetrics metrics) {
+        return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, size, metrics));
+    }
+}