Created detector and sample

example/src/main/java/co/kyash/rxkeyboarddetector/MainActivity.kt

@@ -1,12 +1,20 @@
 package co.kyash.rxkeyboarddetector;
 
-import android.os.Bundle;
-import android.support.v7.app.AppCompatActivity;
+import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
+import android.widget.TextView
+import co.kyash.rkd.KeyboardDetector
 
 class MainActivity : AppCompatActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
+
+        val textView = findViewById<TextView>(R.id.status)
+
+        KeyboardDetector(this).observe().subscribe({
+            textView.text = it.name
+        })
     }
 }

example/src/main/res/layout/activity_main.xml

@@ -1,12 +1,60 @@
 <?xml version="1.0" encoding="utf-8"?>
-<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
+    android:orientation="vertical">
 
-    <TextView
-        android:layout_width="wrap_content"
+    <android.support.v7.widget.Toolbar
+        android:id="@+id/toolbar"
+        android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:layout_centerInParent="true"
-        android:text="Hello World!" />
+        android:background="@color/white"
+        android:elevation="4dp"
+        app:elevation="4dp"
+        app:title="@string/app_name" />
 
-</RelativeLayout>
+    <ScrollView
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical">
+
+            <TextView
+                android:id="@+id/status"
+                style="@style/Title"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:gravity="center"
+                android:padding="@dimen/space_16dp" />
+
+        </LinearLayout>
+
+    </ScrollView>
+
+    <View
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:background="@color/grey500" />
+
+    <FrameLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_gravity="bottom"
+        android:background="@color/white"
+        android:paddingBottom="@dimen/space_16dp"
+        android:paddingEnd="@dimen/space_8dp"
+        android:paddingLeft="@dimen/space_8dp"
+        android:paddingRight="@dimen/space_8dp"
+        android:paddingStart="@dimen/space_8dp"
+        android:paddingTop="@dimen/space_16dp">
+
+        <EditText style="@style/BaseEditText" />
+
+    </FrameLayout>
+
+</LinearLayout>

library/src/main/java/co/kyash/rkd/KeyboardDetector.kt

@@ -0,0 +1,63 @@
+package co.kyash.rkd
+
+import android.app.Activity
+import android.graphics.Rect
+import android.util.DisplayMetrics
+import android.util.Log
+import android.view.View
+import android.view.ViewGroup
+import android.view.ViewTreeObserver
+import android.view.WindowManager
+import io.reactivex.Observable
+
+
+class KeyboardDetector constructor(
+        private val activity: Activity?
+) {
+
+    companion object {
+        const val TAG = "KeyboardDetector"
+        const val MIN_KEYBOARD_HEIGHT_RATIO = 0.15
+    }
+
+    fun observe(): Observable<KeyboardStatus> {
+        if (activity == null) {
+            Log.w(TAG, "Activity is null")
+            return Observable.just(KeyboardStatus.CLOSED)
+        }
+
+        val softInputMethod = activity.window.attributes.softInputMode
+        if (WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE != softInputMethod
+                && WindowManager.LayoutParams.SOFT_INPUT_ADJUST_UNSPECIFIED != softInputMethod) {
+            throw IllegalArgumentException("Activity window SoftInputMethod is not ADJUST_RESIZE")
+        }
+
+        val rootView = (activity.findViewById<View>(android.R.id.content) as ViewGroup)
+
+        val windowHeight = DisplayMetrics().let {
+            activity.windowManager.defaultDisplay.getMetrics(it)
+            it.heightPixels
+        }
+
+        return Observable.create<KeyboardStatus> { emitter ->
+            val listener = ViewTreeObserver.OnGlobalLayoutListener {
+                val rect = Rect().apply { rootView.getWindowVisibleDisplayFrame(this) }
+                val keyboardHeight = windowHeight - rect.height()
+
+                if (keyboardHeight > windowHeight * MIN_KEYBOARD_HEIGHT_RATIO) {
+                    emitter.onNext(KeyboardStatus.OPENED)
+                } else {
+                    emitter.onNext(KeyboardStatus.CLOSED)
+                }
+            }
+
+            rootView.viewTreeObserver.addOnGlobalLayoutListener(listener)
+
+            emitter.setCancellable {
+                rootView.viewTreeObserver.removeOnGlobalLayoutListener(listener)
+            }
+
+        }.distinctUntilChanged()
+    }
+
+}

library/src/main/java/co/kyash/rkd/KeyboardStatus.kt

@@ -0,0 +1,6 @@
+package co.kyash.rkd
+
+enum class KeyboardStatus {
+    OPENED,
+    CLOSED
+}