Add AnimationHelper.kt

app/src/main/java/chat/rocket/android/helper/AnimationHelper.kt

+package chat.rocket.android.helper
+
+import android.animation.Animator
+import android.animation.AnimatorListenerAdapter
+import android.animation.AnimatorSet
+import android.animation.ObjectAnimator
+import android.content.Context
+import android.os.Build
+import android.os.VibrationEffect
+import android.os.Vibrator
+import android.view.View
+
+object AnimationHelper {
+
+    /**
+     * Shakes a view.
+     */
+    fun shakeView(viewToShake: View, x: Float = 2F, num: Int = 0) {
+        if (num == 6) {
+            viewToShake.translationX = 0.toFloat()
+            return
+        }
+
+        val animatorSet = AnimatorSet()
+        animatorSet.playTogether(ObjectAnimator.ofFloat(viewToShake, "translationX", dp(viewToShake.context, x)))
+        animatorSet.duration = 50
+        animatorSet.addListener(object : AnimatorListenerAdapter() {
+            override fun onAnimationEnd(animation: Animator) {
+                shakeView(viewToShake, if (num == 5) 0.toFloat() else -x, num + 1)
+            }
+        })
+        animatorSet.start()
+    }
+
+    /**
+     * Vibrates the smart phone.
+     */
+    fun vibrate(context: Context) {
+        val vibrator = context.getSystemService(Context.VIBRATOR_SERVICE) as Vibrator
+        if (Build.VERSION.SDK_INT >= 26) {
+            vibrator.vibrate(VibrationEffect.createOneShot(200, VibrationEffect.DEFAULT_AMPLITUDE))
+        } else {
+            vibrator.vibrate(200)
+        }
+    }
+
+    private fun dp(context: Context, value: Float): Float {
+        val density = context.resources.displayMetrics.density
+        val result = Math.ceil(density.times(value.toDouble()))
+        return result.toFloat()
+    }
+}
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