adding some swiping improvements

app/src/main/kotlin/com/simplemobiletools/launcher/activities/MainActivity.kt

@@ -1,9 +1,11 @@
 package com.simplemobiletools.launcher.activities
 
+import android.animation.ObjectAnimator
 import android.content.res.Configuration
 import android.graphics.Color
 import android.os.Bundle
 import android.view.MotionEvent
+import android.view.animation.DecelerateInterpolator
 import android.widget.FrameLayout
 import com.simplemobiletools.commons.extensions.appLaunched
 import com.simplemobiletools.commons.extensions.realScreenSize
@@ -14,9 +16,9 @@ import com.simplemobiletools.launcher.fragments.AllAppsFragment
 import kotlinx.android.synthetic.main.activity_main.*
 
 class MainActivity : SimpleActivity() {
-    private var mTouchDownY = 0
+    var mTouchDownY = -1
+    var mCurrentFragmentY = 0
     private var mScreenHeight = 0
-    private var mCurrentFragmentY = 0
 
     override fun onCreate(savedInstanceState: Bundle?) {
         useDynamicTheme = false
@@ -52,12 +54,27 @@ class MainActivity : SimpleActivity() {
             }
 
             MotionEvent.ACTION_MOVE -> {
-                val diffY = mTouchDownY - event.y
-                val newY = mCurrentFragmentY - diffY
-                all_apps_fragment.y = Math.min(Math.max(0f, newY), mScreenHeight.toFloat())
+                if (mTouchDownY != -1) {
+                    val diffY = mTouchDownY - event.y
+                    val newY = mCurrentFragmentY - diffY
+                    all_apps_fragment.y = Math.min(Math.max(0f, newY), mScreenHeight.toFloat())
+                }
+            }
+
+            MotionEvent.ACTION_CANCEL,
+            MotionEvent.ACTION_UP -> {
+                mTouchDownY = -1
+                showAllAppsFragment()
             }
         }
 
         return true
     }
+
+    private fun showAllAppsFragment() {
+        ObjectAnimator.ofFloat(all_apps_fragment, "y", 0f).apply {
+            interpolator = DecelerateInterpolator()
+            start()
+        }
+    }
 }

app/src/main/kotlin/com/simplemobiletools/launcher/fragments/AllAppsFragment.kt

@@ -8,6 +8,7 @@ import android.content.pm.PackageManager
 import android.graphics.drawable.Drawable
 import android.os.Process
 import android.util.AttributeSet
+import android.view.MotionEvent
 import android.view.Surface
 import android.view.WindowManager
 import android.widget.RelativeLayout
@@ -16,19 +17,29 @@ import com.simplemobiletools.commons.helpers.ensureBackgroundThread
 import com.simplemobiletools.commons.helpers.isRPlus
 import com.simplemobiletools.commons.views.MyGridLayoutManager
 import com.simplemobiletools.launcher.R
-import com.simplemobiletools.launcher.activities.SimpleActivity
+import com.simplemobiletools.launcher.activities.MainActivity
 import com.simplemobiletools.launcher.adapters.LaunchersAdapter
 import com.simplemobiletools.launcher.extensions.getColumnCount
 import com.simplemobiletools.launcher.models.AppLauncher
 import kotlinx.android.synthetic.main.all_apps_fragment.view.*
 
 class AllAppsFragment(context: Context, attributeSet: AttributeSet) : RelativeLayout(context, attributeSet) {
-    private var activity: SimpleActivity? = null
+    private var touchDownY = -1
+    private var activity: MainActivity? = null
 
-    fun setupFragment(activity: SimpleActivity) {
+    @SuppressLint("ClickableViewAccessibility")
+    fun setupFragment(activity: MainActivity) {
         this.activity = activity
         getLaunchers()
         setBackgroundColor(activity.getProperBackgroundColor())
+
+        all_apps_grid.setOnTouchListener { v, event ->
+            if (event.actionMasked == MotionEvent.ACTION_UP || event.actionMasked == MotionEvent.ACTION_CANCEL) {
+                touchDownY = -1
+            }
+
+            return@setOnTouchListener false
+        }
     }
 
     fun onConfigurationChanged() {
@@ -42,6 +53,22 @@ class AllAppsFragment(context: Context, attributeSet: AttributeSet) : RelativeLa
         setupAdapter(launchers)
     }
 
+    override fun onInterceptTouchEvent(event: MotionEvent): Boolean {
+        var shouldIntercept = false
+        if (touchDownY != -1) {
+            shouldIntercept = touchDownY - event.y < 0 && all_apps_grid.computeVerticalScrollOffset() == 0
+            if (shouldIntercept) {
+                activity?.mTouchDownY = touchDownY
+                activity?.mCurrentFragmentY = y.toInt()
+                touchDownY = -1
+            }
+        } else {
+            touchDownY = event.y.toInt()
+        }
+
+        return shouldIntercept
+    }
+
     @SuppressLint("WrongConstant")
     private fun getLaunchers() {
         val allApps = ArrayList<AppLauncher>()