add fling handling at showing/hiding all app icons

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

@@ -4,21 +4,26 @@ import android.animation.ObjectAnimator
 import android.content.res.Configuration
 import android.graphics.Color
 import android.os.Bundle
+import android.view.GestureDetector
 import android.view.MotionEvent
 import android.view.animation.DecelerateInterpolator
 import android.widget.FrameLayout
+import androidx.core.view.GestureDetectorCompat
 import com.simplemobiletools.commons.extensions.appLaunched
 import com.simplemobiletools.commons.extensions.realScreenSize
 import com.simplemobiletools.commons.extensions.statusBarHeight
 import com.simplemobiletools.launcher.BuildConfig
 import com.simplemobiletools.launcher.R
 import com.simplemobiletools.launcher.fragments.AllAppsFragment
+import com.simplemobiletools.launcher.interfaces.FlingListener
 import kotlinx.android.synthetic.main.activity_main.*
 
-class MainActivity : SimpleActivity() {
+class MainActivity : SimpleActivity(), FlingListener {
-    var mTouchDownY = -1
+    private var mTouchDownY = -1
-    var mCurrentFragmentY = 0
+    private var mCurrentFragmentY = 0
     private var mScreenHeight = 0
+    private var mIgnoreUpEvent = false
+    private lateinit var mDetector: GestureDetectorCompat
 
     override fun onCreate(savedInstanceState: Bundle?) {
         useDynamicTheme = false
@@ -27,6 +32,8 @@ class MainActivity : SimpleActivity() {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
         appLaunched(BuildConfig.APPLICATION_ID)
+
+        mDetector = GestureDetectorCompat(this, MyGestureListener(this))
         window.setDecorFitsSystemWindows(false)
         (all_apps_fragment as AllAppsFragment).setupFragment(this)
         mScreenHeight = realScreenSize.y
@@ -47,10 +54,12 @@ class MainActivity : SimpleActivity() {
     }
 
     override fun onTouchEvent(event: MotionEvent): Boolean {
+        mDetector.onTouchEvent(event)
         when (event.actionMasked) {
             MotionEvent.ACTION_DOWN -> {
                 mTouchDownY = event.y.toInt()
                 mCurrentFragmentY = all_apps_fragment.y.toInt()
+                mIgnoreUpEvent = false
             }
 
             MotionEvent.ACTION_MOVE -> {
@@ -64,17 +73,57 @@ class MainActivity : SimpleActivity() {
             MotionEvent.ACTION_CANCEL,
             MotionEvent.ACTION_UP -> {
                 mTouchDownY = -1
-                showAllAppsFragment()
+                if (!mIgnoreUpEvent) {
+                    if (all_apps_fragment.y < mScreenHeight * 0.7) {
+                        showAllAppsFragment()
+                    } else {
+                        hideAllAppsFragment()
+                    }
+                }
             }
         }
 
         return true
     }
 
+    fun startHandlingTouches(touchDownY: Int) {
+        mTouchDownY = touchDownY
+        mCurrentFragmentY = all_apps_fragment.y.toInt()
+        mIgnoreUpEvent = false
+    }
+
     private fun showAllAppsFragment() {
         ObjectAnimator.ofFloat(all_apps_fragment, "y", 0f).apply {
             interpolator = DecelerateInterpolator()
             start()
         }
     }
+
+    private fun hideAllAppsFragment() {
+        ObjectAnimator.ofFloat(all_apps_fragment, "y", mScreenHeight.toFloat()).apply {
+            interpolator = DecelerateInterpolator()
+            start()
+        }
+    }
+
+    private class MyGestureListener(private val flingListener: FlingListener) : GestureDetector.SimpleOnGestureListener() {
+        override fun onFling(event1: MotionEvent, event2: MotionEvent, velocityX: Float, velocityY: Float): Boolean {
+            if (velocityY > 0) {
+                flingListener.onFlingDown()
+            } else {
+                flingListener.onFlingUp()
+            }
+            return true
+        }
+    }
+
+    override fun onFlingUp() {
+        mIgnoreUpEvent = true
+        showAllAppsFragment()
+    }
+
+    override fun onFlingDown() {
+        mIgnoreUpEvent = true
+        hideAllAppsFragment()
+    }
 }

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

@@ -58,8 +58,7 @@ class AllAppsFragment(context: Context, attributeSet: AttributeSet) : RelativeLa
         if (touchDownY != -1) {
             shouldIntercept = touchDownY - event.y < 0 && all_apps_grid.computeVerticalScrollOffset() == 0
             if (shouldIntercept) {
-                activity?.mTouchDownY = touchDownY
+                activity?.startHandlingTouches(touchDownY)
-                activity?.mCurrentFragmentY = y.toInt()
                 touchDownY = -1
             }
         } else {

app/src/main/kotlin/com/simplemobiletools/launcher/interfaces/FlingListener.kt

@@ -0,0 +1,7 @@
+package com.simplemobiletools.launcher.interfaces
+
+interface FlingListener {
+    fun onFlingUp()
+
+    fun onFlingDown()
+}