improve gesture detection

app/src/main/java/de/jrpie/android/launcher/ui/HomeActivity.kt

@@ -6,14 +6,11 @@ import android.content.res.Resources
 import android.os.Build
 import android.os.Bundle
 import android.util.DisplayMetrics
-import android.view.GestureDetector
 import android.view.KeyEvent
 import android.view.MotionEvent
 import android.view.View
-import android.view.ViewConfiguration
 import android.window.OnBackInvokedDispatcher
 import androidx.appcompat.app.AppCompatActivity
-import androidx.core.view.GestureDetectorCompat
 import androidx.core.view.isVisible
 import de.jrpie.android.launcher.R
 import de.jrpie.android.launcher.actions.Action
@@ -23,13 +20,6 @@ import de.jrpie.android.launcher.databinding.HomeBinding
 import de.jrpie.android.launcher.preferences.LauncherPreferences
 import de.jrpie.android.launcher.ui.tutorial.TutorialActivity
 import java.util.Locale
-import java.util.Timer
-import kotlin.concurrent.fixedRateTimer
-import kotlin.math.abs
-import kotlin.math.max
-import kotlin.math.min
-import kotlin.math.tan
-
 
 /**
  * [HomeActivity] is the actual application Launcher,
@@ -43,10 +33,10 @@ import kotlin.math.tan
  * - Setting global variables (preferences etc.)
  * - Opening the [TutorialActivity] on new installations
  */
-class HomeActivity : UIObject, AppCompatActivity(),
+class HomeActivity : UIObject, AppCompatActivity() {
-    GestureDetector.OnGestureListener, GestureDetector.OnDoubleTapListener {
 
     private lateinit var binding: HomeBinding
+    private lateinit var touchGestureDetector: TouchGestureDetector
 
     private var sharedPreferencesListener =
         SharedPreferences.OnSharedPreferenceChangeListener { _, prefKey ->
@@ -61,22 +51,29 @@ class HomeActivity : UIObject, AppCompatActivity(),
             }
         }
 
-    private var edgeWidth = 0.15f
-
-    private var bufferedPointerCount = 1 // how many fingers on screen
-    private var pointerBufferTimer = Timer()
-
-    private lateinit var mDetector: GestureDetectorCompat
-
-
     override fun onCreate(savedInstanceState: Bundle?) {
         super<AppCompatActivity>.onCreate(savedInstanceState)
         super<UIObject>.onCreate()
 
+
+        val displayMetrics = DisplayMetrics()
+        windowManager.defaultDisplay.getMetrics(displayMetrics)
+
+        val width = displayMetrics.widthPixels
+        val height = displayMetrics.heightPixels
+
+        touchGestureDetector = TouchGestureDetector(
+            this,
+            width,
+            height,
+            LauncherPreferences.enabled_gestures().edgeSwipeEdgeWidth() / 100f
+        )
+
         // Initialise layout
         binding = HomeBinding.inflate(layoutInflater)
         setContentView(binding.root)
 
+
         // Handle back key / gesture on Android 13+, cf. onKeyDown()
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
             onBackInvokedDispatcher.registerOnBackInvokedCallback(
@@ -95,9 +92,6 @@ class HomeActivity : UIObject, AppCompatActivity(),
     override fun onStart() {
         super<AppCompatActivity>.onStart()
 
-        mDetector = GestureDetectorCompat(this, this)
-        mDetector.setOnDoubleTapListener(this)
-
         super<UIObject>.onStart()
 
         LauncherPreferences.getSharedPreferences()
@@ -172,7 +166,8 @@ class HomeActivity : UIObject, AppCompatActivity(),
     override fun onResume() {
         super.onResume()
 
-        edgeWidth = LauncherPreferences.enabled_gestures().edgeSwipeEdgeWidth() / 100f
+        touchGestureDetector.edgeWidth =
+            LauncherPreferences.enabled_gestures().edgeSwipeEdgeWidth() / 100f
 
         initClock()
         updateSettingsFallbackButtonVisibility()
@@ -211,95 +206,8 @@ class HomeActivity : UIObject, AppCompatActivity(),
         return true
     }
 
-    override fun onFling(e1: MotionEvent?, e2: MotionEvent, dX: Float, dY: Float): Boolean {
-
-        if (e1 == null) return false
-
-
-        val displayMetrics = DisplayMetrics()
-        windowManager.defaultDisplay.getMetrics(displayMetrics)
-
-        val width = displayMetrics.widthPixels
-        val height = displayMetrics.heightPixels
-
-        val diffX = e1.x - e2.x
-        val diffY = e1.y - e2.y
-
-        val doubleActions = LauncherPreferences.enabled_gestures().doubleSwipe()
-        val edgeActions = LauncherPreferences.enabled_gestures().edgeSwipe()
-
-        val threshold = ViewConfiguration.get(this).scaledTouchSlop
-        val angularThreshold = tan(Math.PI / 6)
-
-        var gesture = if (angularThreshold * abs(diffX) > abs(diffY)) { // horizontal swipe
-            if (diffX > threshold)
-                Gesture.SWIPE_LEFT
-            else if (diffX < -threshold)
-                Gesture.SWIPE_RIGHT
-            else null
-        } else if (angularThreshold * abs(diffY) > abs(diffX)) { // vertical swipe
-            // Only open if the swipe was not from the phones top edge
-            // TODO: replace 100px by sensible dp value (e.g. twice the height of the status bar)
-            if (diffY < -threshold && e1.y > 100)
-                Gesture.SWIPE_DOWN
-            else if (diffY > threshold)
-                Gesture.SWIPE_UP
-            else null
-        } else null
-
-        if (doubleActions && bufferedPointerCount > 1) {
-            gesture = gesture?.let(Gesture::getDoubleVariant)
-        }
-
-        if (edgeActions) {
-            if (max(e1.x, e2.x) < edgeWidth * width) {
-                gesture = gesture?.getEdgeVariant(Gesture.Edge.LEFT)
-            } else if (min(e1.x, e2.x) > (1 - edgeWidth) * width) {
-                gesture = gesture?.getEdgeVariant(Gesture.Edge.RIGHT)
-            }
-
-            if (max(e1.y, e2.y) < edgeWidth * height) {
-                gesture = gesture?.getEdgeVariant(Gesture.Edge.TOP)
-            } else if (min(e1.y, e2.y) > (1 - edgeWidth) * height) {
-                gesture = gesture?.getEdgeVariant(Gesture.Edge.BOTTOM)
-            }
-        }
-        gesture?.invoke(this)
-
-        return true
-    }
-
-    override fun onLongPress(event: MotionEvent) {
-        Gesture.LONG_CLICK(this)
-    }
-
-    override fun onDoubleTap(event: MotionEvent): Boolean {
-        Gesture.DOUBLE_CLICK(this)
-        return false
-    }
-
-    // Tooltip
-    override fun onSingleTapConfirmed(event: MotionEvent): Boolean {
-
-        return false
-    }
-
     override fun onTouchEvent(event: MotionEvent): Boolean {
-
+        return touchGestureDetector.onTouchEvent(event) || super.onTouchEvent(event)
-        // Buffer / Debounce the pointer count
-        if (event.pointerCount > bufferedPointerCount) {
-            bufferedPointerCount = event.pointerCount
-            pointerBufferTimer = fixedRateTimer("pointerBufferTimer", true, 300, 1000) {
-                bufferedPointerCount = 1
-                this.cancel() // a non-recurring timer
-            }
-        }
-
-        return if (mDetector.onTouchEvent(event)) {
-            false
-        } else {
-            super.onTouchEvent(event)
-        }
     }
 
     override fun setOnClicks() {
@@ -329,16 +237,4 @@ class HomeActivity : UIObject, AppCompatActivity(),
     override fun isHomeScreen(): Boolean {
         return true
     }
-
-
-    /* TODO: Remove those. For now they are necessary
-     *  because this inherits from GestureDetector.OnGestureListener */
-    override fun onDoubleTapEvent(event: MotionEvent): Boolean { return false }
-    override fun onDown(event: MotionEvent): Boolean { return false }
-    override fun onScroll(e1: MotionEvent?, e2: MotionEvent, dX: Float, dY: Float): Boolean { return false }
-    override fun onShowPress(event: MotionEvent) {}
-    override fun onSingleTapUp(event: MotionEvent): Boolean { return false }
-
-
-
 }

app/src/main/java/de/jrpie/android/launcher/ui/TouchGestureDetector.kt

@@ -0,0 +1,199 @@
+package de.jrpie.android.launcher.ui
+
+import android.content.Context
+import android.view.MotionEvent
+import android.view.ViewConfiguration
+import de.jrpie.android.launcher.actions.Gesture
+import de.jrpie.android.launcher.preferences.LauncherPreferences
+import kotlin.math.abs
+import kotlin.math.max
+import kotlin.math.min
+import kotlin.math.tan
+
+class TouchGestureDetector(
+    private val context: Context,
+    val width: Int,
+    val height: Int,
+    var edgeWidth: Float
+) {
+    private val ANGULAR_THRESHOLD = tan(Math.PI / 6)
+    private val TOUCH_SLOP: Int
+    private val TOUCH_SLOP_SQUARE: Int
+    private val DOUBLE_TAP_SLOP: Int
+    private val DOUBLE_TAP_SLOP_SQUARE: Int
+    private val LONG_PRESS_TIMEOUT: Int
+    private val TAP_TIMEOUT: Int
+    private val DOUBLE_TAP_TIMEOUT: Int
+
+
+    data class Vector(val x: Float, val y: Float) {
+        fun absSquared(): Float {
+            return this.x * this.x + this.y * this.y
+        }
+        fun plus(vector: Vector): Vector {
+            return Vector(this.x + vector.x, this.y + vector.y)
+        }
+        fun max(other: Vector): Vector {
+            return Vector(max(this.x, other.x), max(this.y, other.y))
+        }
+        fun min(other: Vector): Vector {
+            return Vector(min(this.x, other.x), min(this.y, other.y))
+        }
+        operator fun minus(vector: Vector): Vector {
+            return Vector(this.x - vector.x, this.y - vector.y)
+        }
+    }
+
+
+    class PointerPath(
+        val number: Int,
+        val start: Vector,
+        var last: Vector = start
+    ) {
+        var min = Vector(Float.POSITIVE_INFINITY, Float.POSITIVE_INFINITY)
+        var max = Vector(Float.NEGATIVE_INFINITY, Float.NEGATIVE_INFINITY)
+        fun sizeSquared(): Float {
+            return (max - min).absSquared()
+        }
+        fun getDirection(): Vector {
+            return last - start
+        }
+        fun update(vector: Vector) {
+            min = min.min(vector)
+            max = max.max(vector)
+            last = vector
+        }
+    }
+    private fun PointerPath.isTap(): Boolean {
+        return sizeSquared() < TOUCH_SLOP_SQUARE
+    }
+
+    init {
+        val configuration = ViewConfiguration.get(context)
+        TOUCH_SLOP = configuration.scaledTouchSlop
+        TOUCH_SLOP_SQUARE = TOUCH_SLOP * TOUCH_SLOP
+        DOUBLE_TAP_SLOP = configuration.scaledDoubleTapSlop
+        DOUBLE_TAP_SLOP_SQUARE = DOUBLE_TAP_SLOP * DOUBLE_TAP_SLOP
+
+        LONG_PRESS_TIMEOUT = ViewConfiguration.getLongPressTimeout()
+        TAP_TIMEOUT = ViewConfiguration.getTapTimeout()
+        DOUBLE_TAP_TIMEOUT = ViewConfiguration.getDoubleTapTimeout()
+    }
+
+    private var paths = HashMap<Int, PointerPath>()
+
+    private var lastTappedTime = 0L
+    private var lastTappedLocation: Vector? = null
+
+    fun onTouchEvent(event: MotionEvent): Boolean {
+        val pointerIdToIndex =
+            (0..<event.pointerCount).associateBy { event.getPointerId(it) }
+
+        if (event.actionMasked == MotionEvent.ACTION_DOWN) {
+            paths = HashMap()
+        }
+
+        // add new pointers
+        (0..<event.pointerCount).filter {
+            !paths.containsKey(event.getPointerId(it))
+        }.forEach {
+            val index = pointerIdToIndex[it] ?: return@forEach
+            paths[it] = PointerPath(
+                paths.entries.size,
+                Vector(event.getX(index), event.getY(index))
+            )
+        }
+
+        (0..<event.pointerCount).forEach {
+            val index = pointerIdToIndex[it] ?: return@forEach
+            paths[it]?.update(Vector(event.getX(index), event.getY(index)))
+        }
+
+        if (event.actionMasked == MotionEvent.ACTION_UP) {
+            classifyPaths(paths, event.downTime, event.eventTime)
+        }
+        return true
+    }
+
+    private fun getGestureForDirection(direction: Vector): Gesture? {
+        return if (ANGULAR_THRESHOLD * abs(direction.x) > abs(direction.y)) { // horizontal swipe
+            if (direction.x > TOUCH_SLOP)
+                Gesture.SWIPE_RIGHT
+            else if (direction.x < -TOUCH_SLOP)
+                Gesture.SWIPE_LEFT
+            else null
+        } else if (ANGULAR_THRESHOLD * abs(direction.y) > abs(direction.x)) { // vertical swipe
+            if (direction.y < -TOUCH_SLOP)
+                Gesture.SWIPE_UP
+            else if (direction.y > TOUCH_SLOP)
+                Gesture.SWIPE_DOWN
+            else null
+        } else null
+    }
+
+    private fun classifyPaths(paths: Map<Int, PointerPath>, timeStart: Long, timeEnd: Long) {
+        val duration = timeEnd - timeStart
+        val pointerCount = paths.entries.size
+        if (paths.entries.isEmpty()) {
+            return
+        }
+
+        val mainPointerPath = paths.entries.firstOrNull { it.value.number == 0 }?.value ?: return
+
+        // Ignore swipes at the very top, since this interferes with the status bar.
+        // TODO: replace 100px by sensible dp value (e.g. twice the height of the status bar)
+        if (paths.entries.any { it.value.start.y < 100 }) {
+            return
+        }
+
+        if (pointerCount == 1 && mainPointerPath.isTap()) {
+            // detect taps
+
+            if (duration in 0..TAP_TIMEOUT) {
+                if (timeStart - lastTappedTime < DOUBLE_TAP_TIMEOUT &&
+                    lastTappedLocation?.let {
+                        (mainPointerPath.last - it).absSquared() < DOUBLE_TAP_SLOP_SQUARE} == true
+                ) {
+                    Gesture.DOUBLE_CLICK.invoke(context)
+                } else {
+                    lastTappedTime = timeEnd
+                    lastTappedLocation = mainPointerPath.last
+                }
+            } else if (duration > LONG_PRESS_TIMEOUT) {
+                // TODO: Don't wait until the finger is lifted.
+                // Instead set a timer to start long click as soon as LONG_PRESS_TIMEOUT is reached
+                Gesture.LONG_CLICK.invoke(context)
+            }
+        } else {
+            // detect swipes
+
+            val doubleActions = LauncherPreferences.enabled_gestures().doubleSwipe()
+            val edgeActions = LauncherPreferences.enabled_gestures().edgeSwipe()
+
+            var gesture = getGestureForDirection(mainPointerPath.getDirection())
+
+            if (doubleActions && pointerCount > 1) {
+                if (paths.entries.any { getGestureForDirection(it.value.getDirection()) != gesture }) {
+                    // the directions of the pointers don't match
+                    return
+                }
+                gesture = gesture?.let(Gesture::getDoubleVariant)
+            }
+
+            if (edgeActions) {
+                if (mainPointerPath.max.x < edgeWidth * width) {
+                    gesture = gesture?.getEdgeVariant(Gesture.Edge.LEFT)
+                } else if (mainPointerPath.min.x > (1 - edgeWidth) * width) {
+                    gesture = gesture?.getEdgeVariant(Gesture.Edge.RIGHT)
+                }
+
+                if (mainPointerPath.max.y < edgeWidth * height) {
+                    gesture = gesture?.getEdgeVariant(Gesture.Edge.TOP)
+                } else if (mainPointerPath.min.y > (1 - edgeWidth) * height) {
+                    gesture = gesture?.getEdgeVariant(Gesture.Edge.BOTTOM)
+                }
+            }
+            gesture?.invoke(context)
+        }
+    }
+}