Handle multiple clicks on the touch screen

This allows games that rely on multi-touch to work

app/src/main/java/me/magnum/melonds/ui/emulator/input/TouchscreenInputHandler.kt

@@ -1,6 +1,8 @@
 package me.magnum.melonds.ui.emulator.input
 
+import android.annotation.SuppressLint
 import android.view.MotionEvent
+import android.view.MotionEvent.PointerCoords
 import android.view.View
 import me.magnum.melonds.MelonEmulator.onScreenRelease
 import me.magnum.melonds.domain.model.Input
@@ -9,18 +11,15 @@ import me.magnum.melonds.domain.model.Point
 class TouchscreenInputHandler(inputListener: IInputListener) : BaseInputHandler(inputListener) {
     private val touchPoint: Point = Point()
 
+    @SuppressLint("ClickableViewAccessibility")
     override fun onTouch(v: View, event: MotionEvent): Boolean {
         when (event.action) {
             MotionEvent.ACTION_DOWN -> {
                 inputListener.onKeyPress(Input.TOUCHSCREEN)
-                val x = event.x
-                val y = event.y
-                inputListener.onTouch(normalizeTouchCoordinates(x, y, v.width, v.height))
+                inputListener.onTouch(normalizeTouchCoordinates(event, v.width, v.height))
             }
             MotionEvent.ACTION_MOVE -> {
-                val x = event.x
-                val y = event.y
-                inputListener.onTouch(normalizeTouchCoordinates(x, y, v.width, v.height))
+                inputListener.onTouch(normalizeTouchCoordinates(event, v.width, v.height))
             }
             MotionEvent.ACTION_UP -> {
                 inputListener.onKeyReleased(Input.TOUCHSCREEN)
@@ -30,9 +29,24 @@ class TouchscreenInputHandler(inputListener: IInputListener) : BaseInputHandler(
         return true
     }
 
-    private fun normalizeTouchCoordinates(x: Float, y: Float, viewWidth: Int, viewHeight: Int): Point {
-        touchPoint.x = (x / viewWidth * 256).toInt().coerceIn(0, 255)
-        touchPoint.y = (y / viewHeight * 192).toInt().coerceIn(0, 191)
+    private fun normalizeTouchCoordinates(event: MotionEvent, viewWidth: Int, viewHeight: Int): Point {
+        var averageTouchX = 0f
+        var averageTouchY = 0f
+        val pointerCoordinates = PointerCoords()
+
+        // Average out touch positions. Even though the DS has a resistive touch screen, some games rely on the nuances
+        // of this technology for some mechanics. Averaging out the coordinates of the touch position allows us to
+        // simulate those nuances to some degree
+        for (i in 0 until event.pointerCount) {
+            event.getPointerCoords(i, pointerCoordinates)
+            averageTouchX += pointerCoordinates.x
+            averageTouchY += pointerCoordinates.y
+        }
+        averageTouchX /= event.pointerCount
+        averageTouchY /= event.pointerCount
+
+        touchPoint.x = (averageTouchX / viewWidth * 256).toInt().coerceIn(0, 255)
+        touchPoint.y = (averageTouchY / viewHeight * 192).toInt().coerceIn(0, 191)
         return touchPoint
     }
 }