Bugfix/#86 cancel fling with touch

app/src/main/java/com/otaliastudios/zoom/demo/ColorGridView.java

@@ -5,16 +5,17 @@
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.graphics.drawable.ColorDrawable;
-import androidx.annotation.AttrRes;
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
 import android.text.Layout;
 import android.text.StaticLayout;
 import android.text.TextPaint;
 import android.util.AttributeSet;
 import android.view.View;
 import android.widget.GridLayout;
 
+import androidx.annotation.AttrRes;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 import java.util.Random;
 
 
@@ -65,6 +66,13 @@ public void onClick(View view) {
                 view.setBackgroundColor(Color.BLACK);
             }
         });
+        view.setOnLongClickListener(new OnLongClickListener() {
+            @Override
+            public boolean onLongClick(View view) {
+                view.setBackgroundColor(Color.WHITE);
+                return true;
+            }
+        });
         return view;
     }
 

library/src/main/java/com/otaliastudios/zoom/ZoomEngine.kt

@@ -159,6 +159,7 @@ internal constructor(context: Context) : ZoomApi {
     // Internal
     private lateinit var container: View
     private val callbacks = Callbacks()
+
     @Suppress("LeakingThis")
     private val dispatcher = UpdatesDispatcher(this)
     private val stateController = StateController(callbacks)
@@ -516,7 +517,7 @@ internal constructor(context: Context) : ZoomApi {
      */
     internal fun setContainer(container: View) {
         this.container = container
-        this.container.addOnAttachStateChangeListener(object: View.OnAttachStateChangeListener {
+        this.container.addOnAttachStateChangeListener(object : View.OnAttachStateChangeListener {
             override fun onViewAttachedToWindow(view: View) {
                 view.viewTreeObserver.addOnGlobalLayoutListener(callbacks)
             }
@@ -833,7 +834,10 @@ internal constructor(context: Context) : ZoomApi {
      * @return true if anything was cancelled, false otherwise
      */
     override fun cancelAnimations(): Boolean {
-        if (stateController.isFlinging() || stateController.isAnimating()) {
+        if (stateController.isFlinging()) {
+            scrollFlingDetector.cancelFling()
+            return true
+        } else if (stateController.isAnimating()) {
             stateController.makeIdle()
             return true
         }

library/src/main/java/com/otaliastudios/zoom/internal/StateController.kt

@@ -3,6 +3,7 @@ package com.otaliastudios.zoom.internal
 import android.view.MotionEvent
 import androidx.annotation.IntDef
 import com.otaliastudios.zoom.ZoomLogger
+import com.otaliastudios.zoom.internal.StateController.Callback
 
 /**
  * Deals with touch input, holds the internal [state] integer,
@@ -50,6 +51,7 @@ internal class StateController(private val callback: Callback) {
     /**
      * Private function to set the current state.
      * External callers should use [setPinching], [setScrolling], [makeIdle]... instead.
+     * @return true if the new state was applied, false otherwise
      */
     private fun setState(@State newState: Int): Boolean {
         LOG.v("trySetState:", newState.toStateName())

library/src/main/java/com/otaliastudios/zoom/internal/gestures/ScrollFlingDetector.kt

@@ -7,8 +7,8 @@ import android.widget.OverScroller
 import com.otaliastudios.zoom.ScaledPoint
 import com.otaliastudios.zoom.ZoomApi
 import com.otaliastudios.zoom.ZoomLogger
-import com.otaliastudios.zoom.internal.matrix.MatrixController
 import com.otaliastudios.zoom.internal.StateController
+import com.otaliastudios.zoom.internal.matrix.MatrixController
 import com.otaliastudios.zoom.internal.movement.PanManager
 import kotlin.math.abs
 import kotlin.math.pow
@@ -65,17 +65,28 @@ internal class ScrollFlingDetector(
      * idle state.
      */
     internal fun cancelScroll() {
+        if (!correctOverpan()) {
+            stateController.makeIdle()
+        }
+    }
+
+    /**
+     * Initiates an animation to correct any existing overpan
+     * @return true if a correction was initiated, false otherwise
+     */
+    private fun correctOverpan(): Boolean {
         if (panManager.isOverEnabled) {
             val fix = panManager.correction
             if (fix.x != 0f || fix.y != 0f) {
                 matrixController.animateUpdate { panBy(fix, true) }
-                return
+                return true
             }
         }
-        stateController.makeIdle()
+        return false
     }
 
     override fun onDown(e: MotionEvent): Boolean {
+        cancelFling()
         return true // We are interested in the gesture.
     }
 
@@ -107,6 +118,9 @@ internal class ScrollFlingDetector(
         }
         // Must be after the other conditions.
         if (!stateController.setFlinging()) return false
+        // disable long press detection while we are flinging
+        // to prevent long presses from interrupting a possible followup scroll gesture
+        detector.setIsLongpressEnabled(false)
 
         @ZoomApi.ScaledPan val overScrollX = if (panManager.horizontalOverPanEnabled) panManager.maxOverPan else 0F
         @ZoomApi.ScaledPan val overScrollY = if (panManager.verticalOverPanEnabled) panManager.maxOverPan else 0F
@@ -122,6 +136,8 @@ internal class ScrollFlingDetector(
             override fun run() {
                 if (flingScroller.isFinished) {
                     stateController.makeIdle()
+                    // re-enable long press detection
+                    detector.setIsLongpressEnabled(true)
                 } else if (flingScroller.computeScrollOffset()) {
                     val newPan = ScaledPoint(flingScroller.currX.toFloat(), flingScroller.currY.toFloat())
                     // OverScroller will eventually go back to our bounds.