warn the brittle SwipeAction.toFling and remove its use in StepBasedScroller

optimize AccessibilityEventScrollStepStrategy to match UiAutomator

Change-Id: Iacac499659ca6d94daf82f5889700234b231e4d9

3 files changed, 64 insertions, 9 deletions

diff --git a/src/com/google/android/droiddriver/actions/SwipeAction.java b/src/com/google/android/droiddriver/actions/SwipeAction.java
index ca165f1..186b5dc 100644
--- a/src/com/google/android/droiddriver/actions/SwipeAction.java
+++ b/src/com/google/android/droiddriver/actions/SwipeAction.java
@@ -22,6 +22,7 @@ import static com.google.android.droiddriver.scroll.Direction.PhysicalDirection.
 import static com.google.android.droiddriver.scroll.Direction.PhysicalDirection.UP;
 
 import android.graphics.Rect;
+import android.os.Build;
 import android.os.SystemClock;
 import android.view.ViewConfiguration;
 
@@ -31,6 +32,7 @@ import com.google.android.droiddriver.scroll.Direction.PhysicalDirection;
 import com.google.android.droiddriver.util.Events;
 import com.google.common.base.Objects;
 import com.google.common.base.Objects.ToStringHelper;
+import com.google.common.primitives.Ints;
 
 /**
  * A {@link ScrollAction} that swipes the touch screen. Note the scroll
@@ -42,13 +44,18 @@ public class SwipeAction extends ScrollAction {
   // The action is a fling if the ACTION_MOVE velocity is greater than
   // ViewConfiguration#getScaledMinimumFlingVelocity. The velocity is calculated
   // as <distance between ACTION_MOVE points> / ACTION_MOVE_INTERVAL
+  // Note: ACTION_MOVE_INTERVAL is the minimum interval between injected events;
+  // the actual interval typically is longer.
   private static final int ACTION_MOVE_INTERVAL = 5;
   // ViewConfiguration.MINIMUM_FLING_VELOCITY = 50, so if there is no scale, in
   // theory a swipe of 20 steps is a scroll instead of fling on devices that
   // have 20 * 50 * 5 = 5000 pixels in one direction. Make it 40 for safety.
   private static final int SCROLL_STEPS = 40;
-  // FLING_STEPS = 2 does not work on GingerBread
-  private static final int FLING_STEPS = 3;
+  // TODO: Find the exact version-dependent fling steps. It is observed that 2
+  // does not work on GINGERBREAD; we haven't tested all versions so <JELLY_BEAN
+  // is used as a guess.
+  private static final int FLING_STEPS = Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN ? 3
+      : 2;
 
   /**
    * Common instances for convenience. The direction in names reflects the
@@ -88,6 +95,13 @@ public class SwipeAction extends ScrollAction {
   /**
    * Gets canned common instances for flinging. Note the scroll direction
    * specifies where the content will move, instead of the finger.
+   * <p>
+   * Note: This may not actually fling, depending on the size of the target
+   * UiElement and the SDK version of the device. If it does not behave as
+   * expected, you can use SwipeAction instances with custom steps.
+   * </p>
+   *
+   * @see ViewConfiguration#getScaledMinimumFlingVelocity
    */
   // TODO: We may use "smart" steps that depend on the size of the UiElement and
   // ViewConfiguration#getScaledMinimumFlingVelocity.
@@ -127,15 +141,15 @@ public class SwipeAction extends ScrollAction {
   /**
    * @param direction the scroll direction specifying where the content will
    *        move, instead of the finger.
-   * @param steps (steps-1) is the number of {@code ACTION_MOVE} that will be
-   *        injected between {@code ACTION_DOWN} and {@code ACTION_UP}
+   * @param steps minimum 2; (steps-1) is the number of {@code ACTION_MOVE} that
+   *        will be injected between {@code ACTION_DOWN} and {@code ACTION_UP}.
    * @param drag whether this is a drag
    * @param timeoutMillis
    */
   public SwipeAction(PhysicalDirection direction, int steps, boolean drag, long timeoutMillis) {
     super(timeoutMillis);
     this.direction = direction;
-    this.steps = steps;
+    this.steps = Ints.max(2, steps);
     this.drag = drag;
   }
 
diff --git a/src/com/google/android/droiddriver/scroll/AccessibilityEventScrollStepStrategy.java b/src/com/google/android/droiddriver/scroll/AccessibilityEventScrollStepStrategy.java
index 0333d77..9a4fe05 100644
--- a/src/com/google/android/droiddriver/scroll/AccessibilityEventScrollStepStrategy.java
+++ b/src/com/google/android/droiddriver/scroll/AccessibilityEventScrollStepStrategy.java
@@ -17,14 +17,17 @@ package com.google.android.droiddriver.scroll;
 
 import android.app.UiAutomation;
 import android.app.UiAutomation.AccessibilityEventFilter;
+import android.util.Log;
 import android.view.accessibility.AccessibilityEvent;
 
 import com.google.android.droiddriver.DroidDriver;
 import com.google.android.droiddriver.UiElement;
 import com.google.android.droiddriver.actions.SwipeAction;
 import com.google.android.droiddriver.finders.Finder;
+import com.google.android.droiddriver.scroll.Direction.Axis;
 import com.google.android.droiddriver.scroll.Direction.DirectionConverter;
 import com.google.android.droiddriver.scroll.Direction.PhysicalDirection;
+import com.google.android.droiddriver.util.Logs;
 
 import java.util.concurrent.TimeoutException;
 
@@ -53,6 +56,9 @@ public class AccessibilityEventScrollStepStrategy implements ScrollStepStrategy
   private final long scrollEventTimeoutMillis;
   private final DirectionConverter directionConverter;
 
+  private Finder containerFinderAtEnd;
+  private PhysicalDirection directionAtEnd;
+
   public AccessibilityEventScrollStepStrategy(UiAutomation uiAutomation,
       long scrollEventTimeoutMillis, DirectionConverter converter) {
     this.uiAutomation = uiAutomation;
@@ -63,14 +69,28 @@ public class AccessibilityEventScrollStepStrategy implements ScrollStepStrategy
   @Override
   public boolean scroll(DroidDriver driver, Finder containerFinder,
       final PhysicalDirection direction) {
+    // Check if we've reached end after last scroll.
+    if (containerFinderAtEnd == containerFinder && directionAtEnd == direction) {
+      return false;
+    }
+
     final UiElement container = driver.on(containerFinder);
     try {
-      uiAutomation.executeAndWaitForEvent(new Runnable() {
+      AccessibilityEvent event = uiAutomation.executeAndWaitForEvent(new Runnable() {
         @Override
         public void run() {
           SwipeAction.toScroll(direction).perform(container.getInjector(), container);
         }
       }, SCROLL_EVENT_FILTER, scrollEventTimeoutMillis);
+
+      if (detectEnd(direction.axis(), event)) {
+        containerFinderAtEnd = containerFinder;
+        directionAtEnd = direction;
+        Logs.log(Log.DEBUG, "reached scroll end");
+      } else {
+        containerFinderAtEnd = null;
+        directionAtEnd = null;
+      }
     } catch (TimeoutException e) {
       // If no TYPE_VIEW_SCROLLED event, no more scrolling is possible
       return false;
@@ -78,6 +98,23 @@ public class AccessibilityEventScrollStepStrategy implements ScrollStepStrategy
     return true;
   }
 
+  // Copied from UiAutomator.
+  // AdapterViews have indices we can use to check for the beginning.
+  private static boolean detectEnd(Axis axis, AccessibilityEvent event) {
+    boolean foundEnd = false;
+    if (event.getFromIndex() != -1 && event.getToIndex() != -1 && event.getItemCount() != -1) {
+      foundEnd = event.getFromIndex() == 0 || (event.getItemCount() - 1) == event.getToIndex();
+    } else if (event.getScrollX() != -1 && event.getScrollY() != -1) {
+      if (axis == Axis.VERTICAL) {
+        foundEnd = event.getScrollY() == 0 || event.getScrollY() == event.getMaxScrollY();
+      } else if (axis == Axis.HORIZONTAL) {
+        foundEnd = event.getScrollX() == 0 || event.getScrollX() == event.getMaxScrollX();
+      }
+    }
+    event.recycle();
+    return foundEnd;
+  }
+
   @Override
   public final DirectionConverter getDirectionConverter() {
     return directionConverter;
diff --git a/src/com/google/android/droiddriver/scroll/StepBasedScroller.java b/src/com/google/android/droiddriver/scroll/StepBasedScroller.java
index 2ba8ceb..d7fd368 100644
--- a/src/com/google/android/droiddriver/scroll/StepBasedScroller.java
+++ b/src/com/google/android/droiddriver/scroll/StepBasedScroller.java
@@ -24,7 +24,6 @@ import com.google.android.droiddriver.DroidDriver;
 import com.google.android.droiddriver.Poller;
 import com.google.android.droiddriver.UiElement;
 import com.google.android.droiddriver.actions.SingleKeyAction;
-import com.google.android.droiddriver.actions.SwipeAction;
 import com.google.android.droiddriver.exceptions.ElementNotFoundException;
 import com.google.android.droiddriver.exceptions.TimeoutException;
 import com.google.android.droiddriver.finders.By;
@@ -149,8 +148,13 @@ public class StepBasedScroller implements Scroller {
         container.perform(MOVE_HOME);
         Logs.log(Log.DEBUG, "MOVE_HOME used");
       } else {
-        // Fling to beginning
-        container.perform(SwipeAction.toFling(backwardDirection));
+        // Fling to beginning is not reliable; scroll to beginning
+        // container.perform(SwipeAction.toFling(backwardDirection));
+        for (int i = 0; i < maxScrolls; i++) {
+          if (!scrollStepStrategy.scroll(driver, containerFinder, backwardDirection)) {
+            break;
+          }
+        }
       }
     } else {
       // search backward