Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/contextualsearch/SwipeRecognizer.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.contextualsearch;
+
+import android.content.Context;
+import android.graphics.PointF;
+import android.view.GestureDetector;
+import android.view.GestureDetector.SimpleOnGestureListener;
+import android.view.MotionEvent;
+
+import org.chromium.chrome.browser.compositor.layouts.eventfilter.EdgeSwipeEventFilter.ScrollDirection;
+import org.chromium.chrome.browser.compositor.layouts.eventfilter.EdgeSwipeHandler;
+
+/**
+ * TODO(pedrosimonetti): Confirm with dtrainor@ the proper location for this file.
+ *
+ * Recognizes directional swipe gestures using supplied {@link MotionEvent}s.
+ * The {@EdgeSwipeHandler} callbacks will notify users when a particular gesture
+ * has occurred, if the handler supports the particular direction of the swipe.
+ *
+ * To use this class:
+ * <ul>
+ *  <li>Create an instance of the {@code SwipeRecognizer} for your View
+ *  <li>In the View#onTouchEvent(MotionEvent) method ensure you call
+ *          {@link #onTouchEvent(MotionEvent)}. The methods defined in your callback
+ *          will be executed when the gestures occur.
+ *  <li>Before trying to recognize the gesture, the class will call
+ *          {@link #shouldRecognizeSwipe(MotionEvent, MotionEvent)}, which allow
+ *          ignoring swipe recognition based on the MotionEvents.
+ *  <li>Once a swipe gesture is detected, the class will check if the the direction
+ *          is supported by calling {@link EdgeSwipeHandler#isSwipeEnabled(ScrollDirection)}.
+ * </ul>
+
+ * Internally, this class uses a {@link GestureDetector} to recognize swipe gestures.
+ * For convenience, this class also extends {@link SimpleOnGestureListener} which
+ * is passed to the {@GestureDetector}. This means that this class can also be
+ * used to detect simple gestures defined in {@link GestureDetector}.
+ */
+public class SwipeRecognizer extends SimpleOnGestureListener {
+
+    /**
+     * The threshold for a vertical swipe gesture, in dps.
+     */
+    private static final float SWIPE_VERTICAL_DRAG_THRESHOLD_DP = 5.f;
+
+    /**
+     * The threshold for a horizontal swipe gesture, in dps.
+     */
+    private static final float SWIPE_HORIZONTAL_DRAG_THRESHOLD_DP = 10.f;
+
+    /**
+     * The {@link EdgeSwipeHandler} that will respond to recognized gestures.
+     */
+    private EdgeSwipeHandler mSwipeHandler;
+
+    /**
+     * The direction of the swipe gesture.
+     * TODO(pedrosimonetti): Consider renaming ScrollDirection to SwipeDirection.
+     * Also consider renaming EdgeSwipeHandler to SwipeHandler or DirectionalSwipeHandler.
+     * Finally, consider moving the ScrollDirection/SwipeDirection enum to this class.
+     */
+    private ScrollDirection mSwipeDirection = ScrollDirection.UNKNOWN;
+
+    /**
+     * The point that originated the swipe gesture.
+     */
+    private final PointF mMotionStartPoint = new PointF();
+
+    /**
+     * The dps per pixel ratio.
+     */
+    private final float mPxToDp;
+
+    /**
+     * The internal {@GestureDetector} used to recognize swipe gestures.
+     */
+    private final GestureDetector mGestureDetector;
+
+    /**
+     * @param context The current Android {@link Context}.
+     */
+    public SwipeRecognizer(Context context) {
+        mPxToDp = 1.f / context.getResources().getDisplayMetrics().density;
+        mGestureDetector = new GestureDetector(context, this);
+    }
+
+    /**
+     * Sets the {@link EdgeSwipeHandler} that will respond to recognized gestures.
+     * @param handler The {@link EdgeSwipeHandler}.
+     */
+    public void setSwipeHandler(EdgeSwipeHandler handler) {
+        mSwipeHandler = handler;
+    }
+
+    /**
+     * Analyzes the given motion event by feeding it to a {@GestureDetector}. Depending on the
+     * results from the onScroll() and onFling() methods, it triggers the appropriate callbacks
+     * on the {@link EdgeSwipeHandler} supplied.
+     *
+     * @param event The {@link MotionEvent}.
+     * @return Whether the event has been consumed.
+     */
+    public boolean onTouchEvent(MotionEvent event) {
+        boolean consumed = mGestureDetector.onTouchEvent(event);
+
+        if (mSwipeHandler != null) {
+            final int action = event.getAction();
+            if ((action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_CANCEL)
+                    && mSwipeDirection != ScrollDirection.UNKNOWN) {
+                mSwipeHandler.swipeFinished();
+                mSwipeDirection = ScrollDirection.UNKNOWN;
+                consumed = true;
+            }
+        }
+
+        return consumed;
+    }
+
+    /**
+     * Checks whether the swipe gestures should be recognized. If this method returns false,
+     * then the whole swipe recognition process will be ignored. By default this method returns
+     * true. If a more complex logic is needed, this method should be overridden.
+     *
+     * @param e1 The first {@link MotionEvent}.
+     * @param e2 The second {@link MotionEvent}.
+     * @return Whether the swipe gestures should be recognized
+     */
+    public boolean shouldRecognizeSwipe(MotionEvent e1, MotionEvent e2) {
+        return true;
+    }
+
+    // ============================================================================================
+    // Swipe Recognition Helpers
+    // ============================================================================================
+
+    @Override
+    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
+        if (mSwipeHandler == null || e1 == null || e2 == null) return false;
+
+        final float x = e2.getRawX() * mPxToDp;
+        final float y = e2.getRawY() * mPxToDp;
+
+        if (mSwipeDirection == ScrollDirection.UNKNOWN && shouldRecognizeSwipe(e1, e2)) {
+            float tx = (e2.getRawX() - e1.getRawX()) * mPxToDp;
+            float ty = (e2.getRawY() - e1.getRawY()) * mPxToDp;
+
+            ScrollDirection direction = ScrollDirection.UNKNOWN;
+
+            if (Math.abs(tx) > SWIPE_HORIZONTAL_DRAG_THRESHOLD_DP) {
+                direction = tx > 0.f ? ScrollDirection.RIGHT : ScrollDirection.LEFT;
+            } else if (Math.abs(ty) > SWIPE_VERTICAL_DRAG_THRESHOLD_DP) {
+                direction = ty > 0.f ? ScrollDirection.DOWN : ScrollDirection.UP;
+            }
+
+            if (direction != ScrollDirection.UNKNOWN && mSwipeHandler.isSwipeEnabled(direction)) {
+                mSwipeDirection = direction;
+                mSwipeHandler.swipeStarted(direction, x, y);
+                mMotionStartPoint.set(e2.getRawX(), e2.getRawY());
+            }
+        }
+
+        if (mSwipeDirection != ScrollDirection.UNKNOWN) {
+            final float tx = (e2.getRawX() - mMotionStartPoint.x) * mPxToDp;
+            final float ty = (e2.getRawY() - mMotionStartPoint.y) * mPxToDp;
+            final float dx = -distanceX * mPxToDp;
+            final float dy = -distanceY * mPxToDp;
+
+            mSwipeHandler.swipeUpdated(x, y, dx, dy, tx, ty);
+            return true;
+        }
+
+        return false;
+    }
+
+    @Override
+    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
+        if (mSwipeHandler == null) return false;
+
+        if (mSwipeDirection != ScrollDirection.UNKNOWN) {
+            final float x = e2.getRawX() * mPxToDp;
+            final float y = e2.getRawY() * mPxToDp;
+            final float tx = (e2.getRawX() - mMotionStartPoint.x) * mPxToDp;
+            final float ty = (e2.getRawY() - mMotionStartPoint.y) * mPxToDp;
+            final float vx = velocityX * mPxToDp;
+            final float vy = velocityY * mPxToDp;
+
+            mSwipeHandler.swipeFlingOccurred(x, y, tx, ty, vx, vy);
+            return true;
+        }
+
+        return false;
+    }
+}