Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchSelectionController.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.os.Handler;
+
+import org.chromium.base.VisibleForTesting;
+import org.chromium.chrome.browser.ChromeActivity;
+import org.chromium.chrome.browser.Tab;
+import org.chromium.content.browser.ContentViewCore;
+import org.chromium.content_public.browser.GestureStateListener;
+import org.chromium.ui.touch_selection.SelectionEventType;
+
+/**
+ * Controls selection gesture interaction for Contextual Search.
+ */
+public class ContextualSearchSelectionController {
+
+    /**
+     * The type of selection made by the user.
+     */
+    public enum SelectionType {
+        UNDETERMINED,
+        TAP,
+        LONG_PRESS
+    }
+
+    // The number of milliseconds to wait for a selection change after a tap before considering
+    // the tap invalid.  This can't be too small or the subsequent taps may not have established
+    // a new selection in time.  This is because selectWordAroundCaret doesn't always select.
+    // TODO(donnd): Fix in Blink, crbug.com/435778.
+    private static final int INVALID_IF_NO_SELECTION_CHANGE_AFTER_TAP_MS = 50;
+    private static final double RETAP_DISTANCE_SQUARED_DP = Math.pow(75, 2);
+
+    private final ChromeActivity mActivity;
+    private final ContextualSearchSelectionHandler mHandler;
+    private final Runnable mHandleInvalidTapRunnable;
+    private final Handler mRunnableHandler;
+    private final float mPxToDp;
+
+    private String mSelectedText;
+    private SelectionType mSelectionType;
+    private boolean mWasTapGestureDetected;
+    private boolean mIsSelectionBeingModified;
+    private boolean mWasLastTapValid;
+    private boolean mIsWaitingForInvalidTapDetection;
+
+    private float mX;
+    private float mY;
+
+    private class ContextualSearchGestureStateListener extends GestureStateListener {
+        @Override
+        public void onScrollStarted(int scrollOffsetY, int scrollExtentY) {
+            mHandler.handleScroll();
+        }
+
+        // TODO(donnd): Remove this once we get notification of the selection changing
+        // after a tap-select gets a subsequent tap nearby.  Currently there's no
+        // notification in this case.
+        // See crbug.com/444114.
+        @Override
+        public void onSingleTap(boolean consumed, int x, int y) {
+            // We may be notified that a tap has happened even when the system consumed the event.
+            // This is being considered for support for tapping an existing selection to show the
+            // pins.  We should only process this tap if it has not been consumed by the system.
+            if (!consumed) scheduleInvalidTapNotification();
+        }
+    }
+
+    /**
+     * Constructs a new Selection controller for the given activity.  Callbacks will be issued
+     * through the given selection handler.
+     * @param activity The {@link ChromeActivity} to control.
+     * @param handler The handler for callbacks.
+     */
+    public ContextualSearchSelectionController(ChromeActivity activity,
+            ContextualSearchSelectionHandler handler) {
+        mActivity = activity;
+        mHandler = handler;
+        mPxToDp = 1.f / mActivity.getResources().getDisplayMetrics().density;
+
+        mRunnableHandler = new Handler();
+        mHandleInvalidTapRunnable = new Runnable() {
+            @Override
+            public void run() {
+                onInvalidTapDetectionTimeout();
+            }
+        };
+    }
+
+    /**
+     * Returns a new {@code GestureStateListener} that will listen for events in the Base Page.
+     * This listener will handle all Contextual Search-related interactions that go through the
+     * listener.
+     */
+    public ContextualSearchGestureStateListener getGestureStateListener() {
+        return new ContextualSearchGestureStateListener();
+    }
+
+    /**
+     * @return the type of the selection.
+     */
+    SelectionType getSelectionType() {
+        return mSelectionType;
+    }
+
+    /**
+     * @return the selected text.
+     */
+    String getSelectedText() {
+        return mSelectedText;
+    }
+
+    /**
+     * Clears the selection.
+     */
+    void clearSelection() {
+        ContentViewCore baseContentView = getBaseContentView();
+        if (baseContentView != null) {
+            baseContentView.clearSelection();
+        }
+        mHandler.onClearSelection();
+
+        resetAllStates();
+    }
+
+    /**
+     * Handles a change in the current Selection.
+     * @param selection The selection portion of the context.
+     */
+    void handleSelectionChanged(String selection) {
+        if (selection == null || selection.isEmpty()) {
+            scheduleInvalidTapNotification();
+            // When the user taps on the page it will place the caret in that position, which
+            // will trigger a onSelectionChanged event with an empty string.
+            if (mSelectionType == SelectionType.TAP) {
+                // Since we mostly ignore a selection that's empty, we only need to partially reset.
+                resetSelectionStates();
+                return;
+            }
+        }
+        if (selection != null && !selection.isEmpty()) {
+            unscheduleInvalidTapNotification();
+        }
+        if (mIsSelectionBeingModified) {
+            mSelectedText = selection;
+            mHandler.handleSelectionModification(selection, mX, mY);
+        } else if (mWasTapGestureDetected) {
+            mSelectedText = selection;
+            mSelectionType = SelectionType.TAP;
+            mHandler.handleSelection(selection, mSelectionType, mX, mY);
+            mWasTapGestureDetected = false;
+        }
+    }
+
+    /**
+     * Handles a notification that a selection event took place.
+     * @param eventType The type of event that took place.
+     * @param posXPix The x coordinate of the selection start handle.
+     * @param posYPix The y coordinate of the selection start handle.
+     */
+    void handleSelectionEvent(int eventType, float posXPix, float posYPix) {
+        boolean shouldHandleSelection = false;
+        switch (eventType) {
+            case SelectionEventType.SELECTION_SHOWN:
+                mWasTapGestureDetected = false;
+                mSelectionType = SelectionType.LONG_PRESS;
+                shouldHandleSelection = true;
+                break;
+            case SelectionEventType.SELECTION_CLEARED:
+                mHandler.onClearSelection();
+                resetAllStates();
+                break;
+            case SelectionEventType.SELECTION_DRAG_STARTED:
+                mIsSelectionBeingModified = true;
+                break;
+            case SelectionEventType.SELECTION_DRAG_STOPPED:
+                mIsSelectionBeingModified = false;
+                shouldHandleSelection = true;
+                break;
+            default:
+        }
+
+        if (shouldHandleSelection) {
+            ContentViewCore baseContentView = getBaseContentView();
+            if (baseContentView != null) {
+                String selection = baseContentView.getSelectedText();
+                if (selection != null) {
+                    mX = posXPix;
+                    mY = posYPix;
+                    mSelectedText = selection;
+                    mHandler.handleSelection(selection, SelectionType.LONG_PRESS, mX, mY);
+                }
+            }
+        }
+    }
+
+    /**
+     * Resets all internal state of this class, including the tap state.
+     */
+    private void resetAllStates() {
+        resetSelectionStates();
+        mWasLastTapValid = false;
+    }
+
+    /**
+     * Resets all of the internal state of this class that handles the selection.
+     */
+    private void resetSelectionStates() {
+        mSelectionType = SelectionType.UNDETERMINED;
+        mSelectedText = null;
+
+        mWasTapGestureDetected = false;
+        mIsSelectionBeingModified = false;
+    }
+
+    /**
+     * Handles an unhandled tap gesture.
+     */
+    void handleShowUnhandledTapUIIfNeeded(int x, int y) {
+        mWasTapGestureDetected = false;
+        if (mSelectionType != SelectionType.LONG_PRESS && shouldHandleTap(x, y)) {
+            mX = x;
+            mY = y;
+            mWasLastTapValid = true;
+            mWasTapGestureDetected = true;
+            // TODO(donnd): Find a better way to determine that a navigation will be triggered
+            // by the tap, or merge with other time-consuming actions like gathering surrounding
+            // text or detecting page mutations.
+            new Handler().postDelayed(new Runnable() {
+                @Override
+                public void run() {
+                    mHandler.handleValidTap();
+                }
+            }, ContextualSearchFieldTrial.getNavigationDetectionDelay());
+        }
+        if (!mWasTapGestureDetected) {
+            mWasLastTapValid = false;
+            mHandler.handleInvalidTap();
+        }
+    }
+
+    /**
+     * @return The Base Page's {@link ContentViewCore}, or {@code null} if there is no current tab.
+     */
+    ContentViewCore getBaseContentView() {
+        Tab currentTab = mActivity.getActivityTab();
+        return currentTab != null ? currentTab.getContentViewCore() : null;
+    }
+
+    /**
+     * @return whether a tap at the given coordinates should be handled or not.
+     */
+    private boolean shouldHandleTap(int x, int y) {
+        return !mWasLastTapValid || wasTapCloseToPreviousTap(x, y);
+    }
+
+    /**
+     * Determines whether a tap at the given coordinates is considered "close" to the previous
+     * tap.
+     */
+    private boolean wasTapCloseToPreviousTap(int x, int y) {
+        float deltaXDp = (mX - x) * mPxToDp;
+        float deltaYDp = (mY - y) * mPxToDp;
+        float distanceSquaredDp =  deltaXDp * deltaXDp + deltaYDp * deltaYDp;
+        return distanceSquaredDp <= RETAP_DISTANCE_SQUARED_DP;
+    }
+
+    /**
+     * Schedules a notification to check if the tap was invalid.
+     * When we call selectWordAroundCaret it selects nothing in cases where the tap was invalid.
+     * We have no way to know other than scheduling a notification to check later.
+     * This allows us to hide the bar when there's no selection.
+     */
+    private void scheduleInvalidTapNotification() {
+        // TODO(donnd): Fix selectWordAroundCaret to we can tell if it selects, instead
+        // of using a timer here!  See crbug.com/435778.
+        mRunnableHandler.postDelayed(mHandleInvalidTapRunnable,
+                INVALID_IF_NO_SELECTION_CHANGE_AFTER_TAP_MS);
+    }
+
+    /**
+     * Un-schedules all pending notifications to check if a tap was invalid.
+     */
+    private void unscheduleInvalidTapNotification() {
+        mRunnableHandler.removeCallbacks(mHandleInvalidTapRunnable);
+        mIsWaitingForInvalidTapDetection = true;
+    }
+
+    /**
+     * Notify's the system that tap gesture has been completed.
+     */
+    private void onInvalidTapDetectionTimeout() {
+        mHandler.handleInvalidTap();
+        mIsWaitingForInvalidTapDetection = false;
+    }
+
+    /**
+     * @return whether a tap gesture has been detected, for testing.
+     */
+    @VisibleForTesting
+    boolean wasAnyTapGestureDetected() {
+        return mIsWaitingForInvalidTapDetection;
+    }
+}