MouseInputHandler.java revision 60dadaeed4f5cee272b575dfde6c02e3506a2fa0 
1/*
2 * Copyright 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package androidx.recyclerview.selection;
18
19import static androidx.core.util.Preconditions.checkArgument;
20import static androidx.core.util.Preconditions.checkState;
21import static androidx.recyclerview.selection.Shared.DEBUG;
22import static androidx.recyclerview.selection.Shared.VERBOSE;
23
24import android.util.Log;
25import android.view.MotionEvent;
26
27import androidx.annotation.NonNull;
28import androidx.annotation.Nullable;
29import androidx.recyclerview.selection.ItemDetailsLookup.ItemDetails;
30import androidx.recyclerview.widget.RecyclerView;
31
32/**
33 * A MotionInputHandler that provides the high-level glue for mouse driven selection. This
34 * class works with {@link RecyclerView}, {@link GestureRouter}, and {@link GestureSelectionHelper}
35 * to implement the primary policies around mouse input.
36 */
37final class MouseInputHandler<K> extends MotionInputHandler<K> {
38
39    private static final String TAG = "MouseInputDelegate";
40
41    private final ItemDetailsLookup<K> mDetailsLookup;
42    private final OnContextClickListener mOnContextClickListener;
43    private final OnItemActivatedListener<K> mOnItemActivatedListener;
44    private final FocusDelegate<K> mFocusDelegate;
45
46    // The event has been handled in onSingleTapUp
47    private boolean mHandledTapUp;
48    // true when the previous event has consumed a right click motion event
49    private boolean mHandledOnDown;
50
51    MouseInputHandler(
52            @NonNull SelectionTracker<K> selectionTracker,
53            @NonNull ItemKeyProvider<K> keyProvider,
54            @NonNull ItemDetailsLookup<K> detailsLookup,
55            @NonNull OnContextClickListener onContextClickListener,
56            @NonNull OnItemActivatedListener<K> onItemActivatedListener,
57            @NonNull FocusDelegate<K> focusDelegate) {
58
59        super(selectionTracker, keyProvider, focusDelegate);
60
61        checkArgument(detailsLookup != null);
62        checkArgument(onContextClickListener != null);
63        checkArgument(onItemActivatedListener != null);
64
65        mDetailsLookup = detailsLookup;
66        mOnContextClickListener = onContextClickListener;
67        mOnItemActivatedListener = onItemActivatedListener;
68        mFocusDelegate = focusDelegate;
69    }
70
71    @Override
72    public boolean onDown(@NonNull MotionEvent e) {
73        if (VERBOSE) Log.v(TAG, "Delegated onDown event.");
74        if ((MotionEvents.isAltKeyPressed(e) && MotionEvents.isPrimaryMouseButtonPressed(e))
75                || MotionEvents.isSecondaryMouseButtonPressed(e)) {
76            mHandledOnDown = true;
77            return onRightClick(e);
78        }
79
80        return false;
81    }
82
83    @Override
84    public boolean onScroll(@NonNull MotionEvent e1, @NonNull MotionEvent e2,
85            float distanceX, float distanceY) {
86        // Don't scroll content window in response to mouse drag
87        // If it's two-finger trackpad scrolling, we want to scroll
88        return !MotionEvents.isTouchpadScroll(e2);
89    }
90
91    @Override
92    public boolean onSingleTapUp(@NonNull MotionEvent e) {
93        // See b/27377794. Since we don't get a button state back from UP events, we have to
94        // explicitly save this state to know whether something was previously handled by
95        // DOWN events or not.
96        if (mHandledOnDown) {
97            if (VERBOSE) Log.v(TAG, "Ignoring onSingleTapUp, previously handled in onDown.");
98            mHandledOnDown = false;
99            return false;
100        }
101
102        if (!mDetailsLookup.overItemWithSelectionKey(e)) {
103            if (DEBUG) Log.d(TAG, "Tap not associated w/ model item. Clearing selection.");
104            mSelectionTracker.clearSelection();
105            mFocusDelegate.clearFocus();
106            return false;
107        }
108
109        if (MotionEvents.isTertiaryMouseButtonPressed(e)) {
110            if (DEBUG) Log.d(TAG, "Ignoring middle click");
111            return false;
112        }
113
114        if (mSelectionTracker.hasSelection()) {
115            onItemClick(e, mDetailsLookup.getItemDetails(e));
116            mHandledTapUp = true;
117            return true;
118        }
119
120        return false;
121    }
122
123    // tap on an item when there is an existing selection. We could extend
124    // a selection, we could clear selection (then launch)
125    private void onItemClick(@NonNull MotionEvent e, @NonNull ItemDetails<K> item) {
126        checkState(mSelectionTracker.hasSelection());
127        checkArgument(item != null);
128
129        if (isRangeExtension(e)) {
130            extendSelectionRange(item);
131        } else {
132            if (shouldClearSelection(e, item)) {
133                mSelectionTracker.clearSelection();
134            }
135            if (mSelectionTracker.isSelected(item.getSelectionKey())) {
136                if (mSelectionTracker.deselect(item.getSelectionKey())) {
137                    mFocusDelegate.clearFocus();
138                }
139            } else {
140                selectOrFocusItem(item, e);
141            }
142        }
143    }
144
145    @Override
146    public boolean onSingleTapConfirmed(@NonNull MotionEvent e) {
147        if (mHandledTapUp) {
148            if (VERBOSE) {
149                Log.v(TAG,
150                        "Ignoring onSingleTapConfirmed, previously handled in onSingleTapUp.");
151            }
152            mHandledTapUp = false;
153            return false;
154        }
155
156        if (mSelectionTracker.hasSelection()) {
157            return false;  // should have been handled by onSingleTapUp.
158        }
159
160        if (!mDetailsLookup.overItem(e)) {
161            if (DEBUG) Log.d(TAG, "Ignoring Confirmed Tap on non-item.");
162            return false;
163        }
164
165        if (MotionEvents.isTertiaryMouseButtonPressed(e)) {
166            if (DEBUG) Log.d(TAG, "Ignoring middle click");
167            return false;
168        }
169
170        @Nullable ItemDetails<K> item = mDetailsLookup.getItemDetails(e);
171        if (item == null || !item.hasSelectionKey()) {
172            return false;
173        }
174
175        if (mFocusDelegate.hasFocusedItem() && MotionEvents.isShiftKeyPressed(e)) {
176            mSelectionTracker.startRange(mFocusDelegate.getFocusedPosition());
177            mSelectionTracker.extendRange(item.getPosition());
178        } else {
179            selectOrFocusItem(item, e);
180        }
181        return true;
182    }
183
184    @Override
185    public boolean onDoubleTap(@NonNull MotionEvent e) {
186        mHandledTapUp = false;
187
188        if (!mDetailsLookup.overItemWithSelectionKey(e)) {
189            if (DEBUG) Log.d(TAG, "Ignoring DoubleTap on non-model-backed item.");
190            return false;
191        }
192
193        if (MotionEvents.isTertiaryMouseButtonPressed(e)) {
194            if (DEBUG) Log.d(TAG, "Ignoring middle click");
195            return false;
196        }
197
198        ItemDetails<K> item = mDetailsLookup.getItemDetails(e);
199        return (item != null) && mOnItemActivatedListener.onItemActivated(item, e);
200    }
201
202    private boolean onRightClick(@NonNull MotionEvent e) {
203        if (mDetailsLookup.overItemWithSelectionKey(e)) {
204            @Nullable ItemDetails<K> item = mDetailsLookup.getItemDetails(e);
205            if (item != null && !mSelectionTracker.isSelected(item.getSelectionKey())) {
206                mSelectionTracker.clearSelection();
207                selectItem(item);
208            }
209        }
210
211        // We always delegate final handling of the event,
212        // since the handler might want to show a context menu
213        // in an empty area or some other weirdo view.
214        return mOnContextClickListener.onContextClick(e);
215    }
216
217    private void selectOrFocusItem(@NonNull ItemDetails<K> item, @NonNull MotionEvent e) {
218        if (item.inSelectionHotspot(e) || MotionEvents.isCtrlKeyPressed(e)) {
219            selectItem(item);
220        } else {
221            focusItem(item);
222        }
223    }
224}
225