summaryrefslogtreecommitdiff
path: root/library/core-src/com/android/uiautomator/core/UiScrollable.java
blob: f5306afdcfba89ca89f1cf44375391eef29b0785 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.uiautomator.core;

import android.graphics.Rect;
import android.util.Log;
import android.view.accessibility.AccessibilityNodeInfo;

/**
 * UiScrollable is a {@link UiCollection} and provides support for searching for items in a
 * scrollable UI elements. Used with horizontally or vertically scrollable UI.
 * @since API Level 16
 */
public class UiScrollable extends UiCollection {
    private static final String LOG_TAG = UiScrollable.class.getSimpleName();

    // More steps slows the swipe and prevents contents from being flung too far
    private static final int SCROLL_STEPS = 55;

    private static final int FLING_STEPS = 5;

    // Restrict a swipe's starting and ending points inside a 10% margin of the target
    private static final double DEFAULT_SWIPE_DEADZONE_PCT = 0.1;

    // Limits the number of swipes/scrolls performed during a search
    private static int mMaxSearchSwipes = 30;

    // Used in ScrollForward() and ScrollBackward() to determine swipe direction
    private boolean mIsVerticalList = true;

    private double mSwipeDeadZonePercentage = DEFAULT_SWIPE_DEADZONE_PCT;

    /**
     * UiScrollable is a {@link UiCollection} and as such requires a {@link UiSelector} to
     * identify the container UI element of the scrollable collection. Further operations on
     * the items in the container will require specifying UiSelector as an item selector.
     *
     * @param container a {@link UiSelector} selector
     * @since API Level 16
     */
    public UiScrollable(UiSelector container) {
        // wrap the container selector with container so that QueryController can handle
        // this type of enumeration search accordingly
        super(container);
    }

    /**
     * Set the direction of swipes when performing scroll search
     * @return reference to itself
     * @since API Level 16
     */
    public UiScrollable setAsVerticalList() {
        Tracer.trace();
        mIsVerticalList = true;
        return this;
    }

    /**
     * Set the direction of swipes when performing scroll search
     * @return reference to itself
     * @since API Level 16
     */
    public UiScrollable setAsHorizontalList() {
        Tracer.trace();
        mIsVerticalList = false;
        return this;
    }

    /**
     * Used privately when performing swipe searches to decide if an element has become
     * visible or not.
     *
     * @param selector
     * @return true if found else false
     * @since API Level 16
     */
    protected boolean exists(UiSelector selector) {
        if(getQueryController().findAccessibilityNodeInfo(selector) != null) {
            return true;
        }
        return false;
    }

    /**
     * Searches for child UI element within the constraints of this UiScrollable {@link UiSelector}
     * container. It looks for any child matching the <code>childPattern</code> argument within its
     * hierarchy with a matching content-description text. The returned UiObject will represent the
     * UI element matching the <code>childPattern</code> and not the sub element that matched the
     * content description.</p>
     * By default this operation will perform scroll search while attempting to find the UI element
     * See {@link #getChildByDescription(UiSelector, String, boolean)}
     *
     * @param childPattern {@link UiSelector} selector of the child pattern to match and return
     * @param text String of the identifying child contents of of the <code>childPattern</code>
     * @return {@link UiObject} pointing at and instance of <code>childPattern</code>
     * @throws UiObjectNotFoundException
     * @since API Level 16
     */
    @Override
    public UiObject getChildByDescription(UiSelector childPattern, String text)
            throws UiObjectNotFoundException {
        Tracer.trace(childPattern, text);
        return getChildByDescription(childPattern, text, true);
    }

    /**
     * See {@link #getChildByDescription(UiSelector, String)}
     *
     * @param childPattern {@link UiSelector} selector of the child pattern to match and return
     * @param text String may be a partial match for the content-description of a child element.
     * @param allowScrollSearch set to true if scrolling is allowed
     * @return {@link UiObject} pointing at and instance of <code>childPattern</code>
     * @throws UiObjectNotFoundException
     * @since API Level 16
     */
    public UiObject getChildByDescription(UiSelector childPattern, String text,
            boolean allowScrollSearch) throws UiObjectNotFoundException {
        Tracer.trace(childPattern, text, allowScrollSearch);
        if (text != null) {
            if (allowScrollSearch) {
                scrollIntoView(new UiSelector().descriptionContains(text));
            }
            return super.getChildByDescription(childPattern, text);
        }
        throw new UiObjectNotFoundException("for description= \"" + text + "\"");
    }

    /**
     * Searches for child UI element within the constraints of this UiScrollable {@link UiSelector}
     * selector. It looks for any child matching the <code>childPattern</code> argument and
     * return the <code>instance</code> specified. The operation is performed only on the visible
     * items and no scrolling is performed in this case.
     *
     * @param childPattern {@link UiSelector} selector of the child pattern to match and return
     * @param instance int the desired matched instance of this <code>childPattern</code>
     * @return {@link UiObject} pointing at and instance of <code>childPattern</code>
     * @since API Level 16
     */
    @Override
    public UiObject getChildByInstance(UiSelector childPattern, int instance)
            throws UiObjectNotFoundException {
        Tracer.trace(childPattern, instance);
        UiSelector patternSelector = UiSelector.patternBuilder(getSelector(),
                UiSelector.patternBuilder(childPattern).instance(instance));
        return new UiObject(patternSelector);
    }

    /**
     * Searches for child UI element within the constraints of this UiScrollable {@link UiSelector}
     * container. It looks for any child matching the <code>childPattern</code> argument that has
     * a sub UI element anywhere within its sub hierarchy that has text attribute
     * <code>text</code>. The returned UiObject will point at the <code>childPattern</code>
     * instance that matched the search and not at the text matched sub element</p>
     * By default this operation will perform scroll search while attempting to find the UI
     * element.
     * See {@link #getChildByText(UiSelector, String, boolean)}
     *
     * @param childPattern {@link UiSelector} selector of the child pattern to match and return
     * @param text String of the identifying child contents of of the <code>childPattern</code>
     * @return {@link UiObject} pointing at and instance of <code>childPattern</code>
     * @throws UiObjectNotFoundException
     * @since API Level 16
     */
    @Override
    public UiObject getChildByText(UiSelector childPattern, String text)
            throws UiObjectNotFoundException {
        Tracer.trace(childPattern, text);
        return getChildByText(childPattern, text, true);
    }

    /**
     * See {@link #getChildByText(UiSelector, String)}
     *
     * @param childPattern {@link UiSelector} selector of the child pattern to match and return
     * @param text String of the identifying child contents of of the <code>childPattern</code>
     * @param allowScrollSearch set to true if scrolling is allowed
     * @return {@link UiObject} pointing at and instance of <code>childPattern</code>
     * @throws UiObjectNotFoundException
     * @since API Level 16
     */
    public UiObject getChildByText(UiSelector childPattern, String text, boolean allowScrollSearch)
            throws UiObjectNotFoundException {
        Tracer.trace(childPattern, text, allowScrollSearch);
        if (text != null) {
            if (allowScrollSearch) {
                scrollIntoView(new UiSelector().text(text));
            }
            return super.getChildByText(childPattern, text);
        }
        throw new UiObjectNotFoundException("for text= \"" + text + "\"");
    }

    /**
     * Performs a swipe Up on the UI element until the requested content-description
     * is visible or until swipe attempts have been exhausted. See {@link #setMaxSearchSwipes(int)}
     *
     * @param text to look for anywhere within the contents of this scrollable.
     * @return true if item us found else false
     * @since API Level 16
     */
    public boolean scrollDescriptionIntoView(String text) throws UiObjectNotFoundException {
        Tracer.trace(text);
        return scrollIntoView(new UiSelector().description(text));
    }

    /**
     * Perform a scroll search for a UI element matching the {@link UiSelector} selector argument.
     * See {@link #scrollDescriptionIntoView(String)} and {@link #scrollTextIntoView(String)}.
     *
     * @param obj {@link UiObject}
     * @return true if the item was found and now is in view else false
     * @since API Level 16
     */
    public boolean scrollIntoView(UiObject obj) throws UiObjectNotFoundException {
        Tracer.trace(obj.getSelector());
        return scrollIntoView(obj.getSelector());
    }

    /**
     * Perform a scroll search for a UI element matching the {@link UiSelector} selector argument.
     * See {@link #scrollDescriptionIntoView(String)} and {@link #scrollTextIntoView(String)}.
     *
     * @param selector {@link UiSelector} selector
     * @return true if the item was found and now is in view else false
     * @since API Level 16
     */
    public boolean scrollIntoView(UiSelector selector) throws UiObjectNotFoundException {
        Tracer.trace(selector);
        // if we happen to be on top of the text we want then return here
        UiSelector childSelector = getSelector().childSelector(selector);
        if (exists(childSelector)) {
            return (true);
        } else {
            // we will need to reset the search from the beginning to start search
            scrollToBeginning(mMaxSearchSwipes);
            if (exists(childSelector)) {
                return (true);
            }
            for (int x = 0; x < mMaxSearchSwipes; x++) {
                boolean scrolled = scrollForward();
                if(exists(childSelector)) {
                    return true;
                }
                if (!scrolled) {
                    return false;
                }
            }
        }
        return false;
    }

    /**
     * Ensures the child object is fully visible in the scrollable container
     *
     * Current implementation may actually scroll the item's edges off screen
     * Current implementation does not check if the item can fully fit into the display area
     *
     * @param childSelector
     * @return
     * @throws UiObjectNotFoundException
     * @hide
     */
    public boolean ensureFullyVisible(UiObject childObject) throws UiObjectNotFoundException {
        Rect actual = childObject.getBounds();
        Rect visible = childObject.getVisibleBounds();
        if (visible.width() * visible.height() == actual.width() * actual.height()) {
            // area match, item fully visible
            return true;
        }
        boolean shouldSwipeForward = false;
        if (mIsVerticalList) {
            // if list is vertical, matching top edge implies obscured bottom edge
            // so we need to scroll list forward
            shouldSwipeForward = actual.top == visible.top;
        } else {
            // if list is horizontal, matching left edge implies obscured right edge,
            // so we need to scroll list forward
            shouldSwipeForward = actual.left == visible.left;
        }
        if (mIsVerticalList) {
            if (shouldSwipeForward) {
                return swipeUp(10);
            } else {
                return swipeDown(10);
            }
        } else {
            if (shouldSwipeForward) {
                return swipeLeft(10);
            } else {
                return swipeRight(10);
            }
        }
    }

    /**
     * Performs a swipe up on the UI element until the requested text is visible
     * or until swipe attempts have been exhausted. See {@link #setMaxSearchSwipes(int)}
     *
     * @param text to look for
     * @return true if item us found else false
     * @since API Level 16
     */
    public boolean scrollTextIntoView(String text) throws UiObjectNotFoundException {
        Tracer.trace(text);
        return scrollIntoView(new UiSelector().text(text));
    }

    /**
     * {@link #getChildByDescription(UiSelector, String)} and
     * {@link #getChildByText(UiSelector, String)} use an arguments that specifies if scrolling is
     * allowed while searching for the UI element.  The number of scrolls allowed to perform a
     * search can be modified by this method.  The current value can be read by calling
     * {@link #getMaxSearchSwipes()}
     *
     * @param swipes is the number of search swipes until abort
     * @return reference to itself
     * @since API Level 16
     */
    public UiScrollable setMaxSearchSwipes(int swipes) {
        Tracer.trace(swipes);
        mMaxSearchSwipes = swipes;
        return this;
    }

    /**
     * {@link #getChildByDescription(UiSelector, String)} and
     * {@link #getChildByText(UiSelector, String)} use an arguments that specifies if scrolling is
     * allowed while searching for the UI element.  The number of scrolls currently allowed to
     * perform a search can be read by this method.
     * See {@link #setMaxSearchSwipes(int)}
     *
     * @return max value of the number of swipes currently allowed during a scroll search
     * @since API Level 16
     */
    public int getMaxSearchSwipes() {
        Tracer.trace();
        return mMaxSearchSwipes;
    }

    /**
     * A convenience version of {@link UiScrollable#scrollForward(int)}, performs a fling
     *
     * @return true if scrolled and false if can't scroll anymore
     * @since API Level 16
     */
    public boolean flingForward() throws UiObjectNotFoundException {
        Tracer.trace();
        return scrollForward(FLING_STEPS);
    }

    /**
     * A convenience version of {@link UiScrollable#scrollForward(int)}, performs a regular scroll
     *
     * @return true if scrolled and false if can't scroll anymore
     * @since API Level 16
     */
    public boolean scrollForward() throws UiObjectNotFoundException {
        Tracer.trace();
        return scrollForward(SCROLL_STEPS);
    }

    /**
     * Perform a scroll forward. If this list is set to vertical (see {@link #setAsVerticalList()}
     * default) then the swipes will be executed from the bottom to top. If this list is set
     * to horizontal (see {@link #setAsHorizontalList()}) then the swipes will be executed from
     * the right to left. Caution is required on devices configured with right to left languages
     * like Arabic and Hebrew.
     *
     * @param steps use steps to control the speed, so that it may be a scroll, or fling
     * @return true if scrolled and false if can't scroll anymore
     * @since API Level 16
     */
    public boolean scrollForward(int steps) throws UiObjectNotFoundException {
        Tracer.trace(steps);
        Log.d(LOG_TAG, "scrollForward() on selector = " + getSelector());
        AccessibilityNodeInfo node = findAccessibilityNodeInfo(WAIT_FOR_SELECTOR_TIMEOUT);
        if(node == null) {
            throw new UiObjectNotFoundException(getSelector().toString());
        }
        Rect rect = new Rect();
        node.getBoundsInScreen(rect);

        int downX = 0;
        int downY = 0;
        int upX = 0;
        int upY = 0;

        // scrolling is by default assumed vertically unless the object is explicitly
        // set otherwise by setAsHorizontalContainer()
        if(mIsVerticalList) {
            int swipeAreaAdjust = (int)(rect.height() * getSwipeDeadZonePercentage());
            // scroll vertically: swipe down -> up
            downX = rect.centerX();
            downY = rect.bottom - swipeAreaAdjust;
            upX = rect.centerX();
            upY = rect.top + swipeAreaAdjust;
        } else {
            int swipeAreaAdjust = (int)(rect.width() * getSwipeDeadZonePercentage());
            // scroll horizontally: swipe right -> left
            // TODO: Assuming device is not in right to left language
            downX = rect.right - swipeAreaAdjust;
            downY = rect.centerY();
            upX = rect.left + swipeAreaAdjust;
            upY = rect.centerY();
        }
        return getInteractionController().scrollSwipe(downX, downY, upX, upY, steps);
    }

    /**
     * See {@link UiScrollable#scrollBackward(int)}
     *
     * @return true if scrolled and false if can't scroll anymore
     * @since API Level 16
     */
    public boolean flingBackward() throws UiObjectNotFoundException {
        Tracer.trace();
        return scrollBackward(FLING_STEPS);
    }

    /**
     * See {@link UiScrollable#scrollBackward(int)}
     *
     * @return true if scrolled and false if can't scroll anymore
     * @since API Level 16
     */
    public boolean scrollBackward() throws UiObjectNotFoundException {
        Tracer.trace();
        return scrollBackward(SCROLL_STEPS);
    }

    /**
     * Perform a scroll backward. If this list is set to vertical (see {@link #setAsVerticalList()}
     * default) then the swipes will be executed from the top to bottom. If this list is set
     * to horizontal (see {@link #setAsHorizontalList()}) then the swipes will be executed from
     * the left to right. Caution is required on devices configured with right to left languages
     * like Arabic and Hebrew.
     *
     * @param steps use steps to control the speed, so that it may be a scroll, or fling
     * @return true if scrolled and false if can't scroll anymore
     * @since API Level 16
     */
    public boolean scrollBackward(int steps) throws UiObjectNotFoundException {
        Tracer.trace(steps);
        Log.d(LOG_TAG, "scrollBackward() on selector = " + getSelector());
        AccessibilityNodeInfo node = findAccessibilityNodeInfo(WAIT_FOR_SELECTOR_TIMEOUT);
        if (node == null) {
            throw new UiObjectNotFoundException(getSelector().toString());
        }
        Rect rect = new Rect();
        node.getBoundsInScreen(rect);

        int downX = 0;
        int downY = 0;
        int upX = 0;
        int upY = 0;

        // scrolling is by default assumed vertically unless the object is explicitly
        // set otherwise by setAsHorizontalContainer()
        if(mIsVerticalList) {
            int swipeAreaAdjust = (int)(rect.height() * getSwipeDeadZonePercentage());
            Log.d(LOG_TAG, "scrollToBegining() using vertical scroll");
            // scroll vertically: swipe up -> down
            downX = rect.centerX();
            downY = rect.top + swipeAreaAdjust;
            upX = rect.centerX();
            upY = rect.bottom - swipeAreaAdjust;
        } else {
            int swipeAreaAdjust = (int)(rect.width() * getSwipeDeadZonePercentage());
            Log.d(LOG_TAG, "scrollToBegining() using hotizontal scroll");
            // scroll horizontally: swipe left -> right
            // TODO: Assuming device is not in right to left language
            downX = rect.left + swipeAreaAdjust;
            downY = rect.centerY();
            upX = rect.right - swipeAreaAdjust;
            upY = rect.centerY();
        }
        return getInteractionController().scrollSwipe(downX, downY, upX, upY, steps);
    }

    /**
     * Scrolls to the beginning of a scrollable UI element. The beginning could be the top most
     * in case of vertical lists or the left most in case of horizontal lists. Caution is required
     * on devices configured with right to left languages like Arabic and Hebrew.
     *
     * @param steps use steps to control the speed, so that it may be a scroll, or fling
     * @return true on scrolled else false
     * @since API Level 16
     */
    public boolean scrollToBeginning(int maxSwipes, int steps) throws UiObjectNotFoundException {
        Tracer.trace(maxSwipes, steps);
        Log.d(LOG_TAG, "scrollToBeginning() on selector = " + getSelector());
        // protect against potential hanging and return after preset attempts
        for(int x = 0; x < maxSwipes; x++) {
            if(!scrollBackward(steps)) {
                break;
            }
        }
        return true;
    }

    /**
     * See {@link UiScrollable#scrollToBeginning(int, int)}
     *
     * @param maxSwipes
     * @return true on scrolled else false
     * @since API Level 16
     */
    public boolean scrollToBeginning(int maxSwipes) throws UiObjectNotFoundException {
        Tracer.trace(maxSwipes);
        return scrollToBeginning(maxSwipes, SCROLL_STEPS);
    }

    /**
     * See {@link UiScrollable#scrollToBeginning(int, int)}
     *
     * @param maxSwipes
     * @return true on scrolled else false
     * @since API Level 16
     */
    public boolean flingToBeginning(int maxSwipes) throws UiObjectNotFoundException {
        Tracer.trace(maxSwipes);
        return scrollToBeginning(maxSwipes, FLING_STEPS);
    }

    /**
     * Scrolls to the end of a scrollable UI element. The end could be the bottom most
     * in case of vertical controls or the right most for horizontal controls. Caution
     * is required on devices configured with right to left languages like Arabic and Hebrew.
     *
     * @param steps use steps to control the speed, so that it may be a scroll, or fling
     * @return true on scrolled else false
     * @since API Level 16
     */
    public boolean scrollToEnd(int maxSwipes, int steps) throws UiObjectNotFoundException {
        Tracer.trace(maxSwipes, steps);
        // protect against potential hanging and return after preset attempts
        for(int x = 0; x < maxSwipes; x++) {
            if(!scrollForward(steps)) {
                break;
            }
        }
        return true;
    }

    /**
     * See {@link UiScrollable#scrollToEnd(int, int)}
     *
     * @param maxSwipes
     * @return true on scrolled else false
     * @since API Level 16
     */
    public boolean scrollToEnd(int maxSwipes) throws UiObjectNotFoundException {
        Tracer.trace(maxSwipes);
        return scrollToEnd(maxSwipes, SCROLL_STEPS);
    }

    /**
     * See {@link UiScrollable#scrollToEnd(int, int)}
     *
     * @param maxSwipes
     * @return true on scrolled else false
     * @since API Level 16
     */
    public boolean flingToEnd(int maxSwipes) throws UiObjectNotFoundException {
        Tracer.trace(maxSwipes);
        return scrollToEnd(maxSwipes, FLING_STEPS);
    }

    /**
     * Returns the percentage of a widget's size that's considered as no touch zone when swiping
     *
     * Dead zones are set as percentage of a widget's total width or height where
     * swipe start point cannot start or swipe end point cannot end. It is like a margin
     * around the actual dimensions of the widget. Swipes will always be start and
     * end inside this margin.
     *
     * This is important when the widget being swiped may not respond to the swipe if
     * started at a point too near to the edge. The default is 10% from either edge.
     *
     * @return a value between 0 and 1
     * @since API Level 16
     */
    public double getSwipeDeadZonePercentage() {
        Tracer.trace();
        return mSwipeDeadZonePercentage;
    }

    /**
     * Sets the percentage of a widget's size that's considered as no touch zone when swiping
     *
     * Dead zones are set as percentage of a widget's total width or height where
     * swipe start point cannot start or swipe end point cannot end. It is like a margin
     * around the actual dimensions of the widget. Swipes will always start and
     * end inside this margin.
     *
     * This is important when the widget being swiped may not respond to the swipe if
     * started at a point too near to the edge. The default is 10% from either edge
     *
     * @param swipeDeadZonePercentage is a value between 0 and 1
     * @return reference to itself
     * @since API Level 16
     */
    public UiScrollable setSwipeDeadZonePercentage(double swipeDeadZonePercentage) {
        Tracer.trace(swipeDeadZonePercentage);
        mSwipeDeadZonePercentage = swipeDeadZonePercentage;
        return this;
    }
}