DisplayContent.java revision b15758ab7a6481717d0d29612e870d7241061c31
1/*
2 * Copyright (C) 2012 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 com.android.server.wm;
18
19import static android.app.ActivityManager.StackId.DOCKED_STACK_ID;
20import static android.app.ActivityManager.StackId.HOME_STACK_ID;
21import static android.app.ActivityManager.StackId.PINNED_STACK_ID;
22import static com.android.server.wm.WindowManagerService.DEBUG_VISIBILITY;
23import static com.android.server.wm.WindowManagerService.TAG;
24import static com.android.server.wm.WindowState.RESIZE_HANDLE_WIDTH_IN_DP;
25
26import android.app.ActivityManager.StackId;
27import android.graphics.Rect;
28import android.graphics.Region;
29import android.util.DisplayMetrics;
30import android.util.Slog;
31import android.view.Display;
32import android.view.DisplayInfo;
33import android.view.Surface;
34
35import java.io.PrintWriter;
36import java.util.ArrayList;
37
38class DisplayContentList extends ArrayList<DisplayContent> {
39}
40
41/**
42 * Utility class for keeping track of the WindowStates and other pertinent contents of a
43 * particular Display.
44 *
45 * IMPORTANT: No method from this class should ever be used without holding
46 * WindowManagerService.mWindowMap.
47 */
48class DisplayContent {
49
50    /** Unique identifier of this stack. */
51    private final int mDisplayId;
52
53    /** Z-ordered (bottom-most first) list of all Window objects. Assigned to an element
54     * from mDisplayWindows; */
55    private final WindowList mWindows = new WindowList();
56
57    int mInitialDisplayWidth = 0;
58    int mInitialDisplayHeight = 0;
59    int mInitialDisplayDensity = 0;
60    int mBaseDisplayWidth = 0;
61    int mBaseDisplayHeight = 0;
62    int mBaseDisplayDensity = 0;
63    boolean mDisplayScalingDisabled;
64    private final DisplayInfo mDisplayInfo = new DisplayInfo();
65    private final Display mDisplay;
66    private final DisplayMetrics mDisplayMetrics = new DisplayMetrics();
67
68    Rect mBaseDisplayRect = new Rect();
69    Rect mContentRect = new Rect();
70
71    // Accessed directly by all users.
72    boolean layoutNeeded;
73    int pendingLayoutChanges;
74    final boolean isDefaultDisplay;
75
76    /** Window tokens that are in the process of exiting, but still on screen for animations. */
77    final ArrayList<WindowToken> mExitingTokens = new ArrayList<>();
78
79    /** Array containing all TaskStacks on this display.  Array
80     * is stored in display order with the current bottom stack at 0. */
81    private final ArrayList<TaskStack> mStacks = new ArrayList<>();
82
83    /** A special TaskStack with id==HOME_STACK_ID that moves to the bottom whenever any TaskStack
84     * (except a future lockscreen TaskStack) moves to the top. */
85    private TaskStack mHomeStack = null;
86
87    /** Detect user tapping outside of current focused task bounds .*/
88    TaskTapPointerEventListener mTapDetector;
89
90    /** Detect user tapping outside of current focused stack bounds .*/
91    Region mTouchExcludeRegion = new Region();
92
93    /** Detect user tapping in a non-resizeable task in docked or fullscreen stack .*/
94    Region mNonResizeableRegion = new Region();
95
96    /** Save allocating when calculating rects */
97    private Rect mTmpRect = new Rect();
98    private Rect mTmpRect2 = new Rect();
99
100    /** For gathering Task objects in order. */
101    final ArrayList<Task> mTmpTaskHistory = new ArrayList<Task>();
102
103    final WindowManagerService mService;
104
105    /** Remove this display when animation on it has completed. */
106    boolean mDeferredRemoval;
107
108    final DockedStackDividerController mDividerControllerLocked;
109
110    final DimLayerController mDimLayerController;
111
112    /**
113     * @param display May not be null.
114     * @param service You know.
115     */
116    DisplayContent(Display display, WindowManagerService service) {
117        mDisplay = display;
118        mDisplayId = display.getDisplayId();
119        display.getDisplayInfo(mDisplayInfo);
120        display.getMetrics(mDisplayMetrics);
121        isDefaultDisplay = mDisplayId == Display.DEFAULT_DISPLAY;
122        mService = service;
123        initializeDisplayBaseInfo();
124        mDividerControllerLocked = new DockedStackDividerController(service.mContext, this);
125        mDimLayerController = new DimLayerController(this);
126    }
127
128    int getDisplayId() {
129        return mDisplayId;
130    }
131
132    WindowList getWindowList() {
133        return mWindows;
134    }
135
136    Display getDisplay() {
137        return mDisplay;
138    }
139
140    DisplayInfo getDisplayInfo() {
141        return mDisplayInfo;
142    }
143
144    DisplayMetrics getDisplayMetrics() {
145        return mDisplayMetrics;
146    }
147
148    DockedStackDividerController getDockedDividerController() {
149        return mDividerControllerLocked;
150    }
151
152    /**
153     * Returns true if the specified UID has access to this display.
154     */
155    public boolean hasAccess(int uid) {
156        return mDisplay.hasAccess(uid);
157    }
158
159    public boolean isPrivate() {
160        return (mDisplay.getFlags() & Display.FLAG_PRIVATE) != 0;
161    }
162
163    ArrayList<TaskStack> getStacks() {
164        return mStacks;
165    }
166
167    /**
168     * Retrieve the tasks on this display in stack order from the bottommost TaskStack up.
169     * @return All the Tasks, in order, on this display.
170     */
171    ArrayList<Task> getTasks() {
172        mTmpTaskHistory.clear();
173        final int numStacks = mStacks.size();
174        for (int stackNdx = 0; stackNdx < numStacks; ++stackNdx) {
175            mTmpTaskHistory.addAll(mStacks.get(stackNdx).getTasks());
176        }
177        return mTmpTaskHistory;
178    }
179
180    TaskStack getHomeStack() {
181        if (mHomeStack == null && mDisplayId == Display.DEFAULT_DISPLAY) {
182            Slog.e(TAG, "getHomeStack: Returning null from this=" + this);
183        }
184        return mHomeStack;
185    }
186
187    void updateDisplayInfo() {
188        mDisplay.getDisplayInfo(mDisplayInfo);
189        mDisplay.getMetrics(mDisplayMetrics);
190        for (int i = mStacks.size() - 1; i >= 0; --i) {
191            mStacks.get(i).updateDisplayInfo(null);
192        }
193    }
194
195    void initializeDisplayBaseInfo() {
196        // Bootstrap the default logical display from the display manager.
197        final DisplayInfo newDisplayInfo =
198                mService.mDisplayManagerInternal.getDisplayInfo(mDisplayId);
199        if (newDisplayInfo != null) {
200            mDisplayInfo.copyFrom(newDisplayInfo);
201        }
202        mBaseDisplayWidth = mInitialDisplayWidth = mDisplayInfo.logicalWidth;
203        mBaseDisplayHeight = mInitialDisplayHeight = mDisplayInfo.logicalHeight;
204        mBaseDisplayDensity = mInitialDisplayDensity = mDisplayInfo.logicalDensityDpi;
205        mBaseDisplayRect.set(0, 0, mBaseDisplayWidth, mBaseDisplayHeight);
206    }
207
208    void getLogicalDisplayRect(Rect out) {
209        // Uses same calculation as in LogicalDisplay#configureDisplayInTransactionLocked.
210        final int orientation = mDisplayInfo.rotation;
211        boolean rotated = (orientation == Surface.ROTATION_90
212                || orientation == Surface.ROTATION_270);
213        final int physWidth = rotated ? mBaseDisplayHeight : mBaseDisplayWidth;
214        final int physHeight = rotated ? mBaseDisplayWidth : mBaseDisplayHeight;
215        int width = mDisplayInfo.logicalWidth;
216        int left = (physWidth - width) / 2;
217        int height = mDisplayInfo.logicalHeight;
218        int top = (physHeight - height) / 2;
219        out.set(left, top, left + width, top + height);
220    }
221
222    /** Refer to {@link WindowManagerService#attachStack(int, int, boolean)} */
223    void attachStack(TaskStack stack, boolean onTop) {
224        if (stack.mStackId == HOME_STACK_ID) {
225            if (mHomeStack != null) {
226                throw new IllegalArgumentException("attachStack: HOME_STACK_ID (0) not first.");
227            }
228            mHomeStack = stack;
229        }
230        if (onTop) {
231            mStacks.add(stack);
232        } else {
233            mStacks.add(0, stack);
234        }
235        layoutNeeded = true;
236    }
237
238    void moveStack(TaskStack stack, boolean toTop) {
239        if (stack.mStackId == PINNED_STACK_ID && !toTop) {
240            // Pinned stack is always-on-top silly...
241            Slog.w(TAG, "Ignoring move of always-on-top stack=" + stack + " to bottom");
242            return;
243        }
244
245        if (!mStacks.remove(stack)) {
246            Slog.wtf(TAG, "moving stack that was not added: " + stack, new Throwable());
247        }
248
249        int addIndex = toTop ? mStacks.size() : 0;
250
251        if (toTop
252                && mService.isStackVisibleLocked(PINNED_STACK_ID)
253                && stack.mStackId != PINNED_STACK_ID) {
254            // The pinned stack is always the top most stack (always-on-top) when it is visible.
255            // So, stack is moved just below the pinned stack.
256            addIndex--;
257            TaskStack topStack = mStacks.get(addIndex);
258            if (topStack.mStackId != PINNED_STACK_ID) {
259                throw new IllegalStateException("Pinned stack isn't top stack??? " + mStacks);
260            }
261        }
262        mStacks.add(addIndex, stack);
263    }
264
265    void detachStack(TaskStack stack) {
266        mDimLayerController.removeDimLayerUser(stack);
267        mStacks.remove(stack);
268    }
269
270    /**
271     * Propagate the new bounds to all child stacks.
272     * @param contentRect The bounds to apply at the top level.
273     */
274    void resize(Rect contentRect) {
275        mContentRect.set(contentRect);
276    }
277
278    int taskIdFromPoint(int x, int y) {
279        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
280            TaskStack stack = mStacks.get(stackNdx);
281            stack.getBounds(mTmpRect);
282            if (!mTmpRect.contains(x, y)) {
283                continue;
284            }
285            final ArrayList<Task> tasks = stack.getTasks();
286            for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
287                final Task task = tasks.get(taskNdx);
288                final WindowState win = task.getTopVisibleAppMainWindow();
289                if (win == null) {
290                    continue;
291                }
292                // We need to use the task's dim bounds (which is derived from the visible
293                // bounds of its apps windows) for any touch-related tests. Can't use
294                // the task's original bounds because it might be adjusted to fit the
295                // content frame. For example, the presence of the IME adjusting the
296                // windows frames when the app window is the IME target.
297                task.getDimBounds(mTmpRect);
298                if (mTmpRect.contains(x, y)) {
299                    return task.mTaskId;
300                }
301            }
302        }
303        return -1;
304    }
305
306    /**
307     * Find the task whose outside touch area (for resizing) (x, y) falls within.
308     * Returns null if the touch doesn't fall into a resizing area.
309     */
310    Task findTaskForControlPoint(int x, int y) {
311        final int delta = mService.dipToPixel(RESIZE_HANDLE_WIDTH_IN_DP, mDisplayMetrics);
312        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
313            TaskStack stack = mStacks.get(stackNdx);
314            if (!StackId.isTaskResizeAllowed(stack.mStackId)) {
315                break;
316            }
317            final ArrayList<Task> tasks = stack.getTasks();
318            for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
319                final Task task = tasks.get(taskNdx);
320                if (task.isFullscreen()) {
321                    return null;
322                }
323
324                // We need to use the task's dim bounds (which is derived from the visible
325                // bounds of its apps windows) for any touch-related tests. Can't use
326                // the task's original bounds because it might be adjusted to fit the
327                // content frame. One example is when the task is put to top-left quadrant,
328                // the actual visible area would not start at (0,0) after it's adjusted
329                // for the status bar.
330                task.getDimBounds(mTmpRect);
331                mTmpRect.inset(-delta, -delta);
332                if (mTmpRect.contains(x, y)) {
333                    mTmpRect.inset(delta, delta);
334                    if (!mTmpRect.contains(x, y)) {
335                        return task;
336                    }
337                    // User touched inside the task. No need to look further,
338                    // focus transfer will be handled in ACTION_UP.
339                    return null;
340                }
341            }
342        }
343        return null;
344    }
345
346    void setTouchExcludeRegion(Task focusedTask) {
347        mTouchExcludeRegion.set(mBaseDisplayRect);
348        final int delta = mService.dipToPixel(RESIZE_HANDLE_WIDTH_IN_DP, mDisplayMetrics);
349        boolean addBackFocusedTask = false;
350        mNonResizeableRegion.setEmpty();
351        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
352            TaskStack stack = mStacks.get(stackNdx);
353            final ArrayList<Task> tasks = stack.getTasks();
354            for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
355                final Task task = tasks.get(taskNdx);
356                final WindowState win = task.getTopVisibleAppMainWindow();
357                if (win == null) {
358                    continue;
359                }
360
361                /**
362                 * Exclusion region is the region that TapDetector doesn't care about.
363                 * Here we want to remove all non-focused tasks from the exclusion region.
364                 * We also remove the outside touch area for resizing for all freeform
365                 * tasks (including the focused).
366                 *
367                 * (For freeform focused task, the below logic will first remove the enlarged
368                 * area, then add back the inner area.)
369                 */
370                final boolean isFreeformed = task.inFreeformWorkspace();
371                if (task != focusedTask || isFreeformed) {
372                    task.getDimBounds(mTmpRect);
373                    if (isFreeformed) {
374                        // If we're removing a freeform, focused app from the exclusion region,
375                        // we need to add back its touchable frame later. Remember the touchable
376                        // frame now.
377                        if (task == focusedTask) {
378                            addBackFocusedTask = true;
379                            mTmpRect2.set(mTmpRect);
380                        }
381                        // If the task is freeformed, enlarge the area to account for outside
382                        // touch area for resize.
383                        mTmpRect.inset(-delta, -delta);
384                        // Intersect with display content rect. If we have system decor (status bar/
385                        // navigation bar), we want to exclude that from the tap detection.
386                        // Otherwise, if the app is partially placed under some system button (eg.
387                        // Recents, Home), pressing that button would cause a full series of
388                        // unwanted transfer focus/resume/pause, before we could go home.
389                        mTmpRect.intersect(mContentRect);
390                    }
391                    mTouchExcludeRegion.op(mTmpRect, Region.Op.DIFFERENCE);
392                }
393                if (task.isDockedInEffect() && !task.isResizeable()) {
394                    stack.getBounds(mTmpRect);
395                    mNonResizeableRegion.op(mTmpRect, Region.Op.UNION);
396                    break;
397                }
398            }
399        }
400        // If we removed the focused task above, add it back and only leave its
401        // outside touch area in the exclusion. TapDectector is not interested in
402        // any touch inside the focused task itself.
403        if (addBackFocusedTask) {
404            mTouchExcludeRegion.op(mTmpRect2, Region.Op.UNION);
405        }
406        if (mTapDetector != null) {
407            mTapDetector.setTouchExcludeRegion(mTouchExcludeRegion, mNonResizeableRegion);
408        }
409    }
410
411    void switchUserStacks() {
412        final WindowList windows = getWindowList();
413        for (int i = 0; i < windows.size(); i++) {
414            final WindowState win = windows.get(i);
415            if (win.isHiddenFromUserLocked()) {
416                if (DEBUG_VISIBILITY) Slog.w(TAG, "user changing, hiding " + win
417                        + ", attrs=" + win.mAttrs.type + ", belonging to " + win.mOwnerUid);
418                win.hideLw(false);
419            }
420        }
421
422        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
423            mStacks.get(stackNdx).switchUser();
424        }
425    }
426
427    void resetAnimationBackgroundAnimator() {
428        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
429            mStacks.get(stackNdx).resetAnimationBackgroundAnimator();
430        }
431    }
432
433    boolean animateDimLayers() {
434        return mDimLayerController.animateDimLayers();
435    }
436
437    void resetDimming() {
438        mDimLayerController.resetDimming();
439    }
440
441    boolean isDimming() {
442        return mDimLayerController.isDimming();
443    }
444
445    void stopDimmingIfNeeded() {
446        mDimLayerController.stopDimmingIfNeeded();
447    }
448
449    void close() {
450        mDimLayerController.close();
451        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
452            mStacks.get(stackNdx).close();
453        }
454    }
455
456    boolean isAnimating() {
457        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
458            final TaskStack stack = mStacks.get(stackNdx);
459            if (stack.isAnimating()) {
460                return true;
461            }
462        }
463        return false;
464    }
465
466    void checkForDeferredActions() {
467        boolean animating = false;
468        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
469            final TaskStack stack = mStacks.get(stackNdx);
470            if (stack.isAnimating()) {
471                animating = true;
472            } else {
473                if (stack.mDeferDetach) {
474                    mService.detachStackLocked(this, stack);
475                }
476                final ArrayList<Task> tasks = stack.getTasks();
477                for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
478                    final Task task = tasks.get(taskNdx);
479                    AppTokenList tokens = task.mAppTokens;
480                    for (int tokenNdx = tokens.size() - 1; tokenNdx >= 0; --tokenNdx) {
481                        AppWindowToken wtoken = tokens.get(tokenNdx);
482                        if (wtoken.mIsExiting) {
483                            wtoken.removeAppFromTaskLocked();
484                        }
485                    }
486                }
487            }
488        }
489        if (!animating && mDeferredRemoval) {
490            mService.onDisplayRemoved(mDisplayId);
491        }
492    }
493
494    void rotateBounds(int oldRotation, int newRotation, Rect bounds) {
495        final int rotationDelta = DisplayContent.deltaRotation(oldRotation, newRotation);
496        getLogicalDisplayRect(mTmpRect);
497        switch (rotationDelta) {
498            case Surface.ROTATION_0:
499                mTmpRect2.set(bounds);
500                break;
501            case Surface.ROTATION_90:
502                mTmpRect2.top = mTmpRect.bottom - bounds.right;
503                mTmpRect2.left = bounds.top;
504                mTmpRect2.right = mTmpRect2.left + bounds.height();
505                mTmpRect2.bottom = mTmpRect2.top + bounds.width();
506                break;
507            case Surface.ROTATION_180:
508                mTmpRect2.top = mTmpRect.bottom - bounds.bottom;
509                mTmpRect2.left = mTmpRect.right - bounds.right;
510                mTmpRect2.right = mTmpRect2.left + bounds.width();
511                mTmpRect2.bottom = mTmpRect2.top + bounds.height();
512                break;
513            case Surface.ROTATION_270:
514                mTmpRect2.top = bounds.left;
515                mTmpRect2.left = mTmpRect.right - bounds.bottom;
516                mTmpRect2.right = mTmpRect2.left + bounds.height();
517                mTmpRect2.bottom = mTmpRect2.top + bounds.width();
518                break;
519        }
520        bounds.set(mTmpRect2);
521    }
522
523    static int deltaRotation(int oldRotation, int newRotation) {
524        int delta = newRotation - oldRotation;
525        if (delta < 0) delta += 4;
526        return delta;
527    }
528
529    public void dump(String prefix, PrintWriter pw) {
530        pw.print(prefix); pw.print("Display: mDisplayId="); pw.println(mDisplayId);
531        final String subPrefix = "  " + prefix;
532        pw.print(subPrefix); pw.print("init="); pw.print(mInitialDisplayWidth); pw.print("x");
533            pw.print(mInitialDisplayHeight); pw.print(" "); pw.print(mInitialDisplayDensity);
534            pw.print("dpi");
535            if (mInitialDisplayWidth != mBaseDisplayWidth
536                    || mInitialDisplayHeight != mBaseDisplayHeight
537                    || mInitialDisplayDensity != mBaseDisplayDensity) {
538                pw.print(" base=");
539                pw.print(mBaseDisplayWidth); pw.print("x"); pw.print(mBaseDisplayHeight);
540                pw.print(" "); pw.print(mBaseDisplayDensity); pw.print("dpi");
541            }
542            if (mDisplayScalingDisabled) {
543                pw.println(" noscale");
544            }
545            pw.print(" cur=");
546            pw.print(mDisplayInfo.logicalWidth);
547            pw.print("x"); pw.print(mDisplayInfo.logicalHeight);
548            pw.print(" app=");
549            pw.print(mDisplayInfo.appWidth);
550            pw.print("x"); pw.print(mDisplayInfo.appHeight);
551            pw.print(" rng="); pw.print(mDisplayInfo.smallestNominalAppWidth);
552            pw.print("x"); pw.print(mDisplayInfo.smallestNominalAppHeight);
553            pw.print("-"); pw.print(mDisplayInfo.largestNominalAppWidth);
554            pw.print("x"); pw.println(mDisplayInfo.largestNominalAppHeight);
555            pw.print(subPrefix); pw.print("deferred="); pw.print(mDeferredRemoval);
556                pw.print(" layoutNeeded="); pw.println(layoutNeeded);
557        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
558            final TaskStack stack = mStacks.get(stackNdx);
559            pw.print(prefix); pw.print("mStacks[" + stackNdx + "]"); pw.println(stack.mStackId);
560            stack.dump(prefix + "  ", pw);
561        }
562        pw.println();
563        pw.println("  Application tokens in top down Z order:");
564        int ndx = 0;
565        for (int stackNdx = mStacks.size() - 1; stackNdx >= 0; --stackNdx) {
566            final TaskStack stack = mStacks.get(stackNdx);
567            pw.print("  mStackId="); pw.println(stack.mStackId);
568            ArrayList<Task> tasks = stack.getTasks();
569            for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
570                final Task task = tasks.get(taskNdx);
571                pw.print("    mTaskId="); pw.println(task.mTaskId);
572                AppTokenList tokens = task.mAppTokens;
573                for (int tokenNdx = tokens.size() - 1; tokenNdx >= 0; --tokenNdx, ++ndx) {
574                    final AppWindowToken wtoken = tokens.get(tokenNdx);
575                    pw.print("    Activity #"); pw.print(tokenNdx);
576                            pw.print(' '); pw.print(wtoken); pw.println(":");
577                    wtoken.dump(pw, "      ");
578                }
579            }
580        }
581        if (ndx == 0) {
582            pw.println("    None");
583        }
584        pw.println();
585        if (!mExitingTokens.isEmpty()) {
586            pw.println();
587            pw.println("  Exiting tokens:");
588            for (int i=mExitingTokens.size()-1; i>=0; i--) {
589                WindowToken token = mExitingTokens.get(i);
590                pw.print("  Exiting #"); pw.print(i);
591                pw.print(' '); pw.print(token);
592                pw.println(':');
593                token.dump(pw, "    ");
594            }
595        }
596        pw.println();
597        mDimLayerController.dump(prefix + "  ", pw);
598    }
599
600    @Override
601    public String toString() {
602        return "Display " + mDisplayId + " info=" + mDisplayInfo + " stacks=" + mStacks;
603    }
604
605    TaskStack getDockedStackLocked() {
606        final TaskStack stack = mService.mStackIdToStack.get(DOCKED_STACK_ID);
607        return (stack != null && stack.isVisibleLocked()) ? stack : null;
608    }
609}
610