Track window position with task position.

Windows were previously ordered by TaskStack/ActivityStack order. This
change provides a data structure in DisplayContent that tracks task
movement. Previously Recents and Home activity windows were always
adjacent because they were on the same stack. With this change windows
from other activities can be placed between the two.

Fixes bug 11338594.

Change-Id: Ie34443ff22f330d015141d97db79370c54920d28

services/java/com/android/server/wm/DisplayContent.java

@@ -107,7 +107,7 @@ class DisplayContent {
     Region mTouchExcludeRegion = new Region();
 
     /** Save allocating when retrieving tasks */
-    ArrayList<Task> mTmpTasks = new ArrayList<Task>();
+    ArrayList<Task> mTaskHistory = new ArrayList<Task>();
 
     /** Save allocating when calculating rects */
     Rect mTmpRect = new Rect();
@@ -163,7 +163,7 @@ class DisplayContent {
     void moveStack(TaskStack stack, boolean toTop) {
         mStackHistory.remove(stack);
         mStackHistory.add(toTop ? mStackHistory.size() : 0, stack);
-        mService.moveStackWindowsLocked(stack);
+        mService.moveStackWindowsLocked(this);
     }
 
     public boolean isPrivate() {
@@ -175,14 +175,35 @@ class DisplayContent {
      * @return All the Tasks, in order, on this display.
      */
     ArrayList<Task> getTasks() {
-        mTmpTasks.clear();
-        final int numStacks = mStackHistory.size();
-        for (int stackNdx = 0; stackNdx < numStacks; ++stackNdx) {
-            mTmpTasks.addAll(mStackHistory.get(stackNdx).getTasks());
+        return mTaskHistory;
+    }
+
+    void addTask(Task task, boolean toTop) {
+        mTaskHistory.remove(task);
+
+        final int userId = task.mUserId;
+        int taskNdx;
+        final int numTasks = mTaskHistory.size();
+        if (toTop) {
+            for (taskNdx = numTasks - 1; taskNdx >= 0; --taskNdx) {
+                if (mTaskHistory.get(taskNdx).mUserId == userId) {
+                    break;
+                }
+            }
+            ++taskNdx;
+        } else {
+            for (taskNdx = 0; taskNdx < numTasks; ++taskNdx) {
+                if (mTaskHistory.get(taskNdx).mUserId == userId) {
+                    break;
+                }
+            }
         }
-        if (WindowManagerService.DEBUG_LAYERS) Slog.i(TAG, "getTasks: mStackHistory=" +
-                mStackHistory);
-        return mTmpTasks;
+
+        mTaskHistory.add(taskNdx, task);
+    }
+
+    void removeTask(Task task) {
+        mTaskHistory.remove(task);
     }
 
     TaskStack getHomeStack() {
@@ -205,10 +226,9 @@ class DisplayContent {
 
     /** @return The number of tokens in all of the Tasks on this display. */
     int numTokens() {
-        getTasks();
         int count = 0;
-        for (int taskNdx = mTmpTasks.size() - 1; taskNdx >= 0; --taskNdx) {
-            count += mTmpTasks.get(taskNdx).mAppTokens.size();
+        for (int taskNdx = mTaskHistory.size() - 1; taskNdx >= 0; --taskNdx) {
+            count += mTaskHistory.get(taskNdx).mAppTokens.size();
         }
         return count;
     }
@@ -469,8 +489,8 @@ class DisplayContent {
             pw.println();
             pw.println("  Application tokens in Z order:");
             getTasks();
-            for (int taskNdx = mTmpTasks.size() - 1; taskNdx >= 0; --taskNdx) {
-                AppTokenList tokens = mTmpTasks.get(taskNdx).mAppTokens;
+            for (int taskNdx = mTaskHistory.size() - 1; taskNdx >= 0; --taskNdx) {
+                AppTokenList tokens = mTaskHistory.get(taskNdx).mAppTokens;
                 for (int tokenNdx = tokens.size() - 1; tokenNdx >= 0; --tokenNdx) {
                     final AppWindowToken wtoken = tokens.get(tokenNdx);
                     pw.print("  App #"); pw.print(ndx--);

services/java/com/android/server/wm/TaskStack.java

@@ -120,6 +120,7 @@ public class TaskStack {
         mTasks.add(stackNdx, task);
 
         task.mStack = this;
+        mDisplayContent.addTask(task, toTop);
         return mDisplayContent.moveHomeStackBox(mStackId == HOME_STACK_ID);
     }
 
@@ -145,6 +146,7 @@ public class TaskStack {
         if (DEBUG_TASK_MOVEMENT) Slog.d(TAG, "removeTask: task=" + task);
         mStackBox.makeDirty();
         mTasks.remove(task);
+        mDisplayContent.removeTask(task);
     }
 
     int remove() {

services/java/com/android/server/wm/WindowManagerService.java

@@ -4733,11 +4733,9 @@ public class WindowManagerService extends IWindowManager.Stub
         return index;
     }
 
-    void moveStackWindowsLocked(TaskStack stack) {
-        DisplayContent displayContent = stack.getDisplayContent();
-
+    void moveStackWindowsLocked(DisplayContent displayContent) {
         // First remove all of the windows from the list.
-        final ArrayList<Task> tasks = stack.getTasks();
+        final ArrayList<Task> tasks = displayContent.getTasks();
         final int numTasks = tasks.size();
         for (int taskNdx = 0; taskNdx < numTasks; ++taskNdx) {
             AppTokenList tokens = tasks.get(taskNdx).mAppTokens;
@@ -4813,7 +4811,7 @@ public class WindowManagerService extends IWindowManager.Stub
                 }
                 final TaskStack stack = task.mStack;
                 stack.moveTaskToBottom(task);
-                moveStackWindowsLocked(stack);
+                moveStackWindowsLocked(stack.getDisplayContent());
             }
         } finally {
             Binder.restoreCallingIdentity(origId);