Limit resizing to within the stable bounds

Resizing into the navbar area caused the task's bottom resize
handles to be unaccesible for new drag-resize interactions because
the touch/drag would be stolen by the system gesture detector to
swipe up.
This change disallows the task to be resized into the gesture area
in the first place, so that there's no overlap between the task's
edges and the gesture region.

Note that it is still possible to run into this overlap if the task
is moved, not resized, into the gesture area. Whether the task
should be forbidden from moving there (and offscreen), or if the
gesture should add the task edges as 'exclusion' regions is TBD.

Bug: 269659818
Test: atest WMShellUnitTests
Change-Id: I2dfe037062dad46db93e0e54c94e0cfdafa76bf6

libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskPositioner.java

@@ -40,6 +40,7 @@ class TaskPositioner implements DragPositioningCallback {
     private final DisplayController mDisplayController;
     private final WindowDecoration mWindowDecoration;
 
+    private final Rect mTempBounds = new Rect();
     private final Rect mTaskBoundsAtDragStart = new Rect();
     private final PointF mRepositionStartPoint = new PointF();
     private final Rect mRepositionTaskBounds = new Rect();
@@ -117,17 +118,32 @@ class TaskPositioner implements DragPositioningCallback {
         final float deltaX = x - mRepositionStartPoint.x;
         final float deltaY = y - mRepositionStartPoint.y;
         mRepositionTaskBounds.set(mTaskBoundsAtDragStart);
+
+        final Rect stableBounds = mTempBounds;
+        // Make sure the new resizing destination in any direction falls within the stable bounds.
+        // If not, set the bounds back to the old location that was valid to avoid conflicts with
+        // some regions such as the gesture area.
+        mDisplayController.getDisplayLayout(mWindowDecoration.mDisplay.getDisplayId())
+                .getStableBounds(stableBounds);
         if ((mCtrlType & CTRL_TYPE_LEFT) != 0) {
-            mRepositionTaskBounds.left += deltaX;
+            final int candidateLeft = mRepositionTaskBounds.left + (int) deltaX;
+            mRepositionTaskBounds.left = (candidateLeft > stableBounds.left)
+                    ? candidateLeft : oldLeft;
         }
         if ((mCtrlType & CTRL_TYPE_RIGHT) != 0) {
-            mRepositionTaskBounds.right += deltaX;
+            final int candidateRight = mRepositionTaskBounds.right + (int) deltaX;
+            mRepositionTaskBounds.right = (candidateRight < stableBounds.right)
+                    ? candidateRight : oldRight;
         }
         if ((mCtrlType & CTRL_TYPE_TOP) != 0) {
-            mRepositionTaskBounds.top += deltaY;
+            final int candidateTop = mRepositionTaskBounds.top + (int) deltaY;
+            mRepositionTaskBounds.top = (candidateTop > stableBounds.top)
+                    ? candidateTop : oldTop;
         }
         if ((mCtrlType & CTRL_TYPE_BOTTOM) != 0) {
-            mRepositionTaskBounds.bottom += deltaY;
+            final int candidateBottom = mRepositionTaskBounds.bottom + (int) deltaY;
+            mRepositionTaskBounds.bottom = (candidateBottom < stableBounds.bottom)
+                    ? candidateBottom : oldBottom;
         }
         if (mCtrlType == CTRL_TYPE_UNDEFINED) {
             mRepositionTaskBounds.offset((int) deltaX, (int) deltaY);

libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/TaskPositionerTest.kt

@@ -5,13 +5,16 @@ import android.app.WindowConfiguration
 import android.graphics.Rect
 import android.os.IBinder
 import android.testing.AndroidTestingRunner
+import android.view.Display
 import android.window.WindowContainerToken
+import android.window.WindowContainerTransaction
 import android.window.WindowContainerTransaction.Change.CHANGE_DRAG_RESIZING
 import androidx.test.filters.SmallTest
 import com.android.wm.shell.common.DisplayController
 import com.android.wm.shell.common.DisplayLayout
 import com.android.wm.shell.ShellTaskOrganizer
 import com.android.wm.shell.ShellTestCase
+import com.android.wm.shell.windowdecor.TaskPositioner.CTRL_TYPE_BOTTOM
 import com.android.wm.shell.windowdecor.TaskPositioner.CTRL_TYPE_RIGHT
 import com.android.wm.shell.windowdecor.TaskPositioner.CTRL_TYPE_TOP
 import com.android.wm.shell.windowdecor.TaskPositioner.CTRL_TYPE_UNDEFINED
@@ -19,10 +22,11 @@ import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.mockito.Mock
+import org.mockito.Mockito.`when`
+import org.mockito.Mockito.any
 import org.mockito.Mockito.argThat
 import org.mockito.Mockito.never
 import org.mockito.Mockito.verify
-import org.mockito.Mockito.`when`
 import org.mockito.MockitoAnnotations
 
 /**
@@ -51,6 +55,8 @@ class TaskPositionerTest : ShellTestCase() {
     private lateinit var mockDisplayController: DisplayController
     @Mock
     private lateinit var mockDisplayLayout: DisplayLayout
+    @Mock
+    private lateinit var mockDisplay: Display
 
     private lateinit var taskPositioner: TaskPositioner
 
@@ -68,6 +74,9 @@ class TaskPositionerTest : ShellTestCase() {
         `when`(taskToken.asBinder()).thenReturn(taskBinder)
         `when`(mockDisplayController.getDisplayLayout(DISPLAY_ID)).thenReturn(mockDisplayLayout)
         `when`(mockDisplayLayout.densityDpi()).thenReturn(DENSITY_DPI)
+        `when`(mockDisplayLayout.getStableBounds(any())).thenAnswer { i ->
+            (i.arguments.first() as Rect).set(STABLE_BOUNDS)
+        }
 
         mockWindowDecoration.mTaskInfo = ActivityManager.RunningTaskInfo().apply {
             taskId = TASK_ID
@@ -78,6 +87,8 @@ class TaskPositionerTest : ShellTestCase() {
             displayId = DISPLAY_ID
             configuration.windowConfiguration.bounds = STARTING_BOUNDS
         }
+        mockWindowDecoration.mDisplay = mockDisplay
+        `when`(mockDisplay.displayId).thenAnswer { DISPLAY_ID }
     }
 
     @Test
@@ -451,6 +462,72 @@ class TaskPositionerTest : ShellTestCase() {
         })
     }
 
+    fun testDragResize_toDisallowedBounds_freezesAtLimit() {
+        taskPositioner.onDragPositioningStart(
+                CTRL_TYPE_RIGHT or CTRL_TYPE_BOTTOM, // Resize right-bottom corner
+                STARTING_BOUNDS.right.toFloat(),
+                STARTING_BOUNDS.bottom.toFloat()
+        )
+
+        // Resize the task by 10px to the right and bottom, a valid destination
+        val newBounds = Rect(
+                STARTING_BOUNDS.left,
+                STARTING_BOUNDS.top,
+                STARTING_BOUNDS.right + 10,
+                STARTING_BOUNDS.bottom + 10)
+        taskPositioner.onDragPositioningMove(
+                newBounds.right.toFloat(),
+                newBounds.bottom.toFloat()
+        )
+
+        // Resize the task by another 10px to the right (allowed) and to just in the disallowed
+        // area of the Y coordinate.
+        val newBounds2 = Rect(
+                newBounds.left,
+                newBounds.top,
+                newBounds.right + 10,
+                DISALLOWED_RESIZE_AREA.top
+        )
+        taskPositioner.onDragPositioningMove(
+                newBounds2.right.toFloat(),
+                newBounds2.bottom.toFloat()
+        )
+
+        taskPositioner.onDragPositioningEnd(newBounds2.right.toFloat(), newBounds2.bottom.toFloat())
+
+        // The first resize falls in the allowed area, verify there's a change for it.
+        verify(mockShellTaskOrganizer).applyTransaction(argThat { wct ->
+            return@argThat wct.changes.any { (token, change) ->
+                token == taskBinder && change.ofBounds(newBounds)
+            }
+        })
+        // The second resize falls in the disallowed area, verify there's no change for it.
+        verify(mockShellTaskOrganizer, never()).applyTransaction(argThat { wct ->
+            return@argThat wct.changes.any { (token, change) ->
+                token == taskBinder && change.ofBounds(newBounds2)
+            }
+        })
+        // Instead, there should be a change for its allowed portion (the X movement) with the Y
+        // staying frozen in the last valid resize position.
+        verify(mockShellTaskOrganizer).applyTransaction(argThat { wct ->
+            return@argThat wct.changes.any { (token, change) ->
+                token == taskBinder && change.ofBounds(
+                        Rect(
+                                newBounds2.left,
+                                newBounds2.top,
+                                newBounds2.right,
+                                newBounds.bottom // Stayed at the first resize destination.
+                        )
+                )
+            }
+        })
+    }
+
+    private fun WindowContainerTransaction.Change.ofBounds(bounds: Rect): Boolean {
+        return ((windowSetMask and WindowConfiguration.WINDOW_CONFIG_BOUNDS) != 0) &&
+                bounds == configuration.windowConfiguration.bounds
+    }
+
     companion object {
         private const val TASK_ID = 5
         private const val MIN_WIDTH = 10
@@ -458,6 +535,19 @@ class TaskPositionerTest : ShellTestCase() {
         private const val DENSITY_DPI = 20
         private const val DEFAULT_MIN = 40
         private const val DISPLAY_ID = 1
+        private const val NAVBAR_HEIGHT = 50
+        private val DISPLAY_BOUNDS = Rect(0, 0, 2400, 1600)
         private val STARTING_BOUNDS = Rect(0, 0, 100, 100)
+        private val DISALLOWED_RESIZE_AREA = Rect(
+                DISPLAY_BOUNDS.left,
+                DISPLAY_BOUNDS.bottom - NAVBAR_HEIGHT,
+                DISPLAY_BOUNDS.right,
+                DISPLAY_BOUNDS.bottom)
+        private val STABLE_BOUNDS = Rect(
+                DISPLAY_BOUNDS.left,
+                DISPLAY_BOUNDS.top,
+                DISPLAY_BOUNDS.right,
+                DISPLAY_BOUNDS.bottom - NAVBAR_HEIGHT
+        )
     }
 }