Create bubbles DropTargetManager

An initial version of DropTargetManager for dragging bubble objects.
Currently this only handles tracking the initial and the current
drag zones, as well as notifying users of drag zone changes.

Flag: EXEMPT not wired
Bug: 393173014
Test: atest DropTargetManager
Change-Id: Ia75a8f25c19d221d9e21433ccd23cea2a4cbbdcb

2 files changed, 269 insertions, 0 deletions

diff --git a/libs/WindowManager/Shell/shared/src/com/android/wm/shell/shared/bubbles/DropTargetManager.kt b/libs/WindowManager/Shell/shared/src/com/android/wm/shell/shared/bubbles/DropTargetManager.kt
new file mode 100644
index 000000000000..29ce8d90e66f
--- /dev/null
+++ b/libs/WindowManager/Shell/shared/src/com/android/wm/shell/shared/bubbles/DropTargetManager.kt
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2025 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.wm.shell.shared.bubbles
+
+/**
+ * Manages animating drop targets in response to dragging bubble icons or bubble expanded views
+ * across different drag zones.
+ */
+class DropTargetManager(
+    private val isLayoutRtl: Boolean,
+    private val dragZoneChangedListener: DragZoneChangedListener
+) {
+
+    private var state: DragState? = null
+
+    /** Must be called when a drag gesture is starting. */
+    fun onDragStarted(draggedObject: DraggedObject, dragZones: List<DragZone>) {
+        val state = DragState(dragZones, draggedObject)
+        dragZoneChangedListener.onInitialDragZoneSet(state.initialDragZone)
+        this.state = state
+    }
+
+    /** Called when the user drags to a new location. */
+    fun onDragUpdated(x: Int, y: Int) {
+        val state = state ?: return
+        val oldDragZone = state.currentDragZone
+        val newDragZone = state.getMatchingDragZone(x = x, y = y)
+        state.currentDragZone = newDragZone
+        if (oldDragZone != newDragZone) {
+            dragZoneChangedListener.onDragZoneChanged(from = oldDragZone, to = newDragZone)
+        }
+    }
+
+    /** Called when the drag ended. */
+    fun onDragEnded() {
+        state = null
+    }
+
+    /** Stores the current drag state. */
+    private inner class DragState(
+        private val dragZones: List<DragZone>,
+        draggedObject: DraggedObject
+    ) {
+        val initialDragZone =
+            if (draggedObject.initialLocation.isOnLeft(isLayoutRtl)) {
+                dragZones.filterIsInstance<DragZone.Bubble.Left>().first()
+            } else {
+                dragZones.filterIsInstance<DragZone.Bubble.Right>().first()
+            }
+        var currentDragZone: DragZone = initialDragZone
+
+        fun getMatchingDragZone(x: Int, y: Int): DragZone {
+            return dragZones.firstOrNull { it.contains(x, y) } ?: currentDragZone
+        }
+    }
+
+    /** An interface to be notified when drag zones change. */
+    interface DragZoneChangedListener {
+        /** An initial drag zone was set. Called when a drag starts. */
+        fun onInitialDragZoneSet(dragZone: DragZone)
+        /** Called when the object was dragged to a different drag zone. */
+        fun onDragZoneChanged(from: DragZone, to: DragZone)
+    }
+}
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/shared/bubbles/DropTargetManagerTest.kt b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/shared/bubbles/DropTargetManagerTest.kt
new file mode 100644
index 000000000000..efb91c5fbfda
--- /dev/null
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/shared/bubbles/DropTargetManagerTest.kt
@@ -0,0 +1,191 @@
+/*
+ * Copyright (C) 2025 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.wm.shell.shared.bubbles
+
+import android.graphics.Rect
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.filters.SmallTest
+import com.google.common.truth.Truth.assertThat
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import kotlin.test.assertFails
+
+/** Unit tests for [DropTargetManager]. */
+@SmallTest
+@RunWith(AndroidJUnit4::class)
+class DropTargetManagerTest {
+
+    private lateinit var dropTargetManager: DropTargetManager
+    private lateinit var dragZoneChangedListener: FakeDragZoneChangedListener
+    private val dropTarget = Rect(0, 0, 0, 0)
+
+    // create 3 drop zones that are horizontally next to each other
+    // -------------------------------------------------
+    // |               |               |               |
+    // |    bubble     |               |    bubble     |
+    // |               |    dismiss    |               |
+    // |     left      |               |     right     |
+    // |               |               |               |
+    // -------------------------------------------------
+    private val bubbleLeftDragZone =
+        DragZone.Bubble.Left(bounds = Rect(0, 0, 100, 100), dropTarget = dropTarget)
+    private val dismissDragZone = DragZone.Dismiss(bounds = Rect(100, 0, 200, 100))
+    private val bubbleRightDragZone =
+        DragZone.Bubble.Right(bounds = Rect(200, 0, 300, 100), dropTarget = dropTarget)
+
+    @Before
+    fun setUp() {
+        dragZoneChangedListener = FakeDragZoneChangedListener()
+        dropTargetManager = DropTargetManager(isLayoutRtl = false, dragZoneChangedListener)
+    }
+
+    @Test
+    fun onDragStarted_notifiesInitialDragZone() {
+        dropTargetManager.onDragStarted(
+            DraggedObject.Bubble(BubbleBarLocation.LEFT),
+            listOf(bubbleLeftDragZone, bubbleRightDragZone)
+        )
+        assertThat(dragZoneChangedListener.initialDragZone).isEqualTo(bubbleLeftDragZone)
+    }
+
+    @Test
+    fun onDragStarted_missingExpectedDragZone_fails() {
+        assertFails {
+            dropTargetManager.onDragStarted(
+                DraggedObject.Bubble(BubbleBarLocation.RIGHT),
+                listOf(bubbleLeftDragZone)
+            )
+        }
+    }
+
+    @Test
+    fun onDragUpdated_notifiesDragZoneChanged() {
+        dropTargetManager.onDragStarted(
+            DraggedObject.Bubble(BubbleBarLocation.LEFT),
+            listOf(bubbleLeftDragZone, bubbleRightDragZone, dismissDragZone)
+        )
+        dropTargetManager.onDragUpdated(
+            bubbleRightDragZone.bounds.centerX(),
+            bubbleRightDragZone.bounds.centerY()
+        )
+        assertThat(dragZoneChangedListener.fromDragZone).isEqualTo(bubbleLeftDragZone)
+        assertThat(dragZoneChangedListener.toDragZone).isEqualTo(bubbleRightDragZone)
+
+        dropTargetManager.onDragUpdated(
+            dismissDragZone.bounds.centerX(),
+            dismissDragZone.bounds.centerY()
+        )
+        assertThat(dragZoneChangedListener.fromDragZone).isEqualTo(bubbleRightDragZone)
+        assertThat(dragZoneChangedListener.toDragZone).isEqualTo(dismissDragZone)
+    }
+
+    @Test
+    fun onDragUpdated_withinSameZone_doesNotNotify() {
+        dropTargetManager.onDragStarted(
+            DraggedObject.Bubble(BubbleBarLocation.LEFT),
+            listOf(bubbleLeftDragZone, bubbleRightDragZone, dismissDragZone)
+        )
+        dropTargetManager.onDragUpdated(
+            bubbleLeftDragZone.bounds.centerX(),
+            bubbleLeftDragZone.bounds.centerY()
+        )
+        assertThat(dragZoneChangedListener.fromDragZone).isNull()
+        assertThat(dragZoneChangedListener.toDragZone).isNull()
+    }
+
+    @Test
+    fun onDragUpdated_outsideAllZones_doesNotNotify() {
+        dropTargetManager.onDragStarted(
+            DraggedObject.Bubble(BubbleBarLocation.LEFT),
+            listOf(bubbleLeftDragZone, bubbleRightDragZone)
+        )
+        val pointX = 200
+        val pointY = 200
+        assertThat(bubbleLeftDragZone.contains(pointX, pointY)).isFalse()
+        assertThat(bubbleRightDragZone.contains(pointX, pointY)).isFalse()
+        dropTargetManager.onDragUpdated(pointX, pointY)
+        assertThat(dragZoneChangedListener.fromDragZone).isNull()
+        assertThat(dragZoneChangedListener.toDragZone).isNull()
+    }
+
+    @Test
+    fun onDragUpdated_hasOverlappingZones_notifiesFirstDragZoneChanged() {
+        // create a drag zone that spans across the width of all 3 drag zones, but extends below
+        // them
+        val splitDragZone = DragZone.Split.Left(bounds = Rect(0, 0, 300, 200))
+        dropTargetManager.onDragStarted(
+            DraggedObject.Bubble(BubbleBarLocation.LEFT),
+            listOf(bubbleLeftDragZone, bubbleRightDragZone, dismissDragZone, splitDragZone)
+        )
+
+        // drag to a point that is within both the bubble right zone and split zone
+        val (pointX, pointY) =
+            Pair(
+                bubbleRightDragZone.bounds.centerX(),
+                bubbleRightDragZone.bounds.centerY()
+            )
+        assertThat(splitDragZone.contains(pointX, pointY)).isTrue()
+        dropTargetManager.onDragUpdated(pointX, pointY)
+        // verify we dragged to the bubble right zone because that has higher priority than split
+        assertThat(dragZoneChangedListener.fromDragZone).isEqualTo(bubbleLeftDragZone)
+        assertThat(dragZoneChangedListener.toDragZone).isEqualTo(bubbleRightDragZone)
+
+        dropTargetManager.onDragUpdated(
+            bubbleRightDragZone.bounds.centerX(),
+            150 // below the bubble and dismiss drag zones but within split
+        )
+        assertThat(dragZoneChangedListener.fromDragZone).isEqualTo(bubbleRightDragZone)
+        assertThat(dragZoneChangedListener.toDragZone).isEqualTo(splitDragZone)
+
+        val (dismissPointX, dismissPointY) =
+            Pair(dismissDragZone.bounds.centerX(), dismissDragZone.bounds.centerY())
+        assertThat(splitDragZone.contains(dismissPointX, dismissPointY)).isTrue()
+        dropTargetManager.onDragUpdated(dismissPointX, dismissPointY)
+        assertThat(dragZoneChangedListener.fromDragZone).isEqualTo(splitDragZone)
+        assertThat(dragZoneChangedListener.toDragZone).isEqualTo(dismissDragZone)
+    }
+
+    @Test
+    fun onDragUpdated_afterDragEnded_doesNotNotify() {
+        dropTargetManager.onDragStarted(
+            DraggedObject.Bubble(BubbleBarLocation.LEFT),
+            listOf(bubbleLeftDragZone, bubbleRightDragZone, dismissDragZone)
+        )
+        dropTargetManager.onDragEnded()
+        dropTargetManager.onDragUpdated(
+            bubbleRightDragZone.bounds.centerX(),
+            bubbleRightDragZone.bounds.centerY()
+        )
+        assertThat(dragZoneChangedListener.fromDragZone).isNull()
+        assertThat(dragZoneChangedListener.toDragZone).isNull()
+    }
+
+    private class FakeDragZoneChangedListener : DropTargetManager.DragZoneChangedListener {
+        var initialDragZone: DragZone? = null
+        var fromDragZone: DragZone? = null
+        var toDragZone: DragZone? = null
+
+        override fun onInitialDragZoneSet(dragZone: DragZone) {
+            initialDragZone = dragZone
+        }
+        override fun onDragZoneChanged(from: DragZone, to: DragZone) {
+            fromDragZone = from
+            toDragZone = to
+        }
+    }
+}