Merge "DisplayTopology: user cannot drag only display" into main

src/com/android/settings/connecteddevice/display/DisplayTopology.kt

@@ -415,8 +415,12 @@ class DisplayTopologyPreference(context : Context)
 
     private fun onBlockTouchDown(
             displayId: Int, displayPos: RectF, block: DisplayBlock, ev: MotionEvent): Boolean {
-        val stationaryDisps = (mTopologyInfo ?: return false)
-                .positions.filter { it.first != displayId }
+        val positions = (mTopologyInfo ?: return false).positions
+
+        // Do not allow dragging for single-display topology, since there is nothing to clamp it to.
+        if (positions.size <= 1) { return false }
+
+        val stationaryDisps = positions.filter { it.first != displayId }
 
         // We have to use rawX and rawY for the coordinates since the view receiving the event is
         // also the view that is moving. We need coordinates relative to something that isn't

tests/robotests/src/com/android/settings/connecteddevice/display/DisplayTopologyPreferenceTest.kt

@@ -102,6 +102,15 @@ class DisplayTopologyPreferenceTest {
                 .map { preference.mPaneContent.getChildAt(it) as DisplayBlock }
                 .toList()
 
+    fun singleDisplayTopology(): DisplayTopology {
+        val primaryId = 22;
+
+        val root = DisplayTopology.TreeNode(
+                primaryId, /* width= */ 200f, /* height= */ 160f, POSITION_LEFT, /* offset= */ 0f)
+
+        return DisplayTopology(root, primaryId)
+    }
+
     fun twoDisplayTopology(childPosition: Int, childOffset: Float): DisplayTopology {
         val primaryId = 1
 
@@ -287,6 +296,36 @@ class DisplayTopologyPreferenceTest {
         assertThat(preference.mTimesReceivedSameTopology).isEqualTo(1)
     }
 
+    @Test
+    fun cannotMoveSingleDisplay() {
+        injector.topology = singleDisplayTopology()
+        preparePane()
+
+        val paneChildren = getPaneChildren()
+        assertThat(paneChildren).hasSize(1)
+        val block = paneChildren[0]
+
+        val origY = block.unpaddedY
+
+        block.dispatchTouchEvent(MotionEventBuilder.newBuilder()
+                .setAction(MotionEvent.ACTION_DOWN)
+                .setPointer(0f, 0f)
+                .build())
+        block.dispatchTouchEvent(MotionEventBuilder.newBuilder()
+                .setAction(MotionEvent.ACTION_MOVE)
+                .setPointer(0f, 30f)
+                .build())
+
+        assertThat(block.unpaddedY).isWithin(0.01f).of(origY)
+
+        block.dispatchTouchEvent(MotionEventBuilder.newBuilder()
+                .setAction(MotionEvent.ACTION_UP)
+                .build())
+
+        // Block should be back to original position.
+        assertThat(block.unpaddedY).isWithin(0.01f).of(origY)
+    }
+
     @Test
     fun updatedTopologyCancelsDragIfNonTrivialChange() {
         val (leftBlock, rightBlock) = setupTwoDisplays(POSITION_LEFT, /* childOffset= */ 42f)