ADFA-6251: Ignore output-panel drags that start above its visible edge

app/src/main/java/com/itsaky/androidide/ui/EditorBottomSheetBehavior.kt

@@ -0,0 +1,37 @@
+package com.itsaky.androidide.ui
+
+import android.content.Context
+import android.util.AttributeSet
+import android.view.MotionEvent
+import android.view.View
+import androidx.coordinatorlayout.widget.CoordinatorLayout
+import com.google.android.material.bottomsheet.BottomSheetBehavior
+
+class EditorBottomSheetBehavior<V : View>(
+	context: Context,
+	attrs: AttributeSet?,
+) : BottomSheetBehavior<V>(context, attrs) {
+	private var gestureStartedInTopPadding = false
+
+	override fun onInterceptTouchEvent(
+		parent: CoordinatorLayout,
+		child: V,
+		event: MotionEvent,
+	): Boolean = !isGestureInTopPadding(child, event) && super.onInterceptTouchEvent(parent, child, event)
+
+	override fun onTouchEvent(
+		parent: CoordinatorLayout,
+		child: V,
+		event: MotionEvent,
+	): Boolean = !isGestureInTopPadding(child, event) && super.onTouchEvent(parent, child, event)
+
+	private fun isGestureInTopPadding(
+		child: V,
+		event: MotionEvent,
+	): Boolean {
+		if (event.actionMasked == MotionEvent.ACTION_DOWN) {
+			gestureStartedInTopPadding = event.y < child.top + child.paddingTop
+		}
+		return gestureStartedInTopPadding
+	}
+}

app/src/main/res/layout-land/content_editor.xml

@@ -165,7 +165,7 @@
 		android:layout_height="match_parent"
 		app:behavior_hideable="false"
 		app:behavior_peekHeight="@dimen/editor_sheet_collapsed_height"
-		app:layout_behavior="com.google.android.material.bottomsheet.BottomSheetBehavior" />
+		app:layout_behavior="com.itsaky.androidide.ui.EditorBottomSheetBehavior" />
 
 	<include
 		android:id="@+id/diagnosticInfo"

app/src/main/res/layout/content_editor.xml

@@ -161,7 +161,7 @@
 		android:layout_height="match_parent"
 		app:behavior_hideable="false"
 		app:behavior_peekHeight="@dimen/editor_sheet_collapsed_height"
-		app:layout_behavior="com.google.android.material.bottomsheet.BottomSheetBehavior" />
+		app:layout_behavior="com.itsaky.androidide.ui.EditorBottomSheetBehavior" />
 
 	<include
 		android:id="@+id/diagnosticInfo"

app/src/test/java/com/itsaky/androidide/ui/EditorBottomSheetBehaviorTest.kt

@@ -0,0 +1,116 @@
+package com.itsaky.androidide.ui
+
+import android.app.Activity
+import android.app.Application
+import android.os.Looper
+import android.os.SystemClock
+import android.view.MotionEvent
+import android.view.View
+import android.view.ViewGroup.LayoutParams.MATCH_PARENT
+import android.widget.FrameLayout
+import androidx.coordinatorlayout.widget.CoordinatorLayout
+import com.google.android.material.bottomsheet.BottomSheetBehavior
+import com.google.common.truth.Truth.assertThat
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.Robolectric
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.Shadows.shadowOf
+import org.robolectric.annotation.Config
+
+@RunWith(RobolectricTestRunner::class)
+@Config(application = Application::class)
+class EditorBottomSheetBehaviorTest {
+	private val activity =
+		Robolectric
+			.buildActivity(Activity::class.java)
+			.setup()
+			.get()
+
+	private val editorActions = mutableListOf<Int>()
+
+	private val editor =
+		View(activity).apply {
+			isClickable = true
+			setOnTouchListener { _, event ->
+				editorActions += event.actionMasked
+				false
+			}
+		}
+
+	private val behavior =
+		EditorBottomSheetBehavior<FrameLayout>(activity, null).apply {
+			peekHeight = PEEK_HEIGHT
+			isHideable = false
+		}
+
+	private val sheet = FrameLayout(activity).apply { setPadding(0, TOP_PADDING, 0, 0) }
+
+	private val parent =
+		CoordinatorLayout(activity).apply {
+			addView(editor, CoordinatorLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT))
+			addView(
+				sheet,
+				CoordinatorLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT).also { it.behavior = behavior },
+			)
+		}
+
+	private fun laidOut() {
+		activity.setContentView(parent)
+		shadowOf(Looper.getMainLooper()).idle()
+		assertThat(behavior.state).isEqualTo(BottomSheetBehavior.STATE_COLLAPSED)
+	}
+
+	private fun dragUpFrom(startY: Float) {
+		val downTime = SystemClock.uptimeMillis()
+		val x = parent.width / 2f
+		val events =
+			listOf(MotionEvent.obtain(downTime, downTime, MotionEvent.ACTION_DOWN, x, startY, 0)) +
+				(1..DRAG_STEPS).map { step ->
+					MotionEvent.obtain(
+						downTime,
+						downTime + step * STEP_MILLIS,
+						MotionEvent.ACTION_MOVE,
+						x,
+						startY - step * STEP_PX,
+						0,
+					)
+				}
+		events.forEach { event ->
+			parent.dispatchTouchEvent(event)
+			event.recycle()
+		}
+	}
+
+	@Test
+	fun `a drag that starts in the sheet's top padding stays with the view underneath`() {
+		laidOut()
+		val collapsedTop = sheet.top
+
+		dragUpFrom(collapsedTop + TOP_PADDING / 2f)
+
+		assertThat(behavior.state).isEqualTo(BottomSheetBehavior.STATE_COLLAPSED)
+		assertThat(sheet.top).isEqualTo(collapsedTop)
+		assertThat(editorActions).doesNotContain(MotionEvent.ACTION_CANCEL)
+		assertThat(editorActions.count { it == MotionEvent.ACTION_MOVE }).isEqualTo(DRAG_STEPS)
+	}
+
+	@Test
+	fun `a drag that starts on the sheet's visible top still drags the sheet`() {
+		laidOut()
+		val collapsedTop = sheet.top
+
+		dragUpFrom(collapsedTop + TOP_PADDING + (PEEK_HEIGHT - TOP_PADDING) / 2f)
+
+		assertThat(behavior.state).isEqualTo(BottomSheetBehavior.STATE_DRAGGING)
+		assertThat(sheet.top).isLessThan(collapsedTop)
+	}
+
+	private companion object {
+		const val PEEK_HEIGHT = 200
+		const val TOP_PADDING = 60
+		const val DRAG_STEPS = 6
+		const val STEP_PX = 20f
+		const val STEP_MILLIS = 16L
+	}
+}