Add failing reproducer for show-taps overlay misplacement

gradle/libs.versions.toml

@@ -16,6 +16,8 @@ dokka = "2.0.0" # https://github.com/kotlin/dokka/releases
 junit = "4.13.2"
 composeLintChecks = "1.4.2" # https://github.com/slackhq/compose-lints/releases
 androidx-test-core = "1.6.1"
+androidx-test-ext-junit = "1.2.1" # https://developer.android.com/jetpack/androidx/releases/test
+robolectric = "4.14.1" # https://github.com/robolectric/robolectric/releases
 mavenPublish = "0.35.0" # https://vanniktech.github.io/gradle-maven-publish-plugin/changelog/
 
 [plugins]
@@ -42,4 +44,7 @@ telephoto = { module = "me.saket.telephoto:zoomable", version.ref = "telephoto"
 
 junit = { module = "junit:junit", version.ref = "junit" }
 androidx-compose-ui-test-junit = { module = "androidx.compose.ui:ui-test-junit4", version.ref = "androidx-compose-ui" }
+androidx-compose-ui-test-manifest = { module = "androidx.compose.ui:ui-test-manifest", version.ref = "androidx-compose-ui" }
 androidx-test-core = { module = "androidx.test:core-ktx", version.ref = "androidx-test-core" }
+androidx-test-ext-junit = { module = "androidx.test.ext:junit", version.ref = "androidx-test-ext-junit" }
+robolectric = { module = "org.robolectric:robolectric", version.ref = "robolectric" }

touchrobot-core/build.gradle.kts

@@ -13,6 +13,11 @@ android {
     compileSdk = libs.versions.compileSdk.get().toInt()
     lint.abortOnError = true
   }
+  testOptions {
+    unitTests {
+      isIncludeAndroidResources = true
+    }
+  }
 }
 
 dependencies {
@@ -21,6 +26,21 @@ dependencies {
   implementation(libs.androidx.ktx)
   implementation(libs.androidx.lifecycle)
   implementation(libs.androidx.savedstate)
+
+  testImplementation(libs.junit)
+  testImplementation(libs.robolectric)
+  testImplementation(libs.androidx.test.ext.junit)
+  testImplementation(libs.androidx.compose.ui.test.junit)
+  debugImplementation(libs.androidx.compose.ui.test.manifest)
+}
+
+// The Compose UI test manifest (which supplies the launcher activity used by createComposeRule)
+// is intentionally debug-only so it never ships in the published release artifact. That leaves the
+// release unit test variant without an activity to launch, so skip it — debug covers these tests.
+tasks.configureEach {
+  if (name.contains("Release") && name.contains("UnitTest")) {
+    enabled = false
+  }
 }
 
 // Used on CI to prevent publishing of non-snapshot versions.

touchrobot-core/src/test/kotlin/me/saket/touchrobot/ShowTapsOverlayPositionTest.kt

@@ -0,0 +1,117 @@
+package me.saket.touchrobot
+
+import android.graphics.Rect
+import android.view.Gravity
+import android.view.View
+import android.view.WindowManager
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.size
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.SideEffect
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalView
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.unit.dp
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Assert.assertEquals
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.annotation.Config
+import org.robolectric.annotation.GraphicsMode
+import kotlin.time.Duration.Companion.milliseconds
+
+/**
+ * Reproducer: the "show taps" overlay window is misplaced when the host view does not fill
+ * the screen.
+ *
+ * rememberTouchRobot() draws taps in a separate window added via WindowManager.addView().
+ * MatchParentSizePopup sizes that window to the host view but leaves
+ * WindowManager.LayoutParams.gravity at its default (0). With gravity == 0, WindowManager centers
+ * the window inside the screen, so an overlay smaller than the screen is drawn offset from the
+ * host view (and therefore offset from the touches, which are injected at the host's top-left).
+ *
+ * Robolectric does not run WindowManager's window-placement math, so View.getLocationOnScreen()
+ * reports (0,0) for the overlay and hides the bug. This test instead reconstructs the on-screen
+ * rect with the exact call WindowManager makes to place a window - Gravity.apply(...) - and asserts
+ * the overlay lands at the host view's position.
+ */
+@RunWith(AndroidJUnit4::class)
+@GraphicsMode(GraphicsMode.Mode.NATIVE)
+// 480x799 hdpi screen; the 300.dp host is 450x450 px, i.e. smaller than the screen.
+@Config(sdk = [35], qualifiers = "w320dp-h533dp-port-hdpi")
+class ShowTapsOverlayPositionTest {
+
+  @get:Rule
+  val composeTestRule = createComposeRule()
+
+  @Test
+  fun showTapsOverlayIsAnchoredToHostView() {
+    lateinit var hostView: View
+
+    composeTestRule.setContent {
+      val view = LocalView.current
+      SideEffect { hostView = view }
+
+      val touchRobot = rememberTouchRobot(showTaps = true)
+      LaunchedEffect(Unit) {
+        touchRobot.onRoot().performGesture {
+          swipe(start = topLeft, stop = center, duration = 200.milliseconds)
+        }
+      }
+
+      // A host view that is smaller than the screen.
+      Box(
+        Modifier
+          .size(300.dp)
+          .background(Color.LightGray)
+      )
+    }
+    composeTestRule.waitForIdle()
+
+    val decorView = hostView.rootView
+    val (overlayView, overlayParams) = topLevelWindows().first { (view, _) ->
+      view !== decorView && view.javaClass.name.contains("ComposeView")
+    }
+
+    val screenRect = Rect(0, 0, decorView.width, decorView.height)
+    val overlayRect = Rect()
+    Gravity.apply(
+      overlayParams.gravity,
+      if (overlayParams.width >= 0) overlayParams.width else overlayView.width,
+      if (overlayParams.height >= 0) overlayParams.height else overlayView.height,
+      screenRect,
+      overlayParams.x,
+      overlayParams.y,
+      overlayRect,
+    )
+
+    val hostLocation = IntArray(2).also { hostView.getLocationOnScreen(it) }
+
+    assertEquals(
+      "Show-taps overlay window is not anchored to the host view. " +
+        "Overlay window at (${overlayRect.left}, ${overlayRect.top}) " +
+        "size ${overlayRect.width()}x${overlayRect.height()}, " +
+        "but host view is at (${hostLocation[0]}, ${hostLocation[1]}) " +
+        "size ${hostView.width}x${hostView.height} on a ${screenRect.width()}x${screenRect.height()} screen. " +
+        "The overlay LayoutParams gravity is ${overlayParams.gravity} (0 = centered by WindowManager).",
+      hostLocation[0] to hostLocation[1],
+      overlayRect.left to overlayRect.top,
+    )
+  }
+
+  /** Reads WindowManagerGlobal's top-level windows via reflection (the API is @hide). */
+  private fun topLevelWindows(): List<Pair<View, WindowManager.LayoutParams>> {
+    val cls = Class.forName("android.view.WindowManagerGlobal")
+    val instance = cls.getMethod("getInstance").invoke(null)
+    @Suppress("UNCHECKED_CAST")
+    val views = cls.getDeclaredField("mViews")
+      .apply { isAccessible = true }.get(instance) as List<View>
+    @Suppress("UNCHECKED_CAST")
+    val params = cls.getDeclaredField("mParams")
+      .apply { isAccessible = true }.get(instance) as List<WindowManager.LayoutParams>
+    return views.indices.map { views[it] to params[it] }
+  }
+}