Implement view attach events + tests

rxbinding-kotlin/src/main/kotlin/com/jakewharton/rxbinding/view/RxView.kt

@@ -3,14 +3,41 @@ package com.jakewharton.rxbinding.view
 import android.view.DragEvent
 import android.view.MotionEvent
 import android.view.View
-import rx.Observable
 import com.jakewharton.rxbinding.internal.Functions
+import rx.Observable
 import rx.functions.Action1
 import rx.functions.Func0
 import rx.functions.Func1
 
 /**
- * Create an observable of timestamps for clicks on `view`.
+ * Create an observable which emits on `view` attach events. The emitted value is
+ * unspecified and should only be used as notification.
+ * 
+ * *Warning:* The created observable keeps a strong reference to `view`. Unsubscribe
+ * to free this reference.
+ */
+public inline fun View.attaches(): Observable<Any> = RxView.attaches(this)
+
+/**
+ * Create an observable of attach and detach events on `view`.
+ * 
+ * *Warning:* The created observable keeps a strong reference to `view`. Unsubscribe
+ * to free this reference.
+ */
+public inline fun View.attachEvents(): Observable<ViewAttachEvent> = RxView.attachEvents(this)
+
+/**
+ * Create an observable which emits on `view` detach events. The emitted value is
+ * unspecified and should only be used as notification.
+ * 
+ * *Warning:* The created observable keeps a strong reference to `view`. Unsubscribe
+ * to free this reference.
+ */
+public inline fun View.detaches(): Observable<Any> = RxView.detaches(this)
+
+/**
+ * Create an observable which emits on `view` click events. The emitted value is
+ * unspecified and should only be used as notification.
  * 
  * *Warning:* The created observable keeps a strong reference to `view`. Unsubscribe
  * to free this reference.
@@ -108,7 +135,8 @@ public inline fun View.focusChanges(): Observable<Boolean> = RxView.focusChanges
 public inline fun View.focusChangeEvents(): Observable<ViewFocusChangeEvent> = RxView.focusChangeEvents(this)
 
 /**
- * Create an observable of timestamps for long-clicks on `view`.
+ * Create an observable which emits on `view` long-click events. The emitted value is
+ * unspecified and should only be used as notification.
  * 
  * *Warning:* The created observable keeps a strong reference to `view`. Unsubscribe
  * to free this reference.
@@ -119,7 +147,8 @@ public inline fun View.focusChangeEvents(): Observable<ViewFocusChangeEvent> = R
 public inline fun View.longClicks(): Observable<Any> = RxView.longClicks(this)
 
 /**
- * Create an observable of timestamps for clicks on `view`.
+ * Create an observable which emits on `view` long-click events. The emitted value is
+ * unspecified and should only be used as notification.
  * 
  * *Warning:* The created observable keeps a strong reference to `view`. Unsubscribe
  * to free this reference.

rxbinding/src/androidTest/AndroidManifest.xml

@@ -4,6 +4,7 @@
     package="com.jakewharton.rxbinding">
 
   <application>
+    <activity android:name=".view.RxViewAttachTestActivity"/>
     <activity android:name=".widget.RxAdapterViewTestActivity"/>
     <activity android:name=".widget.RxRatingBarTestActivity"/>
     <activity android:name=".widget.RxSeekBarTestActivity"/>

rxbinding/src/androidTest/java/com/jakewharton/rxbinding/view/RxViewAttachTest.java

@@ -0,0 +1,131 @@
+package com.jakewharton.rxbinding.view;
+
+import android.app.Instrumentation;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.rule.ActivityTestRule;
+import android.support.test.runner.AndroidJUnit4;
+import android.view.View;
+import android.widget.FrameLayout;
+
+import com.jakewharton.rxbinding.RecordingObserver;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import rx.Subscription;
+import rx.android.schedulers.AndroidSchedulers;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.jakewharton.rxbinding.view.ViewAttachEvent.Kind.ATTACH;
+import static com.jakewharton.rxbinding.view.ViewAttachEvent.Kind.DETACH;
+
+@RunWith(AndroidJUnit4.class)
+public final class RxViewAttachTest {
+  @Rule public final ActivityTestRule<RxViewAttachTestActivity> activityRule =
+      new ActivityTestRule<>(RxViewAttachTestActivity.class);
+
+  private final Instrumentation instrumentation = InstrumentationRegistry.getInstrumentation();
+  private FrameLayout parent;
+  private View child;
+
+  @Before public void setUp() {
+    RxViewAttachTestActivity activity = activityRule.getActivity();
+    parent = activity.parent;
+    child = activity.child;
+  }
+
+  @Test public void attaches() {
+    RecordingObserver<Object> o = new RecordingObserver<>();
+    Subscription subscription = RxView.attaches(child)
+        .subscribeOn(AndroidSchedulers.mainThread())
+        .subscribe(o);
+    o.assertNoMoreEvents(); // No initial value.
+
+    instrumentation.runOnMainSync(new Runnable() {
+      @Override public void run() {
+        parent.addView(child);
+      }
+    });
+    assertThat(o.takeNext()).isNotNull();
+    instrumentation.runOnMainSync(new Runnable() {
+      @Override public void run() {
+        parent.removeView(child);
+      }
+    });
+    o.assertNoMoreEvents();
+
+    subscription.unsubscribe();
+
+    instrumentation.runOnMainSync(new Runnable() {
+      @Override public void run() {
+        parent.addView(child);
+        parent.removeView(child);
+      }
+    });
+    o.assertNoMoreEvents();
+  }
+
+  @Test public void attachEvents() {
+    RecordingObserver<ViewAttachEvent> o = new RecordingObserver<>();
+    Subscription subscription = RxView.attachEvents(child)
+        .subscribeOn(AndroidSchedulers.mainThread())
+        .subscribe(o);
+    o.assertNoMoreEvents(); // No initial value.
+
+    instrumentation.runOnMainSync(new Runnable() {
+      @Override public void run() {
+        parent.addView(child);
+      }
+    });
+    assertThat(o.takeNext().kind()).isEqualTo(ATTACH);
+    instrumentation.runOnMainSync(new Runnable() {
+      @Override public void run() {
+        parent.removeView(child);
+      }
+    });
+    assertThat(o.takeNext().kind()).isEqualTo(DETACH);
+
+    subscription.unsubscribe();
+
+    instrumentation.runOnMainSync(new Runnable() {
+      @Override public void run() {
+        parent.addView(child);
+        parent.removeView(child);
+      }
+    });
+    o.assertNoMoreEvents();
+  }
+
+  @Test public void detaches() {
+    RecordingObserver<Object> o = new RecordingObserver<>();
+    Subscription subscription = RxView.detaches(child)
+        .subscribeOn(AndroidSchedulers.mainThread())
+        .subscribe(o);
+    o.assertNoMoreEvents(); // No initial value.
+
+    instrumentation.runOnMainSync(new Runnable() {
+      @Override public void run() {
+        parent.addView(child);
+      }
+    });
+    o.assertNoMoreEvents();
+    instrumentation.runOnMainSync(new Runnable() {
+      @Override public void run() {
+        parent.removeView(child);
+      }
+    });
+    assertThat(o.takeNext()).isNotNull();
+
+    subscription.unsubscribe();
+
+    instrumentation.runOnMainSync(new Runnable() {
+      @Override public void run() {
+        parent.addView(child);
+        parent.removeView(child);
+      }
+    });
+    o.assertNoMoreEvents();
+  }
+}

rxbinding/src/androidTest/java/com/jakewharton/rxbinding/view/RxViewAttachTestActivity.java

@@ -0,0 +1,18 @@
+package com.jakewharton.rxbinding.view;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.view.View;
+import android.widget.FrameLayout;
+
+public final class RxViewAttachTestActivity extends Activity {
+  FrameLayout parent;
+  View child;
+
+  @Override protected void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    parent = new FrameLayout(this);
+    child = new View(this);
+    setContentView(parent);
+  }
+}

rxbinding/src/main/java/com/jakewharton/rxbinding/view/RxView.java

@@ -4,8 +4,10 @@
 import android.view.DragEvent;
 import android.view.MotionEvent;
 import android.view.View;
-import rx.Observable;
+
 import com.jakewharton.rxbinding.internal.Functions;
+
+import rx.Observable;
 import rx.functions.Action1;
 import rx.functions.Func0;
 import rx.functions.Func1;
@@ -19,7 +21,44 @@
  */
 public final class RxView {
   /**
-   * Create an observable of timestamps for clicks on {@code view}.
+   * Create an observable which emits on {@code view} attach events. The emitted value is
+   * unspecified and should only be used as notification.
+   * <p>
+   * <em>Warning:</em> The created observable keeps a strong reference to {@code view}. Unsubscribe
+   * to free this reference.
+   */
+  public static Observable<Object> attaches(View view) {
+    checkNotNull(view, "view == null");
+    return Observable.create(new ViewAttachesOnSubscribe(view, true));
+  }
+
+  /**
+   * Create an observable of attach and detach events on {@code view}.
+   * <p>
+   * <em>Warning:</em> The created observable keeps a strong reference to {@code view}. Unsubscribe
+   * to free this reference.
+   */
+  @CheckResult
+  public static Observable<ViewAttachEvent> attachEvents(View view) {
+    checkNotNull(view, "view == null");
+    return Observable.create(new ViewAttachEventOnSubscribe(view));
+  }
+
+  /**
+   * Create an observable which emits on {@code view} detach events. The emitted value is
+   * unspecified and should only be used as notification.
+   * <p>
+   * <em>Warning:</em> The created observable keeps a strong reference to {@code view}. Unsubscribe
+   * to free this reference.
+   */
+  public static Observable<Object> detaches(View view) {
+    checkNotNull(view, "view == null");
+    return Observable.create(new ViewAttachesOnSubscribe(view, false));
+  }
+
+  /**
+   * Create an observable which emits on {@code view} click events. The emitted value is
+   * unspecified and should only be used as notification.
    * <p>
    * <em>Warning:</em> The created observable keeps a strong reference to {@code view}. Unsubscribe
    * to free this reference.
@@ -153,7 +192,8 @@ public static Observable<ViewFocusChangeEvent> focusChangeEvents(View view) {
   }
 
   /**
-   * Create an observable of timestamps for long-clicks on {@code view}.
+   * Create an observable which emits on {@code view} long-click events. The emitted value is
+   * unspecified and should only be used as notification.
    * <p>
    * <em>Warning:</em> The created observable keeps a strong reference to {@code view}. Unsubscribe
    * to free this reference.
@@ -168,7 +208,8 @@ public static Observable<Object> longClicks(View view) {
   }
 
   /**
-   * Create an observable of timestamps for clicks on {@code view}.
+   * Create an observable which emits on {@code view} long-click events. The emitted value is
+   * unspecified and should only be used as notification.
    * <p>
    * <em>Warning:</em> The created observable keeps a strong reference to {@code view}. Unsubscribe
    * to free this reference.

rxbinding/src/main/java/com/jakewharton/rxbinding/view/ViewAttachEvent.java

@@ -0,0 +1,56 @@
+package com.jakewharton.rxbinding.view;
+
+import android.content.Context;
+import android.support.annotation.NonNull;
+import android.view.View;
+
+/**
+ * A view attach event on a view.
+ * <p>
+ * <strong>Warning:</strong> Instances keep a strong reference to the view. Operators that
+ * cache instances have the potential to leak the associated {@link Context}.
+ */
+public final class ViewAttachEvent extends ViewEvent<View> {
+
+  public enum Kind {
+    ATTACH, DETACH
+  }
+
+  public static ViewAttachEvent create(@NonNull View view, Kind kind) {
+    return new ViewAttachEvent(view, kind);
+  }
+
+  private final Kind kind;
+
+  private ViewAttachEvent(View view, Kind kind) {
+    super(view);
+    this.kind = kind;
+  }
+
+  public Kind kind() {
+    return kind;
+  }
+
+  @Override public boolean equals(Object o) {
+    if (o == this) return true;
+    if (!(o instanceof ViewAttachEvent)) return false;
+    ViewAttachEvent other = (ViewAttachEvent) o;
+    return other.view() == view()
+        && other.kind() == kind();
+  }
+
+  @Override public int hashCode() {
+    int result = 17;
+    result = result * 37 + view().hashCode();
+    result = result * 37 + kind().hashCode();
+    return result;
+  }
+
+  @Override public String toString() {
+    return "ViewAttachEvent{view="
+        + view()
+        + ", kind="
+        + kind()
+        + '}';
+  }
+}