Add SwipeDismissBehavior event binding

rxbinding-design-kotlin/src/main/kotlin/com/jakewharton/rxbinding/support/design/widget/RxSwipeDismissBehavior.kt

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+package com.jakewharton.rxbinding.support.design.widget
+
+import android.support.design.widget.SwipeDismissBehavior
+import android.view.View
+import rx.Observable
+
+/**
+ * Create an observable which emits the dismiss events from `view` on [SwipeDismissBehavior].
+ * 
+ * *Warning:* The created observable keeps a strong reference to `view`. Unsubscribe
+ * to free this reference.
+ */
+public inline fun View.dismisses(): Observable<View> = RxSwipeDismissBehavior.dismisses(this)

rxbinding-design/src/androidTest/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.jakewharton.rxbinding.support.design">
+
+  <application>
+    <activity
+        android:name="com.jakewharton.rxbinding.support.design.widget.RxSwipeDismissBehaviorTestActivity"
+        android:theme="@style/Theme.AppCompat"
+        />
+  </application>
+</manifest>

rxbinding-design/src/androidTest/java/com/jakewharton/rxbinding/support/design/widget/RxSwipeDismissBehaviorTest.java

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+package com.jakewharton.rxbinding.support.design.widget;
+
+import android.app.Instrumentation;
+import android.support.design.widget.CoordinatorLayout;
+import android.support.design.widget.SwipeDismissBehavior;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.rule.ActivityTestRule;
+import android.support.test.runner.AndroidJUnit4;
+import android.view.View;
+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 android.view.MotionEvent.ACTION_DOWN;
+import static android.view.MotionEvent.ACTION_MOVE;
+import static android.view.MotionEvent.ACTION_UP;
+import static com.google.common.truth.Truth.assertThat;
+import static com.jakewharton.rxbinding.MotionEventUtil.motionEventAtPosition;
+
+@RunWith(AndroidJUnit4.class)
+public final class RxSwipeDismissBehaviorTest {
+  @Rule public final ActivityTestRule<RxSwipeDismissBehaviorTestActivity> activityRule =
+      new ActivityTestRule<>(RxSwipeDismissBehaviorTestActivity.class);
+
+  private final Instrumentation instrumentation = InstrumentationRegistry.getInstrumentation();
+  private View view;
+
+  @Before public void setUp() {
+    RxSwipeDismissBehaviorTestActivity activity = activityRule.getActivity();
+    view = activity.view;
+  }
+
+  @Test public void dismisses() {
+    ((CoordinatorLayout.LayoutParams) view.getLayoutParams()).setBehavior(
+        new SwipeDismissBehavior());
+
+    RecordingObserver<View> o = new RecordingObserver<>();
+    Subscription subscription = RxSwipeDismissBehavior.dismisses(view)
+        .subscribeOn(AndroidSchedulers.mainThread())
+        .subscribe(o);
+    o.assertNoMoreEvents(); // No initial value.
+
+    doSwipeGesture(view);
+    assertThat(o.takeNext()).isEqualTo(view);
+
+    subscription.unsubscribe();
+
+    doSwipeGesture(view);
+    o.assertNoMoreEvents();
+  }
+
+  private void doSwipeGesture(View view) {
+    instrumentation.sendPointerSync(motionEventAtPosition(view, ACTION_DOWN, 50, 0));
+    instrumentation.sendPointerSync(motionEventAtPosition(view, ACTION_MOVE, 500, 0));
+    instrumentation.sendPointerSync(motionEventAtPosition(view, ACTION_UP, 500, 0));
+  }
+}

rxbinding-design/src/androidTest/java/com/jakewharton/rxbinding/support/design/widget/RxSwipeDismissBehaviorTestActivity.java

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+package com.jakewharton.rxbinding.support.design.widget;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.support.design.widget.CoordinatorLayout;
+import android.view.View;
+
+public class RxSwipeDismissBehaviorTestActivity extends Activity {
+  CoordinatorLayout parent;
+  View view;
+
+  @Override protected void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+
+    parent = new CoordinatorLayout(this);
+    view = new View(this);
+    view.setLayoutParams(new CoordinatorLayout.LayoutParams(100, 100));
+    parent.addView(view);
+
+    setContentView(parent);
+  }
+}

rxbinding-design/src/main/java/com/jakewharton/rxbinding/support/design/widget/RxSwipeDismissBehavior.java

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+package com.jakewharton.rxbinding.support.design.widget;
+
+import android.support.annotation.CheckResult;
+import android.support.annotation.NonNull;
+import android.support.design.widget.SwipeDismissBehavior;
+import android.view.View;
+import rx.Observable;
+
+/**
+ * Static factory methods for creating {@linkplain Observable observables}
+ * for {@link SwipeDismissBehavior} on (@link View).
+ */
+public final class RxSwipeDismissBehavior {
+  /**
+   * Create an observable which emits the dismiss events from {@code view} on {@link SwipeDismissBehavior}.
+   * <p>
+   * <em>Warning:</em> The created observable keeps a strong reference to {@code view}. Unsubscribe
+   * to free this reference.
+   */
+  @CheckResult @NonNull
+  public static Observable<View> dismisses(@NonNull View view) {
+    return Observable.create(new SwipeDismissBehaviorOnSubscribe(view));
+  }
+
+  private RxSwipeDismissBehavior() {
+    throw new AssertionError("No instances.");
+  }
+}

rxbinding-design/src/main/java/com/jakewharton/rxbinding/support/design/widget/SwipeDismissBehaviorOnSubscribe.java

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+package com.jakewharton.rxbinding.support.design.widget;
+
+import android.support.design.widget.CoordinatorLayout;
+import android.support.design.widget.SwipeDismissBehavior;
+import android.view.View;
+import com.jakewharton.rxbinding.internal.MainThreadSubscription;
+import rx.Observable;
+import rx.Subscriber;
+
+import static com.jakewharton.rxbinding.internal.Preconditions.checkUiThread;
+
+final class SwipeDismissBehaviorOnSubscribe implements Observable.OnSubscribe<View> {
+  private final View view;
+
+  public SwipeDismissBehaviorOnSubscribe(View view) {
+    this.view = view;
+  }
+
+  @Override public void call(final Subscriber<? super View> subscriber) {
+    checkUiThread();
+
+    SwipeDismissBehavior.OnDismissListener listener = new SwipeDismissBehavior.OnDismissListener() {
+      @Override public void onDismiss(View view) {
+        if (!subscriber.isUnsubscribed()) {
+          subscriber.onNext(view);
+        }
+      }
+
+      @Override public void onDragStateChanged(int i) {
+      }
+    };
+
+    if (!(view.getLayoutParams() instanceof CoordinatorLayout.LayoutParams)) {
+      throw new IllegalArgumentException("The view is not in a Coordinator Layout.");
+    }
+    final SwipeDismissBehavior behavior =
+        (SwipeDismissBehavior) ((CoordinatorLayout.LayoutParams) view.getLayoutParams()).getBehavior();
+    if (behavior == null) {
+      throw new IllegalStateException("There's no behavior set on this view.");
+    }
+    behavior.setListener(listener);
+
+    subscriber.add(new MainThreadSubscription() {
+      @Override protected void onUnsubscribe() {
+        behavior.setListener(null);
+      }
+    });
+  }
+}