Package structure: moved UI utilities.

Part of #963.

src/main/java/de/dennisguse/opentracks/ui/markers/MarkerListActivity.java

@@ -34,7 +34,6 @@ import androidx.loader.content.Loader;
 import de.dennisguse.opentracks.AbstractActivity;
 import de.dennisguse.opentracks.ContextualActionModeCallback;
 import de.dennisguse.opentracks.R;
-import de.dennisguse.opentracks.adapters.ScrollVisibleViews;
 import de.dennisguse.opentracks.content.data.Marker;
 import de.dennisguse.opentracks.content.data.MarkerColumns;
 import de.dennisguse.opentracks.content.data.Track;
@@ -43,6 +42,7 @@ import de.dennisguse.opentracks.databinding.MarkerListBinding;
 import de.dennisguse.opentracks.services.TrackRecordingService;
 import de.dennisguse.opentracks.services.TrackRecordingServiceConnection;
 import de.dennisguse.opentracks.ui.markers.DeleteMarkerDialogFragment.DeleteMarkerCaller;
+import de.dennisguse.opentracks.ui.util.ScrollVisibleViews;
 import de.dennisguse.opentracks.util.ActivityUtils;
 import de.dennisguse.opentracks.util.IntentUtils;
 

src/main/java/de/dennisguse/opentracks/ui/markers/MarkerResourceCursorAdapter.java

@@ -23,11 +23,11 @@ import java.time.Instant;
 import java.time.OffsetDateTime;
 
 import de.dennisguse.opentracks.R;
-import de.dennisguse.opentracks.adapters.ExecutorListViewService;
-import de.dennisguse.opentracks.adapters.ScrollVisibleViews;
 import de.dennisguse.opentracks.content.data.MarkerColumns;
 import de.dennisguse.opentracks.content.data.Track;
 import de.dennisguse.opentracks.content.provider.ContentProviderUtils;
+import de.dennisguse.opentracks.ui.util.ExecutorListViewService;
+import de.dennisguse.opentracks.ui.util.ScrollVisibleViews;
 import de.dennisguse.opentracks.util.ListItemUtils;
 
 public class MarkerResourceCursorAdapter extends ResourceCursorAdapter implements ScrollVisibleViews.VisibleViewsListener {

src/main/java/de/dennisguse/opentracks/ui/util/ExecutorListViewService.java

@@ -0,0 +1,78 @@
+package de.dennisguse.opentracks.ui.util;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+/**
+ * ExecutorService wrap that avoid the execution of the same object in a ListView.
+ *
+ * @param <T> the type of the object that will be used to identified the Runnable.
+ */
+public class ExecutorListViewService<T> {
+
+    private final List<T> enqueueObjects = new ArrayList<>();
+    private final ExecutorService executorService;
+
+    public ExecutorListViewService(int numThreads) {
+        executorService = Executors.newFixedThreadPool(numThreads);
+    }
+
+    public void shutdown() {
+        enqueueObjects.clear();
+        executorService.shutdown();
+    }
+
+    /**
+     * Execute the runnable for the object.
+     *
+     * @param object   the Object.
+     * @param runnable the Runnable.
+     */
+    public void execute(T object, Runnable runnable) {
+        if (!preExecute(object)) {
+            return;
+        }
+
+        new Thread(() -> {
+            Future<?> future = executorService.submit(runnable);
+            try {
+                future.get();
+            } catch (ExecutionException | InterruptedException e) {
+                e.printStackTrace();
+            }
+            postExecute(object);
+        }).start();
+    }
+
+    /**
+     * Before execution it must checks if the object is already enqueued.
+     *
+     * @param object the object to check.
+     * @return       true if it can be executed or false otherwise.
+     */
+    private boolean preExecute(T object) {
+        synchronized (enqueueObjects) {
+            if (!enqueueObjects.contains(object)) {
+                enqueueObjects.add(object);
+                return true;
+            } else {
+                return false;
+            }
+        }
+    }
+
+    /**
+     * After execution remove the object from the queue.
+     *
+     * @param object the object to be removed from the queue.
+     */
+    private void postExecute(T object) {
+        synchronized (enqueueObjects) {
+            enqueueObjects.remove(object);
+        }
+    }
+}

src/main/java/de/dennisguse/opentracks/ui/util/ScrollVisibleViews.java

@@ -0,0 +1,42 @@
+package de.dennisguse.opentracks.ui.util;
+
+import android.view.View;
+import android.widget.AbsListView;
+
+import androidx.annotation.NonNull;
+
+/**
+ * AbsListView.OnScrollListener class that can be used to know what views in a ListView are currently visible while scrolling.
+ */
+public class ScrollVisibleViews implements AbsListView.OnScrollListener {
+    private int from = -1;
+    private int to = -1;
+
+    private final VisibleViewsListener visibleViewsListener;
+
+    public ScrollVisibleViews(@NonNull VisibleViewsListener visibleViewsListener) {
+        this.visibleViewsListener = visibleViewsListener;
+    }
+
+    @Override
+    public void onScrollStateChanged(AbsListView view, int scrollState) {
+        if (scrollState == AbsListView.OnScrollListener.SCROLL_STATE_IDLE || scrollState == AbsListView.OnScrollListener.SCROLL_STATE_FLING || scrollState == AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL) {
+            if (from >= 0 && to >= 0) {
+                for (int i = from; i < to; i++) {
+                    View viewChild = view.getChildAt(i - from);
+                    visibleViewsListener.onViewVisible(viewChild, i);
+                }
+            }
+        }
+    }
+
+    @Override
+    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
+        from = firstVisibleItem;
+        to = firstVisibleItem + visibleItemCount;
+    }
+
+    public interface VisibleViewsListener {
+        void onViewVisible(View view, int position);
+    }
+}