Use NT4 metadata

api/src/main/java/edu/wpi/first/shuffleboard/api/sources/DataSource.java

@@ -7,6 +7,8 @@
 import javafx.beans.property.Property;
 import javafx.beans.property.StringProperty;
 
+import java.util.Optional;
+
 /**
  * A data source provides some kind of data that widgets can display and manipulate. It can be
  * active or inactive; active sources may update at any time, while inactive sources are guaranteed
@@ -161,4 +163,12 @@ default String getId() {
    */
   void removeClient(Sourced client);
 
+  /**
+   * Preferred widget for the source.
+   *
+   * @return optionally a string identifier of the preferred widget type.
+   */
+  default Optional<String> preferredWidget() {
+    return Optional.empty();
+  }
 }

app/src/main/java/edu/wpi/first/shuffleboard/app/WidgetPaneDragHandler.java

@@ -140,7 +140,8 @@ private boolean previewSource(GridPoint point, Dragboard dragboard) {
     }
     SourceEntry entry = DeserializationHelper.sourceFromDrag(dragboard.getContent(DataFormats.source));
     DataSource source = entry.get();
-    Optional<String> componentName = Components.getDefault().pickComponentNameFor(source.getDataType());
+    Optional<String> componentName = source.preferredWidget()
+            .or(() -> Components.getDefault().pickComponentNameFor(source.getDataType()));
     Optional<DataSource<?>> dummySource = DummySource.forTypes(source.getDataType());
     if (componentName.isPresent() && dummySource.isPresent()) {
       if (tilePreviewSize == null) {
@@ -290,7 +291,8 @@ private void handleDragDropped(DragEvent event) {
    * @param point  the point to place the widget for the source
    */
   private void dropSource(DataSource<?> source, GridPoint point) {
-    Components.getDefault().pickComponentNameFor(source.getDataType())
+    source.preferredWidget()
+            .or(() -> Components.getDefault().pickComponentNameFor(source.getDataType()))
         .flatMap(name -> Components.getDefault().createComponent(name, source))
         .filter(widget -> pane.isOpen(point, pane.sizeOfWidget(widget), n -> widget.getView() == n))
         .map(pane::addComponentToTile)

plugins/networktables/src/main/java/edu/wpi/first/shuffleboard/plugin/networktables/TabGenerator.java

@@ -1,5 +1,7 @@
 package edu.wpi.first.shuffleboard.plugin.networktables;
 
+import com.google.gson.JsonParser;
+import com.google.gson.JsonPrimitive;
 import edu.wpi.first.shuffleboard.api.sources.DataSource;
 import edu.wpi.first.shuffleboard.api.sources.SourceTypes;
 import edu.wpi.first.shuffleboard.api.tab.model.ComponentModel;
@@ -337,6 +339,26 @@ private Map<String, Object> properties(String realPath) {
         props.put(k, propsTable.getEntry(k).getValue().getValue());
       }
     }
+    if (!inst.getTopic(realPath).exists()) {
+      var propsTable = inst.getTable(realPath);
+      for (String k : propsTable.getKeys()) {
+        props.put(k, propsTable.getEntry(k).getValue().getValue());
+      }
+    } else {
+      String metadata = inst.getTopic(realPath).getProperties();
+      JsonParser parser = new JsonParser();
+      var obj = parser.parse(metadata).getAsJsonObject();
+      obj.entrySet().forEach(entry -> {
+        JsonPrimitive primitive = entry.getValue().getAsJsonPrimitive();
+        if (primitive.isBoolean()) {
+          props.put(entry.getKey(), primitive.getAsBoolean());
+        } else if (primitive.isNumber()) {
+          props.put(entry.getKey(), primitive.getAsNumber());
+        } else {
+          props.put(entry.getKey(), primitive.getAsString());
+        }
+      });
+    }
     return props;
   }
 
@@ -354,8 +376,9 @@ private void updateWidget(ParentModel parent, String path) {
         preferredComponent(
             path,
             sourceSupplier
-                .map(DataSource::getDataType)
-                .map(componentRegistry::defaultComponentNameFor)
+                .map(source -> source.preferredWidget()
+                                .or(() -> componentRegistry.defaultComponentNameFor(source.getDataType()))
+                )
                 .map(Optional::orElseThrow)
         ),
         properties(path));

plugins/networktables/src/main/java/edu/wpi/first/shuffleboard/plugin/networktables/sources/CompositeNetworkTableSource.java

@@ -1,5 +1,6 @@
 package edu.wpi.first.shuffleboard.plugin.networktables.sources;
 
+import edu.wpi.first.networktables.NetworkTableValue;
 import edu.wpi.first.shuffleboard.api.data.ComplexData;
 import edu.wpi.first.shuffleboard.api.data.ComplexDataType;
 import edu.wpi.first.shuffleboard.api.data.IncompleteDataException;
@@ -14,6 +15,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -28,6 +30,8 @@ public class CompositeNetworkTableSource<D extends ComplexData<D>> extends Netwo
 
   private static final Logger log = Logger.getLogger(CompositeNetworkTableSource.class.getName());
 
+  private Optional<String> preferredWidget;
+
   private final Map<String, Object> backingMap = new HashMap<>();
   private final ComplexDataType<D> dataType;
 
@@ -44,6 +48,7 @@ public CompositeNetworkTableSource(String tableName, ComplexDataType<D> dataType
     this.dataType = dataType;
     String path = NetworkTable.normalizeKey(tableName, false);
     NetworkTable table = NetworkTableInstance.getDefault().getTable(path);
+    preferredWidget = loadWidgetFromWidgetEntry(table);
     setData(dataType.getDefaultValue());
 
     setTableListener((key, event) -> {
@@ -91,4 +96,15 @@ public ComplexDataType<D> getDataType() {
   protected boolean isSingular() {
     return false;
   }
+
+  @Override
+  public Optional<String> preferredWidget() {
+    return preferredWidget;
+  }
+
+  private static Optional<String> loadWidgetFromWidgetEntry(NetworkTable table) {
+    return Optional.ofNullable(table.getValue(".widget"))
+            .filter(NetworkTableValue::isString)
+            .map(NetworkTableValue::getString);
+  }
 }

plugins/networktables/src/main/java/edu/wpi/first/shuffleboard/plugin/networktables/sources/SingleKeyNetworkTableSource.java

@@ -1,5 +1,10 @@
 package edu.wpi.first.shuffleboard.plugin.networktables.sources;
 
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import edu.wpi.first.networktables.NetworkTableEvent.Kind;
+import edu.wpi.first.networktables.Topic;
 import edu.wpi.first.shuffleboard.api.data.DataType;
 import edu.wpi.first.shuffleboard.api.data.DataTypes;
 import edu.wpi.first.shuffleboard.api.sources.Sources;
@@ -9,6 +14,8 @@
 import edu.wpi.first.networktables.NetworkTableEntry;
 import edu.wpi.first.networktables.NetworkTableEvent;
 
+import java.util.Optional;
+
 /**
  * A data source backed by a single key-value pair in a network table.
  */
@@ -21,6 +28,8 @@ public class SingleKeyNetworkTableSource<T> extends NetworkTableSource<T> {
    */
   private volatile boolean initialUpdate = true;
 
+  private Optional<String> preferredWidget;
+
   /**
    * Creates a single-key network table source backed by the value in the given table
    * associated with the given key.
@@ -33,6 +42,7 @@ public class SingleKeyNetworkTableSource<T> extends NetworkTableSource<T> {
   public SingleKeyNetworkTableSource(NetworkTable table, String key, DataType dataType) {
     super(key, dataType);
     setName(key);
+    preferredWidget = loadWidgetFromTopicProps(table.getTopic(key));
     setTableListener((__, event) -> {
       if (event.is(NetworkTableEvent.Kind.kUnpublish)) {
         setActive(false);
@@ -49,6 +59,8 @@ public SingleKeyNetworkTableSource(NetworkTable table, String key, DataType data
         if (isActive()) {
           setData((T) value);
         }
+      } else if (event.is(Kind.kProperties)) {
+        preferredWidget = loadWidgetFromTopicProps(table.getTopic(key));
       }
     });
 
@@ -83,4 +95,27 @@ public SingleKeyNetworkTableSource(NetworkTable table, String key, DataType data
   protected boolean isSingular() {
     return true;
   }
+
+  @Override
+  public Optional<String> preferredWidget() {
+    return preferredWidget;
+  }
+
+  private static Optional<String> loadWidgetFromTopicProps(Topic topic) {
+    String metadata = topic.getProperties();
+    JsonParser parser = new JsonParser();
+    try {
+      JsonObject obj = parser.parse(metadata).getAsJsonObject();
+      JsonElement widgetProp = obj.get("widget");
+      if (widgetProp == null || !widgetProp.isJsonPrimitive()) {
+        System.err.println("Metadata widget field for topic `" + topic.getName()
+                           + "` doesn't exist or isn't primitive!");
+        return Optional.empty();
+      }
+      return Optional.of(widgetProp.getAsString());
+    } catch (Exception e) {
+      e.printStackTrace();
+      return Optional.empty();
+    }
+  }
 }