Improve syntax highlight stability

Author: oowekyala

src/main/java/net/sourceforge/pmd/util/fxdesigner/SourceEditorController.java

@@ -192,6 +192,7 @@ protected void beforeParentInit() {
                   .map(LanguageVersion::getLanguage)
                   .values()
                   .filter(Objects::nonNull)
+                  .distinct()
                   .subscribe(nodeEditionCodeArea::updateSyntaxHighlighter);
 
         ((ASTManagerImpl) astManager).classLoaderProperty().bind(auxclasspathClassLoader);

src/main/java/net/sourceforge/pmd/util/fxdesigner/app/NodeSelectionSource.java

@@ -19,6 +19,8 @@
 import net.sourceforge.pmd.util.fxdesigner.util.controls.AstTreeView;
 import net.sourceforge.pmd.util.fxdesigner.util.reactfx.ReactfxUtil;
 
+import javafx.application.Platform;
+
 
 /**
  * A control or controller that somehow displays nodes in a form that the user can select.
@@ -75,7 +77,7 @@ default Val<Node> initNodeSelectionHandling(DesignerRoot root,
         EventStream<NodeSelectionEvent> selection = channel.messageStream(alwaysHandleSelection, this);
         selection.subscribe(evt -> {
             try {
-                setFocusNode(evt.selected, evt.options);
+                Platform.runLater(() -> setFocusNode(evt.selected, evt.options));
             } catch (Exception e) {
                 logInternalException(e);
                 printShortStackTrace(e);

src/main/java/net/sourceforge/pmd/util/fxdesigner/util/AuxLanguageRegistry.java

@@ -41,7 +41,8 @@ public static LanguageVersion findLanguageVersionByTerseName(String string) {
         if (lang == null) {
             return null;
         }
-        return lang.getVersion(split[1]);
+        return split.length == 1 ? lang.getDefaultVersion()
+                                 : lang.getVersion(split[1]);
     }
 
     @NonNull

src/main/java/net/sourceforge/pmd/util/fxdesigner/util/codearea/HighlightLayerCodeArea.java

@@ -148,6 +148,8 @@ private StyleSpans<Collection<String>> recomputePainting() {
                                                                   .map(UniformStyleCollection::toSpans)
                                                                   .collect(Collectors.toList());
 
+        ensureSyntaxUpToDate();
+
         if (allSpans.isEmpty()) {
             return syntaxHighlight.getOrElse(emptySpan());
         }

src/main/java/net/sourceforge/pmd/util/fxdesigner/util/codearea/PmdCoordinatesSystem.java

@@ -72,6 +72,9 @@ public static TextPos2D getPmdLineAndColumnFromOffset(CodeArea codeArea, int abs
      * </ul>
      */
     public static int getOffsetFromPmdPosition(CodeArea codeArea, int line, int column) {
+        line = max(line, 1);
+        column = max(column, 1);
+
         int parIdx = getRtfxParIndexFromPmdLine(line);
         int raw = codeArea.getAbsolutePosition(parIdx, getRtfxColumnIndexFromPmdColumn(codeArea, parIdx, column));
         return clip(raw, 0, codeArea.getLength() - 1);

src/main/java/net/sourceforge/pmd/util/fxdesigner/util/codearea/SyntaxHighlightingCodeArea.java

@@ -173,11 +173,20 @@ protected StyleSpans<Collection<String>> call() {
         return task;
     }
 
-    /** Removes the current syntax highlighting span. */
+
+    /**
+     * Removes the current syntax highlighting span.
+     */
     protected void clearSyntaxHighlighting() {
         setCurrentSyntaxHighlight(null);
     }
 
+    protected void ensureSyntaxUpToDate() {
+        if (!syntaxHighlighter.isPresent()) {
+            clearSyntaxHighlighting();
+        }
+    }
+
     /**
      * Update the syntax highlighting to the specified value.
      * If null, syntax highlighting is stripped off.

src/main/java/net/sourceforge/pmd/util/fxdesigner/util/controls/NodeEditionCodeArea.java

@@ -164,7 +164,14 @@ private void scrollToNode(Node node, boolean scrollToTop) {
             return;
         }
 
-        int visibleLength = lastVisibleParToAllParIndex() - firstVisibleParToAllParIndex();
+        int visibleLength;
+        try {
+            visibleLength = lastVisibleParToAllParIndex() - firstVisibleParToAllParIndex();
+        } catch (AssertionError e) {
+            // may be thrown when many selection events occur in quick succession?
+            // Something like, the paragraphs
+            return;
+        }
 
         boolean fitsViewPort = node.getEndLine() - node.getBeginLine() <= visibleLength;
         int rtfxLine = getRtfxParIndexFromPmdLine(node.getBeginLine());
@@ -174,15 +181,13 @@ private void scrollToNode(Node node, boolean scrollToTop) {
         boolean isEndVisible = rtfxEndLine <= lastVisibleParToAllParIndex();
 
 
+        if (!isStartVisible && scrollToTop) {
+            showParagraphAtTop(max(rtfxLine - 2, 0));
+        }
         if (fitsViewPort) {
-            if (!isStartVisible && scrollToTop) {
-                showParagraphAtTop(max(rtfxLine - 2, 0));
-            }
             if (!isEndVisible) {
                 showParagraphAtBottom(min(rtfxEndLine, getParagraphs().size()));
             }
-        } else if (!isStartVisible && scrollToTop) {
-            showParagraphAtTop(max(rtfxLine - 2, 0));
         }
     }
 
@@ -298,27 +303,29 @@ public void moveCaret(int line, int column) {
     public void setFocusNode(final Node node, DataHolder options) {
 
 
+        boolean changed = !Objects.equals(node, currentFocusNode.getValue());
+        if (changed) {
+
+            currentFocusNode.setValue(node);
+
+            // editor is only restyled if the selection has changed
+            Platform.runLater(() -> styleNodes(
+                node == null ? emptyList() : singleton(node), StyleLayerIds.FOCUS, true));
+
+            if (node == null) {
+                highlightRelatedNodes(emptyList());
+            } else {
+                Platform.runLater(() -> highlightRelatedNodes(relatedNodesSelector.getValue().getHighlightedNodesWhenSelecting(node)));
+            }
+        }
+
         // editor must not be scrolled when finding a new selection in a
         // tree that is being edited
+        // Editor must be scrolled after styling
         if (node != null && !options.hasData(SELECTION_RECOVERY)) {
             // don't randomly jump to top of eg ClassOrInterfaceBody
             // when selecting from a caret position
-            scrollToNode(node, !options.hasData(CARET_POSITION));
-        }
-
-        if (Objects.equals(node, currentFocusNode.getValue())) {
-            return;
-        }
-
-        currentFocusNode.setValue(node);
-
-        // editor is only restyled if the selection has changed
-        Platform.runLater(() -> styleNodes(node == null ? emptyList() : singleton(node), StyleLayerIds.FOCUS, true));
-
-        if (node == null) {
-            highlightRelatedNodes(emptyList());
-        } else {
-            Platform.runLater(() -> highlightRelatedNodes(relatedNodesSelector.getValue().getHighlightedNodesWhenSelecting(node)));
+            Platform.runLater(() -> scrollToNode(node, !options.hasData(CARET_POSITION)));
         }
     }