feat(gui): on mouse hover highlight identifiers with enabled actions (like 'find usage' or 'rename')

jadx-gui/src/main/java/jadx/gui/ui/codearea/AbstractCodeArea.java

@@ -34,7 +34,7 @@ public abstract class AbstractCodeArea extends RSyntaxTextArea {
 		this.contentPanel = contentPanel;
 		this.node = contentPanel.getNode();
 
-		setMarkOccurrences(true);
+		setMarkOccurrences(false);
 		setEditable(false);
 		setCodeFoldingEnabled(false);
 		loadSettings();

jadx-gui/src/main/java/jadx/gui/ui/codearea/CodeArea.java

@@ -36,7 +36,8 @@ public final class CodeArea extends AbstractCodeArea {
 		super(contentPanel);
 		setSyntaxEditingStyle(node.getSyntaxName());
 
-		if (node instanceof JClass) {
+		boolean isJavaCode = node instanceof JClass;
+		if (isJavaCode) {
 			((RSyntaxDocument) getDocument()).setSyntaxStyle(new JadxTokenMaker(this));
 			addMenuItems();
 		}
@@ -46,6 +47,7 @@ public final class CodeArea extends AbstractCodeArea {
 		CodeLinkGenerator codeLinkGenerator = new CodeLinkGenerator(this);
 		setLinkGenerator(codeLinkGenerator);
 		addMouseListener(new MouseAdapter() {
+			@SuppressWarnings("deprecation")
 			@Override
 			public void mouseClicked(MouseEvent e) {
 				if (e.isControlDown()) {
@@ -57,6 +59,9 @@ public final class CodeArea extends AbstractCodeArea {
 				}
 			}
 		});
+		if (isJavaCode) {
+			addMouseMotionListener(new MouseHoverHighlighter(this, codeLinkGenerator));
+		}
 	}
 
 	@Override

jadx-gui/src/main/java/jadx/gui/ui/codearea/JadxTokenMaker.java

@@ -26,7 +26,7 @@ public final class JadxTokenMaker extends JavaTokenMaker {
 	@Override
 	public Token getTokenList(Segment text, int initialTokenType, int startOffset) {
 		Token tokens = super.getTokenList(text, initialTokenType, startOffset);
-		if (startOffset > 0 && tokens.getType() != TokenTypes.NULL) {
+		if (tokens.getType() != TokenTypes.NULL) {
 			try {
 				processTokens(tokens);
 			} catch (Exception e) {
@@ -41,11 +41,14 @@ public final class JadxTokenMaker extends JavaTokenMaker {
 		Token current = tokens;
 		while (current != null) {
 			if (prev != null) {
-				int tokenType = current.getType();
-				if (tokenType == TokenTypes.IDENTIFIER) {
-					current = mergeLongClassNames(prev, current, false);
-				} else if (tokenType == TokenTypes.ANNOTATION) {
-					current = mergeLongClassNames(prev, current, true);
+				switch (current.getType()) {
+					case TokenTypes.IDENTIFIER:
+						current = mergeLongClassNames(prev, current, false);
+						break;
+
+					case TokenTypes.ANNOTATION:
+						current = mergeLongClassNames(prev, current, true);
+						break;
 				}
 			}
 			prev = current;
@@ -55,7 +58,7 @@ public final class JadxTokenMaker extends JavaTokenMaker {
 
 	@NotNull
 	private Token mergeLongClassNames(Token prev, Token current, boolean annotation) {
-		int offset = current.getOffset();
+		int offset = current.getTextOffset();
 		if (annotation) {
 			offset++;
 		}
@@ -66,7 +69,7 @@ public final class JadxTokenMaker extends JavaTokenMaker {
 			if (annotation && lexeme.length() > 1) {
 				lexeme = lexeme.substring(1);
 			}
-			if (!lexeme.equals(name) && javaNode.getFullName().startsWith(lexeme)) {
+			if (!lexeme.equals(name) && isClassNameStart(javaNode, lexeme)) {
 				// try to replace long class name with one token
 				Token replace = concatTokensUntil(current, name);
 				if (replace != null && prev instanceof TokenImpl) {
@@ -79,6 +82,18 @@ public final class JadxTokenMaker extends JavaTokenMaker {
 		return current;
 	}
 
+	private boolean isClassNameStart(JavaNode javaNode, String lexeme) {
+		if (javaNode.getFullName().startsWith(lexeme)) {
+			// full class name
+			return true;
+		}
+		if (javaNode.getTopParentClass().getName().startsWith(lexeme)) {
+			// inner class references from parent class
+			return true;
+		}
+		return false;
+	}
+
 	@Nullable
 	private Token concatTokensUntil(Token start, String endText) {
 		StringBuilder sb = new StringBuilder();

jadx-gui/src/main/java/jadx/gui/ui/codearea/MouseHoverHighlighter.java

@@ -0,0 +1,57 @@
+package jadx.gui.ui.codearea;
+
+import java.awt.event.MouseEvent;
+import java.awt.event.MouseMotionAdapter;
+
+import javax.swing.text.Highlighter;
+
+import org.fife.ui.rsyntaxtextarea.Token;
+import org.fife.ui.rsyntaxtextarea.TokenTypes;
+import org.fife.ui.rtextarea.SmartHighlightPainter;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import jadx.gui.utils.JumpPosition;
+
+class MouseHoverHighlighter extends MouseMotionAdapter {
+	private static final Logger LOG = LoggerFactory.getLogger(MouseHoverHighlighter.class);
+
+	private final CodeArea codeArea;
+	private final CodeLinkGenerator codeLinkGenerator;
+	private final Highlighter.HighlightPainter highlighter;
+
+	private boolean added;
+
+	public MouseHoverHighlighter(CodeArea codeArea, CodeLinkGenerator codeLinkGenerator) {
+		this.codeArea = codeArea;
+		this.codeLinkGenerator = codeLinkGenerator;
+		this.highlighter = new SmartHighlightPainter(codeArea.getMarkOccurrencesColor());
+	}
+
+	@Override
+	public void mouseMoved(MouseEvent e) {
+		Highlighter highlighter = codeArea.getHighlighter();
+		if (added) {
+			highlighter.removeAllHighlights();
+			added = false;
+		}
+		if (e.getModifiersEx() != 0) {
+			return;
+		}
+		try {
+			Token token = codeArea.viewToToken(e.getPoint());
+			if (token == null || token.getType() != TokenTypes.IDENTIFIER) {
+				return;
+			}
+			JumpPosition jump = codeLinkGenerator.getJumpLinkAtOffset(codeArea, token.getOffset());
+			if (jump == null) {
+				return;
+			}
+			highlighter.removeAllHighlights();
+			highlighter.addHighlight(token.getOffset(), token.getEndOffset(), this.highlighter);
+			added = true;
+		} catch (Exception exc) {
+			LOG.error("Mouse hover highlight error", exc);
+		}
+	}
+}