fix(gui): improve code area performance and line numbers repaint (#1167)

jadx-core/src/main/java/jadx/api/JavaClass.java

@@ -66,11 +66,6 @@ public final class JavaClass implements JavaNode {
 		return cls.getSmali();
 	}
 
-	public synchronized void unload() {
-		cls.unload();
-		listsLoaded = false;
-	}
-
 	/**
 	 * Internal API. Not Stable!
 	 */

jadx-gui/src/main/java/jadx/gui/JadxWrapper.java

@@ -68,8 +68,6 @@ public class JadxWrapper {
 			decompiler.getArgs().setRootDir(dir);
 			decompiler.save(500, (done, total) -> progressMonitor.setProgress((int) (done * 100.0 / total)));
 			progressMonitor.close();
-			LOG.info("decompilation complete, freeing memory ...");
-			decompiler.getClasses().forEach(JavaClass::unload);
 			LOG.info("done");
 		};
 		new Thread(save).start();

jadx-gui/src/main/java/jadx/gui/treemodel/JClass.java

@@ -57,11 +57,11 @@ public class JClass extends JLoadableNode {
 	}
 
 	public synchronized void load() {
-		if (!loaded) {
-			cls.decompile();
-			cls.unload();
-			loaded = true;
+		if (loaded) {
+			return;
 		}
+		cls.decompile();
+		loaded = true;
 		update();
 	}
 
@@ -69,7 +69,6 @@ public class JClass extends JLoadableNode {
 		cls.reload();
 		loaded = true;
 		update();
-		cls.unload();
 	}
 
 	public synchronized void update() {
@@ -93,8 +92,7 @@ public class JClass extends JLoadableNode {
 
 	@Override
 	public @Nullable ICodeInfo getCodeInfo() {
-		load();
-		return cls.getClassNode().getCode();
+		return cls.getCodeInfo();
 	}
 
 	@Override

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

@@ -120,9 +120,6 @@ public class CodePanel extends JPanel {
 		if (codeArea instanceof SmaliArea) {
 			return;
 		}
-		LineNumbers numbers = new LineNumbers(codeArea);
-		numbers.setUseSourceLines(isUseSourceLines());
-		codeScrollPane.setRowHeaderView(numbers);
 		initLineNumbers(isUseSourceLines());
 	}
 

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

@@ -42,7 +42,8 @@ public class LineNumbers extends JPanel implements CaretListener {
 	private static final int NUM_HEIGHT = Integer.MAX_VALUE - 1000000;
 	private static final Map<?, ?> DESKTOP_HINTS = (Map<?, ?>) Toolkit.getDefaultToolkit().getDesktopProperty("awt.font.desktophints");
 
-	private final AbstractCodeArea codeArea;
+	private final transient AbstractCodeArea codeArea;
+	private final transient ICodeInfo codeInfo;
 	private boolean useSourceLines = true;
 
 	private transient int lastDigits;
@@ -55,10 +56,11 @@ public class LineNumbers extends JPanel implements CaretListener {
 
 	private transient Insets textAreaInsets;
 	private transient Rectangle visibleRect = new Rectangle();
-	private transient ICodeInfo codeInfo;
 
 	public LineNumbers(AbstractCodeArea codeArea) {
 		this.codeArea = codeArea;
+		this.codeInfo = codeArea.getNode().getCodeInfo();
+
 		setFont(codeArea.getFont());
 		SyntaxScheme syntaxScheme = codeArea.getSyntaxScheme();
 		numberColor = syntaxScheme.getStyle(Token.LITERAL_NUMBER_DECIMAL_INT).foreground;
@@ -110,8 +112,6 @@ public class LineNumbers extends JPanel implements CaretListener {
 	@SuppressWarnings("deprecation")
 	@Override
 	public void paintComponent(Graphics g) {
-		codeInfo = codeArea.getNode().getCodeInfo();
-
 		visibleRect = g.getClipBounds(visibleRect);
 		if (visibleRect == null) {
 			visibleRect = getVisibleRect();
@@ -127,7 +127,7 @@ public class LineNumbers extends JPanel implements CaretListener {
 
 		Dimension size = getSize();
 		g.setColor(codeArea.getBackground());
-		g.fillRect(0, 0, size.width, size.height);
+		g.fillRect(0, visibleRect.y, size.width, visibleRect.height);
 
 		FontMetrics fontMetrics = codeArea.getFontMetrics(font);
 		Insets insets = getInsets();