another Swing performance fix

src/org/shmidusic/MainPanel.java

@@ -55,8 +55,10 @@ public void replaceSheetMusic(SheetMusic sheetMusic)
 	}
 
 	public void chordChanged() {
-		pianoLayoutPanel.repaint();
+		pianoLayoutPanel.paintImmediately(pianoLayoutPanel.getVisibleRect()); // simple repaint() would sometimes lag for a half second, what was not likable
+		// this may also start lagging, but only if you unfocus window
 		statusField.setText(getStatusText());
+		statusField.paintImmediately(statusField.getVisibleRect());
 		sheetContainer.checkCam();
 	}
 

src/org/shmidusic/sheet_music/staff/StaffComponent.java

@@ -241,10 +241,12 @@ public StaffComponent setFocus(int index)
 
 		if (was != null) {
 			was.setFocusedIndex(-1);
-			was.repaint();
+			was.paintImmediately(was.getVisibleRect()); // simple repaint() would sometimes lag for a half second, what was not likable
+//			was.repaint();
 		}
 		if (staff.getFocusedIndex() != -1) {
-			getFocusedChild().repaint();
+//			getFocusedChild().repaint();
+			getFocusedChild().paintImmediately(getFocusedChild().getVisibleRect()); // simple repaint() would sometimes lag for a half second, what was not likable
 		}
 
 		getModelParent().mainPanel.chordChanged();

src/org/shmidusic/stuff/test/JavaFXTest.java

@@ -21,12 +21,7 @@ private static void initAndShowGUI() {
 		frame.setVisible(true);
 		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
-		Platform.runLater(new Runnable() {
-			@Override
-			public void run() {
-				initFX(fxPanel);
-			}
-		});
+		Platform.runLater(() -> initFX(fxPanel));
 	}
 
 	private static void initFX(JFXPanel fxPanel) {
@@ -51,11 +46,6 @@ private static Scene createScene() {
 	}
 
 	public static void main(String[] args) {
-		SwingUtilities.invokeLater(new Runnable() {
-			@Override
-			public void run() {
-				initAndShowGUI();
-			}
-		});
+		SwingUtilities.invokeLater(() -> initAndShowGUI());
 	}
 }

src/org/shmidusic/stuff/test/SwingRepaintTimingTest.java

@@ -0,0 +1,66 @@
+package org.shmidusic.stuff.test;
+
+// we shall experiment with the time parameter of JComponent::repaint()
+// i presume time we specify is time when buffers will be swapped?
+
+import org.shmidusic.stuff.tools.Fp;
+
+import javax.swing.*;
+import java.awt.*;
+
+public class SwingRepaintTimingTest extends JPanel
+{
+	private static JLabel counter;
+
+	public static void main(String[] args) {
+		JFrame window = new JFrame("zhopa");
+		window.setLayout(new BorderLayout());
+
+		counter = new JLabel("0");
+		window.add(counter, BorderLayout.EAST);
+
+		window.add(new SwingRepaintTimingTest(), BorderLayout.WEST);
+		window.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
+		window.setSize(1600, 800);
+
+		window.setVisible(true);
+	}
+
+	private SwingRepaintTimingTest() {
+		super();
+		setPreferredSize(new Dimension(1440, 800));
+		setFocusable(true);
+		requestFocus();
+
+		addKeyListener(Fp.onKey(k -> repaintWithin(8000)));
+	}
+
+	protected void paintComponent(Graphics g) {
+		super.paintComponent(g);
+		g.drawRect(10, 10, 800, 800);
+
+		for (int i = 0; i < 50000; ++i) {
+			int x = (int) (Math.random() * 1440);
+			int y = (int) (Math.random() * 800);
+
+			g.setColor(new Color(x * 255 / 1440, y * 255 / 800, 0));
+			g.drawLine(10, 10, x, y);
+		}
+	}
+
+	/** repaints into hidden buffer and swaps em after millis */
+	// apparently does not repaint into hidden buffer
+	private void repaintWithin(int millis)
+	{
+		new Thread(() -> {
+			for (int i = millis / 1000; i >= 0; --i) {
+				counter.setText("" + i);
+				try { Thread.sleep(1000); } catch (InterruptedException exc) {}
+			}
+		}).start();
+
+		Timer swingTimer = new Timer(millis, k -> repaint());
+		swingTimer.setRepeats(false);
+		swingTimer.start();
+	}
+}