varren · August 29, 2015 14:23
diff --git a/SwingDrawLines.java b/SwingDrawLines.java
 /*
 I dont really have this problem: here is results from your version 
 Start of drawLines(): 82086490370339
 Done drawing thick lines!
 Time taken (ns): 76994, Time taken(ms): 0
 Done drawing vertical lines!
 Time taken (ns): 54858, Time taken(ms): 0
 Done drawing horizontal lines!
 Time taken (ns): 57424, Time taken(ms): 0

 And here is results from this version:

 Start of drawLines(): 82268401323649
 Done drawing thick lines!
 Time taken (ns): 113886, Time taken(ms): 0
 Done drawing vertical lines!
 Time taken (ns): 53896, Time taken(ms): 0
 Done drawing horizontal lines!
 Time taken (ns): 187993, Time taken(ms): 0

 This version works even slower but has no glitching on my pc
 */

 import java.awt.*;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.awt.geom.GeneralPath;
 import javax.swing.*;

 @SuppressWarnings("serial")
 public class SO_MCVE extends JPanel {

    private DrawingCanvas _drawingCanvas = null;

    private JButton repaintBtn;

    public SO_MCVE() {
        super(new BorderLayout());

        _drawingCanvas = new DrawingCanvas();
        _drawingCanvas.setPreferredSize(new Dimension(600, 600)); //CHANGED THIS LINE

        JLabel repaintLabel = new JLabel(
                "<html><div style=\"text-align: center;\">" +
                        "REPAINT</html>");
        repaintLabel.setHorizontalAlignment(
                SwingConstants.CENTER);

        repaintBtn = new JButton();
        repaintBtn.add(repaintLabel);
        repaintBtn.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

                _drawingCanvas.triggerRepaint();
            }
        });

        add(_drawingCanvas, BorderLayout.CENTER);
        add(repaintBtn, BorderLayout.PAGE_END);
    }

    private static void createAndShowGUI() {
        JFrame frame = new JFrame("StackOverflow MCVE for drawLine");

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new SO_MCVE());
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                UIManager.put("swing.boldMetal", Boolean.FALSE);
                createAndShowGUI();
            }
        });
    }
 }

 @SuppressWarnings("serial")
 class DrawingCanvas extends JComponent { //CHANGED THIS LINE TO JComponent

    public static final Color lightGreen = new Color(0, 255, 0, 180);
    public static final BasicStroke STROKE1PX = new BasicStroke(1.0f);
    public static final BasicStroke STROKE3PX = new BasicStroke(3.0f);

    private static final int LEFT = 50;
    private static final int RIGHT = 550;
    private static final int TOP = 50;
    private static final int BOTTOM = 550;

    private static final double WIDTH = 500.00d;
    private static final double HEIGHT = 500.00d;

    public DrawingCanvas() {
        setBackground(Color.BLACK);
    }


    public void triggerRepaint() {
        repaint();
    }

    public void paintComponent(Graphics g) {

        Graphics2D g2 = (Graphics2D) g;
        Dimension dim = getSize();
        int w = (int) dim.getWidth();
        int h = (int) dim.getHeight();

        // Clears the rectangle that was previously drawn
        g2.setPaint(Color.BLACK);
        g2.fillRect(0, 0, w, h);

        drawLines(g2, w, h);
    }

    /**
     * Draw the lines marking the x-y limits
     **/
    private void drawLines(Graphics2D g2, int w, int h) {

        long start = System.nanoTime();
        System.out.println("Start of drawLines(): " + start);

        // Thick lines
        g2.setPaint(Color.GREEN);
        g2.setStroke(STROKE3PX);
        g2.drawLine(LEFT, 0, LEFT, h);
        g2.drawLine(RIGHT, 0, RIGHT, h);
        g2.drawLine(0, TOP, w, TOP);
        g2.drawLine(0, BOTTOM, w, BOTTOM);

        System.out.println("Done drawing thick lines!");
        long end = System.nanoTime();
        System.out.println("Time taken (ns): " +
                (end - start) + ", Time taken(ms): " +
                ((end - start) / 1000 / 1000));
        start = end;

        //CHANGED THIS LINE
        path = calculatePath(LEFT, TOP, RIGHT, BOTTOM);
        
        System.out.println("Done drawing vertical lines!");
        end = System.nanoTime();
        System.out.println("Time taken (ns): " +
                (end - start) + ", Time taken(ms): " +
                ((end - start) / 1000 / 1000));
        start = end;

        // Thin horizontal lines
        g2.setPaint(lightGreen);
        g2.setStroke(STROKE1PX);
        g2.draw(path); //CHANGED THIS LINE

        System.out.println("Done drawing horizontal lines!");
        end = System.nanoTime();
        System.out.println("Time taken (ns): " +
                (end - start) + ", Time taken(ms): " +
                ((end - start) / 1000 / 1000));

        System.out.println();
    }

    private GeneralPath path = new GeneralPath();

    public GeneralPath calculatePath(int LEFT, int TOP, int RIGHT, int BOTTOM) {

        path.reset();
        // Thin vertical lines

        for (int i = LEFT, wInc = ((int) WIDTH) / 50; i <= RIGHT; i += wInc) {
            path.moveTo(i, TOP);
            path.lineTo(i, BOTTOM);
        }

        // Thin horizontal lines
        for (int i = TOP, hInc = ((int) HEIGHT) / 50; i <= BOTTOM; i += hInc) {
            path.moveTo(LEFT, i);
            path.lineTo(RIGHT, i);
        }

        return path;
    }
 }
	/*
	I dont really have this problem: here is results from your version
	Start of drawLines(): 82086490370339
	Done drawing thick lines!
	Time taken (ns): 76994, Time taken(ms): 0
	Done drawing vertical lines!
	Time taken (ns): 54858, Time taken(ms): 0
	Done drawing horizontal lines!
	Time taken (ns): 57424, Time taken(ms): 0

	And here is results from this version:

	Start of drawLines(): 82268401323649
	Done drawing thick lines!
	Time taken (ns): 113886, Time taken(ms): 0
	Done drawing vertical lines!
	Time taken (ns): 53896, Time taken(ms): 0
	Done drawing horizontal lines!
	Time taken (ns): 187993, Time taken(ms): 0

	This version works even slower but has no glitching on my pc
	*/

	import java.awt.*;
	import java.awt.event.ActionEvent;
	import java.awt.event.ActionListener;
	import java.awt.geom.GeneralPath;
	import javax.swing.*;

	@SuppressWarnings("serial")
	public class SO_MCVE extends JPanel {

	private DrawingCanvas _drawingCanvas = null;

	private JButton repaintBtn;

	public SO_MCVE() {
	super(new BorderLayout());

	_drawingCanvas = new DrawingCanvas();
	_drawingCanvas.setPreferredSize(new Dimension(600, 600)); //CHANGED THIS LINE

	JLabel repaintLabel = new JLabel(
	"<html><div style=\"text-align: center;\">" +
	"REPAINT</html>");
	repaintLabel.setHorizontalAlignment(
	SwingConstants.CENTER);

	repaintBtn = new JButton();
	repaintBtn.add(repaintLabel);
	repaintBtn.addActionListener(new ActionListener() {
	public void actionPerformed(ActionEvent e) {

	_drawingCanvas.triggerRepaint();
	}
	});

	add(_drawingCanvas, BorderLayout.CENTER);
	add(repaintBtn, BorderLayout.PAGE_END);
	}

	private static void createAndShowGUI() {
	JFrame frame = new JFrame("StackOverflow MCVE for drawLine");

	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	frame.add(new SO_MCVE());
	frame.pack();
	frame.setVisible(true);
	}

	public static void main(String[] args) {

	SwingUtilities.invokeLater(new Runnable() {
	public void run() {
	UIManager.put("swing.boldMetal", Boolean.FALSE);
	createAndShowGUI();
	}
	});
	}
	}

	@SuppressWarnings("serial")
	class DrawingCanvas extends JComponent { //CHANGED THIS LINE TO JComponent

	public static final Color lightGreen = new Color(0, 255, 0, 180);
	public static final BasicStroke STROKE1PX = new BasicStroke(1.0f);
	public static final BasicStroke STROKE3PX = new BasicStroke(3.0f);

	private static final int LEFT = 50;
	private static final int RIGHT = 550;
	private static final int TOP = 50;
	private static final int BOTTOM = 550;

	private static final double WIDTH = 500.00d;
	private static final double HEIGHT = 500.00d;

	public DrawingCanvas() {
	setBackground(Color.BLACK);
	}


	public void triggerRepaint() {
	repaint();
	}

	public void paintComponent(Graphics g) {

	Graphics2D g2 = (Graphics2D) g;
	Dimension dim = getSize();
	int w = (int) dim.getWidth();
	int h = (int) dim.getHeight();

	// Clears the rectangle that was previously drawn
	g2.setPaint(Color.BLACK);
	g2.fillRect(0, 0, w, h);

	drawLines(g2, w, h);
	}

	/**
	* Draw the lines marking the x-y limits
	**/
	private void drawLines(Graphics2D g2, int w, int h) {

	long start = System.nanoTime();
	System.out.println("Start of drawLines(): " + start);

	// Thick lines
	g2.setPaint(Color.GREEN);
	g2.setStroke(STROKE3PX);
	g2.drawLine(LEFT, 0, LEFT, h);
	g2.drawLine(RIGHT, 0, RIGHT, h);
	g2.drawLine(0, TOP, w, TOP);
	g2.drawLine(0, BOTTOM, w, BOTTOM);

	System.out.println("Done drawing thick lines!");
	long end = System.nanoTime();
	System.out.println("Time taken (ns): " +
	(end - start) + ", Time taken(ms): " +
	((end - start) / 1000 / 1000));
	start = end;

	//CHANGED THIS LINE
	path = calculatePath(LEFT, TOP, RIGHT, BOTTOM);

	System.out.println("Done drawing vertical lines!");
	end = System.nanoTime();
	System.out.println("Time taken (ns): " +
	(end - start) + ", Time taken(ms): " +
	((end - start) / 1000 / 1000));
	start = end;

	// Thin horizontal lines
	g2.setPaint(lightGreen);
	g2.setStroke(STROKE1PX);
	g2.draw(path); //CHANGED THIS LINE

	System.out.println("Done drawing horizontal lines!");
	end = System.nanoTime();
	System.out.println("Time taken (ns): " +
	(end - start) + ", Time taken(ms): " +
	((end - start) / 1000 / 1000));

	System.out.println();
	}

	private GeneralPath path = new GeneralPath();

	public GeneralPath calculatePath(int LEFT, int TOP, int RIGHT, int BOTTOM) {

	path.reset();
	// Thin vertical lines

	for (int i = LEFT, wInc = ((int) WIDTH) / 50; i <= RIGHT; i += wInc) {
	path.moveTo(i, TOP);
	path.lineTo(i, BOTTOM);
	}

	// Thin horizontal lines
	for (int i = TOP, hInc = ((int) HEIGHT) / 50; i <= BOTTOM; i += hInc) {
	path.moveTo(LEFT, i);
	path.lineTo(RIGHT, i);
	}

	return path;
	}
	}