This question already has answers here:
Triangle Draw Method
(6 answers)
Closed 9 years ago.
Hey I know that it is simple to draw oval/rectangle and fill it using
g.fillOval(30, 40, 20, 20);
but how to draw a triangle? It would be the best if it would have random coordinates.
There are at least two basics ways you can achieve this, based on your needs.
You could use Polygon or you could make use the 2D Graphics Shape API
Which you might choose comes down to your requirements. Polygon requires you to know, in advance the position of the points within 3D space, where the Shape API gives you more freedom to define the shape without caring about the position in advance.
This makes the Shape API more flexible, in that you can define the shape once and simply translate the Graphics context as needed and repaint it.
For example...
Red is a Polygon, green is a Shape, which is translated into position...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.geom.Path2D;
import java.awt.geom.Point2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TriangleTest {
public static void main(String[] args) {
new TriangleTest();
}
public TriangleTest() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private TriangleShape triangleShape;
private Polygon poly;
public TestPane() {
triangleShape = new TriangleShape(
new Point2D.Double(50, 0),
new Point2D.Double(100, 100),
new Point2D.Double(0, 100)
);
poly = new Polygon(
new int[]{50, 100, 0},
new int[]{0, 100, 100},
3);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
g2d.fill(poly);
g2d.setColor(Color.GREEN);
g2d.translate(50, 100);
g2d.fill(triangleShape);
g2d.dispose();
}
}
public class TriangleShape extends Path2D.Double {
public TriangleShape(Point2D... points) {
moveTo(points[0].getX(), points[0].getY());
lineTo(points[1].getX(), points[1].getY());
lineTo(points[2].getX(), points[2].getY());
closePath();
}
}
}
Using the legacy Graphics class, this would be done by using the legacy method
drawPolygon(int[] x, int[] y, int pointCount).
The newer class Graphics2D supports a much nicer implementation using Path2Ds. You will need either the draw(Shape) or fill(Shape) method. Given the fact that almost everywhere in Java a Graphics object is actually a Graphics2D object, you can cast it so, that is the way to go, IMHO.
Graphics g = ...;
Graphics2D g2d = (Graphics2D) g;
Path2D.Double triangle = new Path2D.Double();
triangle.moveTo(x1, y1);
triangle.pathTo(x2, y2);
triangle.pathTo(x3, y3);
triangle.closePath();
g2d.fill(triangle);
Related
I'd like to make a Java panel that creates objects where the user clicks. Since my actual application uses a MVC approach I'd like also for these objects to be able to repaint themselves when a model is changed, and provide menus to change their properties.
I think that the best way to control their x and y locations would be to take a canvas based approach whereby the JPanel calls a draw method on these objects from the paintComponent method. This however will only draw the shape on the canvas and does not add the object itself loosing all abilities to control object properties. I'd be very grateful if someone could tell me the best approach for what I want to do.
I've created some sample code which can be seen below. When clicked I'd like the circle to change colour, which is implemented using a MouseListener (it basically represents changing the models properties in this small example). Also I'd just like to make sure that zooming in/out still works with any sample code/advice can provide so I've added buttons to zoom the objects in and out as a quick test.
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;
import java.awt.geom.Ellipse2D;
public class Main {
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ExamplePanel panel = new ExamplePanel();
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
});
}
//I could not get this to with when it extended JLayeredPane
private static class ExamplePanel extends JPanel {
private static final int maxX = 500;
private static final int maxY = 500;
private static double zoom = 1;
private static final Circle circle = new Circle(100, 100);
public ExamplePanel() {
this.setPreferredSize(new Dimension(maxX, maxY));
this.setFocusable(true);
Button zoomIn = new Button("Zoom In");
zoomIn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
zoom += 0.1;
repaint();
}
});
add(zoomIn);
Button zoomOut = new Button("Zoom Out");
zoomOut.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
zoom -= 0.1;
repaint();
}
});
add(zoomOut);
// add(circle); // Comment back in if using JLayeredPane
}
#Override
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.scale(zoom, zoom);
super.paintComponent(g);
circle.paint(g); // Comment out if using JLayeredPane
}
}
static class Circle extends JPanel {
private Color color = Color.RED;
private final int x;
private final int y;
private static final int DIMENSION = 100;
public Circle(int x, int y) {
// setBounds(x, y, DIMENSION, DIMENSION);
this.x = x;
this.y = y;
addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
color = Color.BLUE;
}
#Override
public void mouseReleased(MouseEvent e) {
}
});
}
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setPaint(color);
g2.fillOval(x, y, DIMENSION, DIMENSION);
}
// I had some trouble getting this to work with JLayeredPane even when setting the bounds
// In the constructor
// #Override
// public void paintComponent(Graphics g) {
// Graphics2D g2 = (Graphics2D) g;
// g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// g2.setPaint(color);
// g2.fillOval(x, y, DIMENSION, DIMENSION);
// }
#Override
public Dimension getPreferredSize(){
return new Dimension(DIMENSION, DIMENSION);
}
}
}
As an aside I did try using a JLayeredPane(useful because I'd also like to layer my objects) but could not get my objects to even render. I know it has no default layout manager so tried calling setBounds in the circle in the constructor, but sadly it did not work. I know it's better to use a layout manager but can't seem to find one suitable for my needs!
Thanks in advance.
Don't override paint components, use paintComponent and don't forget to call super.paintComponent
A component already has a concept of "location", so when painting, the top left position of your component is actually 0x0
What you are doing is actually painting beyond the boundaries of you component
For example, if you place your Circle at 100x100 and then did...
g2.fillOval(x, y, DIMENSION, DIMENSION);
You would actually start painting at 200x200 (100 for the actual location of the component and 100 for you additional positioning).
Instead use
g2.fillOval(x, y, DIMENSION, DIMENSION);
And go back and try using JLayeredPane.
You could actually write your own layout manager that takes the location of the component and it's preferred size and updates the components bounds and then apply this to a JLayeredPane. This gives you the "benefits" of an absolute layout, but keeps you within how Swing works to update its components when things change.
You should also be careful with doing anything like...
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
The Graphics context is a shared resource. That means, anything you apply to, will still be in effect when the next component is painted. This may produce some strange results.
Instead try using...
Graphics2D g2 = (Graphics2D) g.create();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
//...
g2.dispose();
Updated
For zooming I would take a closer look at JXLayer (or JLayer in Java 7)
The JXLayer (and excellent PBar extensions) have gone quite on the net, so you can grab a copy from here
(I tried finding a better example, but this is the best I could do with the limited time I have available)
Updated with working zooming example
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.RenderingHints;
import java.util.HashMap;
import java.util.Map;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import org.jdesktop.jxlayer.JXLayer;
import org.pbjar.jxlayer.demo.TransformUtils;
import org.pbjar.jxlayer.plaf.ext.transform.DefaultTransformModel;
public class TestJLayerZoom {
public static void main(String[] args) {
new TestJLayerZoom();
}
public TestJLayerZoom() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JXLayer<JComponent> layer;
private DefaultTransformModel transformModel;
private JPanel content;
public TestPane() {
content = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridy = 0;
JLabel label = new JLabel("Hello");
JTextField field = new JTextField("World", 20);
content.add(label, gbc);
content.add(field, gbc);
gbc.gridy++;
gbc.gridwidth = GridBagConstraints.REMAINDER;
final JSlider slider = new JSlider(50, 200);
slider.addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
int value = slider.getValue();
double scale = value / 100d;
transformModel.setScale(scale);
}
});
content.add(slider, gbc);
transformModel = new DefaultTransformModel();
transformModel.setScaleToPreferredSize(true);
Map<RenderingHints.Key, Object> hints = new HashMap<>();
//hints.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
//hints.put(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
//hints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
layer = TransformUtils.createTransformJXLayer(content, transformModel, hints);
setLayout(new BorderLayout());
add(layer);
}
}
}
I've left the rendering hints in to demonstrate their use, but I found that they screwed with the positing of the cursor within the text field, but you might like to have a play
I'd just like to add that I fixed the zooming issue not in the way suggested by the answer, but just by keeping the line that applied a scaled transform call in the ExamplePanel paintComponent method:
g2.scale(zoom, zoom);
I thought that this was the nicest implementation since none of the components require any knowledge about zooming and it seemed far simpler than JLayer since I only required basic zooming functionalities.
I have a Graphics2D object and I want to use its drawString method. I can call that method and pass a String and (x, y) positions, which is very nice. However, I also have the possibility to change the font of my Graphics2D object, using the setFont method, which expects a Font object. This is also very nice. Unfortunately this is not enough for me, because I intend to define multiple font texts to my Font object.
This is the textual representation I would like to transfer to my Font object:
font-family:"Lucida Grande", "Lucida Sans Unicode", Verdana, Arial, Helvetica, sans-serif
I have seen that I have the possibility to use the AttributedCharacterIterator interface to solve my problem, however, I am not sure how should I use that. I have seen that there is actually an implementation called AttributedString, which has a set of Attributes, but I am not sure how could I create an AttributedString object which could be used by the constructor of Font in such a way that my Graphics2D object will recognize the multiple fonts and apply them when I call drawString.
EDIT:
public static AttributedString getFontByAttributes(String atts, String value)
{
String[] attributes = atts.split(",");
AttributedString attributedString = new AttributedString(value);
for (int attributeIndex = 0; attributeIndex < attributes.length; attributeIndex++)
{
attributedString.addAttribute(TextAttribute.FONT, attributes[attributeIndex].trim());
}
return attributedString;
}
//...
public void drawTitle(Graphics2D g2d)
{
//...
g2d.drawString(getFontByAttributes(Settings.titleFontString, Settings.title).getIterator(), Settings.headerWidthOffset, Settings.headerHeightOffset);
//...
}
In the code above I have tried with Andale Mono, which is known on the system where I test this application, however, in the generated graphics, the text is drawn in Times New Roman font. Something is wrong and unfortunately I don't have a clue about what could I be missing.
Basically, AttributedString provides methods to allow you to apply rendering attributes to a String. Seems obvious really.
After that, you can pass the AttributedString's AttributedCharacterIterator to Graphics2D for rendering...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.font.LineMetrics;
import java.awt.font.TextAttribute;
import java.text.AttributedString;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestAttributedString {
public static void main(String[] args) {
new TestAttributedString();
}
public TestAttributedString() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
AttributedString text = new AttributedString("Bunny rabits and flying ponies");
text.addAttribute(TextAttribute.FONT, new Font("Arial", Font.BOLD, 24), 0, "Bunny rabits".length());
text.addAttribute(TextAttribute.FOREGROUND, Color.RED, 0, "Bunny rabits".length());
text.addAttribute(TextAttribute.FONT, new Font("Arial", Font.BOLD & Font.ITALIC, 32), 17, 17 + "flying ponies".length());
text.addAttribute(TextAttribute.FOREGROUND, Color.BLUE, 17, 17 + "flying ponies".length());
FontMetrics fm = g2d.getFontMetrics();
LineMetrics lm = fm.getLineMetrics(text.getIterator(), 0, text.getIterator().getEndIndex(), g);
g2d.drawString(text.getIterator(), 0, (int)lm.getAscent() + lm.getHeight());
g2d.dispose();
}
}
}
You can check out this for more details
Graphics2D has a drawString(AttributedCharacterIterator, int, int) method that you'll want to use.
Simply build up your AttributedString with all the different TextAttribute.FONT properties you want for each specific sub-range of the string, then call:
g2d.drawString(myAttributedString.getIterator(), x, y);
I am really new in Java. Thought I had figure some stuff out by now, but I have a problem that proves otherwise!
Ok! Here it is. I have this code (Edited - Not original):
import java.util.*;
import java.awt.*;
public class MyClass extends HisClass
{
public void drawRectangle(int width, int height)
{
int x1 = this.getXPos();
int y1 = this.getYPos();
java.awt.Graphics.drawRect(x1, y1, width, height);
}
public static void main(String[] args)
{
AnotherClass theOther = new AnotherClass();
MyClass mine = new MyClass(theOther);
mine.move();
}
}
The error it gives me is this:
MyClass.java:66: error: non-static method drawRect(int,int,int,int) cannot be referenced from a static context
Can you please provide me with a solution?
It would be very appreciated. Thanks.
java.awt.Graphics.drawRect(x1, y1, width, height);
drawRect method is not static.. You should get an instance of your Graphics class somehow to use it: -
(graphicsInstance).drawRect(x1, y1, width, height);
Since Graphics class is abstract, so you need to find appropriate way to instantiate your Graphics object, to get graphicsInstance
You can use GraphicsContext to draw whatever you want to.. GraphicsContext is an object belonging to Graphics class which you can use to drawRect()
See these post. Might be useful: -
How do I initialize a Graphics object in Java?
what is a graphics context (In Java)?
Here is some example code that draws a Rectangle using drawRect() onto the JPanel by overriding its paintComponent(Graphics g) method and adding it to the JFrame:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class DrawRect extends JPanel {
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
//draw our rect
g.setColor(Color.blue);
g.drawRect(10, 10, 100, 50);
}
//or else we wont see the JPanel
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setTitle("DrawRect");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new DrawRect());
frame.pack();
frame.setVisible(true);
}
}
Write a program that fills the window with a larrge ellipse. The ellipse shoud touch the window boundaries, even if the window is resized.
I have the following code:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import javax.swing.JComponent;
public class EllipseComponent extends JComponent {
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
Ellipse2D.Double ellipse = new Ellipse2D.Double(0,0,150,200);
g2.draw(ellipse);
g2.setColor(Color.red);
g2.fill(ellipse);
}
}
And the main class:
import javax.swing.JFrame;
public class EllipseViewer {
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(150, 200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
EllipseComponent component = new EllipseComponent();
frame.add(component);
frame.setVisible(true);
}
}
in your EllipseComponent you do:
Ellipse2D.Double ellipse = new Ellipse2D.Double(0,0,getWidth(),getHeight());
I'd also recommend the changes given by Hovercraft Full Of Eels. In this simple case it might not be an issue but as the paintComponent method grows in complexity you realy want as little as possible to be computed in the paintComponent method.
Do not resize components within paintComponent. In fact, do not create objects or do any program logic within this method. The method needs to be lean, fast as possible, do drawing, and that's it. You must understand that you do not have complete control over when or even if this method is called, and you certainly don't want to add code to it unnecessarily that may slow it down.
You should create your ellipse in the class's constructor. To resize it according to the JComponent's size and on change of size, use a ComponentListener.:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import javax.swing.JComponent;
public class EllipseComponent extends JComponent {
Ellipse2D ellipse = null;
public EllipseComponent {
ellipse = new Ellipse2D.Double(0,0,150,200);
addComponentListener(new ComponentAdapter() {
public void componentResized(ComponentEvent e) {
// set the size of your ellipse here
// based on the component's width and height
}
});
}
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
g2.draw(ellipse);
g2.setColor(Color.red);
g2.fill(ellipse);
}
}
Caveat: code not run nor tested
Could any body diagnose the problem I am facing?
As you run the demo you can see the middle part left blank, I need to fill the entire area..
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class FillDemo
{
public static void main(String aths[])
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel pnl = new PolygonDemo();
pnl.setSize(100, 200);
f.getContentPane().add(pnl);
f.setSize(400,280);
f.setLocation(200,200);
f.setVisible(true);
}
}
class PolygonDemo extends JPanel
{
public PolygonDemo()
{
setBackground(Color.white);
}
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
Polygon p=new Polygon();
p.addPoint(100,0);
p.addPoint(100,100);
p.addPoint(0,100);
p.addPoint(0,0);
p.addPoint(80,0);
p.addPoint(80,20);
p.addPoint(40,20);
p.addPoint(40,40);
p.addPoint(80,40);
p.addPoint(80,100);
p.addPoint(20,100);
p.addPoint(20,80);
p.addPoint(60,80);
p.addPoint(60,60);
p.addPoint(20,60);
p.addPoint(20,0);
p.addPoint(0,0);
g2.setColor(Color.BLACK);
g2.draw(p);
g2.setColor(new Color(120,250,100));
g2.fillPolygon(p);
//g2.fillPolygon(p.xpoints,p.ypoints,p.npoints);
}
}
Many thanks in advance
Your polygon intersects with itself. The fillPolygon method can not clearly decide which point is in and which is out. From the fillPolygon javadoc:
The area inside the polygon is defined using an even-odd fill rule, also known as the alternating rule.
Perhaps you can split your polygon into three single ones.
Draw Rectangle and Fill Color.....
public void paint(Graphics g)
{
int[] xPoints = {100,50,150};
int[] yPoints = {100,200,200};
g.setColor(Color.black);
g.drawPolygon(xPoints, yPoints, 3);
g.setColor(Color.red);
g.fillPolygon(xPoints, yPoints, 3);
}