Develop Reference

How can I set the origin of a component I'm trying to make into a JLabel from top-left to bottom-left?

I'm trying to make a 2D sprite game, and as of now, the JLabel on which the image draws starts at the top left. This presents a problem when I try to move the sprite laterally because if the sprite that's supposed to come next is taller than the previous, it won't be standing on the floor as it should. In this picture, the left is the starting, the middle is what it does now with the top-left as 0,0, and the right is what it should be, screen-grabbed from the actual game.
below is my paint for the model of Mario:
public void paint(Graphics g){
Graphics2D g2 = (Graphics2D) g;
g2.drawImage(sprite, 0,0, null);
}
and below is my paintComponent that's in a class that when run, renders the image onto the screen:
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
marioSprite.paint(g2);
}
and how I extract an image from a file:
//generate URL
public static URL urlGenerator(String name){
URL u = lookup().lookupClass().getResource(name);
return u;
}
//return image with filtered color
public static BufferedImage generateAndFilter(BufferedImage b, URL u){
try{
b = ImageIO.read(u);
int width = b.getWidth();
int height = b.getHeight();
int[] pixels = new int[width * height];
b.getRGB(0, 0, width, height, pixels, 0, width);
for (int i = 0; i < pixels.length; i++) {
if (pixels[i] == 0xFFff00fe) {
pixels[i] = 0x00ff00fe;
}
}
BufferedImage newSprite = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
newSprite.setRGB(0, 0, width, height, pixels, 0, width);
b = newSprite;
}
catch(IOException e){
System.out.println("sprite not found");
e.printStackTrace();
}
return b;
}
each instance of Mario has a sprite set by:
public void setSprite(String spriteName){
URL spriteAtLoc = Utils.urlGenerator(spriteName);
this.sprite = Utils.generateAndFilter(sprite,spriteAtLoc);
this.currentSpriteName = spriteName;
}

how to make ellipse in java swing JPanel TitledBorder?

how to draw this in java swing TitledBorder or any other panel ?
i tried the following code and didn't work, kept drawing half ellipse and the other half was cut.
#Override
public void paintBorder(Component c, Graphics g, int x, int y, int width,
int height) {
Graphics2D g2 = (Graphics2D)g;
g2.setColor(Color.BLUE);
FontMetrics m = c.getFontMetrics(getTitleFont());
Ellipse2D shape = new java.awt.geom.Ellipse2D.Float(2, -20,m.stringWidth(title)+10, m.getHeight()+40);
g2.fill(shape);
g2.draw(shape);
super.paintBorder(c, g, x, y, width, height);
}

JPanel repaint from another class

I have a JPanel which displays an image. In a separate class, I'm reading from an xml file points. I am firstly creating an arraylist of triangles from these points. However I need to show the triangles on the image, i.e. draw them on! (yes this should be simple). But as these points and triangles are created in another class, I do not seem to be able to draw them on the already-displayed image within the GUI class. I have tried creating a ArrayList in the JPanel itself, which I update and then want to repaint, although it will not let me do this as shown below:
Class
triangles = clips.getTriangles();
tempPanel.setTriangles(triangles){
JPanel
public void settriangles(ArrayList<Point[]> t){
triangles = t;
repaint();
}
My only other idea is for the JPanel to have a listener waiting for when triangles are returned, updating the field and hence then repainting.
Any ideas?
Thanks
Edit: Code for Drawing
public void settriangles(ArrayList<Point[]> t){
triangles = t;
repaint();
}
public void paintComponent(Graphics g) {
System.out.println("in paint component");
if (g != null) {
Graphics2D graphics = (Graphics2D) g;
try {
Rectangle back_rect = new Rectangle(0, 0, getWidth(),
getHeight());
graphics.setColor(GuiComponentGenerator.GUI_BACKGROUND_COLOUR);
graphics.fill(back_rect);
if (image != null) {
int width = Math.round(image.getWidth() * magnification);
int height = Math.round(image.getHeight() * magnification);
Rectangle image_rect = new Rectangle(offset.x, offset.y,
width, height);
graphics.setColor(Color.BLACK);
graphics.draw(image_rect);
graphics.drawImage(image, offset.x, offset.y, width,
height, null);
graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
for(int pos = 0; pos < triangles.size(); pos++){
Point[] current = triangles.get(pos);
ArrayList<Point> current_triangle = new ArrayList<Point>();
current_triangle.add(current[0]);
current_triangle.add(current[1]);
current_triangle.add(current[2]);
drawRegion(graphics, current_triangle);
}
}
}
finally {
graphics.dispose();
}
}
private void drawRegion(Graphics2D graphics, ArrayList<Point> points) {
graphics.setColor(trans_grey);
Area area = getArea(points);
graphics.fill(area);
graphics.setStroke(new BasicStroke(2));
graphics.setColor(Color.BLACK);
graphics.draw(area);
}
private Area getArea(ArrayList<Point> points) {
Area area = new Area(getPath(points, true));
return area;
}
private GeneralPath getPath(ArrayList<Point> points, boolean close_path) {
GeneralPath path = new GeneralPath();
Point current_screen_point = calculateScreenPoint(points.get(0));
path.moveTo(current_screen_point.x, current_screen_point.y);
for (int point_num = 1; point_num < points.size(); point_num++) {
current_screen_point = calculateScreenPoint(points.get(point_num));
path.lineTo(current_screen_point.x, current_screen_point.y);
}
if (close_path)
path.closePath();
return path;
}
public Point calculateScreenPoint(Point image_point) {
float h_proportion = (float) image_point.x / (float) image.getWidth();
float v_proportion = (float) image_point.y / (float) image.getHeight();
float image_width_in_panel = (float) image.getWidth() * magnification;
float image_height_in_panel = (float) image.getHeight() * magnification;
Point on_screen_point = new Point(0, 0);
on_screen_point.x = offset.x
+ Math.round(h_proportion * image_width_in_panel);
on_screen_point.y = offset.y
+ Math.round(v_proportion * image_height_in_panel);
return on_screen_point;
}

Your paintComponent leaves a little to be desired ;)
Firstly, you should never get a null graphics unless the paint method has been called in correctly, which in case they deserve for it to fail.
You should try and use Graphics.create to create a copy of the incoming Graphics context. This allows you to mess with the Graphics properties (such as transforms etc) without adversly effecting the original
I don't know what the image is all about, but basically, if its null, your triangles will never paint (don't know if this is what you want or not).
I don't know what the offset relates to, but just in case, the 0x0 point is always the top, left corner of your component.
public void paintComponent(Graphics g) {
// This is important, you will to have a very good reason not to call this
super.paintComponent(g);
System.out.println("in paint component");
// Should never need this. You should never call the paintComponent
// directly.
// if (g != null) {
// Create a copy of the graphics, with which you can play...
Graphics2D graphics = (Graphics2D) g.create();
try {
Rectangle back_rect = new Rectangle(0, 0, getWidth(),
getHeight());
graphics.setColor(Color.GREEN);
graphics.fill(back_rect);
// What's this trying to do...
// Where do you produce this???
// Because I didn't know where the image was been produced
// I commented out the code, but you should be aware
// That if the image is null, you triangles will never paint...
// if (image != null) {
// int width = Math.round(image.getWidth() * magnification);
// int height = Math.round(image.getHeight() * magnification);
//
// Rectangle image_rect = new Rectangle(offset.x, offset.y,
// width, height);
// graphics.setColor(Color.BLACK);
// graphics.draw(image_rect);
// graphics.drawImage(image, offset.x, offset.y, width,
// height, null);
graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
for (int pos = 0; pos < triangles.size(); pos++) {
Point[] current = triangles.get(pos);
ArrayList<Point> current_triangle = new ArrayList<Point>(3);
current_triangle.add(current[0]);
current_triangle.add(current[1]);
current_triangle.add(current[2]);
drawRegion(graphics, current_triangle);
}
//} // From the image != null
} finally {
graphics.dispose();
}
}
I'd also suggest you have a read through
2D Graphics
Performing Custom Painting in Swing
If you haven't already ;)

This article will give you all the info you need http://java.sun.com/products/jfc/tsc/articles/painting/
but I think you are missing -
super.paintComponent(g);
public class MyPanel extends JPanel {
protected void paintComponent(Graphics g) {
// Let UI delegate paint first
// (including background filling, if I'm opaque)
super.paintComponent(g);
// paint my contents next....
}
}

I worked out how to draw triangles on the image, when passing through an arrayList, where each Point[] represents the points of the triangle.
Note that this is now in a single entire class which is passed the information, rather than trying to call repaint from another class.
public AnnotatedDisplayTriangles(BufferedImage image, String image_path, ArrayList<Point[]> triangles) {
this.image = image;
this.image_path = image_path;
this.triangles = triangles;
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Draw image centered.
int x = (getWidth() - image.getWidth())/2;
int y = (getHeight() - image.getHeight())/2;
g.drawImage(image, x, y, this);
Stroke drawingStroke = new BasicStroke(2);
Graphics2D graph = (Graphics2D)g;
graph.setStroke(drawingStroke);
graph.setPaint(Color.black);
for(int p = 0; p < triangles.size(); p++){
Point[] current_triangles = triangles.get(p);
for(int triangle = 0; triangle < current_triangles.length; triangle++ ){
Point current = current_triangles[triangle];
Point next;
if(triangle == current_triangles.length -1 )
next = current_triangles[0];
else
next = current_triangles[triangle + 1];
Line2D line = new Line2D.Double(current.x, current.y, next.x, next.y);
graph.draw(line);
}
}
}
public static void main(String image_path,ArrayList<Point[]> triangles, String panel_name) throws IOException {
String path = image_path;
BufferedImage image = ImageIO.read(new File(path));
AnnotatedDisplayTriangles contentPane = new AnnotatedDisplayTriangles(image, path, triangles);
// You'll want to be sure this component is opaque
// since it is required for contentPanes. Some
// LAFs may use non-opaque components.
contentPane.setOpaque(true);
int w = image.getWidth();
int h = image.getHeight();
JFrame f = new JFrame(panel_name);
// f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setContentPane(contentPane);
f.setSize(w,h);
f.setLocation(200,200);
f.setVisible(true);
}

Java Graphics2D Panning and Zooming / Translating and Scaling

I've got a JPanel I'm drawing onto and I'm trying to get it so that you can use the mouse wheel to "zoom" in and out by modifying the variable scale. Right now what happens is you can zoom in or out but all of the drawing shifts to the right and downwards when you zoom in and then back up and left when zooming out.
I want to make it so that it adjusts as if you were zooming in on the point at the center of the JPanel but I can't figure out how to calculate the right offset to translate by…
Anybody got an idea of how to do this, or even better a cleaner way of achieving this whole pan and zoom ability?
I am basically plotting a bunch of coordinates that came from a system where 0,0 is in the lower left corner and fall between the bounds:
xMin = 661208
xMax = 662618
yMin = 4291657
yMax = 4293285
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
double scale = details.getScale();
double xOffset = details.getxOffset();
double yOffset = details.getyOffset();
g2.scale(scale, -scale);
// Dividing offset by scale makes panning 1:1 with the cursor still. yMax to account for the
// fact we needed to flip around the y axis to make it right-side up.
g2.translate((-xMin + xOffset / scale), (-yMax + yOffset / scale));
// Code to draw stuff goes here. It uses coordinates between xMin-xMax and yMin-yMax to draw.
.
.
.
}

Here is an example with the wheel:
public class GraphicsOnly extends JPanel implements MouseWheelListener {
Shape[] shapes;
Dimension size;
double scale = 1.0;
private static int source = 100;
public GraphicsOnly() {
addMouseWheelListener(this);
size = new Dimension(10,10);
setBackground(new Color(240,200,200));
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
if(shapes == null) initShapes();
// Keep shapes centered on panel.
double x = (getWidth() - scale*size.width)/2;
double y = (getHeight() - scale*size.height)/2;
AffineTransform at = AffineTransform.getTranslateInstance(x, y);
at.scale(scale, scale);
g2.setPaint(Color.blue);
g2.draw(at.createTransformedShape(shapes[0]));
g2.setPaint(Color.green.darker());
g2.draw(at.createTransformedShape(shapes[1]));
g2.setPaint(new Color(240,240,200));
g2.fill(at.createTransformedShape(shapes[2]));
g2.setPaint(Color.red);
g2.draw(at.createTransformedShape(shapes[2]));
}
public Dimension getPreferredSize() {
int w = (int)(scale*size.width);
int h = (int)(scale*size.height);
return new Dimension(w, h);
}
private void initShapes() {
shapes = new Shape[3];
int w = getWidth();
int h = getHeight();
shapes[0] = new Rectangle2D.Double(w/16, h/16, w*7/8, h*7/8);
shapes[1] = new Line2D.Double(w/16, h*15/16, w*15/16, h/16);
shapes[2] = new Ellipse2D.Double(w/4, h/4, w/2, h/2);
size.width = w;
size.height = h;
}
public static void main(String[] args) {
GraphicsOnly app = new GraphicsOnly();
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add(new JScrollPane(app));
f.setSize(400, 400);
f.setLocation(200,200);
f.setVisible(true);
}
#Override
public void mouseWheelMoved(MouseWheelEvent e) {
// TODO Auto-generated method stub
if(e.getWheelRotation() >0){
source = source-e.getScrollAmount();
}else{
source = source+e.getScrollAmount();
}
scale = source/100.0;
System.out.println(scale);
repaint();
revalidate();
}
}

How to output a String on multiple lines using Graphics

My Program overrides public void paint(Graphics g, int x, int y); in order to draw some stings using g.drawString(someString, x+10, y+30);
Now someString can be quite long and thus, it may not fit on one line.
What is the best way to write the text on multiple line. For instance, in a rectangle (x1, y1, x2, y2)?

Thanks to Epaga's hint and a couple of examples on the Net (not so obvious to find! I used mainly Break a Line for text layout), I could make a component to display wrapped text. It is incomplete, but at least it shows the intended effect.
class TextContainer extends JPanel
{
private int m_width;
private int m_height;
private String m_text;
private AttributedCharacterIterator m_iterator;
private int m_start;
private int m_end;
public TextContainer(String text, int width, int height)
{
m_text = text;
m_width = width;
m_height = height;
AttributedString styledText = new AttributedString(text);
m_iterator = styledText.getIterator();
m_start = m_iterator.getBeginIndex();
m_end = m_iterator.getEndIndex();
}
public String getText()
{
return m_text;
}
public Dimension getPreferredSize()
{
return new Dimension(m_width, m_height);
}
public void paint(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
FontRenderContext frc = g2.getFontRenderContext();
LineBreakMeasurer measurer = new LineBreakMeasurer(m_iterator, frc);
measurer.setPosition(m_start);
float x = 0, y = 0;
while (measurer.getPosition() < m_end)
{
TextLayout layout = measurer.nextLayout(m_width);
y += layout.getAscent();
float dx = layout.isLeftToRight() ?
0 : m_width - layout.getAdvance();
layout.draw(g2, x + dx, y);
y += layout.getDescent() + layout.getLeading();
}
}
}
Just for fun, I made it fitting a circle (alas, no justification, it seems):
public void paint(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
FontRenderContext frc = g2.getFontRenderContext();
LineBreakMeasurer measurer = new LineBreakMeasurer(m_iterator, frc);
measurer.setPosition(m_start);
float y = 0;
while (measurer.getPosition() < m_end)
{
double ix = Math.sqrt((m_width / 2 - y) * y);
float x = m_width / 2.0F - (float) ix;
int width = (int) ix * 2;
TextLayout layout = measurer.nextLayout(width);
y += layout.getAscent();
float dx = layout.isLeftToRight() ?
0 : width - layout.getAdvance();
layout.draw(g2, x + dx, y);
y += layout.getDescent() + layout.getLeading();
}
}
I am not too sure about dx computation, though.

java.awt.font.TextLayout might be helpful. Here's a snippet of their example code:
Graphics2D g = ...;
Point2D loc = ...;
Font font = Font.getFont("Helvetica-bold-italic");
FontRenderContext frc = g.getFontRenderContext();
TextLayout layout = new TextLayout("This is a string", font, frc);
layout.draw(g, (float)loc.getX(), (float)loc.getY());
Rectangle2D bounds = layout.getBounds();
bounds.setRect(bounds.getX()+loc.getX(),
bounds.getY()+loc.getY(),
bounds.getWidth(),
bounds.getHeight());
g.draw(bounds);
Otherwise you could always use a Swing text element to do the job for you, just pass in the Graphics you want it to paint into.

Incrementally build your string, one word at a time, using Epaga's method to find the length of your string. Once the length is longer than your rectangle, remove the last word and print. Repeat until you run out of words.
It sounds like a bad algorithm, but for each line, it's really O(screenWidth/averageCharacterWidth) => O(1).
Still, use a StringBuffer to build your string!

Had some trouble myself this is my solution:
Graphics2D g=....
FontRenderContext frc = g.getFontRenderContext();
TextLayout layout = new TextLayout(text, font, frc);
String[] outputs = text.split("\n");
for(int i=0; i<outputs.length; i++){
g.drawString(outputs[i], 15,(int) (15+i*layout.getBounds().getHeight()+0.5));
Hope that helps.... simple but it works.

You can use a JLabel and embed the text with html.
JLabel.setText("<html>"+line1+"<br>"+line2);