Develop Reference

I want to iterate through an arraylist of Images

I have an arraylist of images, I am trying to have each image, slide through the screen repeatedly..
public class GraphicsT extends JPanel implements ActionListener {
Timer timer = new Timer(1, this);
Image image;
Image image2;
int x1;
int x2;
int y1;
int y2;
int num;
List<String> imageList1 = new ArrayList<String>();
GraphicsT() {
imageList1.add("image/java.jpeg");
imageList1.add("image/slide.jpg");
imageList1.add("image/giphy.gif");
x1 = 100;
y1 = 100;
x2 = 200;
y2 = 200;
num = 0;
}
public void paint(Graphics g) {
ImageIcon i2 = new ImageIcon("image/street.jpg");
image2 = i2.getImage();
g.drawImage(image2, 0, 0, null);
for (int i = 1; i < imageList1.size(); i++) {
ImageIcon im = new ImageIcon(imageList1.get(i));
image = im.getImage();
g.drawImage(image, x1, y1, x2, y2, 100, 120, 120, 240, null);
System.out.println(imageList1.get(i));
}
timer.start();
}
#Override
public void actionPerformed(ActionEvent e) {
num++;
if (num % 100 == 0) {
x1 = x1 + 10;
x2 = x2 + 10;
}
if (x2 >= 570) {
// end reached
x1 = 0;
x2 = 100;
}
repaint();
}
}
public class GraphicsApp extends JFrame {
GraphicsT gt = new GraphicsT();
public GraphicsApp() {
this.setTitle("Multiple Slide");
this.setSize(450, 400);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
this.add(gt);
}
public static void main(String[] args) {
new GraphicsApp();
}
}
my current code can only pick one image, but i want a situation whereby after the first images goes out of the screen, the second image can follow, then the third, and so on...
Please help will be much appreciated.

Several issues:
you should be overriding paintComponent() not paint() and you invoke super.paintComponent(...) to make sure the background is painted first.
a painting method is for painting only. You should NOT be doing I/O to read the images. The images should be read in the constructor of your class
You should NOT start the Timer in the painting method. The Timer is started in the constructor.
Your basic painting code is wrong. You should have a couple of instance variables, a) the "currentImage", b) "imageNumber". Then in the painting method you simply paint the currentImage at the x/y location.
In the ActionListener, when the image is off the screen you increment the "imageNumber" and copy the image from the ArrayList to the "currentImage". Then you reset the x/y location so the image is painted starting from the right.
When the "imageNumber" reaches the end of the ArrayList you reset it back to 0.

Way to repaint this JPanel after given count

Hello I would like to prevent graphics drawing and drawing again but I don't know how to do, I just want my panel delete all painted graphics and restart with same code. I tried some methods posted here but no one does the job.
public class Main extends JPanel implements ActionListener {
Timer timer;
private double angle = 444;
private double scale = 1;
private double delta = 0.0001;
RoundRectangle2D.Float r = new RoundRectangle2D.Float();
int counter = 0;
public Main() {
timer = new Timer(55, this);
timer.start();
}
public void paint(Graphics g) {
counter++;
int h = getHeight();
int w = getWidth();
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(new Color(randomNumber(0, 155), randomNumber(0, 255),randomNumber(0, 155), randomNumber(0, 255)));
drawCircles(g2d, getWidth()/2, getHeight()/2, 250);
if(counter > 200){
g2d.clearRect (0, 0, getWidth(), getHeight());
super.paintComponent(g2d);
counter = 0;
}
}
public int randomNumber(int min, int max) {
int c = new Random().nextInt((max - min) + 1);
return c;
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setUndecorated(true);
Dimension dim = new Dimension(Toolkit.getDefaultToolkit()
.getScreenSize().width, Toolkit.getDefaultToolkit()
.getScreenSize().height);
frame.setSize(dim);
frame.setLocation(0, 0);
frame.setBackground(new Color(0, 0, 0, 255));
frame.add(new Main());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
void drawCircles(Graphics graphics, int xMid, int yMid, int radius) {
// end recursion
if(radius < 5)
return;
// Draw circle
// start recursion
//left
drawCircles(graphics, xMid-radius, yMid, radius / 2);
((Graphics2D) graphics).rotate(angle);
graphics.drawOval(xMid - radius, yMid - radius, radius * 2, radius * 2);
//right
drawCircles(graphics, xMid+radius, yMid, radius / 2);
graphics.drawOval(xMid - radius, yMid - radius, radius * 2, radius * 2);
((Graphics2D) graphics).rotate(angle);
((Graphics2D) graphics).rotate(angle);
((Graphics2D) graphics).setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
((Graphics2D) graphics).setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
}
public void actionPerformed(ActionEvent e) {
if (scale < 0.01)
delta = -delta;
else if (scale > 0.99)
delta = -delta;
scale += delta;
angle += 0.001;
repaint();
}
}

I am not sure I understand you fully, but you can use a JToggleButton (for example) where is the toggle button is down it prevents drawing. I can see something like this inside your drawCircles() method:
void drawCircles(Graphics graphics, int xMid, int yMid, int radius)
{
if(!toggleBtn.isSelected() // the toggle button is pressed
{
// draw something
}
}
In your example, you are drawing two circles and two ovals. If I understood you correctly, you want to be able to pause in the middle of the method, for example, and only draw the first circle. Then, at some point, you want to continue drawing the two ovals and the remaining circle. Unfortunately, you cannot do that. You cannot stop (or pause) a method in the middle of it.
Methods have to execute to completion (whether to the end, or an exception is thrown). However, you can create some kind of task to draw ONE shape (for example, a circle). If you create multiple tasks, you can draw many circles. To accomplish this, you will need to learn about Concurrency and probably about Java Tasks. You can have these tasks execute in some kind of order and because of concurrency, you could pause and resume these drawing tasks the way I think you would want.

How can I rotate an onscreen component in Java?

import javax.swing.*;
import java.awt.*;
public class JFrameAnimationTest extends JFrame {
public static void main(String[] args) throws Exception{
AnimationPanel animation = new AnimationPanel();
JFrameAnimationTest frame = new JFrameAnimationTest();
frame.setSize(600, 480);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(animation);
frame.setVisible(true);
for(int i = 0; i < 100; i++) {
animation.incX(1);
//animation.incY(1);
animation.repaint();
Thread.sleep(10);
}
}
}
class AnimationPanel extends JPanel {
int x = 10;
int y = 10;
public AnimationPanel() {
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.BLUE);
g.drawRect(x, y, 20, 20);
g.fillRect(x, y, 20, 20);
}
protected void incX(int X) {
x += X;
}
protected void incY(int Y) {
y += Y;
}
}
So anyways theres my code. It probably looks a bit jumbled as I am not used to stackoverflow just yet so I apologize.
Here's my question: This program makes this small rectangle slowly move to the right; how can I add rotation to the rectangles movement during that time period?

Note: I haven't actually compiled this code, but you get the gist.
public void paintComponent( Graphics g )
{
super.paintComponent( g );
Graphics2D g2d = (Graphics2D) g;
// The 20x20 rectangle that you want to draw
Rectangle2D rect = new Rectangle2D.Double( 0, 0, 20, 20 );
// This transform is used to modify the rectangle (an affine
// transform is a way to do operations like translations, rotations,
// scalings, etc...)
AffineTransform transform = new AffineTransform();
// 3rd operation performed: translate the rectangle to the desired
// x and y position
transform.translate( x + 10, y + 10 );
// 2nd operation performed: rotate the rectangle around the origin
transform.rotate( rotation );
// 1st operation performed: translate the rectangle such that it is
// centered on the origin
transform.translate( -10, -10 );
// Apply the affine transform
Shape s = transform.createTransformedShape( rect );
// Fill the shape with the current paint
g2d.fill( s );
// Stroke the edge of the shape with the current paint
g2d.draw( s );
}
Also note that you should really be using something like a javax.swing.Timer when you modify x, y, and rotation and when you call repaint(). That way all of it happens on the event dispatch thread.

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();
}
}