Clicking on an oval in JPanel

[chielt]

I am making a paint applet, which draws shapes on a 'canvas' by storing shapes into an arraylist (using the Graphics class).

I need to be able te erase complete shapes by clicking them with the eraser tool.

I managed to make this work for rectangles, filled rectangles and lines. I am not managing to do this with ovals. This because the radius is not equal along the entire circumference. How can I calculate whether a user clicked withing the oval, or on the (variable) stroke of an open oval?

For an example this is what the code for the filled rectangle:

// p1 and p2 are startpoint and endpoint (class vars).
// p is the point clicked by the user
// iMargin is the amount of pixel the user is allowed to miss the shape by (class var).

private boolean fillRectRaak(Point p) 
{
	if(p.x <= this.p2.x + iStroke + iMargin &&
			p.x >= this.p1.x - iStroke - iMargin)
	{
		if(p.y <= this.p2.y + iStroke + iMargin &&
		p.y >= this.p1.y - iStroke - iMargin)
		{
			return true;
		}
	}
	return false;
}

[mrmatt1111]

http://java.sun.com/javase/6/docs/ap...Ellipse2D.html

the method "contains(...)"

[chielt]

I am not using the java.awt.geom. I am using the Graphics class. When trying to use a Ellipse2D.Double it tells me that the method Double(double, double, double, double) is undefined for the type Ellipse2D.

Is there a way to continue using the Graphics class or can someone help me implement the Ellipse2D class?

[Fubarable]

If you can, you should post the code that doesn't work, that's throwing the errors, and we can then help point out what's wrong. Also, if you can post a small compilable (or attempt at a compilable) program that we can compile, test and possibly run, then we could likely get you focused help a lot quicker. Much luck!

[chielt]

		switch (iToolID) 
		{
	        case PEN_TOOL: 										; break;
	        case LINE_TOOL: 		g.drawLine(p1.x, p1.y, p2.x, p2.y)	; break;
	        case RECT_TOOL: 		g.drawRect(xy.x, xy.y, wh.width, wh.height)	; break;
	        case FILL_RECT_TOOL: 	g.fillRect(xy.x, xy.y, wh.width, wh.height)	; break;
	        //case OVAL_TOOL:  		g.drawOval(xy.x, xy.y, wh.width, wh.height)	; break;
	        case OVAL_TOOL:  		Ellipse2D.Double(2.0,2.0,2.0,2.0)	; break;
	        case FILL_OVAL_TOOL:  	g.fillOval(xy.x, xy.y, wh.width, wh.height)	; break;
	        case TEXT_TOOL: 		g.drawString(s, xy.x, xy.y)		; break;
		}

That is the part that doesn't work.

A link to my complete project till now:
Download Schets.rar

The class that creates an object of a shape is "SchetsElementen". Most of the variable names are in Dutch, I can translate any words that give problems.

[Fubarable]

You need to add a new Ellipse2D into a List<Shape> and then iterate through this list in the paintComponent method drawing each Shape as you go. For instance, here's a simple example that draws an Ellipse2D with the left mouse button and erases the most recent shape with the right button:

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;
import java.util.List;

import javax.swing.*;

@SuppressWarnings("serial")
public class ShapeEg extends JPanel {
  private List<Shape> shapeList = new ArrayList<Shape>();
  private Shape tempShape = null;

  public ShapeEg() {
    setBackground(Color.white);
    setPreferredSize(new Dimension(500, 500));
    MouseAdapter adapter = new MyMouseAdapter();
    addMouseListener(adapter);
    addMouseMotionListener(adapter);
  }

  @Override
  protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
        RenderingHints.VALUE_ANTIALIAS_ON);
    g2.setColor(Color.lightGray);
    if (tempShape != null) {
      g2.draw(tempShape);
    }
    g2.setColor(Color.blue);
    g2.setStroke(new BasicStroke(4));
    for (Shape s : shapeList) {
      g2.draw(s);
    }
  }

  private class MyMouseAdapter extends MouseAdapter {
    Point start = null;
    Point end = null;

    @Override
    public void mousePressed(MouseEvent me) {
      if (me.getButton() == MouseEvent.BUTTON1) {
        start = me.getPoint();        
      } 
      
      // else if right mouse button pressed and there are shapes 
      // held in our shape list -- delete a shape if the button presses
      // on top of one.
      else if (me.getButton() == MouseEvent.BUTTON3 && shapeList.size() > 0) {
        // iterate backwards to delete most recent shape
        for (int i = shapeList.size() - 1; i >= 0; i--) {
          if (shapeList.get(i).contains(me.getPoint())) {
            shapeList.remove(i);
            repaint();
            break;
          }
        }
      }
    }

    @Override
    public void mouseDragged(MouseEvent me) {
      if (start == null) {
        return;
      }
      end = me.getPoint();
      int x = Math.min(start.x, end.x);
      int y = Math.min(start.y, end.y);
      int w = Math.abs(start.x - end.x);
      int h = Math.abs(start.y - end.y);
      tempShape = new Ellipse2D.Double(x, y, w, h);
      repaint();
    }

    @Override
    public void mouseReleased(MouseEvent me) {
      if (me.getButton() == MouseEvent.BUTTON1) {
        end = me.getPoint();
        int x = Math.min(start.x, end.x);
        int y = Math.min(start.y, end.y);
        int w = Math.abs(start.x - end.x);
        int h = Math.abs(start.y - end.y);
        shapeList.add(new Ellipse2D.Double(x, y, w, h));
        start = null;
        end = null;
        tempShape = null;
        repaint();
      }
    }

  }

  private static void createAndShowGUI() {
    JFrame frame = new JFrame("ShapeEg Application");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(new ShapeEg());
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });

  }
}

[chielt]

A friend helped me out. I used the following method:

		private boolean fillOvalRaak(Point p) {
			
		    Dimension wh = puntAfstand(p1, p2);
			int x1=(p2.x+p1.x)/2; 
			int y1=(p2.y+p1.y)/2;
			int xx=2*(p.x-x1)/wh.width; 
			int yy=2*(p.y-y1)/wh.height;
			if (xx*xx+yy*yy<1)
			{
				return true;
			}
			
			return false;
		}