Question

I have to create a Java paint/drawing application.

The JFrame app must support the following functions:
 Draw curves, specified by a mouse drag.
 Draw filled rectangles or ovals, specified by a mouse drag (don't worry about dynamically drawing the shape during the drag - just draw the final shape indicated).
 Shape selection (line, rectangle or oval) selected by a combo box OR menu.
 Color selection using radio buttons OR menu.
 Line thickness using a combo box OR menu.
 A CLEAR button.

I have most of it done, but can't seem to get the combo boxes for the shape and line thickness selections to work. Help!

Answer 1

Java Paint Application:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class PaintApp extends JApplet {

public static void main(String[] args) {
JFrame window = new JFrame("Paint Application");
SetPaintPanel content = new SetPaintPanel();
window.setContentPanel(content);
window.setSize(600,480);
window.setLocation(100,100);
window.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
window.setVisible(true);
}

public void init() {
setContentPanel( new SetPaintPanel() );
}

public static class SetPaintPanel extends JPanel
implements MouseListener, MouseMotionListener {

private final static int BLACK = 0,
RED = 1,
GREEN = 2,
BLUE = 3,
CYAN = 4,
MAGENTA = 5,
YELLOW = 6;

private int currentColor = BLACK;

private int prevX, prevY;

private boolean dragging;

private Graphics graphicsForDrawing;

SetPaintPanel() {
setBackground(Color.WHITE);
addMouseListener(this);
addMouseMotionListener(this);
}

public void paintComponent(Graphics g) {

super.paintComponent(g);

int width = getWidth();
int height = getHeight();

int colorSpacing = (height - 56) / 7;

g.setColor(Color.GRAY);
g.drawRect(0, 0, width-1, height-1);
g.drawRect(1, 1, width-3, height-3);
g.drawRect(2, 2, width-5, height-5);

g.fillRect(width - 56, 0, 56, height);

g.setColor(Color.WHITE);
g.fillRect(width-53, height-53, 50, 50);
g.setColor(Color.BLACK);
g.drawRect(width-53, height-53, 49, 49);
g.drawString("CLEAR", width-48, height-23);

g.setColor(Color.BLACK);
g.fillRect(width-53, 3 + 0*colorSpacing, 50, colorSpacing-3);
g.setColor(Color.RED);
g.fillRect(width-53, 3 + 1*colorSpacing, 50, colorSpacing-3);
g.setColor(Color.GREEN);
g.fillRect(width-53, 3 + 2*colorSpacing, 50, colorSpacing-3);
g.setColor(Color.BLUE);
g.fillRect(width-53, 3 + 3*colorSpacing, 50, colorSpacing-3);
g.setColor(Color.CYAN);
g.fillRect(width-53, 3 + 4*colorSpacing, 50, colorSpacing-3);
g.setColor(Color.MAGENTA);
g.fillRect(width-53, 3 + 5*colorSpacing, 50, colorSpacing-3);
g.setColor(Color.YELLOW);
g.fillRect(width-53, 3 + 6*colorSpacing, 50, colorSpacing-3);

g.setColor(Color.WHITE);
g.drawRect(width-55, 1 + currentColor*colorSpacing, 53, colorSpacing);
g.drawRect(width-54, 2 + currentColor*colorSpacing, 51, colorSpacing-2);
}

private void onColorChange(int y) {

int width = getWidth();
int height = getHeight();
int colorSpacing = (height - 56) / 7;
int newColor = y / colorSpacing;

if (newColor < 0 || newColor > 6)
return;

Graphics g = getGraphics();
g.setColor(Color.GRAY);
g.drawRect(width-55, 1 + currentColor*colorSpacing, 53, colorSpacing);
g.drawRect(width-54, 2 + currentColor*colorSpacing, 51, colorSpacing-2);
currentColor = newColor;
g.setColor(Color.WHITE);
g.drawRect(width-55, 1 + currentColor*colorSpacing, 53, colorSpacing);
g.drawRect(width-54, 2 + currentColor*colorSpacing, 51, colorSpacing-2);
g.dispose();
}

private void setUpDrawingGraphics() {
graphicsForDrawing = getGraphics();
switch (currentColor) {
case BLACK:
graphicsForDrawing.setColor(Color.BLACK);
break;
case RED:
graphicsForDrawing.setColor(Color.RED);
break;
case GREEN:
graphicsForDrawing.setColor(Color.GREEN);
break;
case BLUE:
graphicsForDrawing.setColor(Color.BLUE);
break;
case CYAN:
graphicsForDrawing.setColor(Color.CYAN);
break;
case MAGENTA:
graphicsForDrawing.setColor(Color.MAGENTA);
break;
case YELLOW:
graphicsForDrawing.setColor(Color.YELLOW);
break;
}
}

public void mousePressed(MouseEvent evt) {
int x = evt.getX();
int y = evt.getY();

int width = getWidth();
int height = getHeight();

if (dragging == true)
return;

if (x > width - 53) {
if (y > height - 53)
repaint();
else
onColorChange(y);
}
else if (x > 3 && x < width - 56 && y > 3 && y < height - 3) {
prevX = x;
prevY = y;
dragging = true;
setUpDrawingGraphics();
}
}

public void mouseReleased(MouseEvent evt) {
if (dragging == false)
return;
dragging = false;
graphicsForDrawing.dispose();
graphicsForDrawing = null;
}

public void mouseDragged(MouseEvent evt) {
if (dragging == false)
return;

int x = evt.getX();
int y = evt.getY();

if (x < 3)
x = 3;
if (x > getWidth() - 57)
x = getWidth() - 57;

if (y < 3)
y = 3;
if (y > getHeight() - 4)
y = getHeight() - 4;
graphicsForDrawing.drawLine(prevX, prevY, x, y);
prevX = x;
prevY = y;
}

public void mouseEntered(MouseEvent evt) { }
public void mouseExited(MouseEvent evt) { }
public void mouseClicked(MouseEvent evt) { }
public void mouseMoved(MouseEvent evt) { }
}
}