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116 lines
3 KiB
Markdown
116 lines
3 KiB
Markdown
# Lecture for November 20
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## Adding a drawing panel to the GUI
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You can't put swing and graphics together, therefore you need to make a seperate JPanels for swing and graphics.
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Add necessary libraries
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```java
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import java.awt.*;
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import java.awt.Graphics;
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import java.awt.event.*;
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import javax.swing.*;
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```
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```java
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public class drawingWindow extends JPanel {
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JTextField field;
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JButton draw;
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DrawingPanel drawingPanel;
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public drawingWindow() {
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// Each new component would be vertically stacked upon each other
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setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
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JPanel swingSTuff = new JPanel();
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// Add things to the screen
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draw = new JButton("Draw");
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field = new JTextField();
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swingStuff.add(field);
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swingStuff.add(draw)
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// Add the drawing panel onto the screen
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drawingPanel = new DrawingPanel(200, 400);
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add(drawingPanel);
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// Activate the listener if the button was pressed
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draw.addActionListener(new Listener());
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}
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// Add the listener to respond to events
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private class listener implements ActionListener {
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public void actionPerformed(ActionEvent event) {
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if (event.getSource() == draw) {
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drawingPanel.setFlag(1);
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// Repaints the screen so the oval can appear
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drawingPanel.repaint();
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}
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}
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}
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// Create the draw panel so we can add it to the screen
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private class DrawingPanel extends JPanel {
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private int width, height;
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DrawingPanel(int width, int height) {
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this.width = width;
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this.height = height;
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setPreferredSize(new Dimension(width, height));
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}
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public void setFlag(int flag) {
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this.flag = flag;
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}
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public void paintComponent(Graphics g) {
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super.paintComponent(g);
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// Every time the flag is set, draw an oval at a random location and color
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if (flag == 1) {
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Random rand = new Random();
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int x = rand.nextInt(width);
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int y = rand.nextInt(height);
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g.setColor(Color.RED);
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g.fillOval(x, y, 20, 30);
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}
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}
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}
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}
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```
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There are a myriad of different methods you can use.
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```java
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// Assume width, height, y, x, etc are defined above
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public void paintComponent(Graphics g) {
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//....
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g.dispose(); // Flushes the graphics buffer
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}
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```
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You have the traditional fill and draw methods. Fill creates the shape shaded in with a color. Draw creates an outline of the shape.
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```java
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// ...
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g.fillRect(x ,y, width, height);
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g.drawRect(x, y, width, height);
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g.fillOval(x, y, width, height);
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g.drawOval(x, y, width, height);
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//g.drawPoly(parematers...);
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//g.fillPoly(parameters...);
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g.drawArc(x, y, width, height, startingAngle, sweepingAngle);
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g.fillArc(x, y, width, height, startingAngle, sweepingAngle);
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```
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You can also create complex shapes like a polygon. When adding points, you need to make sure you add them Clockwise or Counterclockwise (but NOT both)
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```java
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Polygon tri = new Polygon();
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tri.addPoint(150, 10);
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tri.addPoint(175, 100);
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tri.addPoint(125, 100);
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// Add points clockwise or counterclockwise (NOT BOTH)
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```
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