Adding graphics to JFrame using BorderLayout
I am trying to do some simple homework where I am displaying a line of text showing if a door object is open or not. Beneath that, I visualize it (using the drawRect method). And at the bottom I have two buttons that can open or close the door, thus changing the text and rectangle.
Edit: List of code that can be compiled now:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Test {
public static void main(String[] args) {
// Creates new JFrame called frame, with title "Door"
// (displayed at top of screen).
JFrame frame = new JFrame ("Door");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
TempDoorPanel panel = new TempDoorPanel();
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
}
class Door {
private String state;
private String message;
Door (String state) {
this.state = state;
message = "The door is currently closed.";
}
public boolean isOpen() {
return state.equals ("open");
}
public boolean isClosed() {
return state.equals ("closed");
}
public void setState(String state) {
this.state = state;
}
public String getMessage() {
return message;
}
public void open() {
if (state.equals("open")) {
message = "The door is already open.";
}
else {
state = "open";
message = "The door has been opened.";
}
}
public void drawOpenDoor (Graphics page) {
page.drawRect(100, 100, 100, 100);
}
}
class TempDoorPanel extends JPanel {
private Door door;
private JTextField currentStateOfDoor;
private JButton openDoor;
public TempDoorPanel() {
super.setLayout(new BorderLayout());
door = new Door("closed");
super.setBackground(Color.blue);
super.setPreferredSize(new Dimension (360, 400));
currentStateOfDoor = new JTextField(14);
currentStateOfDoor.setText(door.getMessage());
super.add(currentStateOfDoor, BorderLayout.NORTH);
openDoor = new JButton("Open Door");
class openDoorListener implements ActionListener {
public void actionPerformed (ActionEvent event) {
door.open();
repaintText();
}
}
openDoorListener openlistener = new openDoorListener();
openDoor.addActionListener(openlistener);
JPanel holder = new JPanel();
holder.add(openDoor);
super.add(holder, BorderLayout.SOUTH);
}
private void repaintText() {
currentStateOfDoor.setText(door.getMessage());
// These methods are from Door class.
}
public void paintComponent (Graphics page) {
super.paintComponent(page);
if (door.isOpen())
door.drawOpenDoor(page);
// isOpen is a boolean method from Door class.
}
}
What works:
- The buttons are displayed at the desired location on the screen, on BorderLayout.SOUTH, one after the other.
- JTextField appears in the right place on BorderLayout.NORTH
- Finally, a blue area appears in the right place in the center of the screen.
What I am trying to fix:
- I don't know how to display the rectangle in the middle of this blue area correctly. I tried changing the coordinates and size of the rectangle, which doesn't resize it at all. I can do drawRect (100, 100, 100, 100) and it doesn't change anything.
- I also know that the rectangle is currently hidden behind the top left corner of the JTextField, but I cannot figure out how to move it to the BorderLayout.
Questions:
- How to place a rectangle in BorderLayout?
- How would you adjust the size of the rectangle drawn via drawrect () in such a layout?
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As you add components to the JPanel, which you draw on JTextField
is covering your drawing.
Decision:
1) Either compensate for this by specifying the height JTextField
in the methoddrawRect(..)
or better
2) Don't add components to the JPanel
ones you paint if it doesn't help.
So basically I made yours TempDoorPanel
add a new one JPanel
in BorderLayout.CENTER
, which is a drawing pane that we can now use drawRect(0,0,10,10)
and it will show up in the upper left corner JPanel
drawingPanel
.
-
Also don't call
setPreferredSize
onJPanel
rather overridegetPreferredSize()
and returnDimension
that match your drawings. -
To call
paintComponent
outside of a class, just call anrepaint()
instance of it
See this example that uses point # 2:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class Test {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame("Door");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
TempDoorPanel panel = new TempDoorPanel();
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
});
}
}
class Door {
private String state;
private String message;
public Door(String state) {
this.state = state;
message = "The door is currently closed.";
}
public void drawOpenDoor(Graphics page) {
page.setColor(Color.GREEN);
page.drawRect(0, 0, 10, 10);
}
}
class TempDoorPanel extends JPanel {
private Door door;
private JTextField currentStateOfDoor;
private JButton openDoor;
public TempDoorPanel() {
super.setLayout(new BorderLayout());
door = new Door("closed");
currentStateOfDoor = new JTextField(14);
//AcurrentStateOfDoor.setText(door.getMessage());
super.add(currentStateOfDoor, BorderLayout.NORTH);
openDoor = new JButton("Open Door");
final JPanel drawingPanel = new JPanel() {
@Override
protected void paintComponent(Graphics grphcs) {
super.paintComponent(grphcs);
// if (door.isOpen()) {
door.drawOpenDoor(grphcs);
// }
// isOpen is a boolean method from Door class.
}
};
drawingPanel.setBackground(Color.blue);
add(drawingPanel);
class openDoorListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
//door.open();
repaintText();
drawingPanel.repaint();//so paint component of drawing panel is called
}
}
openDoorListener openlistener = new openDoorListener();
openDoor.addActionListener(openlistener);
JPanel holder = new JPanel();
holder.add(openDoor);
super.add(holder, BorderLayout.SOUTH);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
private void repaintText() {
// currentStateOfDoor.setText(door.getMessage());
// These methods are from Door class.
}
}
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When you handle the listener opening door event,
class openDoorListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
door.open();
repaintText();
}
}
you are not actually including a call to redraw the panel; therefore the panel method is paintComponent()
neither called door.drawOpenDoor()
nor called. You can check this by clicking the button and then resizing the frame. When you resize, the panel is automatically repainted and bingo, your door appears.
You can fix this by adding a call repaint()
to your ActionListener;
class openDoorListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
door.open();
repaintText();
repaint(); // requests that the panel be repainted
}
}
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