Thread: Help needed with Images.

See this post:

Images: read/write and drawing

Some things to check:

1. Is there any error information displayed (like file not found exceptions, or ioexceptions)? If so, please post them.

2. Does the image contain something (for example, is it not just a white rectangle being drawn onto a white background)?

3. Have you considered the size of the image (too small, too big)? This method doesn't properly scale the image to fit the region. There are other paint methods you can use to draw a scaled version of the image, or you can scale the image before-hand (either in code or externally)

edit:

as a side note, you don't want to put any print statements into the paintComponent method. This method gets called quite frequently, and if you have print statements, it can significantly reduce the performance of your application, as well as flooding the console and making any other console output pretty much useless.

as a side note, you don't want to put any print statements into the paintComponent method.

I disagree. For debugging one time, its useful to see when/if a method is being called. I use print statements a lot to verify that. Then remove them after the they've shown what is happening.

If fact in this case the print shows what is wrong!!!
The hey is printed before the image is loaded. If you add a print after img is given a value you will see this:

hey
img=BufferedImage@6bade9: type = 0 ColorModel: #pixelBits = 24 numComponents = 3 color space = java.awt.color.ICC_ColorSpace@166afb3 transparency = 1 has alpha = false isAlphaPre = false ByteInterleavedRaster: width = 1024 height = 537 #numDataElements 3 dataOff[0] = 0

paint is called before the image is available.

Move the setVisible to after you have the image, the image is shown and you'll see:

img=BufferedImage@126f75b: type = 0 ColorModel: #pixelBits = 24 numComponents = 3 color space = java.awt.color.ICC_ColorSpace@139b78e transparency = 1 has alpha = false isAlphaPre = false ByteInterleavedRaster: width = 1024 height = 537 #numDataElements 3 dataOff[0] = 0
hey

Also you need to add the JPanel(this) to the frame.

I just remembered... For some reason my paintComponent method is NEVER called. ("hey" never prints in the terminal) I even put a while loop to keep the program running.

while(true)
		gui.updateScreen();

Here is my current gui.class

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
 
import javax.imageio.ImageIO;
import javax.swing.*;
 
public class gui extends JPanel {
	BufferedImage img;
	chatBox chatBox;
	public gui(chatBox chatBox){
		JFrame f = new JFrame("BrettScape");
		f.setSize(640,480);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
		try {
			img = ImageIO.read(new File("testtile.png"));
		} catch (IOException e) {
			e.printStackTrace();
		}
		f.setVisible(true);
 
	}
 
	public void updateScreen(){
		repaint();
	}
 
	public void paintComponent(Graphics g){
		g.drawImage(img, 0, 0, null);
	}
}

Its better to copy and paste from the actual program than to try to remember what the code was.

Now that you have the code working, you need to rework it. Putting the JFrame code in the gui constructor doesn't make sense.

For testing your gui class, add a main() method to it and move all the JFrame code out of the gui constructor to the main method.
Leave the image code there because that belongs to the gui class.

After testing, you can comment out the main() method.

Originally Posted by Norm

I disagree. For debugging one time, its useful to see when/if a method is being called. I use print statements a lot to verify that. Then remove them after the they've shown what is happening.

true, I guess I tend to use debug tools more (breakpoints, watches, variables, stack traces, etc.).