Thread: Convert JFrame graphics into a jpeg file

Hello everyone, I have had this problem for quite a while but never thought to come and ask on a forum. I just looked around because I thought it was a simple problem that required a key word in the coding or something. Turns out, I can't find any help anywhere.

My problem is I want to turn a user specified graphic made in a simple JFrame program into a jpeg (or really any 'picture' format) but I don't know how. The way I have saved it is by saving the pixels in the pic into an array that is printed into a text file. So really, my jpeg file is a text file. This runs far too slow because I need to be able to load the pic several times in animations.

Here is the code. It's a very simple, user size specified, black and white checkered pic that is saved into a text file to either be loaded or written over by a new pic the next time you run the program:

/*Hello, welcome to SimplePic. This program:
 *	1. asks weather you want to create a new pic or load the last pic created.
 *	2. if you choose to make a new pic, it asks for the width and height in pixels
 *	3. the program then creates a checkered pic of the specified size (or loads the last pic you made) starting with a black pixel in the top left corner always.
 *To see the save file, look for a text file called 'picText.txt' in the same folder as this program. It will have 2 numbers for the first 2 lines (width then height),
 *and then it will have (if word wrap is turned off; it doesn't have to be) a square of letters ababab...representing the pixel array in this program.
 *
 *MY MAIN PROBLEM: I want to convert this text file/pic into a jpeg or some kind of picture file so that:
 *	1. a text file is not necessary
 *	2. the program loads the pic much faster like it was openning a pic you drew in microsoft paint.
 *I need this because I want to be able to create this pic, but then load it repeatedly in animations.
 *
 *Good luck and thank you.
 *-Ben 
*/
 
//needed libraries
import javax.swing.JFrame;
import java.awt.*;
import java.util.*;
import java.io.*;
 
public class SimplePic extends JFrame{
	//variables
	private Color c1 = new Color(0,0,0);//black
	private Color c2 = new Color(255,255,255);//white
	private char char1 = 'a';
	private char char2 = 'b';
	private char[][]pixels;
	private int width,height;
	private Container contents;
 
	//new SimplePic
	public SimplePic(int xsize,int ysize){
		width=xsize;
		height=ysize;
		pixels=new char[xsize][ysize];
		generatePic();
		contents=getContentPane();
		setSize(xsize,ysize);
		setVisible(true);
	}
 
	//load SimplePic
	public SimplePic(){
		super("SimplePic");
		loadPic("picText.txt");
		contents=getContentPane();
		setSize(width,height);
		setVisible(true);
	}
 
	//generate Pic, creates a fine checkered pic based on remainders when dividing by 2
	public void generatePic(){
		for(int y=0;y<height;y++){//top to bottom
			for(int x=0;x<width;x++){//left to right
				//if x and y coordinate pixel has no remainder, set to black
				if(x%2==0&&y%2==0){
					pixels[x][y]=char1;
				}
				//if x coordinate pixel has a remainder of 1, but y does not, set to white	
				if(x%2==1&&y%2==0){
					pixels[x][y]=char2;
				}
				//if y coordinate pixel has a remainder of 1, but x does not, set to white
				if(x%2==0&&y%2==1){
					pixels[x][y]=char2;
				}
				//if x and y coordinate pixel has a remainder of 1, set to black
				if(x%2==1&&y%2==1){
					pixels[x][y]=char1;
				}
			}
		}
	}
 
	//render pic
	public void paint(Graphics g){
		super.paint(g);
		Color color=c1;
		for(int y=0;y<height;y++){
			for(int x=0;x<width;x++){
				//convert char array to colors black and white
				switch(pixels[x][y]){
					case 'a':color=c1;break;
					case 'b':color=c2;break;
				}
				g.setColor(color);
				g.fillRect(x,y,1,1);
			}
		}
	}
 
	//main method
	public static void main(String[]args){
		//i did not bother making any code for input error checking, this is a bare bones example
		Scanner scan=new Scanner(System.in);
		System.out.println("new pic or load pic? (n or l)");
		String choice=scan.nextLine();
		char c=choice.charAt(0);
		if(c=='n'){
			System.out.println("please enter width of pic (int)");
			int x=scan.nextInt();
			System.out.println("please enter height of pic (int)");
			int y=scan.nextInt();
			SimplePic newPic=new SimplePic(x,y);
			newPic.savePic("picText.txt");
			newPic.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		}
		if(c=='l'){
			SimplePic loadPic=new SimplePic();
			loadPic.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		}
 
	}
 
	//save current pic
	public void savePic(String fn){
		try{
			PrintWriter out=new PrintWriter(new FileWriter(fn));
			//the first 2 lines of the txt file are reserved for width and height
			out.println(width);
			out.println(height);
			//turn word wrap off in the txt file to see a checkered square of letters representing the pixels array
			for(int y=0;y<height;y++){
				for(int x=0;x<width;x++){
					out.print(pixels[x][y]);
				}
				out.println();
			}
			out.close();
			System.out.println("Saved to "+fn);
		}
		catch(IOException e){System.out.println("Error saving to "+fn);}
	}
 
	//load previous pic
	public void loadPic(String fn){
		System.out.println("Reading "+fn+", loading...");
		try{
			BufferedReader br=new BufferedReader(new FileReader(fn));
			String line;
			char charLine[];
			int numRows=0;
			//read the first 2 lines of the txt file to get the width and height
			String swidth=br.readLine();
			String sheight=br.readLine();
			width=Integer.parseInt(swidth);
			height=Integer.parseInt(sheight);
			//turn the square of letters in the txt file into the pixel array (turn word wrap off in the txt file to see more clearly)
			pixels=new char[width][height];
			while((line=br.readLine())!=null){
				while(numRows<height){
					charLine=line.toCharArray();
			        int x=0;
			        while((x<width)){
			          	pixels[x][numRows]=charLine[x];
			          	x++;
		        	}
		        	numRows++;
		        	line=br.readLine();
				}
			}
			br.close();
		}
		catch (IOException e){
			System.out.println("Error reading maze plan from " + fn);
      		System.exit(0);
    	}
	}
}

I think I made it as clear as possible, but if you have any questions, I'd be glad to answer them. I really need this answered.

Have you looked at the ImageIO class?
It will write images to files.

                    javax.imageio.ImageIO.write((BufferedImage)theImg, "PNG", imgFile);

Originally Posted by Norm

Have you looked at the ImageIO class?
It will write images to files.

                    javax.imageio.ImageIO.write((BufferedImage)theImg, "PNG", imgFile);

So would I make a method to replace my savePic method and use ImageIO.write instead of FileWriter? could you give some sample code regarding ImageIO.write?

THANK YOU SIR!!!! I have no idea why this was so hard for me to find, but you pointed me in the right direction and I figured it out. I have been wandering around this site today a bit, and I have found you to be a regular helper, so I'm guessing you are probably quite experienced. However, if you are unable to get a question solved and it regards general logic or arrays, I would be glad to help. Just send a message. Syntax is my problem, but I think I'm pretty good with logic, I figured things out my teacher couldn't. I'm not bragging, seriously if you need help in those 2 areas, I think I may be of some assistance.