Question

Ok so for those of you that have actually seen my posts, my code has evolved nicely to the point that i can now display my sprite sheet the way i want. Here is my code:

import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.ScrollPaneConstants;

public class AnimTest
{
public static void main(String[] args)
{
    AnimTest test = new AnimTest();
    test.go();
}

public void go()
{
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    MyDrawP drawP = new MyDrawP();
    frame.getContentPane().add(drawP);
    frame.setSize(640,640);
    frame.setVisible(true);
    frame.setResizable(true);

}
}

class MyDrawP extends JPanel
{

public void paintComponent(Graphics g)
{
    super.paintComponent(g);
    try {

        BufferedImage bigImg = ImageIO.read(new File("C:/Users/scott/Desktop/Personal Work/Pixel Art/terrain.png"));

        final int width = 64;
        final int height = 64;
        final int rows = 5;
        final int cols = 16;
        final int mapX = 10;
        final int mapY = 8;

        BufferedImage[][] sprites = new BufferedImage[cols][rows];

        for (int i = 0; i < rows; i++)
        {
            for (int j = 0; j < cols; j++)
            {
                //System.out.println("J is: " + j);
                //System.out.println("I is: " + i);
                //System.out.println("i * width is: " + i * width);
                //System.out.println("j * height is: " + j * height);
                //System.out.println("");

                sprites[j][i] = bigImg.getSubimage(j * width, i * height, width, height);
                //g.drawImage(sprites[j][i], 5, 5, this);
            }
        }
            for (int i = 0; i < mapX; i++)
            {
                for (int j = 0; j < mapY; j++)
                {
                ArrayList<BufferedImage> spriteListRoad = new ArrayList<BufferedImage>();
                BufferedImage road4way = sprites[0][0];
                spriteListRoad.add(road4way);
                BufferedImage roadS = sprites[1][0];
                spriteListRoad.add(roadS);
                BufferedImage roadV = sprites[2][0];
                spriteListRoad.add(roadV);
                BufferedImage roadH = sprites[3][0];
                spriteListRoad.add(roadH);
                BufferedImage roadEndU = sprites[4][0];
                spriteListRoad.add(roadEndU);
                BufferedImage roadEndL = sprites[5][0];
                spriteListRoad.add(roadEndL);
                BufferedImage roadEndR = sprites[6][0];
                spriteListRoad.add(roadEndR);
                BufferedImage roadEndD = sprites[7][0];
                spriteListRoad.add(roadEndD);
                BufferedImage roadLU = sprites[8][0];
                spriteListRoad.add(roadLU);
                BufferedImage roadRU = sprites[9][0];
                spriteListRoad.add(roadRU);
                BufferedImage roadLD = sprites[10][0];
                spriteListRoad.add(roadLD);
                BufferedImage roadRD = sprites[11][0];
                spriteListRoad.add(roadRD);
                BufferedImage roadUT = sprites[12][0];
                spriteListRoad.add(roadUT);
                BufferedImage roadLT = sprites[13][0];
                spriteListRoad.add(roadLT);
                BufferedImage roadRT = sprites[14][0];
                spriteListRoad.add(roadRT);
                BufferedImage roadDT = sprites[15][0];
                spriteListRoad.add(roadDT);

                ArrayList<BufferedImage> spriteListRiver = new ArrayList<BufferedImage>();
                BufferedImage riverV = sprites[0][1];
                spriteListRiver.add(riverV);
                BufferedImage riverH = sprites[1][1];
                spriteListRiver.add(riverH);
                BufferedImage riverLU = sprites[2][1];
                spriteListRiver.add(riverLU);
                BufferedImage riverRU = sprites[3][1];
                spriteListRiver.add(riverRU);
                BufferedImage riverLD = sprites[4][1];
                spriteListRiver.add(riverLD);
                BufferedImage riverRD = sprites[5][1];
                spriteListRiver.add(riverRD);
                BufferedImage riverRoadV = sprites[6][1];
                spriteListRiver.add(riverRoadV);
                BufferedImage riverRoadH = sprites[7][1];
                spriteListRiver.add(riverRoadH);

                ArrayList<BufferedImage> spriteListTerrain = new ArrayList<BufferedImage>();
                BufferedImage grass = sprites[0][2];
                spriteListTerrain.add(grass);
                BufferedImage trees = sprites[1][2];
                spriteListTerrain.add(trees);
                BufferedImage mountain = sprites[2][2];
                spriteListTerrain.add(mountain);

                ArrayList<BufferedImage> spriteListOre = new ArrayList<BufferedImage>();
                BufferedImage copper = sprites[0][3];
                spriteListOre.add(copper);
                BufferedImage dornite = sprites[1][3];
                spriteListOre.add(dornite);
                BufferedImage kryz = sprites[2][3];
                spriteListOre.add(kryz);
                BufferedImage iron = sprites[3][3];
                spriteListOre.add(iron);
                BufferedImage shallux = sprites[4][3];
                spriteListOre.add(shallux);
                BufferedImage mithril = sprites[5][3];
                spriteListOre.add(mithril);

                ArrayList<BufferedImage> spriteListWood = new ArrayList<BufferedImage>();
                BufferedImage oak = sprites[0][4];
                spriteListWood.add(oak);
                BufferedImage olive = sprites[1][4];
                spriteListWood.add(olive);
                BufferedImage rath = sprites[2][4];
                spriteListWood.add(rath);
                BufferedImage yew = sprites[3][4];
                spriteListWood.add(yew);
                BufferedImage eeth = sprites[4][4];
                spriteListWood.add(eeth);
                BufferedImage ebony = sprites[5][4];
                spriteListWood.add(ebony);

                g.drawImage(spriteListTerrain.get((int) (Math.random() * 3)), i* width, j * height, this); //this one works by itself

                }
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

}

And here is my question. Why is it that when i execute this code, every time i resize the window it runs again and remakes my map? I thought adding scrollbars might fix it, but i cant figure out how to add them in. How can i stop it from re-looping through the code every time i resize?

Thanks.

Answer 1

Why is it that when i execute this code, every time i resize the window it runs again and remakes my map?

Your code for creating the map is located in the paintComponent() method. This method is called every time Swing determines the component needs to be repainted. Resizing the frame is one case where compnents need to be repainted.

For this reason your paintComponent() method should be as efficient as possible. You should not be doing I/O in this method.

Your current code doesn’t make much sense to me. You have two loops using variables i, j, but you build the ArrayLists using hard coded values. The only time you use the i, j variable is for the drawImage() method.

So, I would guess, the code to create the map should be done in an external method and then the paintComponent() method should only invoke the drawImage(..) within your loops.

Also, since the drawImage() method uses the random() method, every time the paintComponent() method is invoked you will be changing the image. This is probably not what you want, so in reality you probably need to create your entire BufferedImage externally. Then the image can be added to a JLabel and add the label to the frame so you don’t need custom painting on the panel.