I looked into the HashMap class and found a way to load images with it so that no image is loaded twice. Thanks:)
Here’s my implementation for those interested.
/*
* SpriteBank class
* Desc: Handles the loading of images/sprites.
* Other objects use this class to access/load their images
* so that no image is loaded twice and that all images are handled
* neatly and seperately.
*
* NOTE: Is a Singleton object! ( Can be instantiated once, and only once ).
*/
import java.util.*; // for List and HashMap
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.*;
import java.awt.image.*;
import javax.imageio.*;
import java.io.*;
public class SpriteBank {
// HashMap - used to store the imagesuniquely as to prevent
// loading the same image twice.
//private HashMap<String,BufferedImage> //HashMap<K,V>
// hm = new HashMap<String,BufferedImage>();
private HashMap<String,BufferedImage> //HashMap<K,V>
hm = new HashMap<String,BufferedImage>();
////
private String path = "gfx/";
//Singleton code -+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-
// Used to holds a reference to ourself (Singleton design)
private static SpriteBank ref = null;
// private Constructor ( Singleton method )
private SpriteBank() {
/* No code required here
* - we just want to make sure that no one can instantiate this class
* without our (itselfs) permission
*/
}
public static synchronized
SpriteBank start() {
// Start/Instantiate the SpriteBank class
if (ref == null) {
// Make sure this class is only instantiated once
// and that it afterwards only references itself
ref = new SpriteBank();
}
// return ref which now points to the instance of SpriteBank we just made
return ref;
}
@Override
public Object clone()
throws CloneNotSupportedException {
// Override the generic clone method ( inherited from Object )
// to prevent cloning ( so there can't be more SpriteBanks than 1
// , not even clones )
throw new CloneNotSupportedException();
// If you try to clone() you'll get tazered with an exception! :P
}
//Singleton code end -+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-
// normal code
private synchronized BufferedImage loadSprite(String sprName) {
// Attempts to load sprite sprName
BufferedImage spr = null;
try {
spr = ImageIO.read(new File(path+sprName));
} catch (IOException e) {
// Error occured
return null;
}
return spr;
}
private boolean sprExists(String sprName) {
// checks if a sprite has already been added/loaded
// into the hash map
boolean b = hm.containsKey(sprName);
return b;
}
public synchronized BufferedImage getSprite(String sprName) {
// used by other objects to load/get their image
// that represents their sprite name.
if(sprExists(sprName)) {
// Sprite already loaded.
return hm.get(sprName);
} else {
// Sprite hasn't been loaded yet.
BufferedImage spr;
spr = loadSprite(sprName);
if(spr == null) {
// An error occured, couldn't load sprite.
return null;
} // else move on
/* transform the loaded sprite into an image
* with the top left pixel color as transparent */
spr =
imageToBufferedImage( makeColorTransparent(spr) );
// save the loaded sprite (and now transparent) into the hashmap
hm.put(sprName, spr);
// and then return the sprite
return spr;
}
}
// Transforms a BufferedImage with a transparent color
// into an Image ( use imagetoBufferedImage(Image imgage) method
// to turn it back into a BufferedImage.
private Image
makeColorTransparent(BufferedImage img) {
final Color c = new Color(img.getRGB(0,0)); /* The color to turn transparent
* is in the top left corner
* of the image */
ImageFilter filter = new RGBImageFilter() {
// the color to turn into transparent (opaque)
int markerRGB = c.getRGB() | 0xFF000000;
public final int filterRGB(int x, int y, int rgb) {
if( (rgb | 0xFF000000) == markerRGB) {
// Mark the alpha bits as zero - transparent
return 0x00FFFFFF & rgb;
} else {
//do nothing
return rgb;
}
}
};
ImageProducer ip = new FilteredImageSource(img.getSource(), filter);
return Toolkit.getDefaultToolkit().createImage(ip);
}
// Turn an Image into a BufferedImage
private BufferedImage imageToBufferedImage(Image image) {
BufferedImage bufferedImage = new BufferedImage(image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = bufferedImage.createGraphics();
g2.drawImage(image, 0, 0, null);
g2.dispose();
return bufferedImage;
/* Source code
http://stackoverflow.com/questions/665406/how-to-make-a-color-transparent-in-a-bufferedimage-and-save-as-png
*/
}
public synchronized int size() {
// return the number of images loaded into memory
return hm.size();
}
}
that holds a sorted ArrayList of ALL ISOObjects that exist in the room). The JPanel calls the room.paintAll() method. The room.paintAll() method iterates through its ArrayList variables, invoking each ISOObjects paint() method. The ISOObjects.paint() method uses the drawImage() method to draw its image on the JPanel’s Graphics “screen”.
