Draw on an empty image...

[jakethesnake]

Couldn't really make a good title there...

I have a map consisting of 1000*1000 tiles, which are 32pixels'32pixels. I've managed to draw these on a dedicated space on the screen and implemented a scrolling system and a zoom. Now I want to make a minimap on the corner of the screen, showing the whole map. The problem is I can't iterate through my tiles on every render call, scale them down and draw them, it will take too much resources. Instead I thought the game would "draw" a picture when loading, so that the full iteration only has to be done once. problem is I don't know how to create an image, then draw stuff on it and save it in the memory. Here's some psydo-code of what I have in mind.

class Minimap{

//the image I'll use.
Image minimap;

//constructor
Minimap (){

minimap = new Image ("desired width", "desired height");

for (every tile that's on the actual "real" map)
minimap."draw a rectangle and then save it"(x,y,color,width,height);

now the minimap should be good to go. Every time I render it, it will be just like drawing a single image.

I hope my question makes sense.
 

[philfrei]

The usual way to draw and save images is with the BufferedImage object. You can get access to the individual pixels with a WriteableRaster. A BufferedImage can be drawn via the command drawImage.

http://docs.oracle.com/javase/7/docs/api/java/awt/image/BufferedImage.html
http://docs.oracle.com/javase/7/docs/api/java/awt/Graphics.html#drawImage%28java.awt.Image,%20int,%20int,%20java.awt.image.ImageObserver%29