java - How to setup desired Coordinates in Graphics2D -

i want set mathematical (where y grows not down) coordinate space (-1, -1) (+1, +1) , have fit in window regardless of window size.

i using anonymous jcomponent subclass in java se 7 , casting incoming graphics in paintcomponent graphics2d , drawing on graphics2d

but graphics2d set computer coordinate space changes size of window. how rescale according window size , have y go upwards? following program should show dark square in upper right quadrant.

import java.awt.graphics; import java.awt.graphics2d; import java.awt.geom.rectangle2d;  import javax.swing.jcomponent; import javax.swing.jframe;  public class g {   public static void main (string [] args) {     jframe frame = new jframe(g.class.getcanonicalname());     frame.setundecorated(true);     jcomponent component = new jcomponent() {       private static final long serialversionuid = 1l;       @override       protected void paintcomponent (graphics g) {         super.paintcomponent(g);         paint2d((graphics2d)g);       }       protected void paint2d (graphics2d g2) {         g2.draw(new rectangle2d.double(0.1, 0.1, 0.9, 0.9));       }     };     frame.add(component);     frame.setdefaultcloseoperation(jframe.exit_on_close);     frame.setsize(400, 400);     frame.setvisible(true);   } } 

setup coordinate system how want, using transform() , translate(). so:

1. you want origin @ (0, height); bottom left.
2. then want flip y axis.

example code:

affinetransform tform = affinetransform.gettranslateinstance( 0, height); tform.scale( 1, -1); g2.settransform( tform); 

---

[my edited version]:

public static void main (string [] args) {     jframe frame = new jframe( g2dtransform_question.class.getcanonicalname());     jcomponent component = new jcomponent() {         private static final long serialversionuid = 1l;         @override         protected void paintcomponent (graphics g) {             super.paintcomponent(g);             paint2d((graphics2d)g);         }         protected void paint2d (graphics2d g2) {             affinetransform tform = affinetransform.gettranslateinstance( 0, getheight());             tform.scale( getwidth(), -getheight());    // note -- make 1.0 'full width'.             g2.settransform( tform);              g2.setcolor( color.blue);  // note -- can *see* something.             g2.fill( new rectangle2d.double(0.1, 0.1, 0.8, 0.8));  // note -- 'fill' works better 'draw'.         }     };      frame.setlayout( new borderlayout());    // note -- make component size frame.     frame.add( component, borderlayout.center);      frame.setdefaultcloseoperation(jframe.exit_on_close);     frame.setsize(400, 400);     frame.setvisible(true); } 

---

[hovercraft's version]: hover!

import java.awt.dimension; import java.awt.graphics; import java.awt.graphics2d; import java.awt.geom.affinetransform; import java.awt.geom.rectangle2d;  import javax.swing.jcomponent; import javax.swing.jframe;  public class g {   public static final int pref_w = 400;   public static final int pref_h = pref_w;  public static void main (string [] args) {     jframe frame = new jframe(g.class.getcanonicalname());     frame.setundecorated(true);     jcomponent component = new jcomponent() {       private static final long serialversionuid = 1l;       @override       protected void paintcomponent (graphics g) {         super.paintcomponent(g);         affinetransform tform = affinetransform.gettranslateinstance( 0, getheight());         tform.scale( 1, -1);         graphics2d g2 = (graphics2d) g.create();         g2.settransform( tform);         paint2d(g2);         g2.dispose();       }       protected void paint2d (graphics2d g2) {         g2.draw(new rectangle2d.double(10, 10, 20, 30));       }        @override       public dimension getpreferredsize() {          return new dimension(pref_w, pref_h);       }     };     frame.add(component);     frame.setdefaultcloseoperation(jframe.exit_on_close);     frame.pack();     frame.setvisible(true);   } }