de.javagl.viewer

Interface Painter

All Known Implementing Classes:

SimpleObjectPainter

public interface Painter

Interface for all classes that may perform painting operations. Instances of classes implementing this interface may be passed to the Viewer.addPainter(Painter) method.

By default, a Painter just offers a method that should perform an arbitrary painting operation. In order to create painters that can paint specific objects, the ObjectPainter interface may be used: The SimpleObjectPainter is an implementation of the Painter interface that allows setting the object that should be painted, and delegates to an ObjectPainter.

Method Summary

Modifier and Type	Method and Description
void	paint(Graphics2D g, AffineTransform worldToScreen, double w, double h) Perform the painting operations on the given Graphics.

Method Detail

paint

void paint(Graphics2D g,
           AffineTransform worldToScreen,
           double w,
           double h)

Perform the painting operations on the given Graphics.

Note that the same Graphics instance will be passed to all painters. No painter should make any assumptions about the state of the Graphics object. Changes in the given Graphics object will affect painters that are called subsequently. This refers to configuration settings, like the rendering hints, but also to the transform of the Graphics.

Settings like the rendering hints will usually be done globally by the Viewer. If a painter modifies these settings, then it should either restore the original settings afterwards, or create a local copy of the Graphics object in order to avoid interferences with other painters.

If the painter needs to transform the Graphics, then it should either use a local copy of the graphics object, or restore the original transform after it finished painting:

 public void paint(
     Graphics2D g, AffineTransform worldToScreen, double w, double h)
 {
     // Store the original transform
     AffineTransform oldAT = g.getTransform();
     
     // Perform custom transforms and painting
     g.translate(100,100);
     g.drawLine(10,20,30,40);
     ...
     
     // Restore the original transform
     g.setTransform(oldAT);
 }
 

The AffineTransform that is passed to this method may also be the same for multiple painters. Usually, the caller should make sure that modifications of this transform do not affect painters that are called subsequently, but in general, it is not recommended to internally store or modify the given affine transform object.

Parameters:

g - The Graphics used for painting

worldToScreen - The world-to-screen transform. This transform encapsulates the translation, rotation and scaling of the viewer to which this painter belongs.

w - The width of the area, in screen coordinates, in which this painter operates. This is the screen size of the viewer to which this painter belongs.

h - The height of the area, in screen coordinates, in which this painter operates. This is the screen size of the viewer to which this painter belongs.