Java Doc for ZoomPane.java in  » GIS » GeoTools-2.4.1 » org » geotools » gui » swing » Java Source Code / Java DocumentationJava Source Code and Java Documentation

• ZoomPane.getArea() , which must return a bounding box for the content to paint. This area can be expressed in arbitrary units. For example, an object wanting to display a geographic map with a content ranging from 10° to 15°E and 40° to 45°N should override this method as follows:

    public Rectangle2D getArea() {
        return new Rectangle2D.Double(10, 40, 5, 5);
    }
   

• ZoomPane.paintComponent(Graphics2D) , which must paint the widget content. Implementation must invoke graphics.transform({link #zoom}) somewhere in its code in order to perform the zoom. Note that, by default, the is initialized in such a way that the y axis points upwards, like the convention in geometry. This is as opposed to the default Java2D axis orientation, where the y axis points downwards. If the implementation wants to paint text, it should do this with the default transform. Example:

    protected void paintComponent(final Graphics2D graphics) {
        graphics.clip({link #getZoomableBounds getZoomableBounds}(null));
        final AffineTransform textTr = graphics.getTransform();
        graphics.transform({link #zoom});
        
        // Paint the widget here, using logical coordinates. The
        // coordinate system is the same as 
  ZoomPane.getArea() 's one.
        
        graphics.setTransform(textTr);
        
        // Paint any text here, in pixel coordinates.
        
    }
   

Subclass can also override ZoomPane.reset , which sets up the initial . The default implementation sets up the initial zoom in such a way that the following relations are approximately held:

Logical coordinates provided by ZoomPane.getPreferredArea() , after an affine transform described by ZoomPane.zoom , match pixel coordinates provided by ZoomPane.getZoomableBounds(Rectangle) .

The "preferred area" is initially the same as ZoomPane.getArea() . The user can specify a different preferred area with ZoomPane.setPreferredArea . The user can also reduce zoomable bounds by inserting an empty border around the widget, e.g.:

  setBorder(BorderFactory.createEmptyBorder(top, left, bottom, right));
 

Zoom actions

Key	Purpose	Action name
	Scroll up	"Up"
	Scroll down	"Down"
	Scroll left	"Left"
	Scroll right	"Right"
	Zoom in	"ZoomIn"
	Zoom out	"ZoomOut"
	Zoom	"Zoom"
	Default zoom	"Reset"
Ctrl+	Anti-clockwise rotation	"RotateLeft"
Ctrl+	Clockwise rotation	"RotateRight"

Note: JScrollPane objects are not suitable for adding scrollbars to a ZoomPane object. Instead, use ZoomPane.createScrollPane . Once again, all movements performed by the user through the scrollbars will be translated by calls to ZoomPane.transform .

• If the pixel's coordinate point is outside the magnifier, then this method do nothing.
• Otherwise, if the pixel's coordinate is inside the magnifier, then this method update point in such a way that it contains the position that the exact same pixel would have in the absence of magnifier.

The returned shape will generally be from a class derived from RectangularShape , but can also be from the class Line2D . Any other class risks firing a ClassCastException at execution. The default implementation always returns a java.awt.geom.Rectangle2D object.
Parameters:
  point - Logical coordinates of the mouse at the moment the button is pressed. Thisinformation can be used by derived classes that wish to consider the mouse positionbefore choosing a geometric shape. Shape from the class {link RectangularShape} or {link Line2D}, or null toindicate that we do not want to select with the mouse.

• If a region has already been defined by a call to ZoomPane.setPreferredArea , this region will be returned.
• If not, the whole region ZoomPane.getArea will be returned.

ZoomPane invokes getZoomableBounds when it needs to set up an initial ZoomPane.zoom value. Subclasses should also set the clip area to this bounding box in their ZoomPane.paintComponent(Graphics2D) method before setting the graphics transform. For example:

 graphics.clip(getZoomableBounds(null));
 graphics.transform(
ZoomPane.zoom );
 

Note: for the derived classes: reset() is the only method of ZoomPane which doesn't have to pass through ZoomPane.transform(AffineTransform) to modify the zoom. This exception is necessary to avoid falling into an infinite loop.

This scrollRectToVisible method allows us to define the sub-region of bounds which must appear in the ZoomPane window.

ZoomPane.zoom .
AffineTransform.concatenate(AffineTransform) concatenate (change);
ZoomPane.fireZoomChanged(AffineTransform) fireZoomChanged (change);
ZoomPane.repaint() repaint (
ZoomPane.getZoomableBounds getZoomableBounds (null));
 

ZoomPane.zoom .
AffineTransform.preConcatenate(AffineTransform) preConcatenate (change);
ZoomPane.fireZoomChanged(AffineTransform) fireZoomChanged (change translated in logical units);
ZoomPane.repaint() repaint (
ZoomPane.getZoomableBounds getZoomableBounds (null));