javax.swing: public class: CellRendererPane

javax.swing
public class: CellRendererPane [javadoc | source]

java.lang.Object
   Container
      javax.swing.CellRendererPane

All Implemented Interfaces:
Accessible

This class is inserted in between cell renderers and the components that use them. It just exists to thwart the repaint() and invalidate() methods which would otherwise propagate up the tree when the renderer was configured. It's used by the implementations of JTable, JTree, and JList. For example, here's how CellRendererPane is used in the code the paints each row in a JList:

cellRendererPane = new CellRendererPane();
...
Component rendererComponent = renderer.getListCellRendererComponent();
renderer.configureListCellRenderer(dataModel.getElementAt(row), row);
cellRendererPane.paintComponent(g, rendererComponent, this, x, y, w, h);

A renderer component must override isShowing() and unconditionally return true to work correctly because the Swing paint does nothing for components with isShowing false.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans^TM has been added to the java.beans package. Please see java.beans.XMLEncoder .

author: Hans - Muller

Nested Class Summary:
protected class	CellRendererPane.AccessibleCellRendererPane	This class implements accessibility support for the `CellRendererPane` class.

Field Summary
protected AccessibleContext	accessibleContext

Constructor:
public CellRendererPane() { super(); setLayout(null); setVisible(false); } Construct a CellRendererPane object.

Constructor:

 public CellRendererPane() {
        super();
        setLayout(null);
        setVisible(false);
}

Construct a CellRendererPane object.

Method from javax.swing.CellRendererPane Summary:
addImpl, getAccessibleContext, invalidate, paint, paintComponent, paintComponent, paintComponent, update

Methods from java.lang.Object:
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from javax.swing.CellRendererPane Detail:
protected void addImpl(Component x, Object constraints, int index) { if (x.getParent() == this) { return; } else { super.addImpl(x, constraints, index); } } If the specified component is already a child of this then we don't bother doing anything - stacking order doesn't matter for cell renderer components (CellRendererPane doesn't paint anyway).<
public AccessibleContext getAccessibleContext() { if (accessibleContext == null) { accessibleContext = new AccessibleCellRendererPane(); } return accessibleContext; } Gets the AccessibleContext associated with this CellRendererPane. For CellRendererPanes, the AccessibleContext takes the form of an AccessibleCellRendererPane. A new AccessibleCellRendererPane instance is created if necessary.
public void invalidate() { } Overridden to avoid propagating a invalidate up the tree when the cell renderer child is configured.
public void paint(Graphics g) { } Shouldn't be called.
public void paintComponent(Graphics g, Component c, Container p, Rectangle r) { paintComponent(g, c, p, r.x, r.y, r.width, r.height); } Calls this.paintComponent() with the rectangles x,y,width,height fields.
public void paintComponent(Graphics g, Component c, Container p, int x, int y, int w, int h) { paintComponent(g, c, p, x, y, w, h, false); } Calls this.paintComponent(g, c, p, x, y, w, h, false).
public void paintComponent(Graphics g, Component c, Container p, int x, int y, int w, int h, boolean shouldValidate) { if (c == null) { if (p != null) { Color oldColor = g.getColor(); g.setColor(p.getBackground()); g.fillRect(x, y, w, h); g.setColor(oldColor); } return; } if (c.getParent() != this) { this.add(c); } c.setBounds(x, y, w, h); if(shouldValidate) { c.validate(); } boolean wasDoubleBuffered = false; if ((c instanceof JComponent) && ((JComponent)c).isDoubleBuffered()) { wasDoubleBuffered = true; ((JComponent)c).setDoubleBuffered(false); } Graphics cg = g.create(x, y, w, h); try { c.paint(cg); } finally { cg.dispose(); } if (wasDoubleBuffered && (c instanceof JComponent)) { ((JComponent)c).setDoubleBuffered(true); } c.setBounds(-w, -h, 0, 0); } Paint a cell renderer component c on graphics object g. Before the component is drawn it's reparented to this (if that's necessary), it's bounds are set to w,h and the graphics object is (effectively) translated to x,y. If it's a JComponent, double buffering is temporarily turned off. After the component is painted it's bounds are reset to -w, -h, 0, 0 so that, if it's the last renderer component painted, it will not start consuming input. The Container p is the component we're actually drawing on, typically it's equal to this.getParent(). If shouldValidate is true the component c will be validated before painted.
public void update(Graphics g) { } Shouldn't be called.

Method from javax.swing.CellRendererPane Detail:

 protected  void addImpl(Component x,
    Object constraints,
    int index) {
        if (x.getParent() == this) {
            return;
        }
        else {
            super.addImpl(x, constraints, index);
        }
}

If the specified component is already a child of this then we don't bother doing anything - stacking order doesn't matter for cell renderer components (CellRendererPane doesn't paint anyway).<

 public AccessibleContext getAccessibleContext() {
                                                     
        if (accessibleContext == null) {
            accessibleContext = new AccessibleCellRendererPane();
        }
        return accessibleContext;
}

Gets the AccessibleContext associated with this CellRendererPane. For CellRendererPanes, the AccessibleContext takes the form of an AccessibleCellRendererPane. A new AccessibleCellRendererPane instance is created if necessary.

 public  void invalidate() {

}

Overridden to avoid propagating a invalidate up the tree when the cell renderer child is configured.

 public  void paint(Graphics g) {

}

Shouldn't be called.

 public  void paintComponent(Graphics g,
    Component c,
    Container p,
    Rectangle r) {
        paintComponent(g, c, p, r.x, r.y, r.width, r.height);
}

Calls this.paintComponent() with the rectangles x,y,width,height fields.

 public  void paintComponent(Graphics g,
    Component c,
    Container p,
    int x,
    int y,
    int w,
    int h) {
        paintComponent(g, c, p, x, y, w, h, false);
}

Calls this.paintComponent(g, c, p, x, y, w, h, false).

 public  void paintComponent(Graphics g,
    Component c,
    Container p,
    int x,
    int y,
    int w,
    int h,
    boolean shouldValidate) {
        if (c == null) {
            if (p != null) {
                Color oldColor = g.getColor();
                g.setColor(p.getBackground());
                g.fillRect(x, y, w, h);
                g.setColor(oldColor);
            }
            return;
        }
        if (c.getParent() != this) {
            this.add(c);
        }
        c.setBounds(x, y, w, h);
        if(shouldValidate) {
            c.validate();
        }
        boolean wasDoubleBuffered = false;
        if ((c instanceof JComponent) && ((JComponent)c).isDoubleBuffered()) {
            wasDoubleBuffered = true;
            ((JComponent)c).setDoubleBuffered(false);
        }
        Graphics cg = g.create(x, y, w, h);
        try {
            c.paint(cg);
        }
        finally {
            cg.dispose();
        }
        if (wasDoubleBuffered && (c instanceof JComponent)) {
            ((JComponent)c).setDoubleBuffered(true);
        }
        c.setBounds(-w, -h, 0, 0);
}

Paint a cell renderer component c on graphics object g. Before the component is drawn it's reparented to this (if that's necessary), it's bounds are set to w,h and the graphics object is (effectively) translated to x,y. If it's a JComponent, double buffering is temporarily turned off. After the component is painted it's bounds are reset to -w, -h, 0, 0 so that, if it's the last renderer component painted, it will not start consuming input. The Container p is the component we're actually drawing on, typically it's equal to this.getParent(). If shouldValidate is true the component c will be validated before painted.

 public  void update(Graphics g) {

}

Shouldn't be called.