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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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package javax.swing;

import java.awt.Graphics2D;

/**

 * <p>A painting delegate. The Painter interface defines exactly one method,

 * <code>paint</code>. It is used in situations where the developer can change

 * the painting routine of a component without having to resort to subclassing

 * the component. It is also generically useful when doing any form of painting

 * delegation.</p>

 *

 * <p><code>Painter</code>s are simply encapsulations of Java2D code and make

 * it fairly trivial to reuse existing <code>Painter</code>s or to combine

 * them together. Implementations of this interface are also trivial to write,

 * such that if you can't find a <code>Painter</code> that does what you need,

 * you can write one with minimal effort. Writing a <code>Painter</code> requires

 * knowledge of Java2D.</p>

 *

 * <p>A <code>Painter</code> may be created with a type parameter. This type will be

 * expected in the <code>paint</code> method. For example, you may wish to write a

 * <code>Painter</code> that only works with subclasses of {@link java.awt.Component}.

 * In that case, when the <code>Painter</code> is declared, you may declare that

 * it requires a <code>Component</code>, allowing the paint method to be type safe. Ex:

 * <pre>

 * {@code

 * Painter<Component> p = new Painter<Component>() {

 *     public void paint(Graphics2D g, Component c, int width, int height) {

 *         g.setColor(c.getBackground());

 *         //and so forth

 *     }

 * }

 * }

 * </pre>

 *

 * <p>This interface makes no guarantees of threadsafety.</p>

 *

 * @author rbair

 */

public interface Painter<T> {

    /**

     * <p>Renders to the given {@link java.awt.Graphics2D} object. Implementations

     * of this method <em>may</em> modify state on the <code>Graphics2D</code>, and are not

     * required to restore that state upon completion. In most cases, it is recommended

     * that the caller pass in a scratch graphics object. The <code>Graphics2D</code>

     * must never be null.</p>

     *

     * <p>State on the graphics object may be honored by the <code>paint</code> method,

     * but may not be. For instance, setting the antialiasing rendering hint on the

     * graphics may or may not be respected by the <code>Painter</code> implementation.</p>

     *

     * <p>The supplied object parameter acts as an optional configuration argument.

     * For example, it could be of type <code>Component</code>. A <code>Painter</code>

     * that expected it could then read state from that <code>Component</code> and

     * use the state for painting. For example, an implementation may read the

     * backgroundColor and use that.</p>

     *

     * <p>Generally, to enhance reusability, most standard <code>Painter</code>s ignore

     * this parameter. They can thus be reused in any context. The <code>object</code>

     * may be null. Implementations must not throw a NullPointerException if the object

     * parameter is null.</p>

     *

     * <p>Finally, the <code>width</code> and <code>height</code> arguments specify the

     * width and height that the <code>Painter</code> should paint into. More

     * specifically, the specified width and height instruct the painter that it should

     * paint fully within this width and height. Any specified clip on the

     * <code>g</code> param will further constrain the region.</p>

     *

     * <p>For example, suppose I have a <code>Painter</code> implementation that draws

     * a gradient. The gradient goes from white to black. It "stretches" to fill the

     * painted region. Thus, if I use this <code>Painter</code> to paint a 500 x 500

     * region, the far left would be black, the far right would be white, and a smooth

     * gradient would be painted between. I could then, without modification, reuse the

     * <code>Painter</code> to paint a region that is 20x20 in size. This region would

     * also be black on the left, white on the right, and a smooth gradient painted

     * between.</p>

     *

     * @param g The Graphics2D to render to. This must not be null.

     * @param object an optional configuration parameter. This may be null.

     * @param width width of the area to paint.

     * @param height height of the area to paint.

     */

    public void paint(Graphics2D g, T object, int width, int height);

}