设置JPanel的背景

import java.awt.Graphics;

import java.awt.Image;



import javax.swing.JPanel;



/**

 * 可设置背景图片的JPanel,提供了三种显示背景图片的方式:居中、平铺和拉伸。 未设置背景图片的情况下,同JPanel。

 * 

 * @author 003

 */

public class JImagePane extends JPanel {

	private static final long serialVersionUID = -8251916094895167058L;



	/**

	 * 居中

	 */

	public static final String CENTRE = "Centre";



	/**

	 * 平铺

	 */

	public static final String TILED = "Tiled";



	/**

	 * 拉伸

	 */

	public static final String SCALED = "Scaled";



	/**

	 * 背景图片

	 */

	private Image backgroundImage;



	/**

	 * 背景图片显示模式

	 */

	private String imageDisplayMode;



	/**

	 * 背景图片显示模式索引(引入此属性有助于必要时扩展)

	 */

	private int modeIndex;



	/**

	 * 构造一个没有背景图片的JImagePane

	 */

	public JImagePane() {

		this(null, CENTRE);

	}



	/**

	 * 构造一个具有指定背景图片和指定显示模式的JImagePane

	 * 

	 * @param image

	 *            背景图片

	 * @param modeName

	 *            背景图片显示模式

	 */

	public JImagePane(Image image, String modeName) {

		super();

		setBackgroundImage(image);

		setImageDisplayMode(modeName);

	}



	/**

	 * 设置背景图片

	 * 

	 * @param image

	 *            背景图片

	 */

	public void setBackgroundImage(Image image) {

		this.backgroundImage = image;

		this.repaint();

	}



	/**

	 * 获取背景图片

	 * 

	 * @return 背景图片

	 */

	public Image getBackgroundImage() {

		return backgroundImage;

	}



	/**

	 * 设置背景图片显示模式

	 * 

	 * @param modeName

	 *            模式名称,取值仅限于ImagePane.TILED ImagePane.SCALED ImagePane.CENTRE

	 */

	public void setImageDisplayMode(String modeName) {

		if (modeName != null) {

			modeName = modeName.trim();



			// 居中

			if (modeName.equalsIgnoreCase(CENTRE)) {

				this.imageDisplayMode = CENTRE;

				modeIndex = 0;

			}

			// 平铺

			else if (modeName.equalsIgnoreCase(TILED)) {

				this.imageDisplayMode = TILED;

				modeIndex = 1;

			}

			// 拉伸

			else if (modeName.equalsIgnoreCase(SCALED)) {

				this.imageDisplayMode = SCALED;

				modeIndex = 2;

			}



			this.repaint();

		}

	}



	/**

	 * 获取背景图片显示模式

	 * 

	 * @return 显示模式

	 */

	public String getImageDisplayMode() {

		return imageDisplayMode;

	}



	/**

	 * 绘制组件

	 * 

	 * @see javax.swing.JComponent#paintComponent(Graphics)

	 */

	@Override

	protected void paintComponent(Graphics g) {

		super.paintComponent(g);



		// 如果设置了背景图片则显示

		if (backgroundImage != null) {

			int width = this.getWidth();

			int height = this.getHeight();

			int imageWidth = backgroundImage.getWidth(this);

			int imageHeight = backgroundImage.getHeight(this);



			switch (modeIndex) {

			// 居中

			case 0: {

				int x = (width - imageWidth) / 2;

				int y = (height - imageHeight) / 2;

				g.drawImage(backgroundImage, x, y, this);

				break;

			}

			// 平铺

			case 1: {

				for (int ix = 0; ix < width; ix += imageWidth) {

					for (int iy = 0; iy < height; iy += imageHeight) {

						g.drawImage(backgroundImage, ix, iy, this);

					}

				}



				break;

			}

			// 拉伸

			case 2: {

				g.drawImage(backgroundImage, 0, 0, width, height, this);

				break;

			}

			}

		}

	}

}

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