Java 如何在JPanel中设置背景图片
你好,我正在使用JPanel作为我的框架容器,然后我真的想在我的面板中使用背景图片,我真的需要帮助这是我的代码到目前为止。这是更新请检查这是我的代码现在Java 如何在JPanel中设置背景图片,java,image,swing,user-interface,jpanel,Java,Image,Swing,User Interface,Jpanel,你好,我正在使用JPanel作为我的框架容器,然后我真的想在我的面板中使用背景图片,我真的需要帮助这是我的代码到目前为止。这是更新请检查这是我的代码现在 import java.awt.*; import javax.swing.*; import java.awt.event.*; public class imagebut extends JFrame { public static void main(String args []) { imagebut w = new i
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class imagebut extends JFrame
{
public static void main(String args [])
{
imagebut w = new imagebut();
w.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
w.setSize(300,300);
w.setVisible(true);
}
public imagebut()
{
setLayout(null); // :-)
PicPanel mainPanel = new PicPanel("picturename.jpg");
mainPanel.setBounds(0,0,500,500);
add(mainPanel);
}
class PicPanel extends JPanel{
private BufferedImage image;
private int w,h;
public PicPanel(String fname){
//reads the image
try {
image = ImageIO.read(new File(fname));
w = image.getWidth();
h = image.getHeight();
} catch (IOException ioe) {
System.out.println("Could not read in the pic");
//System.exit(0);
}
}
public Dimension getPreferredSize() {
return new Dimension(w,h);
}
//this will draw the image
public void paintComponent(Graphics g){
super.paintComponent(g);
g.drawImage(image,0,0,this);
}
}
}
有许多方法可以实现这一点 你可以。。。 免责声明 Cavet,为此使用
JLabel
可能会导致内容物溢出容器,有关详细信息,请参见下文
创建一个JLabel
,将图像应用于其图标
属性,并将其设置为框架内容窗格。然后需要适当地设置布局管理器,因为JLabel
没有默认的布局管理器
JFrame frame = ...;
JLabel background = new JLabel(new ImageIcon(ImageIO.read(...)));
frame.setContentPane(background);
frame.setLayout(...);
frame.add(...);
使用完整示例更新
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class LabelBackground {
public static void main(String[] args) {
new LabelBackground();
}
public LabelBackground() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
try {
// Load the background image
BufferedImage img = ImageIO.read(new File("/path/to/your/image/on/disk"));
// Create the frame...
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Set the frames content pane to use a JLabel
// whose icon property has been set to use the image
// we just loaded
frame.setContentPane(new JLabel(new ImageIcon(img)));
// Supply a layout manager for the body of the content
frame.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
// Add stuff...
frame.add(new JLabel("Hello world"), gbc);
frame.add(new JLabel("I'm on top"), gbc);
frame.add(new JButton("Clickity-clackity"), gbc);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException exp) {
exp.printStackTrace();
}
}
});
}
}
问题是调整帧大小时,JLabel
不会调整图像大小
警告-如果子组件所需空间超过背景图像的大小,则使用JLabel
可能会导致问题,因为JLabel
不会根据其内容计算首选大小,而是根据其图标
和文本
属性计算首选大小
你可以。。。
创建一个自定义组件,从JPanel
扩展,并覆盖它的paintComponent
方法,根据需要绘制背景
请查看以了解更多详细信息
这使您能够在图像的可用空间发生变化时,决定如何最佳地缩放图像。虽然有很多方法可以实现这一点,但你应该通读一遍,了解它们的优缺点
这就提出了一系列新的问题,你想扩展它们并保持纵横比吗?如果是这样的话,您希望将图像适配到可用区域还是填充它(这样它将始终覆盖可用空间)
请查看以了解更多详细信息
其他注意事项
图像通常最好通过ImageIO
API加载,因为它能够加载范围广泛的图像,但在出现问题时也会抛出IOException
有关更多详细信息,请参阅
图像的位置也很重要。如果映像位于应用程序外部(文件系统上的某个位置),则可以使用ImageIO.read(新文件(“/path/to/image”)
。但是,如果图像嵌入到应用程序中(例如存储在Jar中),则需要使用类似于ImageIO.read(getClass().getResource(“/path/to/image”)
的东西来代替
例如
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class LabelBackground {
public static void main(String[] args) {
new LabelBackground();
}
public LabelBackground() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
try {
// Load the background image
BufferedImage img = ImageIO.read(new File("/path/to/your/image/on/disk"));
// Create the frame...
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Set the frames content pane to use a JLabel
// whose icon property has been set to use the image
// we just loaded
frame.setContentPane(new JLabel(new ImageIcon(img)));
// Supply a layout manager for the body of the content
frame.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
// Add stuff...
frame.add(new JLabel("Hello world"), gbc);
frame.add(new JLabel("I'm on top"), gbc);
frame.add(new JButton("Clickity-clackity"), gbc);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException exp) {
exp.printStackTrace();
}
}
});
}
}
此示例演示如何使用作为后台组件的自定义组件。当组件大小超过背景图像的大小时,图像将放大以填充可用内容区域
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.HeadlessException;
import java.awt.RenderingHints;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class SimpleBackground {
public static void main(String[] args) {
new SimpleBackground();
}
public SimpleBackground() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
try {
BackgroundPane background = new BackgroundPane();
background.setBackground(ImageIO.read(new File("/path/to/your/image/on/your/disk")));
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(background);
frame.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
frame.add(new JLabel("Hello world"), gbc);
frame.add(new JLabel("I'm on top"), gbc);
frame.add(new JButton("Clickity-clackity"), gbc);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException exp) {
exp.printStackTrace();
}
}
});
}
public class BackgroundPane extends JPanel {
private BufferedImage img;
private BufferedImage scaled;
public BackgroundPane() {
}
@Override
public Dimension getPreferredSize() {
return img == null ? super.getPreferredSize() : new Dimension(img.getWidth(), img.getHeight());
}
public void setBackground(BufferedImage value) {
if (value != img) {
this.img = value;
repaint();
}
}
@Override
public void invalidate() {
super.invalidate();
if (getWidth() > img.getWidth() || getHeight() > img.getHeight()) {
scaled = getScaledInstanceToFill(img, getSize());
} else {
scaled = img;
}
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (scaled != null) {
int x = (getWidth() - scaled.getWidth()) / 2;
int y = (getHeight() - scaled.getHeight()) / 2;
g.drawImage(scaled, x, y, this);
}
}
}
public static BufferedImage getScaledInstanceToFill(BufferedImage img, Dimension size) {
double scaleFactor = getScaleFactorToFill(img, size);
return getScaledInstance(img, scaleFactor);
}
public static double getScaleFactorToFill(BufferedImage img, Dimension size) {
double dScale = 1;
if (img != null) {
int imageWidth = img.getWidth();
int imageHeight = img.getHeight();
double dScaleWidth = getScaleFactor(imageWidth, size.width);
double dScaleHeight = getScaleFactor(imageHeight, size.height);
dScale = Math.max(dScaleHeight, dScaleWidth);
}
return dScale;
}
public static double getScaleFactor(int iMasterSize, int iTargetSize) {
double dScale = (double) iTargetSize / (double) iMasterSize;
return dScale;
}
public static BufferedImage getScaledInstance(BufferedImage img, double dScaleFactor) {
return getScaledInstance(img, dScaleFactor, RenderingHints.VALUE_INTERPOLATION_BILINEAR, true);
}
protected static BufferedImage getScaledInstance(BufferedImage img, double dScaleFactor, Object hint, boolean bHighQuality) {
BufferedImage imgScale = img;
int iImageWidth = (int) Math.round(img.getWidth() * dScaleFactor);
int iImageHeight = (int) Math.round(img.getHeight() * dScaleFactor);
// System.out.println("Scale Size = " + iImageWidth + "x" + iImageHeight);
if (dScaleFactor <= 1.0d) {
imgScale = getScaledDownInstance(img, iImageWidth, iImageHeight, hint, bHighQuality);
} else {
imgScale = getScaledUpInstance(img, iImageWidth, iImageHeight, hint, bHighQuality);
}
return imgScale;
}
protected static BufferedImage getScaledDownInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality) {
int type = (img.getTransparency() == Transparency.OPAQUE)
? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage) img;
if (targetHeight > 0 || targetWidth > 0) {
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w > targetWidth) {
w /= 2;
if (w < targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h > targetHeight) {
h /= 2;
if (h < targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(Math.max(w, 1), Math.max(h, 1), type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
} while (w != targetWidth || h != targetHeight);
} else {
ret = new BufferedImage(1, 1, type);
}
return ret;
}
protected static BufferedImage getScaledUpInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality) {
int type = BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage) img;
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w < targetWidth) {
w *= 2;
if (w > targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h < targetHeight) {
h *= 2;
if (h > targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(w, h, type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
tmp = null;
} while (w != targetWidth || h != targetHeight);
return ret;
}
}
导入java.awt.Dimension;
导入java.awt.EventQueue;
导入java.awt.Graphics;
导入java.awt.Graphics2D;
导入java.awt.GridBagConstraints;
导入java.awt.GridBagLayout;
导入java.awt.HeadlessException;
导入java.awt.RenderingHints;
导入java.awt.Transparency;
导入java.awt.image.buffereImage;
导入java.io.File;
导入java.io.IOException;
导入javax.imageio.imageio;
导入javax.swing.JButton;
导入javax.swing.JFrame;
导入javax.swing.JLabel;
导入javax.swing.JPanel;
导入javax.swing.UIManager;
导入javax.swing.UnsupportedLookAndFeelException;
公共类SimpleBackground{
公共静态void main(字符串[]args){
新的SimpleBackground();
}
公共SimpleBackground(){
invokeLater(新的Runnable(){
@凌驾
公开募捐{
试一试{
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
}catch(ClassNotFoundException |实例化Exception | IllegalacessException |不支持ookandfeelException ex){
}
试一试{
BackgroundPane background=新的BackgroundPane();
background.setBackground(ImageIO.read(新文件(“/path/to/your/image/on/your/disk”));
JFrame=新JFrame(“测试”);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(背景);
frame.setLayout(新的GridBagLayout());
GridBagConstraints gbc=新的GridBagConstraints();
gbc.gridwidth=GridBagConstraints.rements;
frame.add(新的JLabel(“Hello world”),gbc);
frame.add(新的JLabel(“我在上面”)、gbc;
frame.add(新的JButton(“Clickity clackity”),gbc;
frame.pack();
frame.setLocationRelativeTo(空);
frame.setVisible(true);
}捕获(IOEXP异常){
exp.printStackTrace();
}
}
});
}
公共类背景窗格扩展了JPanel{
专用缓冲图像img;
私有缓冲区图像缩放;
公共背景窗格(){
}
@凌驾
公共维度getPreferredSize(){
返回img==null?super.getPreferredSize():新维度(img.getWidth(),img.getHeight());
}
公共无效设置背景(BuffereImage值){
如果(值!=img){
this.img=值;
重新油漆();
}
}
@凌驾
公共无效{
super.invalidate();
如果(getWidth()>img.getWidth()| | getHeight()>img.getHeight()){
scaled=getScaledInstanceToFill(img,getSize());
}否则{
标度=img;
}
}
@凌驾
保护性空洞痛
JPanel ping = new JPanel(){
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
//draw hare what ever you want and it will be in the back of your components
}
};