java实现图形的放大和缩小，其实就是在画图时，改变图片的长和宽。以下代码参考一下：
import java.awt.Graphics
import java.awt.MouseInfo
import java.awt.Point
import java.awt.event.ActionEvent
import java.awt.event.ActionListener
import java.awt.event.MouseEvent
import java.awt.event.MouseListener
import java.io.File
import javax.swing.ImageIcon
import javax.swing.JButton
import javax.swing.JFileChooser
import javax.swing.JFrame
import javax.swing.JPanel
import javax.swing.filechooser.FileNameExtensionFilter
public class App extends JFrame implements MouseListener, ActionListener {
int x = 0
int y = 0
File[] selectedFiles = null
int fileIndex = 0
int width = 200
int height = 200
public App() {
setDefaultCloseOperation(EXIT_ON_CLOSE)
setLocationRelativeTo(null)
setSize(400, 300)
setResizable(false)
getContentPane().setLayout(null)
JPanel panel = new ImagePanel()
panel.setBounds(12, 40, 370, 218)
getContentPane().add(panel)
addMouseListener(this)
JButton btnBrowse = new JButton("Browse")
btnBrowse.addActionListener(this)
btnBrowse.setBounds(12, 9, 91, 21)
getContentPane().add(btnBrowse)
setVisible(true)
}
public static void main(String[] args) {
new App()
}
public void actionPerformed(ActionEvent e) {
JFileChooser chooser = new JFileChooser()
chooser.setMultiSelectionEnabled(true)
FileNameExtensionFilter filter = new FileNameExtensionFilter(
"JPG & GIF Images", "jpg", "gif")
// 设置文件类型
chooser.setFileFilter(filter)
// 打开选择器面板
int returnVal = chooser.showOpenDialog(this)
if (returnVal == JFileChooser.APPROVE_OPTION) {
selectedFiles = chooser.getSelectedFiles()
repaint()
}
}
public void mouseClicked(MouseEvent e) {
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void mousePressed(MouseEvent e) {
Point point = MouseInfo.getPointerInfo().getLocation()
x = point.x
y = point.y
}
public void mouseReleased(MouseEvent e) {
Point point = MouseInfo.getPointerInfo().getLocation()
int thisX = point.x
int thisY = point.y
System.out.println("thisX=" + thisX + " " + "thisY=" + thisY)
if ((y - thisY < 20 && y - thisY > 0)
|| (y - thisY < 0 && y - thisY > -20)) {
// Y 在20范围内移动认为是水平移动
if (x < thisX) {
// right
if (selectedFiles != null
&& fileIndex < selectedFiles.length - 1) {
fileIndex++
}
} else {
// left
if (selectedFiles != null && fileIndex > 0) {
fileIndex--
}
}
} else {
if (x < thisX) {
// 右下
width += 20
height += 20
} else {
// 左上
width -= 20
height -= 20
}
}
repaint()
}
class ImagePanel extends JPanel {
public void paint(Graphics g) {
super.paint(g)
if (selectedFiles != null) {
ImageIcon icon = new ImageIcon(selectedFiles[fileIndex]
.getPath())
g.drawImage(icon.getImage(), 0, 0, width, height, this)
}
}
}
}
放大像素会失真，如果你要实现这一共能的话可以用JLabel来显示图片。有一个方法可以实现图片的缩放ImageIconii
=
new
ImageIcon("img/item.jpg")
Image
img
=
ii.getImage()
img
=
img.getScaledInstance(100,
100,
Image.SCALE_DEFAULT)
ii
=
new
ImageIcon(img)这个例子的getScaledInstance方法可以生成一个新的Image对象，可以缩放成指定的大小。
Image srcImg = ImageIO.read(new FileInputStream(fnSrc) )//取源图int width = 600//假设要缩小到600点像素
int height = srcImg.getHeight(null)*600/srcImg.getWidth(null)//按比例，将高度缩减
System.out.println("Width: "+srcImg.getWidth(null))// 这几行是调试用
System.out.println("Height: "+srcImg.getHeight(null))
System.out.println("Width2: "+width)
System.out.println("Height2: "+height)
Image smallImg =srcImg.getScaledInstance(width, height, Image.SCALE_SMOOTH)//缩小
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