[code]
import javax.swing.event.MouseInputAdapter;
import java.awt.event.MouseEvent;
import java.awt.*;
import javax.swing.*;
import java.awt.geom.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.BoxLayout;
public class SelectionDemo {
JFrame frame = new JFrame("SelectionDemo");
JButton Get = new JButton("Get it");
JButton finish = new JButton("Ok");
JButton cancel = new JButton("Cancel");
boolean iscut = false;
Rectangle2D rectsave = new Rectangle2D.Double(0.0, 0.0, 0.0, 0.0);
Rectangle2D orgrect = new Rectangle2D.Double(0.0, 0.0, 0.0, 0.0);
private SelectEndingHandler handler;
static ImageIcon imgicon = null;
JLabel label;
JPanel bigpanel = new JPanel();
JPanel panel = new JPanel();
JPanel buttonpanel = new JPanel();
SelectionDemo() {
}
public void show(SelectEndingHandler handler, String starFile) {
this.handler = handler;
finish.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (iscut == true) {
frame.dispose();
} else {
JOptionPane.showMessageDialog(null, "u have not cut already");
}
}
});
cancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
saveAs sve = new saveAs("./images/selectsave.JPG", imgicon.getImage(), orgrect);
sve.save();
frame.dispose();
dispose();
}
});
Get.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if ((rectsave.getWidth() >= 150) && (rectsave.getHeight() >= 150)) {
saveAs sve = new saveAs("./images/selectsave.JPG", imgicon.getImage(), rectsave);
sve.save();
dispose();
iscut = true;
} else {
JOptionPane.showMessageDialog(null, "Size of the image is too small");
}
}
});
label = new JLabel("Drag within the image.");
imgicon = createImageIcon(starFile);
orgrect = new Rectangle2D.Double(0.0, 0.0, (double) imgicon.getIconWidth(), (double) imgicon.getIconHeight());
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
SelectionArea area = new SelectionArea(imgicon, this);
panel.add(area);
label.setLabelFor(area);
panel.add(label);
buttonpanel.add(Get);
buttonpanel.add(finish);
buttonpanel.add(cancel);
area.setAlignmentX(Component.LEFT_ALIGNMENT);
label.setAlignmentX(Component.LEFT_ALIGNMENT);
bigpanel.add(panel);
bigpanel.add(buttonpanel);
frame.setLocation(80, 80);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setResizable(false);
frame.add(bigpanel);
//Display the window.
frame.pack();
frame.setVisible(true);
}
public void dispose() {
handler.selectEnded(this);
}
public void updateLabel(Rectangle rect) {
int width = rect.width;
int height = rect.height;
//Make the coordinates look OK if a dimension is 0.
if (width == 0) {
width = 1;
}
if (height == 0) {
height = 1;
}
label.setText("size=(" + rect.width + "X" + rect.height + ")");
}
protected static ImageIcon createImageIcon(String path) {
if (path != null) {
return new ImageIcon(path);
} else {
System.err.println("Couldn't find file: " + path);
return null;
}
}
private class SelectionArea extends JLabel {
Rectangle currentRect = null;
Rectangle rectToDraw = null;
Rectangle previousRectDrawn = new Rectangle();
SelectionDemo controller;
public SelectionArea(ImageIcon image, SelectionDemo controller) {
super(image); //This component displays an image.
this.controller = controller;
setOpaque(true);
setMinimumSize(new Dimension(10, 10)); //don't hog space
MyListener myListener = new MyListener();
addMouseListener(myListener);
addMouseMotionListener(myListener);
}
private class MyListener extends MouseInputAdapter {
public void mousePressed(MouseEvent e) {
int x = e.getX();
int y = e.getY();
currentRect = new Rectangle(x, y, 0, 0);
updateDrawableRect(getWidth(), getHeight());
repaint();
}
public void mouseDragged(MouseEvent e) {
updateSize(e);
}
public void mouseReleased(MouseEvent e) {
updateSize(e);
}
void updateSize(MouseEvent e) {
int x = e.getX();
int y = e.getY();
currentRect.setSize(x - currentRect.x,
y - currentRect.y);
updateDrawableRect(getWidth(), getHeight());
Rectangle totalRepaint = rectToDraw.union(previousRectDrawn);
repaint(totalRepaint.x, totalRepaint.y,
totalRepaint.width, totalRepaint.height);
}
}
protected void paintComponent(Graphics g) {
super.paintComponent(g); //paints the background and image
//If currentRect exists, paint a box on top.
if (currentRect != null) {
//Draw a rectangle on top of the image.
g.setXORMode(Color.white); //Color of line varies
//depending on image colors
g.drawRect(rectToDraw.x, rectToDraw.y,
rectToDraw.width - 1, rectToDraw.height - 1);
controller.updateLabel(rectToDraw);
rectsave = rectToDraw;
}
}
private void updateDrawableRect(int compWidth, int compHeight) {
int x = currentRect.x;
int y = currentRect.y;
int width = currentRect.width;
int height = currentRect.height;
//Make the width and height positive, if necessary.
if (width < 0) {
width = 0 - width;
x = x - width + 1;
if (x < 0) {
width += x;
x = 0;
}
}
if (height < 0) {
height = 0 - height;
y = y - height + 1;
if (y < 0) {
height += y;
y = 0;
}
}
//The rectangle shouldn't extend past the drawing area.
if ((x + width) > compWidth) {
width = compWidth - x;
}
if ((y + height) > compHeight) {
height = compHeight - y;
}
//Update rectToDraw after saving old value.
if (rectToDraw != null) {
previousRectDrawn.setBounds(
rectToDraw.x, rectToDraw.y,
rectToDraw.width, rectToDraw.height);
rectToDraw.setBounds(x, y, width, height);
} else {
rectToDraw = new Rectangle(x, y, width, height);
}
}
}
}
[/code]
import javax.swing.event.MouseInputAdapter;
import java.awt.event.MouseEvent;
import java.awt.*;
import javax.swing.*;
import java.awt.geom.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.BoxLayout;
public class SelectionDemo {
JFrame frame = new JFrame("SelectionDemo");
JButton Get = new JButton("Get it");
JButton finish = new JButton("Ok");
JButton cancel = new JButton("Cancel");
boolean iscut = false;
Rectangle2D rectsave = new Rectangle2D.Double(0.0, 0.0, 0.0, 0.0);
Rectangle2D orgrect = new Rectangle2D.Double(0.0, 0.0, 0.0, 0.0);
private SelectEndingHandler handler;
static ImageIcon imgicon = null;
JLabel label;
JPanel bigpanel = new JPanel();
JPanel panel = new JPanel();
JPanel buttonpanel = new JPanel();
SelectionDemo() {
}
public void show(SelectEndingHandler handler, String starFile) {
this.handler = handler;
finish.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (iscut == true) {
frame.dispose();
} else {
JOptionPane.showMessageDialog(null, "u have not cut already");
}
}
});
cancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
saveAs sve = new saveAs("./images/selectsave.JPG", imgicon.getImage(), orgrect);
sve.save();
frame.dispose();
dispose();
}
});
Get.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if ((rectsave.getWidth() >= 150) && (rectsave.getHeight() >= 150)) {
saveAs sve = new saveAs("./images/selectsave.JPG", imgicon.getImage(), rectsave);
sve.save();
dispose();
iscut = true;
} else {
JOptionPane.showMessageDialog(null, "Size of the image is too small");
}
}
});
label = new JLabel("Drag within the image.");
imgicon = createImageIcon(starFile);
orgrect = new Rectangle2D.Double(0.0, 0.0, (double) imgicon.getIconWidth(), (double) imgicon.getIconHeight());
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
SelectionArea area = new SelectionArea(imgicon, this);
panel.add(area);
label.setLabelFor(area);
panel.add(label);
buttonpanel.add(Get);
buttonpanel.add(finish);
buttonpanel.add(cancel);
area.setAlignmentX(Component.LEFT_ALIGNMENT);
label.setAlignmentX(Component.LEFT_ALIGNMENT);
bigpanel.add(panel);
bigpanel.add(buttonpanel);
frame.setLocation(80, 80);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setResizable(false);
frame.add(bigpanel);
//Display the window.
frame.pack();
frame.setVisible(true);
}
public void dispose() {
handler.selectEnded(this);
}
public void updateLabel(Rectangle rect) {
int width = rect.width;
int height = rect.height;
//Make the coordinates look OK if a dimension is 0.
if (width == 0) {
width = 1;
}
if (height == 0) {
height = 1;
}
label.setText("size=(" + rect.width + "X" + rect.height + ")");
}
protected static ImageIcon createImageIcon(String path) {
if (path != null) {
return new ImageIcon(path);
} else {
System.err.println("Couldn't find file: " + path);
return null;
}
}
private class SelectionArea extends JLabel {
Rectangle currentRect = null;
Rectangle rectToDraw = null;
Rectangle previousRectDrawn = new Rectangle();
SelectionDemo controller;
public SelectionArea(ImageIcon image, SelectionDemo controller) {
super(image); //This component displays an image.
this.controller = controller;
setOpaque(true);
setMinimumSize(new Dimension(10, 10)); //don't hog space
MyListener myListener = new MyListener();
addMouseListener(myListener);
addMouseMotionListener(myListener);
}
private class MyListener extends MouseInputAdapter {
public void mousePressed(MouseEvent e) {
int x = e.getX();
int y = e.getY();
currentRect = new Rectangle(x, y, 0, 0);
updateDrawableRect(getWidth(), getHeight());
repaint();
}
public void mouseDragged(MouseEvent e) {
updateSize(e);
}
public void mouseReleased(MouseEvent e) {
updateSize(e);
}
void updateSize(MouseEvent e) {
int x = e.getX();
int y = e.getY();
currentRect.setSize(x - currentRect.x,
y - currentRect.y);
updateDrawableRect(getWidth(), getHeight());
Rectangle totalRepaint = rectToDraw.union(previousRectDrawn);
repaint(totalRepaint.x, totalRepaint.y,
totalRepaint.width, totalRepaint.height);
}
}
protected void paintComponent(Graphics g) {
super.paintComponent(g); //paints the background and image
//If currentRect exists, paint a box on top.
if (currentRect != null) {
//Draw a rectangle on top of the image.
g.setXORMode(Color.white); //Color of line varies
//depending on image colors
g.drawRect(rectToDraw.x, rectToDraw.y,
rectToDraw.width - 1, rectToDraw.height - 1);
controller.updateLabel(rectToDraw);
rectsave = rectToDraw;
}
}
private void updateDrawableRect(int compWidth, int compHeight) {
int x = currentRect.x;
int y = currentRect.y;
int width = currentRect.width;
int height = currentRect.height;
//Make the width and height positive, if necessary.
if (width < 0) {
width = 0 - width;
x = x - width + 1;
if (x < 0) {
width += x;
x = 0;
}
}
if (height < 0) {
height = 0 - height;
y = y - height + 1;
if (y < 0) {
height += y;
y = 0;
}
}
//The rectangle shouldn't extend past the drawing area.
if ((x + width) > compWidth) {
width = compWidth - x;
}
if ((y + height) > compHeight) {
height = compHeight - y;
}
//Update rectToDraw after saving old value.
if (rectToDraw != null) {
previousRectDrawn.setBounds(
rectToDraw.x, rectToDraw.y,
rectToDraw.width, rectToDraw.height);
rectToDraw.setBounds(x, y, width, height);
} else {
rectToDraw = new Rectangle(x, y, width, height);
}
}
}
}
[/code]
本文介绍了一个使用Java Swing实现的图片选择器应用,该应用允许用户通过拖拽方式选择图片区域并进行裁剪保存。文章详细展示了如何利用Swing组件及事件监听器来实现交互式的图片选择功能。

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