本文介绍了使用鼠标单击在JLabel内拖动和移动图片的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我在JLabel中有一个图像。
I have an image inside a JLabel.
JLabel label = new JLabel(new ImageIcon("C:\\image.jpg"));
label.setSize(300,300);
我想要以下功能。
- 我点击JLabel内部的一个位置（在图像上）。
-I click on a location inside the JLabel (on the image).
- 按下鼠标按钮，我可以在JLabel中更改图像的位置。 （我将图片拖到JLabel内的不同位置）
-With the mousebutton pressed, I can change the location of the image within the JLabel. (I drag the picture to different positions within the JLabel)
嗯，这意味着在很多情况下，图片将被裁剪并且在视图之外。
Well, this means that in many instances the picture will be cropped and outside of view.
请告诉我如何实现此功能？
Please tell me how to implement this functionality?
要添加到JLabel的正确事件监听器是什么？
What are the correct event listeners to add to my JLabel?
推荐答案
这是一个基本的例子...
This is a basic example...
它的工作原理是划分标签升级为3x3网格，其中每个单元格代表图标的可能位置。
It works by dividing the label up into a 3x3 grid, where each cell represents a possible position for the icon.
public class TestMouseDrag {
public static void main(String[] args) {
new TestMouseDrag();
}
public TestMouseDrag() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new DragMyIcon());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
protected class DragMyIcon extends JPanel {
private JLabel label;
public DragMyIcon() {
ImageIcon icon = null;
try {
icon = new ImageIcon(ImageIO.read(getClass().getResource("/bomb.png")));
} catch (IOException ex) {
ex.printStackTrace();
}
label = new JLabel(icon);
label.setHorizontalAlignment(JLabel.CENTER);
label.setVerticalAlignment(JLabel.CENTER);
setLayout(new BorderLayout());
add(label);
MouseHandler handler = new MouseHandler();
label.addMouseListener(handler);
label.addMouseMotionListener(handler);
}
}
protected class MouseHandler extends MouseAdapter {
private boolean active = false;
@Override
public void mousePressed(MouseEvent e) {
JLabel label = (JLabel) e.getComponent();
Point point = e.getPoint();
active = getIconCell(label).contains(point);
if (active) {
label.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
} else {
label.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
}
}
@Override
public void mouseReleased(MouseEvent e) {
active = false;
JLabel label = (JLabel) e.getComponent();
label.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
}
@Override
public void mouseDragged(MouseEvent e) {
if (active) {
JLabel label = (JLabel) e.getComponent();
Point point = e.getPoint();
int verticalAlign = label.getVerticalAlignment();
int horizontalAlign = label.getHorizontalAlignment();
if (isWithInColumn(label, point, 0)) {
horizontalAlign = JLabel.LEFT;
} else if (isWithInColumn(label, point, 1)) {
horizontalAlign = JLabel.CENTER;
} else if (isWithInColumn(label, point, 2)) {
horizontalAlign = JLabel.RIGHT;
}
if (isWithInRow(label, point, 0)) {
verticalAlign = JLabel.TOP;
} else if (isWithInRow(label, point, 1)) {
verticalAlign = JLabel.CENTER;
} else if (isWithInRow(label, point, 2)) {
verticalAlign = JLabel.BOTTOM;
}
label.setVerticalAlignment(verticalAlign);
label.setHorizontalAlignment(horizontalAlign);
label.invalidate();
label.repaint();
}
}
@Override
public void mouseMoved(MouseEvent e) {
}
protected boolean isWithInColumn(JLabel label, Point p, int gridx) {
int cellWidth = label.getWidth() / 3;
int cellHeight = label.getHeight();
Rectangle bounds = new Rectangle(gridx * cellWidth, 0, cellWidth, cellHeight);
return bounds.contains(p);
}
protected boolean isWithInRow(JLabel label, Point p, int gridY) {
int cellWidth = label.getWidth();
int cellHeight = label.getHeight() / 3;
Rectangle bounds = new Rectangle(0, cellHeight * gridY, cellWidth, cellHeight);
return bounds.contains(p);
}
private Rectangle getIconCell(JLabel label) {
Rectangle bounds = new Rectangle();
int cellWidth = label.getWidth() / 3;
int cellHeight = label.getHeight() / 3;
bounds.width = cellWidth;
bounds.height = cellHeight;
if (label.getHorizontalAlignment() == JLabel.LEFT) {
bounds.x = 0;
} else if (label.getHorizontalAlignment() == JLabel.CENTER) {
bounds.x = cellWidth;
} else if (label.getHorizontalAlignment() == JLabel.RIGHT) {
bounds.x = cellWidth * 2;
} else {
bounds.x = 0;
bounds.width = 0;
}
//if (label.getHorizontalAlignment() == JLabel.TOP) {
// bounds.y = 0;
//} else if (label.getHorizontalAlignment() == JLabel.CENTER) {
// bounds.y = cellHeight;
//} else if (label.getHorizontalAlignment() == JLabel.BOTTOM) {
// bounds.y = cellHeight * 2;
//} else {
// bounds.y = 0;
// bounds.height = 0;
//}
if (label.getVerticalAlignment() == JLabel.TOP) {
bounds.y = 0;
} else if (label.getVerticalAlignment() == JLabel.CENTER) {
bounds.y = cellHeight;
} else if (label.getVerticalAlignment() == JLabel.BOTTOM) {
bounds.y = cellHeight * 2;
} else {
bounds.y = 0;
bounds.height = 0;
}
return bounds;
}
}
}
从反馈中更新
此示例基本上使用 JLayerdPane 允许在它的容器中重新定位 JLabels ...
This example basically uses a JLayerdPane to allow the repositioning of JLabels within it's container...
public class MoveMe {
public static void main(String[] args) {
new MoveMe();
}
public MoveMe() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new MoveMePane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class MoveMePane extends JLayeredPane {
public MoveMePane() {
int width = 400;
int height = 400;
for (int index = 0; index < 10; index++) {
String text = "Label " + index;
JLabel label = new JLabel(text);
label.setSize(label.getPreferredSize());
int x = (int) Math.round(Math.random() * width);
int y = (int) Math.round(Math.random() * height);
if (x + label.getWidth() > width) {
x = width - label.getWidth();
}
if (y + label.getHeight() > width) {
y = width - label.getHeight();
}
label.setLocation(x, y);
add(label);
}
MoveMeMouseHandler handler = new MoveMeMouseHandler();
addMouseListener(handler);
addMouseMotionListener(handler);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
}
public class MoveMeMouseHandler extends MouseAdapter {
private int xOffset;
private int yOffset;
private JLabel draggy;
private String oldText;
@Override
public void mouseReleased(MouseEvent me) {
if (draggy != null) {
draggy.setText(oldText);
draggy.setSize(draggy.getPreferredSize());
draggy = null;
}
}
public void mousePressed(MouseEvent me) {
JComponent comp = (JComponent) me.getComponent();
Component child = comp.findComponentAt(me.getPoint());
if (child instanceof JLabel) {
xOffset = me.getX() - child.getX();
yOffset = me.getY() - child.getY();
draggy = (JLabel) child;
oldText = draggy.getText();
draggy.setText("What a drag");
draggy.setSize(draggy.getPreferredSize());
}
}
public void mouseDragged(MouseEvent me) {
if (draggy != null) {
draggy.setLocation(me.getX() - xOffset, me.getY() - yOffset);
}
}
}
}
这篇关于使用鼠标单击在JLabel内拖动和移动图片的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！