我在我的 JComponent 中绘制了一些曲线等......使用 Graphics G(不是 2D)。
现在我想使用鼠标的滚轮来放大和缩小。
有轨道吗?
我听说过有关 BuferredImage 的讨论?
最佳答案
您需要考虑一些注意事项...
最终结果将取决于您想要实现的目标。如果您使用 Graphics2D API 绘制曲线,则每次渲染组件时简单地缩放坐标可能会更简单。您需要确保比例的任何变化都反射(reflect)在组件本身的首选尺寸中。
例如,您还可以将“默认”输出渲染到 BufferedImage
并简单地使用 AffineTransform
更改用于渲染结果的缩放比例。
这个简单的使用 BufferedImage
并从磁盘加载图片,但基本概念是相同的。
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseWheelEvent;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ZoomPane {
public static void main(String[] args) {
new ZoomPane();
}
public ZoomPane() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new JScrollPane(new TestPane()));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private BufferedImage img;
private float scale = 1;
public TestPane() {
try {
img = ImageIO.read(new File("/path/to/image"));
} catch (IOException ex) {
ex.printStackTrace();
}
addMouseWheelListener(new MouseAdapter() {
@Override
public void mouseWheelMoved(MouseWheelEvent e) {
double delta = 0.05f * e.getPreciseWheelRotation();
scale += delta;
revalidate();
repaint();
}
});
}
@Override
public Dimension getPreferredSize() {
Dimension size = new Dimension(200, 200);
if (img != null) {
size.width = Math.round(img.getWidth() * scale);
size.height = Math.round(img.getHeight() * scale);
}
return size;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
Graphics2D g2d = (Graphics2D) g.create();
AffineTransform at = new AffineTransform();
at.scale(scale, scale);
g2d.drawImage(img, at, this);
g2d.dispose();
}
}
}
}
您还可以缩放直接传递给 paintComponent
方法的 Graphics
上下文。
这里重要的是记得在完成后重置AffineTransform
,否则它会在渲染时传递给其他组件,而不会产生预期的输出...
这个例子基本上创建了 Graphics
上下文的副本,我们可以在不影响原始内容的情况下对其进行操作和处理,使其更易于处理
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseWheelEvent;
import java.awt.geom.AffineTransform;
import java.awt.geom.GeneralPath;
import java.awt.geom.Path2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ZoomPane {
public static void main(String[] args) {
new ZoomPane();
}
public ZoomPane() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new JScrollPane(new TestPane()));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private float scale = 1;
public TestPane() {
addMouseWheelListener(new MouseAdapter() {
@Override
public void mouseWheelMoved(MouseWheelEvent e) {
double delta = 0.05f * e.getPreciseWheelRotation();
scale += delta;
revalidate();
repaint();
}
});
}
@Override
public Dimension getPreferredSize() {
Dimension size = new Dimension(200, 200);
size.width = Math.round(size.width * scale);
size.height = Math.round(size.height * scale);
return size;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
AffineTransform at = new AffineTransform();
at.scale(scale, scale);
g2d.setTransform(at);
g2d.setColor(Color.RED);
// This is for demonstration purposes only
// I prefer to use getWidth and getHeight
int width = 200;
int height = 200;
Path2D.Float path = new Path2D.Float();
int seg = width / 3;
path.moveTo(0, height / 2);
path.curveTo(0, 0, seg, 0, seg, height / 2);
path.curveTo(
seg, height,
seg * 2, height,
seg * 2, height / 2);
path.curveTo(
seg * 2, 0,
seg * 3, 0,
seg * 3, height / 2);
g2d.draw(path);
g2d.dispose();
}
}
}
关于java - 使用鼠标和图形缩放,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/19643637/