在我的程序中，我经常需要打印各种 JComponent（通常是 JPanel），并且我喜欢它们是整页的。我现在的方法是使用以下代码：
g2d.scale(pf.getImageableWidth()/componentToPrint.getWidth(), pf.getImageableHeight()/componentToPrint.getHeight());
但这通常会拉伸或以其他方式使我尝试打印的任何内容变形，而且我更愿意做一些智能调整大小的事情，也许是以下功能的版本：
componentToPrint.setSize(pf.ImageableWidth(), pf.ImageableHeight);
或者说将组件添加到新的 JFrame 中，然后设置框架大小（问题是组件不能同时存在于两个地方）。我不在乎调整大小是否会使 GUI 的其余部分看起来很糟糕，只要它是可以轻松重置的东西。
有没有办法做到这一点？
我认为您正在寻找的解决方案是构建一个包含所需内容的新 JPanel 并打印副本。如果您使用 CellRendererPane 这样做，您可以获得听起来像您正在寻找的确切大小调整行为。
如果您的 JComponents 编写得相当好，那么新建一个新组件并将其模型设置为与原始模型相同应该不是问题。
CellRendererPane cellRendererPane = new CellRendererPane();
// It's important to add the cell renderer pane to something
// you can use the same one for all of your exporting if you like and just
// add it to your main frame's content pane - it won't show up anywhere.
add(cellRendererPane);
JPanel printPanel = createCopy(panel);
cellRendererPane.paintComponent(g, printPanel, null, 0, 0, exportDim.width, exportDim.height, true);
这是一个完整的工作示例。createPanel() 方法应该创建您想要呈现的任何组件。一个真实的例子应该确保使用相同的模型，而不是为一次性组件重新创建一个新模型。
public class SCCE {
public static void main(String[] args) throws Exception {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
final JFrame f = new JFrame("SCCE");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().setLayout(new BorderLayout());
f.getContentPane().add(SCCE.createPanel());
final CellRendererPane backgroundRenderer = new CellRendererPane();
// Add the renderer somewhere where it won't be seen
f.getContentPane().add(backgroundRenderer, BorderLayout.NORTH);
f.getContentPane().add(createSaveButton(backgroundRenderer), BorderLayout.SOUTH);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
// Create your custom component from whatever model here..
private static final Component createPanel() {
DefaultListModel model = new DefaultListModel();
for (int i = 0; i < 10; i++) {
model.addElement("Item number " + i);
}
return new JList(model);
}
private static JButton createSaveButton(final CellRendererPane backgroundRenderer) {
return new JButton(new AbstractAction("Save image to file") {
@Override
public void actionPerformed(ActionEvent e) {
Dimension d = new Dimension(400, 300);
BufferedImage img = new BufferedImage(d.width, d.height, BufferedImage.TYPE_INT_ARGB);
Graphics2D g = img.createGraphics();
backgroundRenderer.paintComponent(g, createPanel(), null, 0, 0, d.width, d.height, true);
g.dispose();
try {
File output = new File("test.png");
System.err.println("Saved to " + output.getAbsolutePath());
ImageIO.write(img, "png", output);
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
}
}
我会将绘图代码从paintComponent()您的实现方法重构JPanel为该面板中的公共/包保护方法，该方法可以绘制到任意Graphics宽度/高度的任意对象（大概绘图代码足够通用）。
这个例子有一个框架，包含一个面板，它有一些绘图逻辑（一个大 X，面板的大小）。此示例的主要方法向您展示了一种获取图像并将其写入文件的方法，即使图像大小与面板大小不同。
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MockFrame extends JFrame {
// throws Exception, as just an example (not really advised to do this)
public static void main(String[] args) throws Exception {
MockFrame frame = new MockFrame();
frame.setVisible(true);
// different sizes from the frame
int WIDTH = 500;
int HEIGHT = 500;
BufferedImage b = new BufferedImage(WIDTH, HEIGHT,
BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = (Graphics2D) b.getGraphics();
// should set some background, as the panel's background
// is dealt with by super.paintComponent()
g2d.setBackground(Color.white);
frame.getPanel().drawingLogic(b.getGraphics(), WIDTH, HEIGHT);
ImageIO.write(b, "png", new File("test.png"));
}
private MockPanel panel;
public MockFrame() {
this.setSize(200, 200);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
panel = new MockPanel();
getContentPane().add(panel);
}
public MockPanel getPanel() {
return panel;
}
private class MockPanel extends JPanel {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
drawingLogic(g, getWidth(), getHeight());
}
public void drawingLogic(Graphics g, int width, int height) {
g.setColor(Color.black);
g.drawLine(0, 0, width, height);
g.drawLine(0, height, width, 0);
}
}
}
这允许 GUI 外部的对象与它的绘图算法挂钩。我看到的一个缺点是，您将在任何想要打印面板的对象与面板的实际实现之间创建依赖关系。但这仍然比动态调整面板的大小要好（我已经尝试过并且似乎有一些问题 - 我认为setSize()传播更改需要一些时间。
编辑：
作为对评论的回应，我提供了上面代码片段的修改版本。这可能不是最好的方法，也不是非常用户友好（所以我不会在最终用户应用程序中使用它），但它会根据布局管理器的规则调整框架中的所有内容。
/* This code snippet describes a way to resize a frame for printing at
* a custom size and then resize it back.
*
* Copyright (C)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
import java.awt.Container;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
public class MockFrame extends JFrame {
// throws Exception, as just an example (not really advised to do this)
public static void main(String[] args) throws Exception {
final MockFrame frame = new MockFrame();
frame.setVisible(true);
// different sizes from the frame
final int WIDTH = 500;
final int HEIGHT = 700;
final BufferedImage b = new BufferedImage(WIDTH, HEIGHT,
BufferedImage.TYPE_INT_ARGB);
final Graphics2D g2d = (Graphics2D) b.getGraphics();
final int previousWidth = frame.getWidth();
final int previousHeight = frame.getHeight();
frame.setSize(WIDTH, HEIGHT);
frame.repaint();
JOptionPane.showMessageDialog(null,
"Press OK when the window has finished resizing");
frame.print(g2d);
frame.setSize(previousWidth, previousHeight);
ImageIO.write(b, "png", new File("test.png"));
}
public MockFrame() {
this.setSize(200, 200);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
boolean shouldFill = true;
boolean shouldWeightX = true;
Container pane = getContentPane();
// code from
// http://java.sun.com/docs/books/tutorial/uiswing/layout/gridbag.html
// just to add some components in the frame... :)
// left out in here for brevity
}
}
该代码基本上调整了框架的大小，向用户显示了一条确认消息，因此可以阻止线程直到重绘完成（可以通过 完成Thread.sleep()，但使用消息更透明）。然后它打印框架并将其调整回原来的形状。有点hacky，但它有效。
-- Flaviu Cipcigan
我认为您面临的问题与规模经营无关。是你的逻辑不正确。在大多数情况下，您的 x 和 y 比例会不同，因为 Imageable 的比例和您的组件的比例不会相同。这就是您的组件在缩放操作后失真的原因。您必须执行以下操作：
double factorX = pf.getImageableWidth() / component.getWidth();
double factorY = pf.getImageableHeight() / component.getHeight();
double factor = Math.min( factorX, factorY );
g2.scale(factor,factor);
之后，您可以根据图像的新尺寸将图像转换为适当的坐标。希望能帮助到你...
我想你回答了你自己的问题。每个组件都有一个方法：
setSize(int width, int height);