我正在尝试将图像绘制到java中的JPanel中,然后我就把它打印下来了。我现在的问题是我正在尝试将其扩展到窗口的完整大小,但它没有这样做。我尝试了方法,它们要么使图像消失,要么根本没有图形变化。
我目前正在处理的代码:
class ImagePanel extends JPanel {
private static final long serialVersionUID = 1L;
private Image img;
public ImagePanel(String img) {
this(new ImageIcon(img).getImage());
}
public ImagePanel(Image img) {
this.img = img;
Dimension size = new Dimension(img.getWidth(null), img.getHeight(null));
setPreferredSize(size);
setMinimumSize(size);
setMaximumSize(size);
setSize(size);
setLayout(null);
}
public void paintComponent(Graphics g) {
g.drawImage(img, 0, 0, null);
}
}
全班:http://pastebin.com/CpcBt2j8
我已尝试在img = img.getScaledInstance(440, 440, Image.SCALE_SMOOTH)
添加代码,但无效。我还尝试制作一个名为scaledImg
的新图片,并将img
的{{1}}值设置为该值,并完全删除图片。
如何将图像缩放到我想要的全尺寸?
答案 0 :(得分:1)
我认为“最简单”的方法是做一些像......
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Image scaled = img.getScaledInstance(getWidth(), getHeight(), Image.SCALE_SMOOTH);
g.drawImage(scaled, 0, 0, null);
}
效率低,成本高,可能无法产生预期效果
首先,请查看The Perils of Image.getScaledInstance()
您还可以查看Java: maintaining aspect ratio of JPanel background image,了解有关保持图像宽高比的详细信息,以及与要填充的比例相适应的比例。
我也会缓冲结果,这样你就不会在paintComponent
方法中反复缩放图像,而这种方法可能经常被捕获......
更新了工作示例
这对我来说很好......
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.HeadlessException;
import java.awt.Image;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestImagePane {
public static void main(String[] args) {
new TestImagePane();
}
public TestImagePane() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
try {
Image img = null;
img = ImageIO.read(new File("/path/to/image"));
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new ImagePanel(img));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException | HeadlessException exp) {
exp.printStackTrace();
}
}
});
}
class ImagePanel extends JPanel {
private static final long serialVersionUID = 1L;
private Image img;
private Image scaled;
public ImagePanel(String img) {
this(new ImageIcon(img).getImage());
}
public ImagePanel(Image img) {
this.img = img;
}
@Override
public void invalidate() {
super.invalidate();
int width = getWidth();
int height = getHeight();
if (width > 0 && height > 0) {
scaled = img.getScaledInstance(getWidth(), getHeight(), Image.SCALE_SMOOTH);
}
}
@Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(this), img.getHeight(this));
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(scaled, 0, 0, null);
}
}
}
答案 1 :(得分:1)
动态缩放您使用的图像:
//g.drawImage(img, 0, 0, null);
g.drawImage(image, 0, 0, getWidth(), getHeight(), null);
有关完整实施以及平铺功能,请参阅Background Panel。