我在 JScrollpane 中有一个 JPanel。 我在 BufferedImage 上绘制,我将其显示在 JPanel 上。 在 JScrollpane 的左上角,我想要一张图片,当我向下滚动查看我的 JPanel 的其余部分时,它总是留在那个角落。 这里是 Jpanel 的 paintComponent 方法:
@Override
public void paintComponent(Graphics g){
super.paintComponent(g);
if (bufferedImage != null){
g.drawImage(bufferedImage, 0, 0, this);
Point p = parent.getViewPosition();
System.out.println("paintComponent(): "+ p.x + "," + p.y);
g.setColor(Color.RED);
g.fillRect(p.x + 20, p.y + 20, 200, 200);
}
}
其中 parent.getViewPosition() 给我 scrollPane.getViewport().getViewPosition()。 当我启动时,我可以看到左上角带有红色矩形的缓冲图像。 当我向下滚动时,我可以看到缓冲图像的其余部分,但是当我向上滚动时,红色矩形向上移动然后消失并且不再出现。 在控制台中,当我滚动时,我可以看到点 p 发生了变化:
paintComponent(): 0,0
paintComponent(): 0,10
paintComponent(): 0,20
paintComponent(): 0,30
paintComponent(): 0,40
paintComponent(): 0,50
谁能帮我解决这个问题?
最佳答案
您可以为此使用一 block 玻璃板,并告诉它在取决于视口(viewport)位置的位置绘制图像。例如:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import javax.swing.*;
@SuppressWarnings("serial")
public class ScrollImgGlass extends JPanel {
private static final int BI_W = 40;
private static final int BI_H = BI_W;
private static final String[] DATA = { "One", "Two", "Three", "Four",
"Five", "Six", "Seven", "Eight", "Nine", "Zero", "One", "Two",
"Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Zero",
"One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight",
"Nine", "Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven",
"Eight", "Nine", "Zero" };
private BufferedImage img = null;
private JViewport viewport;
public ScrollImgGlass(JViewport viewport) {
setOpaque(false);
this.viewport = viewport;
img = new BufferedImage(BI_W, BI_H, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
g2.setColor(Color.red);
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.fillOval(0, 0, BI_W, BI_H);
g2.dispose();
}
@Override
protected void paintComponent(Graphics g) {
Point vpLocation = viewport.getLocationOnScreen();
Point gpLocation = getLocationOnScreen();
int x = vpLocation.x - gpLocation.x;
int y = vpLocation.y - gpLocation.y;
super.paintComponent(g);
if (img != null) {
g.drawImage(img, x, y, this);
}
}
private static void createAndShowGui() {
JList<String> jList = new JList<String>(DATA);
jList.setOpaque(false);
JViewport viewport = new JViewport();
JScrollPane scrollpane = new JScrollPane();
scrollpane.setViewport(viewport);
viewport.setView(jList);
ScrollImgGlass glass = new ScrollImgGlass(viewport);
JFrame frame = new JFrame("ScrollImg");
frame.setGlassPane(glass);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(scrollpane, BorderLayout.CENTER);
// just to show that this works if the viewport is shifted over
frame.getContentPane().add(Box.createRigidArea(new Dimension(20, 20)), BorderLayout.NORTH);
frame.getContentPane().add(Box.createRigidArea(new Dimension(20, 20)), BorderLayout.WEST);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
glass.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
显示如下:
关于java - 我希望图片在滚动时留在 jscrollpane 的左上角,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15467210/