Question

我在JPanel上显示图片，在该图片上我创建了setStroke Graphics2D {8} 8的网格。现在，当我通过设置setStroke来缩放网格线时，它不适用于所有图像。我认为这个问题与图像的分辨率有关。我该如何解决这个问题

BufferedImage bi; //loading buffered image some how

JCombobox jComboBox;  //creating combobox having different zoom factor

Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();

int gridLinesThikness = (int) ((float) jComboBox.getSelectedIndex() * (float) (bi.getWidth() / (float) screen.width));

if (gridLinesThikness < 1)
    gridLinesThikness = 1;
g2.setStroke(new BasicStroke(gridLinesThikness));

Answer 1

试试这段代码：

package sad;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Point;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import java.awt.geom.Rectangle2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

public class zoom extends javax.swing.JPanel {

private static int prevN = 0;
private Dimension preferredSize = new Dimension(400,400);    
private Rectangle2D[] rects = new Rectangle2D[50];

public static void main(String[] args) {        
    JFrame jf = new JFrame("test");
    jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    jf.setSize(800, 800);

    JPanel containerPanel = new JPanel();     // extra JPanel 
    containerPanel.setLayout(new GridBagLayout());
    containerPanel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(1, 0, 1)));

    zoom zoomPanel = new zoom();
    containerPanel.add(zoomPanel);
    zoomPanel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));

    jf.add(new JScrollPane(containerPanel));
    jf.setVisible(true);
}    

public zoom() {
    // generate rectangles with pseudo-random coords
    for (int i=0; i<rects.length; i++) {
        rects[i] = new Rectangle2D.Double(
                Math.random()*.8, Math.random()*.8, 
                Math.random()*.2, Math.random()*.2);
    }

    addMouseWheelListener(new MouseWheelListener() {
        @Override
        public void mouseWheelMoved(MouseWheelEvent e) {
            updatePreferredSize(e.getWheelRotation(), e.getPoint());
        }
    });
}

private void updatePreferredSize(int n, Point p) {

    if(n == 0)              // ideally getWheelRotation() should never return 0. 
        n = -1 * prevN;     // but sometimes it returns 0 during changing of zoom 
                            // direction. so if we get 0 just reverse the direction.

    double d = (double) n * 1.08;
    d = (n > 0) ? 1 / d : -d;

    int w = (int) (getWidth() * d);
    int h = (int) (getHeight() * d);
    preferredSize.setSize(w, h);

    int offX = (int)(p.x * d) - p.x;
    int offY = (int)(p.y * d) - p.y;
    getParent().setLocation(getParent().getLocation().x-offX,getParent().getLocation().y-offY); 
    //in the original code, zoomPanel is being shifted. here we are shifting containerPanel

    getParent().doLayout();             // do the layout for containerPanel
    getParent().getParent().doLayout(); // do the layout for jf (JFrame)

    prevN = n;
}

@Override
public Dimension getPreferredSize() {
    return preferredSize;
}

private Rectangle2D r = new Rectangle2D.Float();
public void paint(Graphics g) {
    super.paint(g);
    g.setColor(Color.red);
    int w = getWidth();
    int h = getHeight();
    for (Rectangle2D rect : rects) {
        r.setRect(rect.getX() * w, rect.getY() * h, 
                rect.getWidth() * w, rect.getHeight() * h);
        ((Graphics2D)g).draw(r);
    }       
  }
}

放大和缩小网格和图像的摆动

1 个答案: