JScrollPane里我定义了ColumnHeaderView和RowHeaderView,当我绘制的图形超出当前的JScrollPane大小时,会自动出现ScrollBar,但当我移动ScrollBar时,却发现我在ColumnHeaderView和RowHeaderView里做的标尺Ruler没有被刷新。该怎样做呢?部分代码如下:(以下代码其实是Java Sample里的)望高手指点。 public ScrollDemo2() {
area = new Dimension(0,0);
circles = new Vector();
drawingPane = new DrawingPane();
scroller = new JScrollPane(drawingPane);
scroller.setPreferredSize(new Dimension(20,20));
columnView = new Rule(Rule.HORIZONTAL, true);
rowView = new Rule(Rule.VERTICAL, true);
scroller.setColumnHeaderView(columnView);
scroller.setRowHeaderView(rowView);
} public class DrawingPane extends JPanel {
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Rectangle rect;
for (int i = 0; i < circles.size(); i++) {
rect = (Rectangle)circles.elementAt(i);
g.setColor(colors[(i % color_n)]);
g.fillOval(rect.x, rect.y, rect.width, rect.height);
} Dimension d = scroller.getPreferredSize();
columnView.setPreferredWidth((int) d.getWidth());
rowView.setPreferredHeight((int) d.getHeight());
columnView.paintComponents(g);
rowView.paintComponents(g);
}
} public void mouseReleased(MouseEvent e) {
final int W = 100;
final int H = 100;
boolean changed = false;
if (SwingUtilities.isRightMouseButton(e)) {
} else {
int x = e.getX() - W/2;
int y = e.getY() - H/2;
if (x < 0) x = 0;
if (y < 0) y = 0;
Rectangle rect = new Rectangle(x, y, W, H);
circles.addElement(rect);
drawingPane.scrollRectToVisible(rect);
int this_width = (x + W + 2);
if (this_width > area.width) {
area.width = this_width; changed=true;
}
int this_height = (y + H + 2);
if (this_height > area.height) {
area.height = this_height; changed=true;
}
}
if (changed) {
drawingPane.setPreferredSize(area);
drawingPane.revalidate();
columnView.setPreferredWidth((int)area.getWidth());
rowView.setPreferredHeight((int)area.getHeight());
scroller.setColumnHeaderView(columnView);
scroller.setRowHeaderView(rowView);
scroller.revalidate();
}
drawingPane.repaint();
scroller.repaint();
}
area = new Dimension(0,0);
circles = new Vector();
drawingPane = new DrawingPane();
scroller = new JScrollPane(drawingPane);
scroller.setPreferredSize(new Dimension(20,20));
columnView = new Rule(Rule.HORIZONTAL, true);
rowView = new Rule(Rule.VERTICAL, true);
scroller.setColumnHeaderView(columnView);
scroller.setRowHeaderView(rowView);
} public class DrawingPane extends JPanel {
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Rectangle rect;
for (int i = 0; i < circles.size(); i++) {
rect = (Rectangle)circles.elementAt(i);
g.setColor(colors[(i % color_n)]);
g.fillOval(rect.x, rect.y, rect.width, rect.height);
} Dimension d = scroller.getPreferredSize();
columnView.setPreferredWidth((int) d.getWidth());
rowView.setPreferredHeight((int) d.getHeight());
columnView.paintComponents(g);
rowView.paintComponents(g);
}
} public void mouseReleased(MouseEvent e) {
final int W = 100;
final int H = 100;
boolean changed = false;
if (SwingUtilities.isRightMouseButton(e)) {
} else {
int x = e.getX() - W/2;
int y = e.getY() - H/2;
if (x < 0) x = 0;
if (y < 0) y = 0;
Rectangle rect = new Rectangle(x, y, W, H);
circles.addElement(rect);
drawingPane.scrollRectToVisible(rect);
int this_width = (x + W + 2);
if (this_width > area.width) {
area.width = this_width; changed=true;
}
int this_height = (y + H + 2);
if (this_height > area.height) {
area.height = this_height; changed=true;
}
}
if (changed) {
drawingPane.setPreferredSize(area);
drawingPane.revalidate();
columnView.setPreferredWidth((int)area.getWidth());
rowView.setPreferredHeight((int)area.getHeight());
scroller.setColumnHeaderView(columnView);
scroller.setRowHeaderView(rowView);
scroller.revalidate();
}
drawingPane.repaint();
scroller.repaint();
}
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首先是ScrollDemo2.java:import javax.swing.*;
import javax.swing.event.MouseInputAdapter;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class ScrollDemo2 extends JPanel implements MouseListener {
private Dimension area; //indicates area taken up by graphics
private Vector circles; //coordinates used to draw graphics
private JPanel drawingPane;
private final Color colors[] = {
Color.red, Color.blue, Color.green, Color.orange,
Color.cyan, Color.magenta, Color.darkGray, Color.yellow};
private final int color_n = colors.length;
private Rule columnView;
private Rule rowView;
private JToggleButton isMetric;
private JPanel buttonCorner;
private JScrollPane scroller; public ScrollDemo2() {
super(new BorderLayout());
area = new Dimension(0,0);
circles = new Vector();
JLabel instructionsLeft = new JLabel("Click left mouse button to place a circle.");
JLabel instructionsRight = new JLabel("Click right mouse button to clear drawing area.");
JPanel instructionPanel = new JPanel(new GridLayout(0,1));
instructionPanel.add(instructionsLeft);
instructionPanel.add(instructionsRight);
drawingPane = new DrawingPane();
drawingPane.setBackground(Color.white);
drawingPane.addMouseListener(this);
scroller = new JScrollPane(drawingPane);
scroller.setPreferredSize(new Dimension(20,20));
add(instructionPanel, BorderLayout.PAGE_START);
add(scroller, BorderLayout.CENTER);
columnView = new Rule(Rule.HORIZONTAL, true);
rowView = new Rule(Rule.VERTICAL, true);
buttonCorner = new JPanel(); //use FlowLayout
isMetric = new JToggleButton("cm", true);
isMetric.setMargin(new Insets(1, 1, 1, 1));
isMetric.setPreferredSize(new Dimension(27, 27));
buttonCorner.add(isMetric);
scroller.setViewportBorder(BorderFactory.createLineBorder(Color.BLACK));
scroller.setColumnHeaderView(columnView);
scroller.setRowHeaderView(rowView);
scroller.setCorner(JScrollPane.UPPER_LEADING_CORNER, buttonCorner);
scroller.setCorner(JScrollPane.LOWER_LEADING_CORNER, new Corner());
scroller.setCorner(JScrollPane.UPPER_TRAILING_CORNER, new Corner());
} public class DrawingPane extends JPanel {
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Rectangle rect;
for (int i = 0; i < circles.size(); i++) {
rect = (Rectangle)circles.elementAt(i);
g.setColor(colors[(i % color_n)]);
g.fillOval(rect.x, rect.y, rect.width, rect.height);
}
Dimension d = scroller.getPreferredSize();
columnView.setPreferredWidth((int) d.getWidth());
rowView.setPreferredHeight((int) d.getHeight());
System.out.println(d);
columnView.paintComponents(g);
rowView.paintComponents(g);
}
} public void mouseReleased(MouseEvent e) {
final int W = 100;
final int H = 100;
boolean changed = false;
if (SwingUtilities.isRightMouseButton(e)) {
circles.removeAllElements();
area.width=0;
area.height=0;
changed = true;
} else {
int x = e.getX() - W/2;
int y = e.getY() - H/2;
if (x < 0) x = 0;
if (y < 0) y = 0;
Rectangle rect = new Rectangle(x, y, W, H);
circles.addElement(rect);
drawingPane.scrollRectToVisible(rect);
int this_width = (x + W + 2);
if (this_width > area.width) {
area.width = this_width; changed=true;
}
int this_height = (y + H + 2);
if (this_height > area.height) {
area.height = this_height; changed=true;
}
}
if (changed) {
drawingPane.setPreferredSize(area);
drawingPane.revalidate();
columnView.setPreferredWidth((int)area.getWidth());
rowView.setPreferredHeight((int)area.getHeight());
scroller.setColumnHeaderView(columnView);
scroller.setRowHeaderView(rowView);
scroller.revalidate();
}
drawingPane.repaint();
scroller.repaint();
}
public void mouseClicked(MouseEvent e){}
public void mouseEntered(MouseEvent e){}
public void mouseExited(MouseEvent e){}
public void mousePressed(MouseEvent e){} private static void createAndShowGUI() {
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("ScrollDemo2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent newContentPane = new ScrollDemo2();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
frame.pack();
frame.setVisible(true);
} public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Toolkit;
import javax.swing.JComponent;public class Rule extends JComponent {
public static final int INCH = Toolkit.getDefaultToolkit().getScreenResolution();
public static final int HORIZONTAL = 0;
public static final int VERTICAL = 1;
public static final int SIZE = 35;
public int orientation;
public boolean isMetric;
private int increment;
private int units;
public boolean isMetric() { return this.isMetric; }
public void setIsMetric(boolean isMetric) {
this.isMetric = isMetric;
setIncrementAndUnits();
repaint();
} public int getIncrement() { return increment; } public void setPreferredHeight(int ph) {
setPreferredSize(new Dimension(SIZE, ph));
} public void setPreferredWidth(int pw) {
setPreferredSize(new Dimension(pw, SIZE));
} public Rule(int o, boolean m) {
orientation = o;
isMetric = m;
setIncrementAndUnits();
} private void setIncrementAndUnits() {
if(isMetric) {
units = (int)((double)INCH / (double)2.54); // dots per centimeter
increment = units;
} else {
units = INCH;
increment = units / 2;
}
} protected void paintComponent(Graphics g) {
Rectangle drawHere = g.getClipBounds();
g.setColor(Color.ORANGE);
g.fillRect(drawHere.x, drawHere.y, drawHere.width, drawHere.height);
g.setFont(new Font("SansSerif", Font.PLAIN, 10));
g.setColor(Color.BLACK);
int end = 0;
int start = 0;
int tickLength = 0;
String text = null;
if(orientation == HORIZONTAL) {
start = (drawHere.x / increment) * increment;
end = (((drawHere.x + drawHere.width) / increment) + 1) * increment;
} else {
start = (drawHere.y / increment) * increment;
end = (((drawHere.y + drawHere.height) / increment) + 1) * increment;
}
if(start == 0) {
text = Integer.toString(0) + (isMetric ? " cm" : " in");
tickLength = 10;
if(orientation == HORIZONTAL) {
g.drawLine(0, SIZE - 1, 0, SIZE - tickLength - 1);
g.drawString(text, 2, 21);
} else {
g.drawLine(SIZE - 1, 0, SIZE - tickLength - 1, 0);
g.drawString(text, 9, 10);
}
text = null;
start = increment;
}
for(int i = start; i < end; i += increment) {
if(i % units == 0) {
tickLength = 10;
text = Integer.toString(i / units);
} else {
tickLength = 7;
text = null;
} if(tickLength != 0) {
if(orientation == HORIZONTAL) {
g.drawLine(i, SIZE - 1, i, SIZE - tickLength - 1);
if(text != null) {
g.drawString(text, i - 3, 21);
}
} else {
g.drawLine(SIZE - 1, i, SIZE - tickLength - 1, i);
if(text != null) {
g.drawString(text, 9, i + 3);
}
}
}
}
}
}
import java.awt.Color;
import java.awt.Graphics;import javax.swing.JComponent;public class Corner extends JComponent {
protected void paintComponent(Graphics g) {
g.setColor(Color.ORANGE);
g.fillRect(0, 0, getWidth(), getHeight());
}
}