spacing issue with drawing a string into a JScrollPane
Hi,
I've produced some rather messy test code whose intention is to 'draw' a
string on a JScrollPane.
The string is a representation of a whole number & fraction number group.
So meaning something like '3 1/2'
The way I've tried to do this is to draw the whole number firstly, find its
pixel width, then add a preset gap length. And then next to that draw the
fraction group at a reduced font size, and also then finding the pixel width
of the fraction group.
So the total length of this string in pixels ought to be "the whole number
string width + the gap width + the width of the fraction group"... ??
Anyway to test that this is the case, I drew a couple of lines either side
of the string. The line on the left seems to be in the correct position,
but the line on the right seems to be 'too far over'.
In fact for small numbers such as 4 2/3 say, then the line seems to be in
the correct position (ie. just to the right of the end of the string), but
the larger the number gets the further and further the line goes beyond the
end of the string.
The variable called 'entry' which appears in the program represents a 'top
heavy' fraction, so a number of the form 17/8 for instance,this is then
converted to whole/fraction format.
Anyway the code is as below, I'd be grateful for any of you to run it and
try to explain why this gap to the right is appearing for larger numbers.
Regards
Jeremy Watts
import javax.swing.*;
import java.awt.*;
import java.util.*;
import java.math.BigDecimal;
import java.math.BigInteger;
/* ScrollDemo2.java requires no other files. */
public class ScrollDemo extends JPanel {
private Dimension area; //indicates area taken up by graphics
private Rectangle circles;
private JPanel drawingPane;
public ScrollDemo() {
super(new BorderLayout());
area = new Dimension(0,0);
circles = new Rectangle();
//Set up the drawing area.
drawingPane = new DrawingPane();
drawingPane.setBackground(Color.white);
//Put the drawing area in a scroll pane.
JScrollPane scroller = new JScrollPane(drawingPane);
scroller.setPreferredSize(new Dimension(200,200));
//Lay out this demo.
add(scroller, BorderLayout.CENTER);
resize();
}
/** The component inside the scroll pane. */
public class DrawingPane extends JPanel {
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int fontSize = 22; /* this also is to be supplied , font size
to lie beteween 18 and 40 */
int fontLook = 0; /* <---- normal, bold, bold & italic etc.
also to be supplied */
Font display;
FontMetrics metrics;
String fontType = "Courier"; /* <--- this is to be supplied
information */
display = new Font(fontType, fontLook, fontSize);
metrics = getFontMetrics(display);
int wholeNumberStringWidth;
String wholeNumberString;
String fractionalNumberString;
int wholeNumberFractionGap; /* gap between whole number &
fraction */
int index;
BigInteger[] entry = new BigInteger[3];
entry[1] = new BigInteger("-113389445411564431");
entry[2] = new BigInteger("2811811");
/* print number in form of 'whole number / fraction' */
BigInteger[] divisionResult;
divisionResult = entry[1].divideAndRemainder(entry[2]);
System.out.println("division result is:-");
System.out.println(divisionResult[0]);
System.out.println(divisionResult[1]);
BigInteger hcf;
if (divisionResult[0].compareTo(BigInteger.ZERO) == -1) {
divisionResult[1] = divisionResult[1].negate();
}
hcf = (divisionResult[1].abs()).gcd(entry[2]);
g.setColor(Color.black);
display = new Font(fontType, fontLook, fontSize);
metrics = getFontMetrics(display);
g.setFont(display);
wholeNumberString = String.valueOf(divisionResult[0]);
wholeNumberStringWidth = metrics.stringWidth(wholeNumberString);
System.out.println("wholeNumberStringWidth");
System.out.println(wholeNumberStringWidth);
wholeNumberFractionGap = (int)(fontSize/7) + 2;
int x = 100;
int y = 100;
boolean slashFound;
int fractionalNumberStringWidth;
g.drawString(wholeNumberString, x, y);
display = new Font(fontType, fontLook, fontSize - 7);
metrics = getFontMetrics(display);
g.setFont(display);
fractionalNumberString =
String.valueOf(divisionResult[1].divide(hcf)) + "/" +
String.valueOf(entry[2].divide(hcf));
fractionalNumberStringWidth =
metrics.stringWidth(fractionalNumberString);
System.out.println("fractionalNumberStringWidth");
System.out.println(fractionalNumberStringWidth);
slashFound = false;
for (index = 0; index <= (fractionalNumberString.length() -
1);index++) {
if ((slashFound == false) &
(fractionalNumberString.charAt(index) != '/')) {
g.drawString(String.valueOf(fractionalNumberString.charAt(index)),
x + wholeNumberStringWidth + (index * (int)(fontSize/2.7)) +
wholeNumberFractionGap, y - 10);
}
if (fractionalNumberString.charAt(index) == '/') {
slashFound = true;
g.drawString(String.valueOf(fractionalNumberString.charAt(index)),
x + wholeNumberStringWidth + (index * (int)(fontSize/2.7)) +
wholeNumberFractionGap, y - 5);
}
if ((slashFound == true) &
(fractionalNumberString.charAt(index) != '/')) {
g.drawString(String.valueOf(fractionalNumberString.charAt(index)),
x + wholeNumberStringWidth + (index * (int)(fontSize/2.7)) +
wholeNumberFractionGap, y);
}
}
g.drawLine(x,y,x,y+50);
g.drawLine(x+wholeNumberStringWidth+wholeNumberFractionGap+fractionalNumberStringWidth,y,x+wholeNumberStringWidth+wholeNumberFractionGap+fractionalNumberStringWidth,y+50);
}
}
public void resize() {
final int W = 2000;
final int H = 1500;
boolean changed = false;
int x = 0;
int y = 0;
circles = new Rectangle(x, y, W, H);
drawingPane.scrollRectToVisible(circles);
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) {
//Update client's preferred size because
//the area taken up by the graphics has
//gotten larger or smaller (if cleared).
drawingPane.setPreferredSize(area);
//Let the scroll pane know to update itself
//and its scrollbars.
drawingPane.revalidate();
}
drawingPane.repaint();
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("ScrollDemo2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create and set up the content pane.
JComponent newContentPane = new ScrollDemo();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}