/*
* Copyright (c) 2004 David Flanagan. All rights reserved.
* This code is from the book Java Examples in a Nutshell, 3nd Edition.
* It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
* You may study, use, and modify it for any non-commercial purpose,
* including teaching and use in open-source projects.
* You may distribute it non-commercially as long as you retain this notice.
* For a commercial use license, or to purchase the book,
* please visit http://www.davidflanagan.com/javaexamples3.
*/
package je3.beans;
import java.awt.*;
import javax.swing.*;
import java.util.StringTokenizer;
/**
* A custom component that displays multiple lines of text with specified
* margins and alignment.
**/
public class MultiLineLabel extends JComponent {
// User-specified properties
protected String label; // The label, not broken into lines
protected int margin_width; // Left and right margins
protected int margin_height; // Top and bottom margins
protected Alignment alignment; // The alignment of the text.
// Computed state values
protected int num_lines; // The number of lines
protected String[] lines; // The label, broken into lines
protected int[] line_widths; // How wide each line is
protected int max_width; // The width of the widest line
protected int line_height; // Total height of the font
protected int line_ascent; // Font height above baseline
protected boolean measured = false; // Have the lines been measured?
// Here are five versions of the constructor.
public MultiLineLabel(String label, int margin_width,
int margin_height, Alignment alignment) {
this.label = label; // Remember all the properties.
this.margin_width = margin_width;
this.margin_height = margin_height;
this.alignment = alignment;
newLabel(); // Break the label up into lines.
}
public MultiLineLabel(String label, int margin_width, int margin_height) {
this(label, margin_width, margin_height, Alignment.LEFT);
}
public MultiLineLabel(String label, Alignment alignment) {
this(label, 10, 10, alignment);
}
public MultiLineLabel(String label) { this(label, 10, 10, Alignment.LEFT);}
public MultiLineLabel() { this(""); }
// Methods to set and query the various attributes of the component.
// Note that some query methods are inherited from the superclass.
public void setLabel(String label) {
this.label = label;
newLabel(); // Break the label into lines.
repaint(); // Request a redraw.
measured = false; // Note that we need to measure lines.
invalidate(); // Tell our containers about this
}
public void setAlignment(Alignment a) { alignment = a; repaint(); }
public void setMarginWidth(int mw) { margin_width = mw; repaint(); }
public void setMarginHeight(int mh) { margin_height = mh; repaint(); }
// Override this property setter method because we need to remeasure
public void setFont(Font f) {
super.setFont(f); // Tell our superclass about the new font.
repaint(); // Request a redraw.
measured = false; // Note that we need to remeasure lines.
invalidate(); // Tell our containers about new size
}
// Property getter methods.
public String getLabel() { return label; }
public Alignment getAlignment() { return alignment; }
public int getMarginWidth() { return margin_width; }
public int getMarginHeight() { return margin_height; }
/**
* This method is called by a layout manager when it wants to
* know how big we'd like to be.
*/
public Dimension getPreferredSize() {
if (!measured) measure();
return new Dimension(max_width + 2*margin_width,
num_lines * line_height + 2*margin_height);
}
/**
* This method is called when the layout manager wants to know
* the bare minimum amount of space we need to get by.
*/
public Dimension getMinimumSize() { return getPreferredSize(); }
/**
* This method draws the component.
* Note that it handles the margins and the alignment, but that
* it doesn't have to worry about the color or font--the superclass
* takes care of setting those in the Graphics object we're passed.
**/
public void paintComponent(Graphics g) {
int x, y;
Dimension size = this.getSize();
if (!measured) measure();
y = line_ascent + (size.height - num_lines * line_height)/2;
for(int i = 0; i < num_lines; i++, y += line_height) {
if (alignment == Alignment.LEFT) x = margin_width;
else if (alignment == Alignment.CENTER)
x = (size.width - line_widths[i])/2;
else x = size.width - margin_width - line_widths[i];
g.drawString(lines[i], x, y);
}
}
/**
* This internal method breaks a specified label up into an array of lines.
* It uses the StringTokenizer utility class.
**/
protected synchronized void newLabel() {
StringTokenizer t = new StringTokenizer(label, "\n");
num_lines = t.countTokens();
lines = new String[num_lines];
line_widths = new int[num_lines];
for(int i = 0; i < num_lines; i++) lines[i] = t.nextToken();
}
/**
* This internal method figures out how the font is, and how wide each
* line of the label is, and how wide the widest line is.
**/
protected synchronized void measure() {
FontMetrics fm = this.getFontMetrics(this.getFont());
line_height = fm.getHeight();
line_ascent = fm.getAscent();
max_width = 0;
for(int i = 0; i < num_lines; i++) {
line_widths[i] = fm.stringWidth(lines[i]);
if (line_widths[i] > max_width) max_width = line_widths[i];
}
measured = true;
}
}
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