ProgressBar中进度条中显示进度百分比字体重影的现象

strawbingo 2006-01-22 06:26:01

下面是一个可运行的java application程序，显示的进度条在背景没有被蓝色覆盖的情况下，
会发生显示进度百分比字体重影的现象，什么原因呢？如何解决？
望达人指点。

/*
* Created on 2005-7-30
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/
package com.examples.swt.webfind.processbar;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontMetrics;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.ProgressBar;
import org.eclipse.swt.widgets.Shell;

public class CountNumbers {
Display display = new Display();
Shell shell = new Shell(display);

Button button;
ProgressBar progressBar;
public CountNumbers() {
GridLayout gridLayout = new GridLayout(1, true);
shell.setLayout(gridLayout);
button = new Button(shell, SWT.BORDER);
button.setText("Start to count");
progressBar = new ProgressBar(shell, SWT.SMOOTH);
progressBar.setMinimum(0);
progressBar.setMaximum(10);
final Thread countThread = new Thread(){
public void run() {
for(int i=0; i<=10; i++) {
final int num = i;
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
shell.getDisplay().asyncExec(new Runnable(){
public void run() {
if(button.isDisposed() || progressBar.isDisposed())
return;
button.setText("Counting: " + num);
progressBar.setSelection(num);
//progressBar.redraw();
}
});
}
}
};
button.addListener(SWT.Selection, new Listener() {
public void handleEvent(Event event) {
button.setEnabled(false);
countThread.start();
}
});
progressBar.addPaintListener(new PaintListener() {
public void paintControl(PaintEvent e) {
System.out.println("PAINT");
// string to draw.
String string = (progressBar.getSelection() * 1.0 /(progressBar.getMaximum()-progressBar.getMinimum()) * 100) + "%";
Point point = progressBar.getSize();
Font font = new Font(shell.getDisplay(),"Courier",12,SWT.BOLD);
e.gc.setFont(font);
//e.gc.setForeground(shell.getDisplay().getSystemColor(SWT.COLOR_WHITE));
e.gc.setForeground(shell.getDisplay().getSystemColor(SWT.COLOR_BLACK));
FontMetrics fontMetrics = e.gc.getFontMetrics();
int stringWidth = fontMetrics.getAverageCharWidth() * string.length();
int stringHeight = fontMetrics.getHeight();
System.out.println(string);
e.gc.drawString(string, (point.x-stringWidth)/2 , (point.y-stringHeight)/2, true);
font.dispose();
}
});
button.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
progressBar.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));

shell.setSize(300, 100);
shell.open();
//textUser.forceFocus();

// Set up the event loop.
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
// If no more entries in event queue
display.sleep();
}
}

display.dispose();
}

private void init() {

}

public static void main(String[] args) {
new CountNumbers();
}
}

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