How can I display scroll like marquee text in Blackberry using J2ME? That moves from left to right or vertically? Any help will be very much appreciated.
可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效,请关闭广告屏蔽插件后再试):
问题:
回答1:
its really easy to display. check the code below .
import java.util.Timer;
import java.util.TimerTask;
import net.rim.device.api.ui.DrawStyle;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.Font;
import net.rim.device.api.ui.Graphics;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.container.MainScreen;
public class MarqueeApp extends UiApplication {
public MarqueeApp() {
pushScreen(new MarqueeScreen());
}
public static void main(String[] args) {
(new MarqueeApp()).enterEventDispatcher();
}
}
class MarqueeScreen extends MainScreen {
public MarqueeScreen() {
setTitle(new LabelField("hi"));
MarqueeLabel testLabel1 = new MarqueeLabel("This is a marquee",
Field.FOCUSABLE);
add(testLabel1);
MarqueeLabel testLabel2 = new MarqueeLabel("This is a long long " +
"long long long long long long long long long long long " +
"long long marquee", Field.FOCUSABLE);
add(testLabel2);
}
}
class MarqueeLabel extends LabelField {
int currentChar = 0;
String currentText = null;
Font ourFont;
private Timer _scrollTimer;
private TimerTask _scrollTimerTask;
public MarqueeLabel(String text, long style) {
super(text, style);
}
public void paint(Graphics graphics) {
currentText = this.getText();
if (currentChar < currentText.length()) {
currentText = currentText.substring(currentChar);
}
graphics.drawText(currentText, 0, 0, DrawStyle.ELLIPSIS, 200);
super.paint(graphics);
}
public void layout(int width, int height) {
ourFont = this.getFont();
setExtent(500, ourFont.getHeight());
}
protected void onDisplay() {
startScroll();
}
protected void onUnfocus() {
startScroll();
}
private void startScroll() {
// Start scrolling
final String fullText = this.getText();
if (_scrollTimer == null) {
_scrollTimer = new Timer();
_scrollTimerTask = new TimerTask() {
public void run() {
currentChar = currentChar + 4;
if (currentChar > fullText.length()) {
currentChar = 0;
}
invalidate();
}
};
_scrollTimer.scheduleAtFixedRate(_scrollTimerTask, 0, 300);
}
}
protected void onFocus(int direction) {
if (_scrollTimer != null) {
_scrollTimerTask.cancel();
_scrollTimer.cancel();
_scrollTimer = null;
_scrollTimerTask = null;
}
}
protected boolean navigationMovement(int dx, int dy,
int status, int time) {
currentText = this.getText();
int oldCurrentChar = currentChar;
if (Math.abs(dx) > Math.abs(dy)) {
// horizontal scroll
if (dx > 0) {
currentChar = Math.min(currentText.length() - 1,
currentChar + 1);
} else if (dx < 0) {
currentChar = Math.max(0, currentChar - 1);
}
if (oldCurrentChar != currentChar) {
this.invalidate();
}
return true;
} else {
return super.navigationMovement(dx, dy, status, time);
}
}
}