如何使用 J2ME 在 Blackberry 中显示类似 marque 的滚动文本? [英] How can I display scroll text like marque in Blackberry using J2ME?

问题描述

如何使用 J2ME 在 Blackberry 中显示滚动条，如选取框文本?那是从左向右移动还是垂直移动?任何帮助将不胜感激.

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.

推荐答案

它真的很容易显示.检查下面的代码.

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);
        }
    }
}

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