BlackBerry为MainScreen添加Banner

要想在MainScreen上实现下图的功能，有什么办法呢？

 

大家都知道在MainScreen中有个方法setBanner()，位置在Title之上。可是找来找去API里面并没有提供的，仅仅能获取数值的。

不过国外有个强人，自己画出来了，虽然有点粗糙，可是提供了一种思路，毕竟使用图片来做的话，局限性比较大。

下面是代码：

import java.util.Timer; import java.util.TimerTask; import net.rim.device.api.i18n.SimpleDateFormat; import net.rim.device.api.system.DeviceInfo; import net.rim.device.api.system.Display; import net.rim.device.api.system.RadioInfo; 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.FontFamily; import net.rim.device.api.ui.Graphics; public class TopBannerField extends Field implements DrawStyle { private Font headerFont = SmallFont(); private SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm:ss"); private SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd"); private String timeString; private String dateString; private String title; private boolean showSignal; private boolean showBattery; private boolean showDate; private boolean showTime; private boolean showTitle; private int fieldWidth; private int fieldHeight; private int fontColour; private int backgroundColour; private int batteryBackground; private Timer headerTimer = new Timer(); private TimerTask headerTask; public TopBannerField(String _title) { super(Field.NON_FOCUSABLE); title = _title; showSignal = true; showBattery = true; showDate = true; showTime = true; showTitle = true; fieldHeight = 20; fieldWidth = Display.getWidth(); fontColour = 0x999999; backgroundColour = 0x000000; batteryBackground = 0x999999; headerTask = new TimerTask() { public void run() { invalidate(); } }; headerTimer.scheduleAtFixedRate(headerTask, 500, 500); } public void setTitle(String _title) { title = _title; invalidate(); } public void setFontColour(int _fontColour) { fontColour = _fontColour; invalidate(); } public void setBatteryBackground(int _batteryBackground) { batteryBackground = _batteryBackground; invalidate(); } public void setBackgroundColour(int _backgroundColour) { backgroundColour = _backgroundColour; invalidate(); } public void showSignal(boolean bool) { showSignal = bool; invalidate(); } public void showBattery(boolean bool) { showBattery = bool; invalidate(); } public void showDate(boolean bool) { showDate = bool; invalidate(); } public void showTime(boolean bool) { showTime = bool; invalidate(); } public void showTitle(boolean bool) { showTitle = bool; invalidate(); } protected void layout(int width, int height) { setExtent(getPreferredWidth(), getPreferredHeight()); } public int getPreferredWidth() { return fieldWidth; } public int getPreferredHeight() { return fieldHeight; } protected void paint(Graphics graphics) { graphics.setFont(headerFont); int graphicsDiff = 0; graphics.setColor(backgroundColour); graphics.fillRect(0, 0, this.getPreferredWidth(), this .getPreferredHeight()); if (showSignal) { graphicsDiff = graphicsDiff + 28; graphics.setColor(0x999999); // draw blank background graphics.fillRect(this.getPreferredWidth() - 26, 8, 6, 4); graphics.fillRect(this.getPreferredWidth() - 21, 6, 6, 6); graphics.fillRect(this.getPreferredWidth() - 16, 4, 6, 8); graphics.fillRect(this.getPreferredWidth() - 11, 2, 6, 10); graphics.fillRect(this.getPreferredWidth() - 6, 0, 6, 12); int signalLevel = RadioInfo.getSignalLevel(); if (signalLevel > -77) { // 5 bands graphics.setColor(0xEFEFEF); graphics.fillRect(this.getPreferredWidth() - 25, 9, 4, 2); graphics.fillRect(this.getPreferredWidth() - 20, 7, 4, 4); graphics.fillRect(this.getPreferredWidth() - 15, 5, 4, 6); graphics.fillRect(this.getPreferredWidth() - 10, 3, 4, 8); graphics.fillRect(this.getPreferredWidth() - 5, 1, 4, 10); } else if (signalLevel > -86) { // 4 bands graphics.setColor(0xEFEFEF); graphics.fillRect(this.getPreferredWidth() - 25, 9, 4, 2); graphics.fillRect(this.getPreferredWidth() - 20, 7, 4, 4); graphics.fillRect(this.getPreferredWidth() - 15, 5, 4, 6); graphics.fillRect(this.getPreferredWidth() - 10, 3, 4, 8); } else if (signalLevel > -92) { // 3 bands graphics.setColor(0xEFEFEF); graphics.fillRect(this.getPreferredWidth() - 25, 9, 4, 2); graphics.fillRect(this.getPreferredWidth() - 20, 7, 4, 4); graphics.fillRect(this.getPreferredWidth() - 15, 5, 4, 6); } else if (signalLevel > -101) { // 2 bands graphics.setColor(0xEFEFEF); graphics.fillRect(this.getPreferredWidth() - 25, 9, 4, 2); graphics.fillRect(this.getPreferredWidth() - 20, 7, 4, 4); } else if (signalLevel > -120) { // 1 band graphics.setColor(0xEFEFEF); graphics.fillRect(this.getPreferredWidth() - 25, 9, 4, 2); } } if (showBattery) { int batteryLevel = DeviceInfo.getBatteryLevel(); graphics.setColor(batteryBackground); graphics.fillRect(this.getPreferredWidth() - 23 - graphicsDiff, 2, 20, 8); graphics.fillRect(this.getPreferredWidth() - 3 - graphicsDiff, 4, 1, 4); if (batteryLevel > 75) { graphics.setColor(0x28f300); } else if (batteryLevel > 50) { graphics.setColor(0x91dc00); } else if (batteryLevel > 25) { graphics.setColor(0xefec00); } else { graphics.setColor(0xff2200); } double powerLong = ((18.00 / 100) * batteryLevel); int power = (int) powerLong; graphics.fillRect(this.getPreferredWidth() - 22 - graphicsDiff, 3, power, 6); graphicsDiff = graphicsDiff + 24; } graphics.setColor(fontColour); if (showTime) { timeString = " " + timeFormat.formatLocal(System.currentTimeMillis()) + " "; } else { timeString = ""; } if (showDate) { dateString = " " + dateFormat.formatLocal(System.currentTimeMillis()) + " "; } else { dateString = ""; } graphics.drawText(dateString + timeString, this.getPreferredWidth() - headerFont.getAdvance(dateString + timeString) - graphicsDiff, 1); if (showTitle) { int limit = 0; if (showSignal) limit = limit + 28; if (showBattery) limit = limit + 25; if (showTime) limit = limit + headerFont.getAdvance(timeString); if (showDate) limit = limit + headerFont.getAdvance(dateString); if (headerFont.getAdvance(title) > this.getPreferredWidth() - limit) { int elippsy = headerFont.getAdvance("..."); int availableWidth = this.getPreferredWidth() - limit - elippsy; String _txt = ""; String shorterTitle = ""; for (int i = 1; i < title.length(); i++) { _txt = title.substring(0, i); if (headerFont.getAdvance(_txt) < availableWidth) { shorterTitle = _txt; } } title = shorterTitle + "..."; } graphics.drawText(title, 1, 0); } } public static Font SmallFont() { try { FontFamily theFam = FontFamily.forName("SYSTEM"); return theFam.getFont(net.rim.device.api.ui.Font.PLAIN, 14); } catch (ClassNotFoundException ex) { ex.printStackTrace(); } return null; } }