有没有办法在黑莓中显示“加载”屏幕动画？
选项：
有这些吗？
谢谢！
【问题讨论】：
标签： user-interface blackberry java-me loading wait
费尔明，安东尼+1。谢谢大家，你给了我答案的一部分。
我的最终解决方案：
1.创建或生成（free Ajax loading gif generator）动画并将其添加到项目中。
2.创建ResponseCallback接口（见Coderholic - Blackberry WebBitmapField）接收线程执行结果：
public interface ResponseCallback {
public void callback(String data);
}
3.创建一个类来处理您的后台线程作业。就我而言，它是 http 请求：
public class HttpConnector
{
static public void HttpGetStream(final String fileToGet,
final ResponseCallback msgs) {
Thread t = new Thread(new Runnable() {
public void run() {
HttpConnection hc = null;
DataInputStream din = null;
try {
hc = (HttpConnection) Connector.open("http://" + fileToGet);
hc.setRequestMethod(HttpsConnection.GET);
din = hc.openDataInputStream();
ByteVector bv = new ByteVector();
int i = din.read();
while (-1 != i) {
bv.addElement((byte) i);
i = din.read();
}
final String response = new String(bv.toArray(), "UTF-8");
UiApplication.getUiApplication().invokeLater(
new Runnable() {
public void run() {
msgs.callback(response);
}
});
}
catch (final Exception e) {
UiApplication.getUiApplication().invokeLater(
new Runnable() {
public void run() {
msgs.callback("Exception (" + e.getClass() + "): "
+ e.getMessage());
}
});
}
finally {
try {
din.close();
din = null;
hc.close();
hc = null;
}
catch (Exception e) {
}
}
}
});
t.start();
}
}
4.Create WaitScreen（FullScreen 和AnimatedGIFField 的混合体，带有 ResponseCallback 接口）：
public class WaitScreen extends FullScreen implements ResponseCallback
{
StartScreen startScreen;
private GIFEncodedImage _image;
private int _currentFrame;
private int _width, _height, _xPos, _yPos;
private AnimatorThread _animatorThread;
public WaitScreen(StartScreen startScreen) {
super(new VerticalFieldManager(), Field.NON_FOCUSABLE);
setBackground(
BackgroundFactory.createSolidTransparentBackground(
Color.WHITE, 100));
this.startScreen = startScreen;
EncodedImage encImg =
GIFEncodedImage.getEncodedImageResource("ajax-loader.gif");
GIFEncodedImage img = (GIFEncodedImage) encImg;
// Store the image and it's dimensions.
_image = img;
_width = img.getWidth();
_height = img.getHeight();
_xPos = (Display.getWidth() - _width) >> 1;
_yPos = (Display.getHeight() - _height) >> 1;
// Start the animation thread.
_animatorThread = new AnimatorThread(this);
_animatorThread.start();
UiApplication.getUiApplication().pushScreen(this);
}
protected void paint(Graphics graphics) {
super.paint(graphics);
// Draw the animation frame.
graphics
.drawImage(_xPos, _yPos, _image
.getFrameWidth(_currentFrame), _image
.getFrameHeight(_currentFrame), _image,
_currentFrame, 0, 0);
}
protected void onUndisplay() {
_animatorThread.stop();
}
private class AnimatorThread extends Thread {
private WaitScreen _theField;
private boolean _keepGoing = true;
private int _totalFrames, _loopCount, _totalLoops;
public AnimatorThread(WaitScreen _theScreen) {
_theField = _theScreen;
_totalFrames = _image.getFrameCount();
_totalLoops = _image.getIterations();
}
public synchronized void stop() {
_keepGoing = false;
}
public void run() {
while (_keepGoing) {
// Invalidate the field so that it is redrawn.
UiApplication.getUiApplication().invokeAndWait(
new Runnable() {
public void run() {
_theField.invalidate();
}
});
try {
// Sleep for the current frame delay before
// the next frame is drawn.
sleep(_image.getFrameDelay(_currentFrame) * 10);
} catch (InterruptedException iex) {
} // Couldn't sleep.
// Increment the frame.
++_currentFrame;
if (_currentFrame == _totalFrames) {
// Reset back to frame 0
// if we have reached the end.
_currentFrame = 0;
++_loopCount;
// Check if the animation should continue.
if (_loopCount == _totalLoops) {
_keepGoing = false;
}
}
}
}
}
public void callback(String data) {
startScreen.updateScreen(data);
UiApplication.getUiApplication().popScreen(this);
}
}
5.最后创建开始界面调用HttpConnector.HttpGetStream并显示WaitScreen：
public class StartScreen extends MainScreen
{
public RichTextField text;
WaitScreen msgs;
public StartScreen() {
text = new RichTextField();
this.add(text);
}
protected void makeMenu(Menu menu, int instance) {
menu.add(runWait);
super.makeMenu(menu, instance);
}
MenuItem runWait = new MenuItem("wait", 1, 1) {
public void run() {
UiApplication.getUiApplication().invokeLater(
new Runnable() {
public void run() {
getFile();
}
});
}
};
public void getFile() {
msgs = new WaitScreen(this);
HttpConnector.HttpGetStream(
"stackoverflow.com/faq", msgs);
}
//you should implement this method to use callback data on the screen.
public void updateScreen(String data)
{
text.setText(data);
}
}
更新：另一个解决方案naviina.eu: A Web2.0/Ajax-style loading popup in a native BlackBerry application
【讨论】：
这种事情的基本模式是：
让一个线程运行一个循环来更新一个变量（例如动画图像的帧索引），然后在绘制图像的字段上调用 invalidate（然后休眠一段时间）。无效将排队重新绘制该字段。
在字段的paint方法中，读取变量并绘制图像的相应帧。
伪代码（不完全完整，但给你一个想法）：
public class AnimatedImageField extends Field implements Runnable {
private int currentFrame;
private Bitmap[] animationFrames;
public void run() {
while(true) {
currentFrame = (currentFrame + 1) % animationFrames.length;
invalidate();
Thread.sleep(100);
}
}
protected void paint(Graphics g) {
g.drawBitmap(0, 0, imageWidth, imageHeight, animationFrames[currentFrame], 0, 0);
}
}
请注意，这里我使用了一组位图，但 EncodedImage 可让您将动画 gif 视为一个对象，并包含获取特定帧的方法。
编辑：为了完整性：将其添加到 PopupScreen （如 Fermin 的回答中）或通过直接覆盖 Screen 创建自己的对话框。单独的线程是必要的，因为 RIM API 不是线程安全的：您需要在事件线程上执行所有与 UI 相关的操作（或者在持有事件锁时，请参阅 BlackBerry UI Threading - The Very Basics
【讨论】：
这是加载屏幕的简单代码......
HorizontalFieldManager popHF = new HorizontalFieldManager();
popHF.add(new CustomLabelField("Pls wait..."));
final PopupScreen waitScreen = new PopupScreen(popHF);
new Thread()
{
public void run()
{
synchronized (UiApplication.getEventLock())
{
UiApplication.getUiApplication().pushScreen(waitScreen);
}
//Here Some Network Call
synchronized (UiApplication.getEventLock())
{
UiApplication.getUiApplication().popScreen(waitScreen);
}
}
}.start();
【讨论】：
如果它只是一个动画，您能否在弹出窗口中显示animated gif 并在加载操作完成时将其关闭？
【讨论】：
最简单的方法可能是使用标准 GaugeField，设置样式 GaugeField.PERCENT。这会给你一个进度条。将此添加到 PopupScreen 中，它将位于您的内容之上。有点像..
private GaugeField _gaugeField;
private PopupScreen _popup;
public ProgressBar() {
DialogFieldManager manager = new DialogFieldManager();
_popup = new PopupScreen(manager);
_gaugeField = new GaugeField(null, 0, 100, 0, GaugeField.PERCENT);
manager.addCustomField(_gaugeField);
}
然后有一个更新方法，它将使用 _gaugeField.setValue(newValue);更新进度条。
我通常会从正在执行工作的任何线程调用它（在您的情况下加载，每次操作完成时，进度条都会更新。
【讨论】：
我建议看看这个简单的实现。我喜欢这个，但从未使用过。可能对你有帮助。
【讨论】：
如果您至少使用 BB OS 6.0，ActivityIndicator 是一个不错的选择。
http://www.brighthub.com/mobile/blackberry-platform/articles/94258.aspx
http://docs.blackberry.com/en/developers/deliverables/17966/Screen_APIs_1245069_11.jsp
【讨论】：