【发布时间】：2011-02-10 05:12:54
【问题描述】：
我有一个关于 BlackBerry VerticalScrollField 和滚动的问题，它似乎锁定或使 UI 不稳定。下面的代码是一个 BlackBerry 屏幕，左边是世界作为内容（在滚动字段中），右边有一个跳转栏，允许点击内容。
当点击一个跳转字母时，setVerticalScroll 方法被调用，它执行滚动，但有一个不幸的副作用是呈现 UI 不稳定或不可用。滚动调用是在 UI 线程上完成的，因此不清楚错误的来源是什么。该应用正在 6.0 模拟器中进行测试。
我已经包含了可以复制到 BB Eclipse 中用于黑客/测试的类。
滚动的部分可以在底部找到，代码如下：
UiApplication.getUiApplication().invokeLater(new Runnable(){
public void run() {
scroller.setVerticalScroll(y, true);
}});
这是完整的课程：
包装测试；导入 java.util.Vector;
导入 net.rim.device.api.system.ApplicationManager； 导入 net.rim.device.api.ui.Field； 导入 net.rim.device.api.ui.Font； 导入 net.rim.device.api.ui.Graphics； 导入 net.rim.device.api.ui.TouchEvent； 导入 net.rim.device.api.ui.UiApplication； 导入 net.rim.device.api.ui.component.LabelField； 导入 net.rim.device.api.ui.component.Status； 导入 net.rim.device.api.ui.container.HorizontalFieldManager； 导入 net.rim.device.api.ui.container.MainScreen； 导入 net.rim.device.api.ui.container.VerticalFieldManager；
公共类启动扩展 UiApplication { 私有 int[] 跳转； 静态最终字符串 [] 单词 = 新字符串 []{ “汽车”、“苹果”、“熊”、“汽车”、“农场”、“雪貂”、“黄金”、 “绿色”、“花园”、“树篱”、“快乐”、“冰屋”、“红外线”、 “果冻”、“袋鼠”、“柠檬”、“狮子”、“大理石”、“月亮”、 “九”、“歌剧”、“橙”、“人”、“小狗”、“梨”、 “木瓜”、“种族”、“奔跑”、“日落”、“令牌”、“柳树”、“斑马” }; 私有最终静态字符串 [] 字母表 = 新字符串 []{"A","B","C","D","E", "F","G","H","I","J","K","L","M","N","O","P","Q","R ", "S","T","U","V","W","X","Y","Z","#"}; 私有 VerticalFieldManager 滚动条；
public Startup() {
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
UiApplication.getUiApplication().pushScreen(new ScrollScreen());
}
});
}
public static void main(String[] args) {
ApplicationManager app = ApplicationManager.getApplicationManager();
while (app.inStartup()) {
try { Thread.sleep(200); } catch (Throwable e) {}
}
Startup startup = new Startup();
startup.enterEventDispatcher();
}
/**
* Screen with content in a scrollbar left and a letters on the right that
* can be used to jump into the content.
*/
class ScrollScreen extends MainScreen {
public ScrollScreen() {
super(NO_HORIZONTAL_SCROLL | NO_VERTICAL_SCROLL);
HorizontalFieldManager hfm = new HorizontalFieldManager(USE_ALL_HEIGHT | NO_VERTICAL_SCROLL | NO_HORIZONTAL_SCROLL){
protected void sublayout(int maxWidth, int maxHeight) {
Field scroll = getField(0);
Field alpha = getField(1);
layoutChild(alpha, maxWidth, maxHeight);
layoutChild(scroll, maxWidth-alpha.getWidth(), maxHeight);
setPositionChild(scroll, 0, 0);
setPositionChild(alpha, maxWidth-alpha.getWidth(), 0);
setExtent(maxWidth, maxHeight);
}
};
hfm.add(createScrollContent());
hfm.add(createAlphabetJumpBar());
add(hfm);
}
private Field createScrollContent() {
Vector vocabulary = new Vector();
for (int ii=0; ii<alphabet.length; ii++)
vocabulary.addElement(alphabet[ii]);
scroller = new VerticalFieldManager(VERTICAL_SCROLL | USE_ALL_WIDTH) {
protected void sublayout(int maxWidth, int maxHeight) {
// Record the jump offsets
int y = 0;
for (int ii=0; ii<getFieldCount(); ii++) {
Field field = getField(ii);
layoutChild(field, maxWidth, maxHeight);
setPositionChild(field, 0, y);
if (field instanceof WordField) {
WordField object = (WordField)field;;
char character = object.getWord().toLowerCase().charAt(0);
int offset = ((int)character)-(int)alphabet[0].toLowerCase().charAt(0);
if (offset < 0 || offset > jump.length)
offset = jump.length-1;
while (offset >= 0 && offset < jump.length && jump[offset] == 0) {
jump[offset] = y;
offset--;
}
}
y += field.getHeight();
}
int offset = jump.length-1;
do {
jump[offset] = y;
offset--;
} while (offset >= 0 && jump[offset] == 0);
setExtent(maxWidth, maxHeight);
setVirtualExtent(maxWidth, y+10);
}
};
jump = new int[alphabet.length];
Font largeFont = Font.getDefault().derive(Font.PLAIN, 46);
for (int ii=0; ii<words.length; ii++) {
WordField wordField = new WordField(words[ii]);
wordField.setFont(largeFont);
scroller.add(wordField);
}
return scroller;
}
private Field createAlphabetJumpBar() {
VerticalFieldManager vfm = new VerticalFieldManager() {
protected void sublayout(int maxWidth, int maxHeight) {
int y = 0;
int width = 0;
double allowedAlphaHeight = (double)maxHeight / (double)getFieldCount();
for (int ii=0; ii<getFieldCount(); ii++) {
WordField field = (WordField)getField(ii);
layoutChild(field, maxWidth, (int)allowedAlphaHeight);
setPositionChild(field, 0, y);
y += field.getHeight();
double paddedY = Math.floor(allowedAlphaHeight*(ii+1));
if (y < paddedY) y = (int)paddedY;
width = Math.max(width, field.getWidth());
}
setExtent(width, maxHeight);
}
};
for (int ii=0; ii<alphabet.length; ii++) {
vfm.add(new AlphaField(alphabet[ii]){
protected boolean touchEvent(TouchEvent message) {
if (message.getEvent() == TouchEvent.UP) {
int startOffset = (int)alphabet[0].charAt(0);
int offset = ((int)getWord().charAt(0)) - startOffset;
final int y = offset == 0 ? 0 : jump[offset - 1];
UiApplication.getUiApplication().invokeLater(new Runnable(){
public void run() {
scroller.setVerticalScroll(y, true);
}});
}
return true;
}
});
}
return vfm;
}
class WordField extends LabelField {
private final String word;
public WordField(String word) {
super(word);
this.word = word;
}
public String getWord() { return word; }
}
Font alphaFont = null;
class AlphaField extends WordField {
public AlphaField(String word) {
super(word);
}
protected void layout(int width, int height) {
if (alphaFont == null)
alphaFont = Font.getDefault().derive(Font.PLAIN, height);
setExtent(alphaFont.getAdvance(getWord()), alphaFont.getHeight());
}
protected void paint(Graphics graphics) {
graphics.setFont(alphaFont);
graphics.drawText(getWord(), 0, 0);
}
}
/**
* For debugging.
* @see net.rim.device.api.ui.Screen#keyChar(char, int, int)
*/
protected boolean keyChar(char c, int status, int time) {
if ('o' == c) { // shows the jump offsets into the scroll field
UiApplication.getUiApplication().invokeLater(new Runnable(){
public void run() {
StringBuffer buf = new StringBuffer();
for (int ii=0; ii<jump.length; ii++) {
buf.append(alphabet[ii]+"="+jump[ii]);
if (ii<jump.length-1)
buf.append(",");
}
Status.show("offsets="+buf.toString());
}});
}
return super.keyChar(c, status, time);
}
}
}
【问题讨论】：
标签： blackberry scroll