我需要在 BlackBerry 中进行如下自定义布局。
我在Android中做了同样的布局。现在我需要在 BlackBerry 中使用相同的布局。我是 BlackBerryapp 开发的新手。像 Android 中的FieldsBlackBerryViews对我来说似乎很令人困惑。
我尝试使用VerticalFieldManager&HorizontalFieldManager通过将这些与BitmapField&混合LabelField来生成我的布局。
我特别失败了放置LabelField在屏幕底部。我用USE_ALL_HEIGHT&FIELD_BOTTOM样式放在底部，但滚动很长时间后才显示。
我的要求是当我的中间列表滚动时页眉和页脚不应该滚动。
添加不随屏幕中间内容滚动的页眉和页脚字段的最简单方法是使用MainScreen#setBanner()and 。这MainScreen#setStatus()是一个示例：
public class HeaderFooterListScreen extends MainScreen {
private static final int BG_COLOR = Color.BLACK;
private static final int HIGHLIGHT_COLOR = Color.BLUE;
private static final int FONT_COLOR = Color.WHITE;
private static final int ROW_HEIGHT = 60;
private Object[] _rowData;
private Field _header;
private Field _footer;
private Field _spacer;
private int _orientation;
public HeaderFooterListScreen() {
super(MainScreen.VERTICAL_SCROLL | MainScreen.VERTICAL_SCROLLBAR);
Background bg = BackgroundFactory.createSolidBackground(BG_COLOR);
setBackground(bg);
getMainManager().setBackground(bg);
// header
Bitmap headerImg = Bitmap.getBitmapResource("header.png");
_header = new BitmapField(headerImg);
setBanner(_header);
// list
_rowData = new Object[] { "row one", "row two", "row three" }; //, "row four", "row five", "row six", "row seven", "row eight", "row nine", "row ten" };
ListField list = new ListField();
int c = Color.RED;
XYEdges edgeColors = new XYEdges(c, c, c, c);
XYEdges edgeThicknesses = new XYEdges(5, 5, 5, 5);
list.setBorder(BorderFactory.createSimpleBorder(edgeThicknesses, edgeColors, Border.STYLE_SOLID));
list.setCallback(new CustomListFieldCallback());
list.setRowHeight(ROW_HEIGHT);
list.setSize(_rowData.length);
add(list);
// footer
_footer = new LabelField("Footer Showing Status As Text", Field.USE_ALL_WIDTH | DrawStyle.HCENTER) {
public void paint(Graphics g) {
// change font color
int oldColor = g.getColor();
g.setColor(FONT_COLOR);
super.paint(g);
g.setColor(oldColor);
}
};
_footer.setFont(_footer.getFont().derive(Font.PLAIN, 24));
setStatus(_footer);
}
private void centerList() {
if (_spacer != null && _spacer.getManager() != null) {
// delete the old spacer field, if there was one
delete(_spacer);
}
int listHeight = _rowData.length * ROW_HEIGHT;
int availableHeight = getHeight() - _footer.getHeight() - _header.getHeight();
if (availableHeight > listHeight) {
boolean firstRun = (_spacer == null);
// add a spacer above the list to force it down enough to be centered
final int SPACE = (availableHeight - listHeight) / 2;
_spacer = new Field() {
protected void layout(int width, int height) {
setExtent(width, SPACE);
}
protected void paint(Graphics graphics) {
}
};
insert(_spacer, 0);
if (firstRun) {
getMainManager().setVerticalScroll(0);
}
}
}
// called when device orientation changes
protected void sublayout(int width, int height) {
super.sublayout(width, height);
if (_orientation != Display.getOrientation()) {
_orientation = Display.getOrientation();
// run with invokeLater() to avoid recursive sublayout() calls
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
// TODO: may have to adjust header, too?
centerList();
}
});
}
}
private class CustomListFieldCallback implements ListFieldCallback {
private final int PAD = 10;
public void drawListRow(ListField listField, Graphics graphics,
int index, int y, int width) {
int oldColor = graphics.getColor();
if (listField.getSelectedIndex() == index) {
graphics.setColor(HIGHLIGHT_COLOR);
} else {
graphics.setColor(BG_COLOR);
}
graphics.fillRect(0, y, width, listField.getRowHeight());
graphics.setColor(FONT_COLOR);
String text = (String)get(listField, index);
graphics.drawText(text, PAD, y + PAD, DrawStyle.LEFT);
graphics.setColor(oldColor);
}
public Object get(ListField listField, int index) {
return _rowData[index];
}
public int getPreferredWidth(ListField listField) {
return Display.getWidth();
}
public int indexOfList(ListField listField, String prefix, int start) {
return -1; // TODO?
}
}
}
你没有具体说明你希望中间的列表如何工作，所以我只是做了一些猜测。我也不确定红色边框是你想要的，还是你用来描述布局的东西。如果您对列表有更多要求，请编辑您的问题或发布新问题。
如果您来自 Android，并且不清楚 BlackBerry UI 类（如Fields和）的作用Managers，这里有一些资源：
