我正在尝试将应用程序从使用 KeywordFilterField 移动到 ListField 并且我一直在努力找出几个小时以来，为什么用不同的y值调用 drawListRow() - 取决于我使用这两个 ListField 中的哪一个：
如果 getRowHeight() 返回 40，那么y值将是 -
对于KeywordFilterField是：0；40; 80; 120; ...（即如预期的那样）
但对于Listfield，我看到：9；49; 89; 129; ... （即由于某种原因偏移9 ）
9从哪里来？ListField 或 ListFieldCallback 中是否有我可以调用来获取此值的方法？我只是想在列表的项目之间画一条浅灰色的线。
下面是我的测试代码，并附上了border.png（用作BasicEditField边框）：
package mypackage;
import java.util.*;
import net.rim.device.api.collection.*;
import net.rim.device.api.collection.util.*;
import net.rim.device.api.system.*;
import net.rim.device.api.ui.*;
import net.rim.device.api.ui.component.*;
import net.rim.device.api.ui.container.*;
import net.rim.device.api.ui.decor.*;
import net.rim.device.api.util.*;
public class MyList extends UiApplication {
public static void main(String args[]) {
MyList app = new MyList();
app.enterEventDispatcher();
}
public MyList() {
pushScreen(new MyScreen());
}
}
class MyScreen extends MainScreen {
static final int EXTRA_ROWS = 2;
MyItemList myItems = new MyItemList();
ListField myList = new ListField(EXTRA_ROWS);
Border myBorder = BorderFactory.createBitmapBorder(
new XYEdges(12, 12, 12, 12),
Bitmap.getBitmapResource("border.png"));
Background myBg = BackgroundFactory.createSolidBackground(0x111111);
StringProvider myProvider = new StringProvider("Search");
BasicEditField myFind = new BasicEditField(USE_ALL_WIDTH) {
protected void paint(Graphics g) {
if (getTextLength() == 0) {
g.setColor(Color.LIGHTGRAY);
g.drawText(myProvider.toString(), 0, 0);
}
g.setColor(Color.BLACK);
super.paint(g);
}
};
public MyScreen() {
getMainManager().setBackground(myBg);
myFind.setBorder(myBorder);
setTitle(myFind);
myItems.doAdd(new MyItem(1, "Eins"));
myItems.doAdd(new MyItem(2, "Zwei"));
myItems.doAdd(new MyItem(3, "Drei"));
myItems.doAdd(new MyItem(4, "Vier"));
myList.setCallback(new MyListFieldCallback());
add(myList);
}
private class MyListFieldCallback implements ListFieldCallback {
public void drawListRow(ListField list, Graphics g, int index, int y, int width) {
System.err.println("XXX index=" + index+ ", y=" + y + ", width=" + width);
g.setColor(Color.WHITE);
if (index < EXTRA_ROWS) {
Font i = getFont().derive(Font.ITALIC);
g.setFont(i);
g.drawText("Add Item", 0, y);
return;
}
if (index >= EXTRA_ROWS) {
MyItem item = (MyItem) myItems.getAt(index - EXTRA_ROWS);
g.drawText(item.toString(), 0, y);
g.setColor(0x333333);
// XXX why do I need to subtract 9 here?
g.drawLine(0, y-9, width, y-9);
return;
}
g.drawText(list.getEmptyString(), 0, y);
}
public Object get(ListField list, int index) {
return myItems.getAt(index);
}
public int getPreferredWidth(ListField list) {
return Display.getWidth();
}
public int indexOfList(ListField list, String prefix, int start) {
return 0;
}
}
class MyItemList extends SortedReadableList {
public MyItemList() {
super(new MyItem.MyComparator());
}
protected void doAdd(Object obj) {
super.doAdd(obj);
myList.setSize(size() + EXTRA_ROWS);
}
protected boolean doRemove(Object obj) {
myList.setSize(size() - 1 + EXTRA_ROWS);
return super.doRemove(obj);
}
}
}
class MyItem {
int _num;
String _name;
public MyItem(int num, String name) {
_num = num;
_name = name;
}
public String toString() {
return _num + ": " + _name;
}
static class MyComparator implements Comparator {
public int compare(Object obj1, Object obj2) {
MyItem item1 = (MyItem) obj1;
MyItem item2 = (MyItem) obj2;
return item1.toString().compareTo(item2.toString());
}
}
static class MyProvider implements KeywordProvider {
public String[] getKeywords(Object obj) {
MyItem item = (MyItem) obj;
return new String[]{ Integer.toString(item._num), item._name };
}
}
}
产生的输出是：
[ 64,890] XXX index=0, y=9, width=360
[ 64,890] XXX index=1, y=49, width=360
[ 64,898] XXX index=2, y=89, width=360
[ 64,898] XXX index=3, y=129, width=360
[ 64,906] XXX index=4, y=169, width=360
[ 64,906] XXX index=5, y=209, width=360
更新以回复 jprofitt
当我尝试您的建议时（我为您的文字和线条使用红色）：
if (index >= EXTRA_ROWS) {
MyItem item = (MyItem) myItems.getAt(index - EXTRA_ROWS);
g.drawText(item.toString(), 0, y);
g.setColor(Color.RED);
g.drawText("XXX", 0, y + (list.getRowHeight() - list.getFont().getHeight())/2);
g.setColor(0x333333);
// XXX why do I need to subtract 9 here?
g.drawLine(0, y-9, width, y-9);
g.setColor(Color.RED);
g.drawLine(0, y, width, y);
return;
}
然后它实际上不起作用 - 因为蓝色焦点线与您建议的（红色）线不对齐。它与我的（灰色）线对齐，这意味着您出于某种原因确实需要减去 -9：
谢谢！亚历克斯