我想自定义出现在树视图左侧的 (+) 号 是否可以 我想把图片放在那个地方
我曾尝试自定义和搜索论坛以及黑莓论坛，其中一个说不可能，但后来
我有一个链接如下所示，这是可能的
http://supportforums.blackberry.com/t5/Java-Development/Custom-TreeField/td-p/354901
HardwareDevice 类似乎缺失的地方
任何人都可以使用链接或他们自己的任何其他答案来解释这个概念吗 请建议？
【问题讨论】：
标签： blackberry treeview customization treefield
[已更新] 如果您想自定义TreeField 的每一行的 (+) 符号和其他属性而不是编写自己的树字段，那么您可以尝试重写TreeFieldCallback 的drawTreeItem 方法，如下所示：
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.system.Display;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.Graphics;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.component.TreeField;
import net.rim.device.api.ui.component.TreeFieldCallback;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.ui.container.VerticalFieldManager;
public class TreeDemo extends MainScreen {
int parent[] = {1,2,3,4,5,6,7,8,9};
int child[][] = new int [10][10];
int child_child[][][] = new int [10][10][10];
int rowHeight = 27;
CustomTreeFieldCallback treeCallback = new CustomTreeFieldCallback();
VerticalFieldManager vm = new VerticalFieldManager(Field.FOCUSABLE | VERTICAL_SCROLL | VERTICAL_SCROLLBAR);
TreeField myTree = new TreeField(treeCallback, Field.FOCUSABLE);
public TreeDemo() {
vm.add(new LabelField("Table:"));
myTree.setRowHeight(rowHeight);
myTree.setIndentWidth(15);
myTree.setDefaultExpanded(false);
for(int i = parent.length-1; i >= 0 ; i--) {
parent[i] = myTree.addChildNode(0, "Parent_" + (i+1));
child[i] = new int[4];
for(int j = child[i].length-1; j >=0 ; j--) {
child[i][j] = myTree.addChildNode(parent[i], "Child_"+ (i+1) + "_" + (j+1));
child_child[i][j] = new int[3];
for(int k = child_child[i][j].length-1; k >= 0 ; k--) {
child_child[i][j][k] = myTree.addChildNode(child[i][j], "Child_of_Child_"+ (i+1) + "_" + (j+1)+ "_" + (k+1));
}
}
}
vm.add(myTree);
add(vm);
}
private class CustomTreeFieldCallback implements TreeFieldCallback {
public void drawTreeItem(TreeField treeField, Graphics graphics, int node,
int y, int width, int indent) {
// TODO Auto-generated method stub
String string = (String) treeField.getCookie(node);
int preservedColor = graphics.getColor();
if(treeField.getCurrentNode() == node) {
graphics.setColor(0x0CCCC0);
} else {
graphics.setColor(0x404040);
}
graphics.fillRect(0, y, Display.getWidth(), treeField.getRowHeight());
Bitmap iconImage;
int iconImageWidth = 0;
indent -= 20; // decrease the extra indentation for all nodes.
if(treeField.getFirstChild(node) != -1){ // if the node is not a leaf node
if(treeField.getExpanded(node)) {
iconImage = Bitmap.getBitmapResource("icon_arrow_down.png");
iconImageWidth = iconImage.getWidth();
} else {
iconImage = Bitmap.getBitmapResource("icon_arrow_right.png");
iconImageWidth = iconImage.getWidth();
}
graphics.drawBitmap(indent, y, indent+iconImageWidth, treeField.getRowHeight(), iconImage, 0, 0);
}
if( treeField.getCurrentNode() == node ) {
graphics.setColor(0x404040);
} else {
graphics.setColor(0x0CCCC0);
}
graphics.drawText(string, indent+iconImageWidth, y);
graphics.setColor(preservedColor);
}
}
}
【讨论】：
试试下面这个带有图像的自定义 treeField 代码
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.system.Display;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.Manager;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.BitmapField;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.component.SeparatorField;
import net.rim.device.api.ui.container.HorizontalFieldManager;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.ui.container.VerticalFieldManager;
/**
* A class extending the MainScreen class, which provides default standard
* behavior for BlackBerry GUI applications.
*/
public final class MyScreen extends MainScreen implements FieldChangeListener
{
/**
* Creates a new MyScreen object
*/
private VerticalFieldManager main_manager;
private HorizontalFieldManager parentNodes;
private LabelField parent_lables[];
private Bitmap bitmap,upbitmap;
private BitmapField bitmap_field[];
private VerticalFieldManager submanager[];
private int sizeOfParentNodes=3;
private int sizeOfChildNodes=5;
private static boolean flag[];
public MyScreen()
{
// Set the displayed title of the screen
bitmap=Bitmap.getBitmapResource("arrow.png");
upbitmap=Bitmap.getBitmapResource("uparrow.png");
main_manager=new VerticalFieldManager(Manager.VERTICAL_SCROLL|VERTICAL_SCROLLBAR){
protected void sublayout(int maxWidth, int maxHeight) {
super.sublayout(Display.getWidth(), Display.getHeight());
setExtent(Display.getWidth(), Display.getHeight());
};
};
parent_lables=new LabelField[sizeOfParentNodes];
flag=new boolean[sizeOfParentNodes];
submanager=new VerticalFieldManager[sizeOfParentNodes];
bitmap_field=new BitmapField[sizeOfParentNodes];
for(int i=0;i<sizeOfParentNodes;i++)
{
submanager[i]=new VerticalFieldManager();
updateGUI(i);
main_manager.add(submanager[i]);
}
add(main_manager);
}
public void fieldChanged(Field field, int context) {
// TODO Auto-generated method stub
synchronized (UiApplication.getEventLock()) {
for(int i=0;i<sizeOfParentNodes;i++)
{ if(field==parent_lables[i])
{
if(flag[i]==true){
flag[i]=false;
submanager[i].deleteAll();
updateGUI(i);
parent_lables[i].setFocus();
}else{
flag[i]=true;
bitmap_field[i].setBitmap(upbitmap);
for(int j=0;j<sizeOfChildNodes;j++)
{
submanager[i].add(new LabelField(" Child :"+i+","+j,Field.FOCUSABLE));
submanager[i].add(new SeparatorField());
}
submanager[i].invalidate();
}
}
}
}
}
public void updateGUI(int index)
{
parentNodes=new HorizontalFieldManager(USE_ALL_WIDTH);
bitmap_field[index]=new BitmapField(bitmap);
parentNodes.add(bitmap_field[index]);
parent_lables[index]=new LabelField("Day"+index,Field.FOCUSABLE){
protected boolean navigationClick(int status, int time) {
fieldChangeNotify(1);
return true;
};
};
parentNodes.add(parent_lables[index]);
parent_lables[index].setChangeListener(this);
submanager[index].add(parentNodes);
}
}
你可以得到输出为
【讨论】：