问题
I want to customise the (+) sign that appears on the left side of tree view Is it possible I want to place image in that place
i have tried to customise and searched the forums also Blackberry forums where one of them said its not possible but then
i got a link for this As below which says it is possible
http://supportforums.blackberry.com/t5/Java-Development/Custom-TreeField/td-p/354901
where the HardwareDevice class seems to be missing
Can anyone explain this concept using the link or any other answer of their own Please suggest ?
回答1:
[UPDATED] If you want to CUSTOMISE the (+)-sign and other attributes of each row of a TreeField rather than writing your own tree field then you can try re-writing the drawTreeItem method of TreeFieldCallback like shown below:
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);
}
}
}
回答2:
Try this following code foe custom treeField with image
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);
}
}
you can get output as
来源：https://stackoverflow.com/questions/9992371/customising-blackberry-treefield