在垂直字段管理器中水平居中字段

Question

vfm = new VerticalFieldManager(Manager.VERTICAL_SCROLL);
    vfm.add(new LabelField("horizontally centered...",Field.FIELD_HCENTER | LabelField.FOCUSABLE));
    vfm.add(new LabelField("horizontally centered...",Field.FIELD_HCENTER | LabelField.USE_ALL_WIDTH | LabelField.FOCUSABLE));

    add(vfm);

为什么我的字段不能水平对齐。我尝试了不同的组合，但无法使单个标签字段居中。如果我在下面使用 USE_ALL_WIDTH 添加第二个字段，那么第一个字段将居中。

我不知道正确的做法是什么！

编辑：

按照下面提供的链接，我尝试这样做：

vfm = new VerticalFieldManager(Field.USE_ALL_WIDTH | Field.USE_ALL_HEIGHT){


        protected void sublayout( int width, int height ) {

            super.sublayout( width, height );

            width = getWidth();
            height = getHeight();

            for (int i = 0;i < this.getFieldCount() - 1; i++)
            {
                System.out.println("field:" + i);
                Field field = this.getField(i);
                //this positions the item in the middle of the manager
                int x = (int)((width - field.getWidth()) * 0.50);
                setPositionChild(field, x, field.getTop());
            }
        }


    };


    vfm.add(new LabelField("Facebook"));


    add(vfm);

问题是我没有得到任何字段。我应该如何实现它？

Answer 1

以下是 BlackBerry 上的对齐规则：

• HorizontalFieldManager 只能垂直对齐其中的字段。因此，在创建这些字段时，只有以下样式（也称为对齐位）有任何效果：FIELD_TOP、FIELD_VCENTER、FIELD_BOTTOM。例如new LabelField("My field", Field.Field_VCENTER)

Horizo​​ntalFieldManager 示例

• VerticalFieldManager 只能水平对齐其中的字段。只有以下样式有效：FIELD_LEFT、FIELD_HCENTER、FIELD_RIGHT。

VerticalFieldManager 示例

水平和垂直对齐示例

这是一个在屏幕中心垂直和水平对齐按钮的示例：

public class AlignmentScreen extends MainScreen{

        public AlignmentScreen(){

            //A MainScreen has a VerticalFieldManager to lay out its 
            //fields from top to bottom, the style bits here tell it
            //to span the whole width of the screen and not to scroll
            super(Manager.USE_ALL_WIDTH | Manager.NO_VERTICAL_SCROLL);

            //Set the VerticalFieldManager to have a GREEN background
            getMainManager().setBackground(BackgroundFactory.createSolidBackground(0xFF00FF00));

            //Create a new HorizontalFieldManager which is centered horizontally
            //and spans the whole height of the containing VerticalFieldManager
            HorizontalFieldManager hfm = new HorizontalFieldManager(Field.FIELD_HCENTER | Manager.USE_ALL_HEIGHT);

            //Set the HorizontalFieldManager's background to RED
            hfm.setBackground(BackgroundFactory.createSolidBackground(0xFFFF0000));

            //Create a button and center align it vertically
            ButtonField button = new ButtonField("Test", Field.FIELD_VCENTER);

            //Add the button to the HoriztonalFieldManager
            hfm.add(button);

            //Add the HorizontalFieldManager to the VerticalFieldManager
            add(hfm);
        }
    }

屏幕应该是这样的：

您应该能够修改上述内容以使您的字段以您想要的方式对齐。

Answer 2

首先将您的 Field 添加到 HorizontalFieldManager（例如 hfm），然后将 hfm 添加到 vfm，希望这能解决你的问题：

VerticalFieldManager vfm = new VerticalFieldManager();
HorizontalFieldManager hfm = new HorizontalFieldManager(Manager.FIELD_HCENTER);
hfm.add(new LabelField("My Label"));
add(hfm);

查看以下链接以查找 An effective way of aligning fields in a VerticalFieldManager

Answer 3

检查此代码 sn-p。不必那么复杂。

public final class CenterScreen extends MainScreen {
    public CenterScreen() {        
        LabelField lbl1 = new LabelField("First and Foremost", Field.FIELD_HCENTER);
        lbl1.setBorder(BorderFactory.createRoundedBorder(new XYEdges(10, 10, 10, 10),
            Color.BLUE, Border.STYLE_SOLID));

        LabelField lbl2 = new LabelField("Second", Field.FIELD_HCENTER);
        lbl2.setBorder(BorderFactory.createRoundedBorder(new XYEdges(10, 10, 10, 10),
            Color.RED, Border.STYLE_SOLID));

        LabelField lbl3 = new LabelField("Last but not least", Field.FIELD_HCENTER);
        lbl3.setBorder(BorderFactory.createRoundedBorder(new XYEdges(10, 10, 10, 10),
            Color.GREEN, Border.STYLE_SOLID));

        VerticalFieldManager vfm = new VerticalFieldManager(Field.USE_ALL_WIDTH);        
        vfm.add(lbl1);
        vfm.add(lbl2);
        vfm.add(lbl3);
        add(vfm);    
    }
}

导致