blackberry - 在垂直字段管理器中将字段水平居中

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labelfield居中。如果我在下面用USE_ALL_WIDTH添加第二个字段，那么第一个字段将居中。

我不知道这样做的正确方法!

编辑:

按照下面提供的链接，我尝试执行以下操作:

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。我应该如何实现呢？

Answer 1

以下是BlackBerry上的对齐规则:

HorizontalFieldManager只能将中的字段垂直对齐。因此，在创建这些字段时，只有以下样式(也称为对齐位)有效:FIELD_TOP，FIELD_VCENTER，FIELD_BOTTOM。例如new LabelField("My field", Field.Field_VCENTER)

Horizo​​ntalFieldManager示例

VerticalFieldManager只能将中的字段水平对齐。仅以下样式有效:FIELD_LEFT，FIELD_HCENTER，FIELD_RIGHT。

VerticalFieldManager示例

水平和垂直对齐示例

这是一个使按钮在屏幕中央垂直和水平对齐的示例:

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);
        }
    }

屏幕应如下所示:

您应该能够修改上面的内容，以使字段与所需的方式保持一致。