How to create CustomLabelField which suites for all blackberry version?

问题

I have created my own customlabelfield, using this customlabelfield i can able to modify the background color,font color,width and height...When i use this label field in the version 4.6 i can get the expected output like,if the text is not suite in single line then it automatically comes to second line but if i use the same in version 4.5 the text is not coming to next line and instead sometimes it showing half of the text and sometimes not even showing single line.If u have any idea to solve this prob pls share with me.

回答1:

My implementation of button control will:

have fixed size, font and text offset
if label cannot fit single line, show label in several lines of maximum width
if no more lines can fit, show ellipsis at the end of the line

alt text http://img297.imageshack.us/img297/8360/multilinebuttons.jpg
A custom button code:

class CustomButton extends ButtonField {
 int mHeight;
 int mWidth;
 int LEFT_OFFSET = 2;
 int TOP_OFFSET = 2;

 public CustomButton(int height, int width, String label) {
  super(label, CONSUME_CLICK);
  mHeight = height;
  mWidth = width;
  setFont(getFont().derive(Font.PLAIN, 16));
 }

 public int getPreferredHeight() {
  return mHeight;
 }

 public int getPreferredWidth() {
  return mWidth;
 }

 protected void layout(int width, int height) {
  super.layout(mWidth, mHeight);
  setExtent(mWidth, mHeight);
 }

 protected void paint(Graphics graphics) {
  int textHeight = getFont().getHeight();
  int twoLinesHeight = 2 * textHeight + TOP_OFFSET;
  // check if first line fit in button height
  int fitHeight = mHeight - 2 * TOP_OFFSET;
  if (textHeight <= fitHeight) {
   graphics.setColor(Color.WHITE);
   String label = getLabel();
   int textLenght = getFont().getAdvance(label);
   // check if whole label fit in button width
   int fitWidth = mWidth - 2 * LEFT_OFFSET;
   if (textLenght <= fitWidth) {
    graphics.drawText(label, LEFT_OFFSET, TOP_OFFSET);
   } else {
    Vector lines = splitLabelToLines();
    int lineTopOffset = TOP_OFFSET;
    int linesCount = lines.size();
    for (int i = 0; i < linesCount; i++) {
     String line = (String) lines.elementAt(i);

     // if lines will not fit in button height, draw ellipsis
     int moreLinesHeight = lineTopOffset + twoLinesHeight;
     boolean moreLinesFit = moreLinesHeight <= fitHeight;
     boolean lastLine = (i == linesCount - 1);
     if (moreLinesFit || lastLine) {
      graphics.drawText(line, LEFT_OFFSET, lineTopOffset);
      lineTopOffset += TOP_OFFSET + textHeight;
     } else {
      line += "...";
      int lineLenght = getFont().getAdvance(line);
      if (lineLenght > fitWidth) {
       int len = Math.max(0, line.length() - 6);
       line = line.substring(0, len) + "...";
      }
      graphics.drawText(line, LEFT_OFFSET, lineTopOffset);
      break;
     }
    }
   }
  }
 }

 private Vector splitLabelToLines() {
  int fitWidth = mWidth - 2 * LEFT_OFFSET;
  String label = getLabel();
  int lbLen = label.length();
  Vector lines = new Vector();
  int begin = 0;
  // while there are more chars in label
  while (begin < lbLen - 1) {
   // new line
   String lnText = "";
   // line width in pixels
   int lnWidth = 0;
   // line width in chars
   int lnLen = 0;
   // while line fit button width or label chars ends
   while ((lnWidth < fitWidth) && (begin + lnLen < lbLen)) {
    lnLen++;
    lnText = label.substring(begin, begin + lnLen);
    lnWidth = getFont().getAdvance(lnText);
   }
   if (begin + lnLen < lbLen)
    lnLen--;
   begin += lnLen;
   lnText = lnText.substring(0, lnLen);
   lines.addElement(lnText);
  }
  return lines;
 }
}

Example of use:

class Scr extends MainScreen {
 CustomButton button1;
 CustomButton button2;
 CustomButton button3;

 public Scr() {
  add(button1 = new CustomButton(20, 60,
    "first buttton it's with a large text"));
  add(button2 = new CustomButton(40, 120,
    "second buttton it's with a large text"));
  add(button3 = new CustomButton(60, 200,
    "third buttton it's with a large text"));
 }
}

来源：https://stackoverflow.com/questions/1612738/how-to-create-customlabelfield-which-suites-for-all-blackberry-version

标签

blackberry