java - Blackberry ListField 文本换行 - 仅两行

Question

在我的 ListField 中，我希望能够获取任何给定的长字符串，并且能够将第一行包裹在屏幕宽度内，然后获取剩余的字符串并将其显示在下面并省略其余字符串。现在，这就是我用来检测绘图调用中的换行的方法:

int totalWidth = 0;
int charWidth = 0;
int lastIndex = 0;
int spaceIndex = 0;
int lineIndex = 0;
String firstLine = "";
String secondLine = "";
boolean isSecondLine = false;

for (int i = 0; i < longString.length(); i++){
  charWidth = Font.getDefault().getAdvance(String.valueOf(longString.charAt(i)));
  //System.out.println("char width: " + charWidth);
  if(longString.charAt(i) == ' ')
  spaceIndex = i;
  if((charWidth + totalWidth) > (this.getWidth()-32)){
            //g.drawText(longString.substring(lastIndex, spaceIndex), xpos, y +_padding, DrawStyle.LEFT, w - xpos);  
            lineIndex++;
    System.out.println("current lines to draw: " + lineIndex);
    /*if (lineIndex = 2){
    int idx =  i;
    System.out.println("first line " + longString.substring(lastIndex, spaceIndex));
    System.out.println("second line " + longString.substring(spaceIndex+1, longString.length()));
  }*/
  //firstLine = longString.substring(lastIndex, spaceIndex);
  firstLine = longString.substring(0, spaceIndex);
  //System.out.println("first new line: " +firstLine);
  //isSecondLine=true;
  //xpos = 0;
  //y += Font.getDefault().getHeight();
  i = spaceIndex + 1;
  lastIndex = i;
  System.out.println("Rest of string: " + longString.substring(lastIndex, longString.length()));

  charWidth = 0;
  totalWidth = 0;
  }
  totalWidth += charWidth;
  System.out.println("total width: " + totalWidth);
  //g.drawText(longString.substring(lastIndex, i+1), xpos, y + (_padding*3)+4, DrawStyle.ELLIPSIS, w - xpos);

  //secondLine = longString.substring(lastIndex, i+1);
  secondLine = longString.substring(lastIndex, longString.length());
  //isSecondLine = true;
}

现在，这实际上可以很好地包装任何给定的字符串(假设 y 值已正确偏移，并​​且仅在字符串宽度超过屏幕宽度后绘制文本，以及之后的剩余字符串)，但是，每个当我尝试获取前两行时，如果字符串超出两行，它总是会返回字符串的最后两行。由于我还没有什么想法，有没有更好的方法来做这种事情？

Answer 1

我不完全确定我理解你的问题，但在我看来，你需要一个在两行后放弃的自动换行算法。如果是这种情况，那么这应该有望为您指明正确的方向。

void wrapString(String inputString, int width, Font font){
    String line1;
    String line2;

    if (font.getAdvance(inputString) <= width){
        line1 = inputString;
        line2 = "";
    }
    else{
        int charsInLine1 = countCharsInLine(inputString, 0, inputString.length()-1, width, font);
        int lineBreak = inputString.lastIndexOf(' ', charsInLine1);
        if (lineBreak == -1)
            lineBreak = charsInLine1;
        line1 = inputString.substring(0, lineBreak);

        line2 = inputString.substring(lineBreak+1, inputString.length());
        if (font.getAdvance(line2) > width){
            int charsInLine2 = countCharsInLine(line2, 0, inputString.length()-1, width - font.getAdvance("..."), font);
            line2 = line2.substring(0, charsInLine2) + "...";
        }
    }

    System.out.println("line1: " + line1);
    System.out.println("line2: " + line2);
}

int countCharsInLine(String str, int min, int max, int width, Font font) {

    if (min >= max)
        return max;

    int guess = min + (max - min) / 2;
    int advance = font.getAdvance(str, 0, guess);

    if (advance < width)
        return countCharsInLine(str, guess+1, max, width, font);
    else if (advance > width)
        return countCharsInLine(str, min, guess-1, width, font);
    else
        return guess;
}