actionscript-3 - 字符串的长度(以像素为单位)

Question

我正在用字符串的 arrayCollection 填充 dropDownList。我希望下拉列表控件的宽度与数组集合中最长字符串的大小(以像素为单位)相匹配。我面临的问题是:集合中字符串的字体宽度不同，例如'W' 看起来比 'l' 宽。所以我估计一个字符的宽度是 8 像素，但这不是很整洁。如果遇到一个包含许多 'W' 和 'M' 的字符串，则估计是错误的。所以我想要字符串的精确像素宽度。如何以像素为单位获得字符串的确切长度？

我估计所有字符为 8 像素宽的解决方案如下:

public function populateDropDownList():void{
    var array:Array = new Array("o","two","three four five six seven eight wwww");
    var sampleArrayCollection:ArrayCollection = new ArrayCollection(array);
    var customDropDownList:DropDownList = new DropDownList();
    customDropDownList.dataProvider=sampleArrayCollection;
    customDropDownList.prompt="Select ...";
    customDropDownList.labelField="Answer Options:";
    //calculating the max width
    var componentWidth=10; //default
    for each(var answerText in array){
     Alert.show("Txt size: "+ answerText.length + " pixels: " + answerText.length*9); 
     if(answerText.length * 8 > componentWidth){
      componentWidth=answerText.length * 8;
     }
    }
    customDropDownList.width=componentWidth;
    answers.addChild(customDropDownList);
   }

任何想法或解决方案都受到高度重视。

谢谢

Answer 1

要获得更准确的测量值，您可以使用字符串填充 TextField，然后测量该 TextField 文本的宽度。

代码:

function measureString(str:String, format:TextFormat):Rectangle {
    var textField:TextField = new TextField();
    textField.defaultTextFormat = format;
    textField.text = str;

    return new Rectangle(0, 0, textField.textWidth, textField.textHeight);
}

用法:

var format:TextFormat = new TextFormat();
format.font = "Times New Roman";
format.size = 16;

var strings:Array = [ "a", "giraffe", "foo", "!" ];

var calculatedWidth:Number = 50;    // Set this to minimum width to start with

for each (var str:String in strings) {
    var stringWidth:Number = measureString(str, format).width;
    if (stringWidth > calculatedWidth) {
        calculatedWidth = stringWidth;
    }
}

trace(calculatedWidth);