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Formatting text

You have several options for programmatically formatting the display of text. You can set properties directly on the TextField instance—for example, the TextFIeld.thickness, TextField.textColor, and TextField.textHeight properties.Or you can designate the content of the text field using the htmlText property and use the supported HTML tags, such as b, i, and u. But you can also apply TextFormat objects to text fields containing plain text, or StyleSheet objects to text fields containing the htmlText property. Using TextFormat and StyleSheet objects provides the most control and consistency over the appearance of text throughout your application. You can define a TextFormat or StyleSheet object and apply it to many or all text fields in your application.

Assigning text formats​

You can use the TextFormat class to set a number of different text display properties and to apply them to the entire contents of a TextField object, or to a range of text.

The following example applies one TextFormat object to an entire TextField object and applies a second TextFormat object to a range of text within that TextField object:

var tf:TextField = new TextField();
tf.text = "Hello Hello";

var format1:TextFormat = new TextFormat();
format1.color = 0xFF0000;

var format2:TextFormat = new TextFormat();
format2.font = "Courier";

tf.setTextFormat(format1);
var startRange:uint = 6;
tf.setTextFormat(format2, startRange);

addChild(tf);

The TextField.setTextFormat() method only affects text that is already displayed in the text field. If the content in the TextField changes, your application might need to call the TextField.setTextFormat() method again to reapply the formatting. You can also set the TextField defaultTextFormat property to specify the format to be used for user-entered text.

Applying cascading style sheets​

Text fields can contain either plain text or HTML-formatted text. Plain text is stored in the text property of the instance, and HTML text is stored in the htmlText property.

You can use CSS style declarations to define text styles that you can apply to many different text fields. CSS style declarations can be created in your application code or loaded in at run time from an external CSS file.

The flash.text.StyleSheet class handles CSS styles. The StyleSheet class recognizes a limited set of CSS properties. For a detailed list of the style properties that the StyleSheet class supports, see the flash.textStylesheet entry in the ActionScript 3.0 Reference.

As the following example shows, you can create CSS in your code and apply those styles to HTML text by using a StyleSheet object:

var style:StyleSheet = new StyleSheet();

var styleObj:Object = new Object();
styleObj.fontSize = "bold";
styleObj.color = "#FF0000";
style.setStyle(".darkRed", styleObj);

var tf:TextField = new TextField();
tf.styleSheet = style;
tf.htmlText = "<span class = 'darkRed'>Red</span> apple";

addChild(tf);

After creating a StyleSheet object, the example code creates a simple object to hold a set of style declaration properties. Then it calls the StyleSheet.setStyle() method, which adds the new style to the style sheet with the name ".darkred". Next, it applies the style sheet formatting by assigning the StyleSheet object to the TextField styleSheet property.

For CSS styles to take effect, the style sheet should be applied to the TextField object before the htmlText property is set.

By design, a text field with a style sheet is not editable. If you have an input text field and assign a style sheet to it, the text field shows the properties of the style sheet, but the text field does not allow users to enter new text into it. Also, you cannot use the following ActionScript APIs on a text field with an assigned style sheet:

  • The TextField.replaceText() method

  • The TextField.replaceSelectedText() method

  • The TextField.defaultTextFormat property

  • The TextField.setTextFormat() method

If a text field has a style sheet assigned to it, but later the TextField.styleSheet property is set to null, the contents of both TextField.text and TextField.htmlText properties add tags and attributes to their content to incorporate the formatting from the previously assigned style sheet. To preserve the original htmlText property, save it in a variable before setting the style sheet to null.

Loading an external CSS file​

The CSS approach to formatting is more powerful when you can load CSS information from an external file at run time. When the CSS data is external to the application itself, you can change the visual style of text in your application without having to change your ActionScript 3.0 source code. After your application has been deployed, you can change an external CSS file to change the look of the application, without having to redeploy the application SWF file.

The StyleSheet.parseCSS() method converts a string that contains CSS data into style declarations in the StyleSheet object. The following example shows how to read an external CSS file and apply its style declarations to a TextField object.

First, here is the content of the CSS file to be loaded, which is named example.css:

p {
    font-family: Times New Roman, Times, _serif;
    font-size: 14;
}

h1 {
    font-family: Arial, Helvetica, _sans;
    font-size: 20;
    font-weight: bold;
}

.bluetext {

color: #0000CC; }

Next is the ActionScript code for a class that loads the example.css file and applies the styles to TextField content:

package
{
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.net.URLLoader;
    import flash.net.URLRequest;
    import flash.text.StyleSheet;
    import flash.text.TextField;
    import flash.text.TextFieldAutoSize;

    public class CSSFormattingExample extends Sprite
    {
        var loader:URLLoader;
        var field:TextField;
        var exampleText:String = "<h1>This is a headline</h1>" +
            "<p>This is a line of text. <span class='bluetext'>" +
            "This line of text is colored blue.</span></p>";

        public function CSSFormattingExample():void
        {
            field = new TextField();
            field.width = 300;
            field.autoSize = TextFieldAutoSize.LEFT;
            field.wordWrap = true;
            addChild(field);

            var req:URLRequest = new URLRequest("example.css");

            loader = new URLLoader();
            loader.addEventListener(Event.COMPLETE, onCSSFileLoaded);
            loader.load(req);
        }

        public function onCSSFileLoaded(event:Event):void
        {
            var sheet:StyleSheet = new StyleSheet();
            sheet.parseCSS(loader.data);
            field.styleSheet = sheet;
            field.htmlText = exampleText;
        }
    }
}

When the CSS data is loaded, the onCSSFileLoaded() method executes and calls the StyleSheet.parseCSS() method to transfer the style declarations to the StyleSheet object.

Formatting ranges of text within a text field​

A useful method of the flash.text.TextField class is the setTextFormat() method. Using setTextFormat(), you can assign specific properties to the contents of a part of a text field to respond to user input, such as forms that need to remind users that certain entries are required or to change the emphasis of a subsection of a passage of text within a text field as a user selects parts of the text.

The following example uses TextField.setTextFormat() on a range of characters to change the appearance of part of the content of myTextField when the user clicks the text field:

var myTextField:TextField = new TextField();
myTextField.text = "No matter where you click on this text field the TEXT IN ALL CAPS changes format.";
myTextField.autoSize = TextFieldAutoSize.LEFT;
addChild(myTextField);
addEventListener(MouseEvent.CLICK, changeText);

var myformat:TextFormat = new TextFormat();
myformat.color = 0xFF0000;
myformat.size = 18;
myformat.underline = true;

function changeText(event:MouseEvent):void
{
    myTextField.setTextFormat(myformat, 49, 65);
}