How to use the Feathers
BitmapFontTextEditor class renders text using bitmap fonts. This text editor is fully integrated with the Starling display list, which means that nothing appears as an overlay when the text editor is focused.
Advantages and disadvantages
Due to limitations in the Adobe AIR runtime, this text editor cannot be used on mobile. Adobe AIR does not offer an API for displaying the soft keyboard on iOS when the text editor receives focus. This text editor should only be used in desktop apps.
Bitmap fonts separate each character into sub-textures inside an atlas. These sub-textures are displayed as images placed next to each other to form words and paragraphs. If the text has a particularly stylized appearance, such as gradients and outlines, bitmap fonts provide the best performance because the styles can be calculated at design time rather than runtime.
While the English language has only 26 letters in the alphabet (in addition to any punctuation and other supporting characters that you might need), some languages require many hundreds of characters. A texture that contains all of those characters may be impossible to use with bitmap fonts because it hits texture memory limits imposed by the Flash runtime or the GPU. In these situations, you may have no choice but to use device fonts.
Bitmap fonts may be scaled, but because they use bitmaps, only scaling down is recommended. Even then, you may lose out on text hinting that would make vector fonts more readable at smaller sizes. It's common to include separate font sizes as separate textures for bitmap fonts to achieve the best looking results, and that can require a lot of memory.
BitmapFontTextEditor does not support multiple font styles. A
BitmapFontTextEditor must use a single bitmap font to render its entire text.
Advanced font styles
To use bitmap fonts with
TextInput, create a
BitmapFontTextEditor class in the appropriate factory exposed by the parent component. In the following example, we'll use the
textEditorFactory of a
Font styles may be customized by passing a
BitmapFontTextFormat instance to the text editor's
Pass the font to display to the
BitmapFontTextFormat constructor. In the code above, we pass in the name of a font registered with
TextField.registerCompositor(). We could also pass in a
starling.text.BitmapFont instance that has not been registered.
The tint of the text can be customized with the
The RGB values of the tint color are multiplied with the RGB values of each of the font texture's pixels, similar to
The alignment of the text can be customized with the
Bitmap fonts have one primary font size. They may be scaled, but scaled bitmap fonts may not render as nicely as scaled vector fonts. However, if needed, we can use the
In most cases, it's not necessary to set the
size property. The primary font size will be detected automatically.
BitmapFontTextEditor provides a number of other advanced properties that may be customized, but aren't included in this quick introduction. For complete details about available properties, please take a look at the
BitmapFontTextEditor API reference and the
BitmapFontTextFormat API reference.
How to change advanced font styles when a parent component has multiple states
TextInput has multiple states, and it's possible to pass a different
BitmapFontTextFormat to the
BitmapFontTextEditor for each state. When the parent component's state changes, the font styles of the text editor will update automatically.
For instance, we can provide a different font style for the focused state of a
TextInput by calling
var defaultFormat:BitmapFontTextFormat = new BitmapFontTextFormat( "FontName", 20, 0xc4c4c4 ); textEditor.textFormat = defaultFormat; var focusedFormat:BitmapFontTextFormat = new BitmapFontTextFormat( "FontName", 20, 0x343434 ); textEditor.setTextFormatForState( TextInput.STATE_FOCUSED, focusedFormat );
We didn't provide separate font styles for other states, like
TextInput.STATE_DISABLED. When the
TextInput is in one of these states, the
BitmapFontTextEditor will fall back to using the value we passed to the