pixi-tagged-text

TaggedText is a multi-style text component for pixi.js that supports multiple TextStyles using HTML-like tags. Includes many additional features not found in PIXI.Text such as embedded images (sprites), underlines, justified layout, and more.

Inspired by the original pixi-multistyle-text

Usage

// constructor
new TaggedText(text, styles, options);

• text - A string containing the text to display. The text can be decorated with tags just like html.
• styles - An object with tag names as keys and PIXI.TextStyle+ objects as the values. The key "default" is used to set base values for all text.
• options - An object with additional confirguration options.

All parameters are optional.

Text & tags

Text

The text can be any UTF-8 string.

• Multiline strings are supported (using "\n" or multiline strings wrapped in backticks).
• Emoji's are supported.
• RTL languages are NOT officially supported but seem to work in a limited capacity.

You can get the text with tags stripped out with the .untaggedText implicit getter.

Tags

• Tags are html-like, e.g. Normal text. <bold>Bold text</bold>
• Self-closing tags are ok e.g. <img />
• Nesting tags is supported. Closing tags must match in a FILO order as opening tags. <b>bold <i>bold italic</i></b>
• Attibutes added to tags will override any existing styles on the tag. <b>bold</b> <b fontStyle="italic">bold italic</b>
• Tags that do not have a matching style are NOT treated as tags. <i><bold>just italic!</bold></i> would render as <bold>just italic!</bold> if there were a style for i but not bold.
• No tag definitions are included by default. e.g. <b> won't be bold unless you include a style for b tags.

Styles

styles is a plain object containing one or more keys. Each key is the name of a tag to style. 'Global' styles that apply everywhere can be set under the default key. Note, some values such as wordWrapWidth are ignored if they are included in any styles other than default.

The style objects are modified versions (supersets) of PIXI.TextStyle (referred to as TextStyleExtended in the source code). In addition to the properties allowed in TextStyle, the following extended properties are added.

(By the way, there is an excellent TextStyle visual editor that you can use to preview how your style will appear. The style objects generated can be used in this component.)

• Everything in PIXI.TextStyle
• align - Has all the options from PIXI.TextStyle plus additional options for justified alignment:
  • "justify-left", "justify-right", and "justify-center" are all types of jutified alignment and they only differ in how they treat the last line of text.
  • "justify-all" justifies all lines of text even the last line.
  • "justify" is an alias for "justify-left".
• valign - Options are "top", "middle", "bottom", "baseline"
• textTransform - Options are "normal", "capitalize", "uppercase", "lowercase"
• fontSize - Has the added ability to use percentage-based sizes which are based on the fontSize in the parent tag. In the example: <small fontSize="10">small<big fontSize="300%">big</big></small>, "small" will be 10px and "big" will be 30px. The default fontSize is 26px.
• fontScaleWidth - Percentage to scale the font e.g. 0.5 = 50%
• fontScaleHeight - Percentage to scale the font e.g. 1.25 = 125%
• paragraphSpacing - Additional spacing between paragraphs that is added when you use an explicit carriage return rather than letting the text wrap at the end of a line. Default is 0. Can also be negative.
• imgSrc - ID of image to include in this tag (see imgMap under Options section)
• imgDisplay - How should the image be displayed. "block" is no scaling, "icon" scales the image to match the text-size and appear inline.
• textDecoration - (i.e. underlines) Adds lines under, over, or through your text. Possible values are either "normal" or one or more of "underline", "overline", "line-through" (as a space separated string). Can also be set using the more fine-grained properties below. By default, decorations have color that matches the fill color of the text, thickness of 1 and offset 0. Note: You may need to enabled the drawWhitespace option in options to avoid seeing gaps in your text decorations between words.
• decorationColor - overrides the default color (fill) for all decorations.
• decorationThickness - overrides the default thickness (1) for all decorations.
• underlineColor - Sets the color of the underline. Default is same as fill
• underlineThickness - Sets the thickness of the underline. Default is 1.
• underlineOffset - Positions the underline above or below the default location. Default is 0.
• overlineColor - Sets the color of the overline. Default is same as fill
• overlineThickness - Sets the thickness of the overline. Default is 1.
• overlineOffset - Positions the overline above or below the default location. Default is 0.
• lineThroughColor - Sets the color of the line-through. Default is same as fill
• lineThroughThickness - Sets the thickness of the line-through. Default is 1.
• lineThroughOffset - Positions the line-through above or below the default location. Default is 0.
• adjustBaseline - Adjusts the position of the text above or below the baseline. Default is 0. Also see the adjustFontBaseline property in the options.

Additionally, the following changes have been made to the default style values:

• wordWrap: false -> true
• wordWrapWidth: 100 -> 500,
• fill, stroke, & dropShadowColor - "black" -> 0x000000

'Default' default styles

Some styles (fontSize, color, etc.) are set by default when you call new TaggedText() but they can all be overridden. The most important default styles are:

{
  align: "left",
  valign: "baseline",
  wordWrap: true,
  wordWrapWidth: 500,
  fill: 0x000000,
}

To get a complete list, you can view the static property TaggedText.defaultStyles or look in the source code for DEFAULT_STYLES

Options

The third parameter in the TaggedText constructor is a set of options.

• debug - If true, generates debug information which is overlaid on the text during draw(). default is false.
• debugConsole - If true, logs debug information to the console during draw(). default is false.
• splitStyle - Allows you to specify how the text should be split into PIXI.Text objects when rendered. This would affect things like animations that operate on each individual piece of text within the component. Possible values are are "words" (default) and "characters".
• imgMap - An object that maps string ids like "myImage" to Sprite objects like PIXI.Sprite.from("./myImage.png"). This id will be used in the imgSrc style property to make a tag with that id render the sprite. As of v2.1.4, in addition to Sprites, you can also use any value supported by Sprite.from() or Texture.from() (including ImageHTMLElement or url strings). When a style contains imgSrc="myImage", the matching sprite is used. By default, each of the keys you provide here will automatically be added as a style in the tagStyles (equivalent to { myImage: { imgSrc: "myImage"}}) so you can add a tag <myImage />. default is {}.
• adjustFontBaseline - For fonts that do not align correctly with the baseline, this adjusts the position of the text relative to the baseline. This should be an object with font names for keys and a value which is a string percentage (of the font's ascent, or height above the baseline) or a numerical value in pixels to adjust the offset. E.g. {"arial": "80%"}. Since this value changes for each fontFamily and for each fontSize it's recomended that you use the percentage values. Default is no adjustments.
• scaleIcons - When true, images in the imgMap that use imgDisplay: icon will scale with the text when fontScaleWidth or fontScaleHeight are set. Default is true.
• drawWhitespace - When true, whitespace characters are rendered as their own Text objects. Default is false.
• wrapEmoji - When true, emoji characters are automatically wrapped in a special tag <__EMOJI__> which allows the user to specify styles for emoji only. A base style is automatically defined for __EMOJI__ that sets the font-family to sans-serif. This helps to solve some issues with rendering on certain fonts that don't handle emojis well. Default is true. (This feature may be removed in future updates)
• skipUpdates - When true, update() will not be called when text or styles are changed; it must be called explicitly or overridden using the skipUpdate parameter in functions such as setText(). default is false.
• skipDraw - When true, draw() will not be called by update() it must be called explicitly or overridden using the skipDraw parameter, e.g. myTaggedText.update(false). default is false.
• supressConsole - When true, prevents warnings and other messages from being logged to the console, however, this does not affect debugConsole.
• errorHandler - A handler function that will receive non-fatal warnings and errors generated by the component. This will not catch any exceptions, only internal messaging such as when you try use an unknown tag. The handler should be in the format (e:ErrorMessage) => void where ErrorMessage is an object with the shape { code: string, message: string, type: "warning" | "error" }.

To see a list of the default options, you can view the static property TaggedText.defaultOptions or look in the source code for DEFAULT_OPTIONS

A note about the component architecture

TaggedText allows you to control text with multiple styles and embedded images as though it were a single Pixi component. It was inspired by pixi-multistyle-text but is structurally very different.

pixi-multistyle-text composes bitmap snapshots of text objects into a single canvas. Conversely, pixi-tagged-text creates a separate PIXI.Text component for each word, or word segment. Using multiple Text components allows developers to have control over individual words or even characters for the purposes of animation or other effects. It also makes embedding sprites into the layout easier. Cosmetically, they're very similar, however, the overhead of creating multiple Text objects is much larger potentially making TaggedText a heavier slower component.

Another similar component is @pixi/text-html which renders a bitmap from an HTML element using the browser's native rendering. While pixi-tagged-text should theoretically render more consistently cross-browsers, this could be a good option if pixel perfection and cross-browser support is not a concern.

Child DisplayObjects

TaggedText generates multiple display objects when it renders the text with draw(). Developers can access these children if desired for example to add additional interactivity or to animated individual elements.

Please note that by default, these are recreated every time text or style properties change (technically, whenever draw() is called). Manipulating the children directly may cause your view to become out of sync with the text and styles properties.

These properties are available:

• textContainer - The Container layer which holds all the text fields rendered by draw.
• spriteContainer - The Container layer which holds all the sprites rendered by draw if you're using an image map (imgMap).
• debugContainer - The SpContainerite layer which holds all debug overlay information (if you're using the debug: true setting).
• decorationContainer - The Container layer which holds all text decorations (underlines).
• textFields - An array containing all the text fields generated by draw.
• sprites - If you're using an image map (imgMap), this array stores references to all the Sprites generated by draw.
• spriteTemplates - The sprites in sprites and spriteContainer are actually clones of the originals passed in via the imgMap option. To get the originals, access them this way.
• decorations - Array of Graphic objects which render the text decorations.

Life-cycle & optional updates

In order to maximize performance of TaggedText, it helps to understand how it renders the input.

1. Constructor - creating the component is the first step. You can set text, styles, and options in the constructor.
2. update() - Update generates a list of plain JS object tokens that hold information on what type of text to create and where to position it. The tokens contain all the information you need to draw the text and are saved as the instance member tokens but also returned by the update() method. Aside from decoupling from the render code, this allows us to write tests to verify every step of the lexing, styling and layout independently without drawing anything at all. By default, this is called every time the text or style definitions are changed (e.g. setTagStyles(), setText()). This is a fairly expensive process but usually faster than draw().
3. draw() - Draw creates the child objects based on the data generated by update(). It clears any existing children (if needed) then recreates and positions them. This is probably the costliest method in the life-cycle. By default, this is called automatically by update().
4. Of course, you won't see anything on your screen until your component is added to a visible PIXI container that's part of the stage in a pixi app.

The methods that normally trigger an update are:

• setText() & myText.text = (implicit setter)
• setTagStyles() & tagStyles = (implicit setter)
• setStyleForTag()
• setDefaultStyle() & defaultStyle = (implicit setter)
• removeStylesForTag()

The methods that normally trigger a draw:

• update()

Please note that direct changes to styles or other objects will not trigger an automatic update unless you use one of the above methods. For example:

const t = new TaggedText("<big>Big text</big>", { big: { fontSize: 25 } }); // renders "Big text" at 25px

t.getStyleForTag("big").fontSize = 100; // The change to the style wasn't detected. It still renders "Big text" at 25px

t.update(); // now it renders correctly.

t.textFields[0].visible = false; // Makes the word "Big" disappear.

t.draw(); // recreates the text fields restoring "Big"

skipUpdates & skipDraw

If performance is becoming an issue, you can use the skipUpdates and skipDraw flags in the options object with new TaggedText() to disable automatic updates and automatic drawing (more on that below). This gives you control over when the update() or draw() function will be called. However, the component can become out of sync with what you see on your screen so use this with caution.

Several other individual functions, such as setText() also give you the option to skipUpdate on an as needed basis.

// Create a new TaggedText but disable automatic updates and draws.
const t = new TaggedText("", {}, {skipUpdate: true, skipDraw: true});
const words = ["lorem", "ipsum", ... ];
// add words until the length of text is > 500 characters.
while (t.untaggedText.length <= 500) {
  t.text += words[i];
}

// Normally, update() will draw() also, but we've disabled that.
// t.tokens will be updated to match the new text but it will not appear on the screen.
t.update();
t.textContainer.length; // 0 - text fields never got created.

// Manually call draw to generate the PIXI.Text fields
t.draw();
t.textContainer.length; // This will now contain all the PIXI.Text objects created by draw.

Contributing

If you'd like to contribute, a great place to start is to log an issue. If you are interested in bug-fixing, please take a look at the issues list and notify one of the owners that you're interested in working on it. Please make sure to test the code you write! If you're not sure how, just ask for help!

Build instructions

yarn install
yarn build

Yarn should automatically install peer dependencies (including the very important pixi.js) but in my experience, you may have to run yarn install again after adding any additional packages.

VSCode Users

If you're using the vscode-jest extension, you may need some additional packages to get the tests to run in your IDE. If you're on a Mac you can use brew bundle install to install these packages.

Demo

You can view examples using the command:

yarn demo

This will start a simple HTTP server running locally on port 8080. Navigate to http://localhost:8080/demo

License

MIT, see LICENSE.md for details.