BBCode in RichTextLabel

Introduction

Label nodes are great for displaying basic text, but they have limitations. If you want to change the color of the text, or its alignment, you can only do that to the entire label. You can't make a part of the text have another color, or have a part of the text centered. To get around these limitations, you would use a RichTextLabel.

RichTextLabel allows for complex formatting of text using a markup syntax or the built-in API. It uses BBCodes for the markup syntax, a system of tags that designate formatting rules for a part of the text. You may be familiar with them if you ever used forums (also known as bulletin boards, hence the "BB" in "BBCode").

Unlike Label, RichTextLabel also comes with its own vertical scrollbar. This scrollbar is automatically displayed if the text does not fit within the control's size. The scrollbar can be disabled by unchecking the Scroll Active property in the RichTextLabel inspector.

Note that the BBCode tags can also be used to some extent in the XML source of the class reference. For more information, see Class reference primer.

See also

You can see how BBCode in RichTextLabel works in action using the Rich Text Label with BBCode demo project.

Using BBCode

By default, RichTextLabel functions like a normal Label. It has the property_text property, which you can edit to have uniformly formatted text. To be able to use BBCode for rich text formatting, you need to turn on the BBCode mode by setting bbcode_enabled. After that, you can edit the text property using available tags. Both properties are located at the top of the inspector after selecting a RichTextLabel node.

For example, BBCode [color=green]test[/color] would render the word "test" with a green color.

Most BBCodes consist of 3 parts: the opening tag, the content and the closing tag. The opening tag delimits the start of the formatted part, and can also carry some configuration options. Some opening tags, like the color one shown above, also require a value to work. Other opening tags may accept multiple options (separated by spaces within the opening tag). The closing tag delimits the end of the formatted part. In some cases, both the closing tag and the content can be omitted.

Unlike BBCode in HTML, leading/trailing whitespace is not removed by a RichTextLabel upon display. Duplicate spaces are also displayed as-is in the final output. This means that when displaying a code block in a RichTextLabel, you don't need to use a preformatted text tag.

[tag]content[/tag]
[tag=value]content[/tag]
[tag option1=value1 option2=value2]content[/tag]
[tag][/tag]
[tag]

Note

RichTextLabel doesn't support entangled BBCode tags. For example, instead of using:

[b]bold[i]bold italic[/b]italic[/i]

Use:

[b]bold[i]bold italic[/i][/b][i]italic[/i]

Handling user input safely

In a scenario where users may freely input text (such as chat in a multiplayer game), you should make sure users cannot use arbitrary BBCode tags that will be parsed by RichTextLabel. This is to avoid inappropriate use of formatting, which can be problematic if [url] tags are handled by your RichTextLabel (as players may be able to create clickable links to phishing sites or similar).

Using RichTextLabel's [lb] and/or [rb] tags, we can replace the opening and/or closing brackets of any BBCode tag in a message with those escaped tags. This prevents users from using BBCode that will be parsed as tags – instead, the BBCode will be displayed as text.

Example of unescaped user input resulting in BBCode injection (2nd line) and escaped user input (3rd line)

The above image was created using the following script:

extends RichTextLabel

func _ready():
    append_chat_line("Player 1", "Hello world!")
    append_chat_line("Player 2", "Hello [color=red]BBCode injection[/color] (no escaping)!")
    append_chat_line_escaped("Player 2", "Hello [color=red]BBCode injection[/color] (with escaping)!")


# Returns escaped BBCode that won't be parsed by RichTextLabel as tags.
func escape_bbcode(bbcode_text):
    # We only need to replace opening brackets to prevent tags from being parsed.
    return bbcode_text.replace("[", "[lb]")


# Appends the user's message as-is, without escaping. This is dangerous!
func append_chat_line(username, message):
    append_text("%s: [color=green]%s[/color]\n" % [username, message])


# Appends the user's message with escaping.
# Remember to escape both the player name and message contents.
func append_chat_line_escaped(username, message):
    append_text("%s: [color=green]%s[/color]\n" % [escape_bbcode(username), escape_bbcode(message)])

Stripping BBCode tags

For certain use cases, it can be desired to remove BBCode tags from the string. This is useful when displaying the RichTextLabel's text in another Control that does not support BBCode (such as a tooltip):

extends RichTextLabel

func _ready():
    var regex = RegEx.new()
    regex.compile("\\[.*?\\]")
    var text_without_tags = regex.sub(text, "", true)
    # `text_without_tags` contains the text with all BBCode tags removed.

Note

Removing BBCode tags entirely isn't advised for user input, as it can modify the displayed text without users understanding why part of their message was removed. Escaping user input should be preferred instead.

Performance

In most cases, you can use BBCode directly as-is since text formatting is rarely a heavy task. However, with particularly large RichTextLabels (such as console logs spanning thousands of lines), you may encounter stuttering during gameplay when the RichTextLabel's text is updated.

There are several ways to alleviate this:

• Use the append_text() function instead of appending to the text property. This function will only parse BBCode for the added text, rather than parsing BBCode from the entire text property.

• Use push_[tag]() and pop() functions to add tags to RichTextLabel instead of using BBCode.

• Enable the Threading > Threaded property in RichTextLabel. This won't speed up processing, but it will prevent the main thread from blocking, which avoids stuttering during gameplay. Only enable threading if it's actually needed in your project, as threading has some overhead.

Using push_[tag]() and pop() functions instead of BBCode

If you don't want to use BBCode for performance reasons, you can use functions provided by RichTextLabel to create formatting tags without writing BBCode in the text.

Every BBCode tag (including effects) has a push_[tag]() function (where [tag] is the tag's name). There are also a few convenience functions available, such as push_bold_italics() that combines both push_bold() and push_italics() into a single tag. See the