sgr_to_html: Convert Control Sequences to HTML Equivalents

View source: R/tohtml.R

sgr_to_htmlR Documentation

Convert Control Sequences to HTML Equivalents


This function is a wrapper around to_html and is kept around for legacy reasons. When we added capabilities for handling OSC hyperlinks, the sgr_ part of the name became an incomplete description of what the function does. The only substantive difference with the new function is this one does not warn when the input contains unescaped "<" or ">".


  warn = getOption("fansi.warn", TRUE),
  term.cap = getOption("fansi.term.cap", dflt_term_cap()),
  classes = FALSE,
  carry = getOption("fansi.carry", TRUE)



a character vector or object that can be coerced to such.


TRUE (default) or FALSE, whether to warn when potentially problematic Control Sequences are encountered. These could cause the assumptions fansi makes about how strings are rendered on your display to be incorrect, for example by moving the cursor (see ?fansi). At most one warning will be issued per element in each input vector. Will also warn about some badly encoded UTF-8 strings, but a lack of UTF-8 warnings is not a guarantee of correct encoding (use validUTF8 for that).


character a vector of the capabilities of the terminal, can be any combination of "bright" (SGR codes 90-97, 100-107), "256" (SGR codes starting with "38;5" or "48;5"), "truecolor" (SGR codes starting with "38;2" or "48;2"), and "all". "all" behaves as it does for the ctl parameter: "all" combined with any other value means all terminal capabilities except that one. fansi will warn if it encounters SGR codes that exceed the terminal capabilities specified (see term_cap_test for details). In versions prior to 1.0, fansi would also skip exceeding SGRs entirely instead of interpreting them. You may add the string "old" to any otherwise valid term.cap spec to restore the pre 1.0 behavior. "old" will not interact with "all" the way other valid values for this parameter do.


FALSE (default), TRUE, or character vector of either 16, 32, or 512 class names. Character strings may only contain ASCII characters corresponding to letters, numbers, the hyphen, or the underscore. It is the user's responsibility to provide values that are legal class names.

  • FALSE: All colors rendered as inline CSS styles.

  • TRUE: Each of the 256 basic colors is mapped to a class in form "fansi-color-###" (or "fansi-bgcol-###" for background colors) where "###" is a zero padded three digit number in 0:255. Basic colors specified with SGR codes 30-37 (or 40-47) map to 000:007, and bright ones specified with 90-97 (or 100-107) map to 008:015. 8 bit colors specified with SGR codes 38;5;### or 48;5;### map directly based on the value of "###". Implicitly, this maps the 8 bit colors in 0:7 to the basic colors, and those in 8:15 to the bright ones even though these are not exactly the same when using inline styles. "truecolor"s specified with 38;2;#;#;# or 48;2;#;#;# do not map to classes and are rendered as inline styles.

  • character(16): The eight basic colors are mapped to the string values in the vector, all others are rendered as inline CSS styles. Basic colors are mapped irrespective of whether they are encoded as the basic colors or as 8-bit colors. Sixteen elements are needed because there must be eight classes for foreground colors, and eight classes for background colors. Classes should be ordered in ascending order of color number, with foreground and background classes alternating starting with foreground (see examples).

  • character(32): Like character(16), except the basic and bright colors are mapped.

  • character(512): Like character(16), except the basic, bright, and all other 8-bit colors are mapped.


TRUE, FALSE (default), or a scalar string, controls whether to interpret the character vector as a "single document" (TRUE or string) or as independent elements (FALSE). In "single document" mode, active state at the end of an input element is considered active at the beginning of the next vector element, simulating what happens with a document with active state at the end of a line. If FALSE each vector element is interpreted as if there were no active state when it begins. If character, then the active state at the end of the carry string is carried into the first element of x (see "Replacement Functions" for differences there). The carried state is injected in the interstice between an imaginary zeroeth character and the first character of a vector element. See the "Position Semantics" section of substr_ctl and the "State Interactions" section of ?fansi for details. Except for strwrap_ctl where NA is treated as the string "NA", carry will cause NAs in inputs to propagate through the remaining vector elements.


A character vector of the same length as x with all escape sequences removed and any basic ANSI CSI SGR escape sequences applied via SPAN HTML tags.


Unlike other functions, the default is carry = TRUE for compatibility with semantics of prior versions of fansi.

fansi documentation built on Jan. 23, 2023, 5:28 p.m.