Proposal for color format

While working on #142, I’ve checked internet for documentation about how other LaTeX-related tools deal with colors. I have not found any evidence that LaTeX supports direct color definition (e.g. \color{rgb}{1.0,1.5,1.0}{mytext}) for either \color or \colorbox. Although, I’ve found a useful piece of documentation on Wikibooks.

I don’t want to add ability to define new colors in WPF-Math LaTeX documents, so I don’t want to add commands such as \definecolor. I believe that the markup should stay static at the moment and should not have any influence on itself (i.e. no macro or color or whatever definitions in markup).

So I suggest that we document and add a modified syntax for \color and \colorbox commands by adding an optional mode parameter. Full syntax will be:

\command [mode] {color} {text}

Where:

• command is either color or colorbox
• mode is one of gray, rgb, RGB, HTML, cmyk (for now let’s stop on that, but the code should be robust enough to add more modes: xcolor manual includes some additional modes)
• color is either a predefined color name (as implemented already) if the mode argument wasn’t provided or a proper color definition according to the wikibooks documentation
• additionally to the standard color definitions, we will support a transparency parameter that will be optional and should be added in a convenient manner to every mode we support

The motivation for adding transparency is clear: while LaTeX was designed to provide mostly a printed documents, we know that we’re working with display graphics in WPF-Math, and transparency could be useful and shouldn’t be too hard to implement, so I think we should add it.

Here’re some syntax samples:

\colorbox{red}{text} // already implemented, "red" is a predefined color name
\colorbox{red,0.5}{text} // predefined color with transparency
\colorbox[gray]{0.5}{text}
\colorbox[gray]{0.5, 0.5}{text} // added transparency; also note that embedded spaces should be supported
\colorbox[rgb]{0,0,0}{text}
\colorbox[rgb]{0,0,0, 0.5}{text}
\colorbox[RGB]{255,255,255}{text}
\colorbox[RGB]{255,255,255,0}{text}
\colorbox[HTML]{FFFFFF}{text}
\colorbox[HTML]{ffffff00}{text}
\colorbox[cmyk]{0,0,0,1}{text}
\colorbox[cmyk]{0,0,0,1,0.5}{text}

[ForNeVeR]

@B3zaleel you’ve already implemented the core of the feature, I’ll take care of the rest, don’t bother yourself 😃

[B3zaleel]

In the command processing function, we could first check for a color model and read the next two arguments.

• If the color model is not null, parse the first argument as a color definition with the color model in a static “ColorUtilities” class. If it is null, try the following.
• Try to get the value of the first argument from the predefined colors.
• Try to modify the modify the first argument using the “Color utilities” class(if given “\color{red, 0.4}{Text}”, get the predefined color, red and give it an alpha value of 0.4 ×255 “floored” ). Nothing can be done if all of the above fail.