What is svg-line?

svg-line is an Emacs package that replaces the text-based bars Emacs draws for its tab bar, tab line, header line, and mode line with SVG images instead. Emacs normally renders those areas as laid-out text, which limits what they can look like and how they behave. By switching to SVG, the package removes several restrictions: bars can be any height, tabs can wrap onto multiple rows instead of being cut off or scrolled horizontally, and each row in a bar can have independent left, center, and right alignment. The package also adds interactivity to all four bar types. Any segment in a bar can have a left-click action, a right-click context menu, and hover tooltip text. This is notable for the tab bar in particular, which the README describes as otherwise uncooperative for those kinds of interactions. svg-line is a rendering engine only. It ships no content and no colors of its own. You define what each bar shows by providing a content function that returns a list of rows, where each row specifies what text or widgets appear on the left, center, and right. Colors and fonts can be literal values or functions that are re-evaluated on every render, which lets them respond to theme changes automatically. Inline SVG bar charts and pie charts are available as built-in segment types. The package requires Emacs 29.1 or newer and only works in graphical mode, not in a terminal. Installation is available through elpaca, straight.el, or by manually adding the file to the load path. The license is GPL-3.0.