Hello! Some time ago, I announced my intent to build a man-page previewer for a text-editor named Atom <https://atom.io/>. Work is coming along nicely: this page <https://cdn.rawgit.com/Alhadis/language-roff/a7c07744a9d44adf32a546646f7a8d57d52e6e58/preview-tty.html> was generated using a lightweight tokeniser <https://github.com/Alhadis/language-roff/blob/renderer/lib/tokeniser.js> written in JavaScript, which processes Groff's intermediate output language into web-based formats. That's the nroff preview... I'm now halfway through developing the troff previewer, which uses HTML5 canvas <https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D> technology to draw realtime previews of an opened Roff document.
So far, so good! <https://cloud.githubusercontent.com/assets/2346707/25514878/732e09ea-2c23-11e7-97ea-9674d3845dd1.png> I'm proud of how this is turning out: bear in mind, that preview updates as the user types, so it'll feel like an efficient replacement for a word processing program, haha. I'm currently stuck with drawing arcs <https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/arc>. This might be the wrong forum to ask for help with trigonometry, but I was planning to announce progress eventually anyway. Now, this pic code: .PS > "+" at 0,0 > arc -> from 0.5,0 to 0,0.5 > arc -> cw from 0,0 to 1,0.5 > arc -> cw from 0,0 to 2,0 rad 15 > .PE ... should look like this <https://cloud.githubusercontent.com/assets/2346707/25515071/4bc46870-2c25-11e7-9883-9248e4b4aa68.png>. Instead, it, uh, looks like this <https://cloud.githubusercontent.com/assets/2346707/25515084/5d84eed6-2c25-11e7-8cdd-bdb65f7804e9.png> . Groff's output gives me these coordinates to go by: - startX, startY - Coordinates of the arc's starting point - centreX, centreY - Coordinates of the arc's centre - endX, endY - Coordinates of the arc's terminal point But the canvas arc method I'm working with requires all of these: - x - The x coordinate of the arc's centre. - y - The y coordinate of the arc's centre. - radius - The arc's radius. - startAngle - The angle at which the arc starts, measured clockwise from the positive x axis and expressed in radians. - endAngle - The angle at which the arc ends, measured clockwise from the positive x axis and expressed in radians. It's embarrassing to be stuck on something so obvious, but this is what's blocking further progress...
