Convert lines home to z

[KTibow]

Paths like m 0 0 h 5 v 5 h -5 v -5 should be converted to m 0 0 h 5 v 5 h -5 z for better minification. That is, convert the line home to z.
(To follow up on that, you could also convert m 0 0 a 2.5 2.5 0 0 0 0 5 a 2.5 2.5 0 0 0 0 -5 z to m 0 0 a 2.5 2.5 0 0 0 0 5 a 2.5 2.5 0 0 0 0 -5. That is, remove a redundant z.)

I already made a plugin that does the first one, but it should probably be rewritten to fit in to the existing path transformer better. And the second one requires disabling on stroke. Anyway, code of the plugin, in case it helps:

	const processPath: Visitor = {
		element: {
			enter(element) {
				const path =
					'pathJS' in element && (element.pathJS as PathDataItem[]);
				if (!path) return;

				const start = [0, 0];
				const cursor = [0, 0];

				for (let i = 0; i < path.length; i += 1) {
					const pathItem = path[i];
					const { command, args } = pathItem;

					// moveto (x y)
					if (command === 'm') {
						cursor[0] += args[0];
						cursor[1] += args[1];
						start[0] = cursor[0];
						start[1] = cursor[1];
					}
					if (command === 'M') {
						cursor[0] = args[0];
						cursor[1] = args[1];
						start[0] = cursor[0];
						start[1] = cursor[1];
					}

					// lineto (x y)
					if (command === 'l') {
						cursor[0] += args[0];
						cursor[1] += args[1];
					}
					if (command === 'L') {
						cursor[0] = args[0];
						cursor[1] = args[1];
					}

					// horizontal lineto (x)
					if (command === 'h') {
						cursor[0] += args[0];
					}
					if (command === 'H') {
						cursor[0] = args[0];
					}

					// vertical lineto (y)
					if (command === 'v') {
						cursor[1] += args[0];
					}
					if (command === 'V') {
						cursor[1] = args[0];
					}

					if (['l', 'L', 'h', 'H', 'v', 'V'].includes(command)) { // !! the part that does stuff
						if (start[0] == cursor[0] && start[1] == cursor[1])
							path[i] = { command: 'z', args: [] };
					}

					// curveto (x1 y1 x2 y2 x y)
					if (command === 'c') {
						cursor[0] += args[4];
						cursor[1] += args[5];
					}
					if (command === 'C') {
						cursor[0] = args[4];
						cursor[1] = args[5];
					}

					// smooth curveto (x2 y2 x y)
					if (command === 's') {
						cursor[0] += args[2];
						cursor[1] += args[3];
					}
					if (command === 'S') {
						cursor[0] = args[2];
						cursor[1] = args[3];
					}

					// quadratic Bézier curveto (x1 y1 x y)
					if (command === 'q') {
						cursor[0] += args[2];
						cursor[1] += args[3];
					}
					if (command === 'Q') {
						cursor[0] = args[2];
						cursor[1] = args[3];
					}

					// smooth quadratic Bézier curveto (x y)
					if (command === 't') {
						cursor[0] += args[0];
						cursor[1] += args[1];
					}
					if (command === 'T') {
						cursor[0] = args[0];
						cursor[1] = args[1];
					}

					// elliptical arc (rx ry x-axis-rotation large-arc-flag sweep-flag x y)
					if (command === 'a') {
						cursor[0] += args[5];
						cursor[1] += args[6];
					}
					if (command === 'A') {
						cursor[0] = args[5];
						cursor[1] = args[6];
					}

					// closepath
					if (command === 'Z' || command === 'z') {
						// reset cursor
						cursor[0] = start[0];
						cursor[1] = start[1];
					}
				}
				element.attributes.d = stringifyPathData({
					pathData: path,
				});
			},
		},
	};