rhythm.styl

/* rhythm(fontsize, baseline, margintop, marginbottom, squash) applies a vertical
 * rhythm to a block-level element. Arguments:
 *
 * 		fontsize: the font size, relative to the base font size
 *
 * 		baseline: the baseline grid unit that we should snap the element's
 * 		line-height to
 *
 * 		margintop, marginbottom: the number of baseline units to add above and
 * 		below the element. Note: this is *baseline units*, not multiples of the
 * 		element's new line-height.
 *
 * 		squash: a float value specifying how much tolerance the line-height
 * 		should have for squashing. 1 means the line-height will never be smaller
 * 		than 1; <1 means it may be squashed; >1 means it must have extra
 *
 * 		allow-half-lines: whether or not to permit rounding to half-lines. Pretty
 * 		important for font-sizes below baseline / 2, actually.
 */

rhythm(fontsize = 1em, baseline = null, margin = 1, squash = 1, allow-half-lines = false) {
	font-size: fontsize;
	line-height: rhythm-line-height(fontsize, baseline, squash, allow-half-lines);

	baseline-size = rhythm-baseline-size(fontsize, baseline);

	margin = expand-sides(margin, 2);
	if (margin[0] != none) {
		margin-top: unit(baseline-size * margin[0], em);
	}
	if (margin[1] != none) {
		margin-bottom: unit(baseline-size * margin[1], em);
	}
}

rhythm-ratio(fontsize = 1em, baseline = null, squash = 1, allow-half-lines = false) {
	baseline = rhythm-get-baseline(baseline);
	warn("Ratio: baseline " + baseline);

	ratio = (fontsize / baseline) * squash;
	warn("Ratio: fontsize " + fontsize);
	warn("Ratio: squash " + squash);
	warn("Ratio: ratio " + ratio);

	if (allow-half-lines) {
		ratio = ceil(ratio * 2) / 2;
	} else {
		ratio = ceil(ratio);
	}
	ratio;
}

// get the size of the baseline grid, in units relative to the given font size
rhythm-baseline-size(fontsize = 1em, baseline = null) {
	baseline = rhythm-get-baseline(baseline);
	warn("rhythm-get-baseline " + baseline);
	warn("Baseline / fontsize " + (baseline / fontsize));
	(baseline / fontsize);
}

// fit the font into the baseline grid
rhythm-line-height(fontsize = 1em, baseline = null, squash = 1, allow-half-lines = false) {
	baseline = rhythm-get-baseline(baseline);
	ratio = rhythm-ratio(fontsize, baseline, squash, allow-half-lines);
	warn("Ratio " + ratio);
	(baseline * ratio / fontsize);
}

// checks for a baseline size defined elsewhere in the CSS before assigning a default of 1.5
rhythm-get-baseline(baseline = null) {
	warn("Baseline " + baseline);
	warn("Baselinesize " + baselinesize);
	baseline ? baseline : (baselinesize is defined ? baselinesize : 1.5);
}