SPACING In fonts, each glyph is placed in a slot with a certain amount of space allocated to it, which generally includes white space on either side. Some errors are subtle to detect, such as the topmost and leftmost points.Ģ. Left is correct on the right, red arrows point to the actual extremes, where there should be an on-curve point. This “rule” isn’t necessary to make the font work, but it is needed for optimal rendering on screen. Any related off-curve points must line up perpendicularly to these on-curve points to create a smooth curve at these extremes. The details are a little different between TrueType and PostScript outlines, but these features are shared between them.Īlso shared between outline formats is the idea that every time a major curve changes direction relative to the X or Y axis, known as the local “extreme” of the curve, it should be described by an on-curve point. The lines are described by points on the grid, and curved lines are additionally described by points around the curve that define its shape. Don’t worry if you don’t know what that means-there won’t be a quiz later. POINTS, POINT PLACEMENT AND EXTREMA Fonts are designed as vector outlines in a Cartesian grid space. Here are twelve things to look for to help you judge font quality, so you can avoid choosing-or creating-fonts that suck, even though they might look interesting at first blush.ġ. But how can you tell? Crack it open with a font editor and take a closer look. Sometimes, though, even if the concept of a typeface is perfect, the execution is off. You’ve read it well, 3.Evaluating type is often a matter of taste and opinion, but there is an art and science to picking typefaces whose design is well-suited to a given project. Their computed line-height goes from 0.618 to 3.378. # It becomes obvious that setting line-height: 1įor what it’s worth, on the 1117 fonts installed on my computer (yes, I installed all fonts from Google Web Fonts), 1059 fonts, around 95%, have a computed line-height greater than 1. All these metrics are font-specific, and set by the font designer. It means that font-size: 100px gives a content-area of 112px (1117 units) and a line-height: normal of 115px (1150 units or 1.15). ![]() Using line-height: 1 can create a line-box smaller than the content-area.Īs a comparison, the Arial font describes an em-square of 2048 units, an ascender of 1854, a descender of 434 and a line gap of 67. The content-area is therefore always on the middle of the virtual-area. Half this leading is added on top of the content-area, the other half is added on the bottom. The computed difference of height between the virtual-area and the content-area is called the leading. # If height is auto, then line-height is used and the content-area is strictly equal to the line-height. ![]() The content-area height and the virtual-area height If you know the height of each line-box, you know the height of an element.Ī p> (black border) is made of line-boxes (white borders) that contain inline elements (solid borders) and anonymous inline elements (dashed borders)Įven though it may sound strange, an inline element has two different height: That means the Catamaran font uses 1100 + 540 units in a 1000 units em-square, which gives a height of 164px when setting font-size: 100px.Įach HTML element is actually a stack of line-boxes. In the browser, relative units are scaled to fit the desired font-size. But it can also be 1024, 2048 or anything else.īased on its relative units, metrics of the fonts are set (ascender, descender, capital height, x-height, etc.).Note that some values can bleed outside of the em-square. This square uses relative units and is generally set at 1000 units. Look at this simple HTML code, a p> tag containing 3 span>, each with a different font-familyĭifferent font-families, same font-size, give various heightsĮlements with font-size: 100px have height that varies from 97px to 164pxĪ font defines its em-square (or UPM, units per em), a kind of container where each character will be drawn. ![]() It breaks down the popular belief that line-height is the distance between baselines. In CSS, the line-height is not the distance between baselines We recommend a used value for 'normal' between 1.0 to 1.2. The value has the same meaning as number>. Tells user agents to set the used value to a "reasonable" value based on the font of the element. ![]() Description: font-size, em, line-height, line-box.
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