Checking your type in the Font by Zaweba live preview
The live preview in Font by Zaweba shows your text as a waterfall from 12 to 200 or as lines, styled beside base, and black on white or white on black.
Letters look different as words than they do on their own. A capital G that seems perfect in the editor can look heavy next to an a, and a spacing setting that's fine in a single word can make a sentence look patchy. The live preview is where you see your font doing its real job: setting text.
In Font by Zaweba the preview updates as you work. Change a slider in the style stack and the preview shows the result, so you can judge every decision on actual words rather than guessing from the grid.
Waterfall or lines
There are two ways to show your text. A waterfall repeats it at a range of sizes, from 12 up to 200, so you can see the same words small and large at once. Lines sets the text as a block, more like a paragraph in a document.
The waterfall is the one to use while you're shaping the font. Letters behave differently at different sizes. Fine details such as hairline serifs, thin contrast strokes and decorations look lovely large and can vanish or turn into specks small. Heavy weights look bold at 200 and clotted at 12. Seeing all sizes together stops you from designing a font that only works at one.
Lines is the better test for anything meant for reading. It shows texture, the overall grey a block of text makes on the page. Uneven spacing, letters that are too dark or too light, and words that seem to fall apart all show up in lines in a way they don't in a single word.
Styled beside base
The preview can show your styled font, or the base and the styled versions side by side. Side by side is a good reality check. It shows how far you've moved from the starting alphabet and makes it easy to see which operation is responsible for a change you don't like. If the base looks fine and the styled version doesn't, the problem is in the stack, not the letter.
Black on white or white on black
You can switch the preview between black text on white and white text on black. The same font looks noticeably different reversed. White text on a dark background tends to look bolder and spread slightly, and thin strokes can disappear. If your font will be used on dark signs, slides or website headers, check it reversed before you export.
What to type
The preview is only as useful as the text you give it. The alphabet is a poor test, because letters never appear in that order. Better choices are real sentences, the actual words the font is for, and words that mix straight and round letters. Include capitals followed by lowercase, figures, and some punctuation. A line of prices, a date, a short quotation in curly quotes: these catch problems that a pangram might miss.
If the font is for a particular job, use that text. A café font should be tested on the menu, a classroom font on worksheet instructions, a business font on the company name and its address.
How it fits with the rest of the app
The preview sits alongside the glyphs grid and the glyph editor. The grid shows every character so nothing is missed. The editor fixes individual letters. The preview tells you whether the fixes made sense in context. Kerning in particular should be judged here: when a pair looks wrong in the preview, open the kerning pair editor, adjust it and lock it, then come back and read the line again.
A few habits
Look at the smallest size in the waterfall every time you make a big change. Read a line of text, not just look at it, since reading is what reveals awkward letters. And step away for a minute now and then. Fresh eyes notice uneven spacing that you've stopped seeing.
The live preview in Font by Zaweba is the closest thing to using the font before it exists. Trust it more than the editor, because it shows what other people will see.
