Can every glyph cell be of a different height in a font ?

[Chandan]

Hi,

I have designed a font, in which some glyphs take up much lesser space compared to the others. Based on it, I want to know the following:

1. Does every square that a glyph occupies in the FC window correspond to a pixel on the screen. So, when the glyph is printed on the terminal, will it occupy that many number of pixels ?

2. I seem to be able to adjust the width of the cell, where the glyph resides, in the FC window by using the two vertical bars. Is there a way to shrink the height of the cell for some glyphs, while leaving it at the default for the rest. I tried moving the horizontal bars, but they appear to be fixed.

Any help would be much appreciated.

Thanks,
TC

[Bhikkhu Pesala]

1. Truetype fonts are scalable, they will occupy as many pixels as they need to suit the size selected in your word-processor. The number of funits in Font Creator is scaled to produce different numbers of pixels on a monitor — how many depends on the point size, the em-square, and the monitor's resolution.

2. See "How Do I Move the Black Lines?" in the FAQ thread.

Line Spacing.png (22.54 KiB) Viewed 4990 times

Each font illustrated above has a different design height, or em-square. That is, in a word-processor, when the font size is set at 10 points, and the line-spacing is set to single (the default), the distance between the baselines of two lines is different.

Arial's spacing is 11.5 pts, that for Embassy BT is 12.5, but the spacing for Arial Black is 14.2 pts, or 142% of the point size. The amount of space is determined by the spacing between the two black horizontal lines — the WinAscent and WinDescent — and must be fixed for any font, but it can vary for different fonts.

[Bhikkhu Pesala]

This is the Capital "I" of Arial Regular selected in the Font Creator glyph edit window, with the Transform tab showing the height of the glyph in funits = 1466 funits

Arial Font Metrics.png (65.62 KiB) Viewed 4990 times

The Font Metrics dialogue shows the WinAscent and WinDescent values. Let's do some maths.

1,854-(-434)+67 = 2,355

2,355/2048 = 1.14990234375 or about 1.15

That explains why 10 pt Arial is spaced at 11.5 points per line.

Now, what has that got to do with 1,466 funits?
If 2,048 funits = 10 points, then
1,466 funits = about 7.158 points

How many pixels that produces on your monitor will depend on your monitor's resolution. So I think you can see it is rather a complex relationship, but they are mathematically related.

Maybe you would like to rephrase your question?

[Dick Pape]

In my mind it's not the number of pixels that's critical to showing an entire character -- but the vertical and horizontal boundaries.

More or fewer pixels will change the smoothness of the shape as the computer will try to create the image the best it can within the size allowed. That's why there is hinting for small sizes -- to help the computer form the character.

I believe FC images are continuous shapes, not square, like pixels.

Truetype fonts are scalable, they will occupy as many pixels as they need to suit the size selected in your word-processor.

1. A glyph will print the same as designed if you assign Left Side Bearing and Advance Width to enclose the glyph (Properties/Glyph Metrics). If you make them too narrow, things will get cut off.

Same thing will happen if your display program (word processor for instance) doesn't show them fully. If too condensed or compressed, you will lose things.

2. A font can only have one height -- same size for all glyphs. (Format/Settings/Metrics specifies the measure -- Win Ascent/Win Descent.)

Again, you can overlap lines in your display program by reducing the line spacing. (Not sure this is allowed in MS Word however.)

Dick

[Dave Crosby]

Well said Dick!

Of course you can move the glyph outlines to any place within the boundaries of the glyph image bearings and Win Asent and Decent.