TrueType Hinting tool»

Toolbar»

With the TrueType Hinting toolbar you can select the hinting direction, the current visual instruction tool, open the code panel, and compile the instructions in it.

The buttons in the local toolbar are for the following operations:

Button	Description
	Set vertical direction. Sets visual instruction tools to work in the vertical direction. I.e. create vertical links, alignment, interpolation and deltas. Instructions in different directions are independent of each other
	Set horizontal direction
	Select the edit tool (E key)
	Select Align command (A key)
	Select Single Link command (S key)
	Select Double Link command (D key)
	Select Interpolate command (I key)
	Select Middle Delta command (M key)
	Select Final Delta command (F key)
	Open the Code panel
	Compile instructions in the Code panel

Preview»

If you enter any characters in the edit field under preview, you will see these characters appear in the preview window. Use the usual FontLab rules to enter special characters (enter the character name after a slash “/” character or two slashes to enter a slash: “//”).

With the waterfall preview you can quickly select the current PPM. Just double-click on the sample PPM you want to select.

Code panel»

To open the code panel, click on . It contains the code for visual TrueType hinting instructions. You can manually edit the code here and apply changes by clicking on the button.

Alignment Zones»

Alignment zones define important vertical positions that are common to many font characters. A good example of an alignment zone is a baseline and the bottom position of the ‘O’ character:

Bottom alignment zone

At low PPM sizes you must set the bottom point of the characters ‘O’, ‘C’ and similar characters to the baseline to suppress the bottom overshoot. In this case we have a so-called bottom alignment zone.

Another example of an alignment zone is the top line of the ‘H’ character and the ‘O’ character:

Top alignment zone

Alignment zones are previewed in the Glyph window with a green and blue colors.

Editing TrueType Alignment Zones»

To add new TrueType zones or edit existing zones, click on the Zones button on the local toolbar.

You will see the Alignment Zones dialog:

The dialog contains a toolbar, two lists of zones and a pair of buttons: Apply and Cancel. The left list stores all information about the top zones (where alignment happens in top-to-bottom direction) and the right list – about the bottom zones.

For each zone you may specify its name, position of the “snap to” line, the zone width and the tag.

To change settings for a zone, simply double-click on the value in the list.

There is a toolbar above zones lists. Use it to call following commands:

Button	Description
	Add new top or bottom zone, respectively
	Remove selected top or bottom zone
	Automatically build zones
	Reset zones

AlignTop and AlignBottom Instructions»

These instructions are available only when the vertical hinting direction is selected.

To add AlignTop or AlignBottom commands:

1. Select the Align tool .
2. Position the cursor over the point that you want to align and click the mouse button.
3. If the selected point was in one of the alignment zones, an AlignTop or AlignBottom command will be added to the hinting program. If the selected point is not in the zone, the “free” Align command will be added.

The AlignTop command appears as:

The AlignBottom command is similar to the AlignTop command.

How AlignTop and AlignBottom Commands Work

1. In the prep program (this program interprets every time the PPM is changed) all alignment zones (stored in the cvt table) are aligned to the closest integer position.
2. When the glyph program interprets, the position of the point aligned to the zone by the AlignTop or AlignBottom command is set equal to the aligned position of the zone if the scaled distance between it and the zone is no more than 16/17 pixels.

The AlignTop and AlignBottom commands have two arguments: the name of the point that is aligned by the command and the name of the zone. In the Code panel these commands appear as:

alignt at01 "T: 1447"
alignb ab01 "B: 0"

where at01 and ab01 are point names and “T: 1447“ and ”B: 0” are names of the top and bottom zones, respectively.

Hinting Alignment Zones»

By default the position of the alignment zones is scaled linearly. Sometimes this may not be satisfactory and you may need to exactly specify the position of the alignment zones at some PPMs.

With FontLab VI you can adjust the position of the zones around the linearly scaled position.

Every alignment zone has a blue or green icon at the left:

You can drag this icon up or down to adjust the position of the zone at the current PPM:

If you move the icon you will see all glyphs that have align commands applied to that zone changed their shape.
You may find this feature useful when you have to add glyphs to an already hinted TrueType font. New glyphs often have a different height at some PPMs and you can correct that with the zone alignment command and zone hinting.

Align Instruction»

Use the Align command when it’s not necessary (or possible – you can’t align points to horizontal alignment zones) to align a point to an alignment zone but you want to align the point’s position to the grid. The Align command is available in both directions.

The Align command allows you to directly control how point coordinates are rounded.

To set an alignment command on the outline:

1. Select the Align tool .
2. Position the mouse cursor on the point that you want to align.
3. Click the mouse button. Hold the Shift key if you are setting vertical commands and the point is inside an alignment zone.

In the Code panel the Align command appears as:

alignv av01 round
alignh ah02 round

where av01 and ah02 are point names and round is the code of the alignment rounding method as shown in the table below.

To select a rounding method, click on the Align instruction (blue circle with anchor) and the Options panel will appear:

Select the align destination and close the panel to apply changes. You will see the code of the alignment rounding method will change in the Code panel.

Here is a graphical description of the various rounding methods:

Rounding	Code	Description
	round	Aligns to the closest grid line
	left	Aligns to the left or bottom grid line
	right	Aligns to the right or top grid line
	center	Aligns to the closest center of pixel
	double	Aligns to closest edge of pixel or center of pixel

Align commands are the very first commands in any hinting program. They do not have base points and affect only one point.

Standard Stems»

All link commands can be connected with one of the standard stems. When a link is connected to a stem it sets the distance between points to the scaled and rounded width of the stem. Using this technique you can implement standard-stem-based hinting, keeping important stem widths the same in every character in which they are used.

Please note that Type 1 standard stems and TrueType stems are different, although they function similarly. There is no limitation to the number of TrueType stems and they may be named.

Single Links»

The single link connects an outline point to a point whose position is set by another command. If you set a single link that linked point will always be at the given distance from the base point:

Single link instruction

A single link may be linked with one of the standard stem widths. If it is so linked then the distance to the base point is replaced by the scaled and rounded stem width. So if several links are connected to the same stem width the distances from the base points will always be the same.

Single links are very straightforward: they have one base point and one affected point.
If a single link is connected with one of the standard stems the linking distance is always rounded to the grid. If the link is not so connected, then it may be rounded or not depending on the currently selected Round length option:

Rounding lengths is the default option for this command because it usually gives better control of the position of the destination point.

There is a special kind of single link called the aligned single link. It can be described as a combination of a single link and the Align command on the linked point. You can’t set a normal Align command at the end of the link but you can use an aligned link in this case. To make a link aligned switch on the Align destination option on the Options panel and choose the rounding method:

To set a single link:

1. Select the single link tool .
2. Position the cursor on the base point. Don’t forget that the position of the base point must be set by an instruction.
3. Press the mouse button and drag the mouse to the point that you want to link. Release the button.

Hold the Shift key down if you do not want to connect the single link to a standard stem width. If you hold the Shift key the stem settings in the Options panel will be set to “None”.

Hold down the Alt key if you want to create the aligned single link.

Hold down the Ctrl key if you want to create the unrounded single link.

If the base point of the link is not aligned by some other command, FontLab VI will automatically set an Align command on it.

In the Glyph window the single link command appears as a directed red line with a mark in the middle (or without a mark if the link is not rounded). The mark is rhombus if the link is not connected to a standard stem width, and square with “R” if it is connected. If the link is connected, the stem name appears near the mark:

In the Code panel a single link command appears as:

singlev sv01, sv02 214 double

where sv01 is the base point; sv02 is the linked point; 214 is the name of the stem to which this link is connected (or “.round” if it is not connected to the stem or “.none” if the Round length option is off); and double is the method of alignment for aligned links.

Customizing the Single Link Command»

There are two ways to customize the single link command: the Options panel and the Code panel.

To customize a command with the Options panel, click on the link red line:

Use the Delete command to remove the command and the other options to customize it. The Stem sub-menu lets you link the command to one of the stems.

The Align Destination option is the same that you can see in the Align command’s Option panel and defines the rounding method of the destination position:

Rounding	Code	Description
	do not round	Alignment is off
	round	Aligns to the closest grid line
	left	Aligns to the left or bottom grid line
	right	Aligns to the right or top grid line
	center	Aligns to the closest center of pixel
	double	Aligns to closest edge of pixel or center of pixel

You can click on the Reverse button, denoted by , to reverse the direction of the link, and on To Double Link button to convert the single link to the double link instruction.

In the Code panel, you can edit the link instruction directly and click on the Compile button to apply changes.

Double Link»

Double links let you set the distance between two “untouched” points. Both points will be moved by this command and both points will be touched afterward.

The distance between points can be connected to one of the standard stem widths using the usual procedure described above. If the distance is connected to the stem width, it will scale with the stem.

You can’t predict where points will move that are connected by a double link so we recommend that you use this command only for stems for which the position is not very important or for stems that will be used as the basis for hinting.

The double link command does not have base points, but it sets the position of points.

To set a double link:

1. Select the double link tool .
2. Position the cursor over one of the points you want to link. Press the mouse button.
3. Drag the cursor to the point you want to link to the first point. Release the button.

Hold the Shift key down if you do not want to connect the double link to a standard stem width. If you hold down the Shift key the stem settings in the Options panel will be set to “None”.

Hold down the Ctrl key if you want to create the unrounded double link.

In the Glyph window the Double link command appears as a blue line with two arrows and a mark in the middle. The mark is a square with “R” if the link is connected to the stem, and a rhombus if it is not connected. If the link is connected the stem width will appear near the mark:

In the Code panel a double link command appears as:

doubleh dh01, dh02 269

where dh01 and dh02 are points that are linked; and 269 is the name of the stem to which this link is connected (or “.round” if it is not connected to the stem or “.none” if the Round length option is off).

Middle Delta Instructions»

A middle delta instruction can move outline points like any other instruction. It can move any outline point in ⅛-pixel increments from one pixel left (or bottom) to one pixel right (or top):

Movement space of delta instruction

Middle delta instructions are interpreted like other commands in the hinting program. They are automatically inserted between “normal” instructions that move points and so can be used to modify the normal interpretation of the hinting program:

In the example above, the vertical stem is moved one pixel to the left when the middle delta instruction is applied.

A middle delta instruction may be applied to a touched or untouched point and the point becomes touched afterwards.

It’s a good idea to use middle delta instructions to correct the rounding direction on some PPMs, like on the character ‘e’ at small PPM sizes.

Another good application of middle delta instructions is the correction of diagonal hints. A middle delta instruction “touches” the point to which it is applied, so any other point between two delta instructions will be interpolated in the final interpolation routine.

To set a middle delta instruction:

1. Select the Middle Delta tool .
2. Move the cursor to the point at which you want to set the delta instruction, press the left mouse button and drag to the needed direction.

The middle delta instruction has 4 arguments: point to move, PPM0, PPM1 (the PPM range in which this instruction works), and the shift distance in eighths of pixels. In the Code panel this instruction looks like:

mdeltav mv01 18-20 -6

where mv01 is the point name, 18–20 is the PPM range, -6 is the distance to move (in this case – move down by ¾ of a pixel). This means that point mv01 will be moved down ¾ of a pixel when PPM is 18, 19 or 20.

By default the PPM range is equal to the current PPM. You can edit the middle delta instruction right in the code or in its Options panel:

Final Delta Instructions»

Final delta instructions are applied after the final interpolation of all untouched points. They are used as a last resort to shift points to remove or add pixels at PPM sizes where it is still necessary after application of zones, stems and all other hints:

Hinted character at 12 PPM without delta instructions	Same character with delta instruction

The sequence of interpretation is the only difference between middle and final delta instructions. They work exactly the same way. To set final delta instructions, select the final delta tool and follow the same instructions as above for middle deltas.

Some recommendations:

1. Delta hinting is a very time-consuming operation because you have to check the rendering results at many PPMs. So always try first to get the best possible results from normal, linear hinting.
2. Use the waterfall preview in the TrueType Hinting panel to see where delta hinting is necessary.
3. Try to set as few delta instructions as possible. They increase font size and complexity.
4. It’s better to set one delta instruction with a larger range than two less comprehensive delta instructions.