Smart Corners and Ink Traps
A Smart Corner lets you change the treatment of a junction while keeping its original corner editable. Use it to soften a sharp vertex or open an ink trap, then tune the treatment as the surrounding strokes change.
Rounded Corners and Ink Traps
A Smart Corner is a live treatment attached to a sharp corner node. Its handle controls the generated shape. Move the handle into the corner's smaller angular region to round the corner; move it to the opposite, larger region to open an ink trap. The two results are alternatives within the same feature.
An ink trap is a notch that gives ink spreading at a junction somewhere to go. Its usefulness depends on the design and intended size: inspect the letter in context at the sizes for which you are making the adjustment. A conspicuous notch in a large outline view may become a much subtler junction in text.
The Smart ink trap generates curved transitions around its notch. A simple ink trap made with the Scissors tool spreads nodes apart directly. A looped corner is another contour construction. Choose the live treatment when you want to keep adjusting the trap without redrawing those transitions.
Add a Smart Corner
- With the Contour tool, select a sharp corner node. Shift-click to add other corners to the selection.
- Choose Contour > Add Smart Corner. You can also use the node's context menu or the Smart control in the Node panel.
- Inspect the blue Smart Corner handle and the generated outline.
- Drag the handle to choose rounding or an ink trap and establish the approximate size.
Start with one corner when learning the control. The smaller-angle rule describes the geometry around the node; “inside the letter” is not a reliable substitute because inner and outer corners have different orientations.
Adjusting and Configuring Smart Corners
The handle changes the size of the treatment without moving the source corner itself. If the handle coincides with the node, hold Alt while dragging to give the Smart Corner handle priority. This helps when the radius is zero or very small.
Select several Smart Corners and drag one of their handles to adjust the selected corners together. Inspect the whole selection afterward: the same adjustment can look different at acute and broad junctions.
You can select the Smart Corner handles with the Frame or Lasso selector. With several rounded-corner handles selected, press Return/Enter to balance their positive radii to a common average. Negative ink-trap radii are not included in that averaging operation. Inspect the resulting corners before continuing.
Size and shape are separate settings
The Node panel provides a Smart Corner radius value. A positive radius gives rounding; a negative value gives an ink trap. Use it for an exact size after finding an approximate result on the canvas.
The Node panel shows the selected smart corner’s settings. Its preview values belong to the current corner rather than the whole font.
The panel also provides a context-sensitive shape setting:
- For a rounded corner, corner tension controls the generated curve's shape and is expressed as a percentage.
- For an ink trap, ink trap width controls the width of the notch.
This setting is separate from the signed radius. Changing an ink trap's width is not the same as changing its depth, and changing corner tension is not the same as increasing the corner's size.
Set defaults, then override exceptions
The master-wide defaults are Corner tension and Ink trap width in Font Info > Font Dimensions. Set these to establish the normal treatment for the master. The ink-trap width is also used by the simple ink-trap workflow.
A Smart Corner without a node-specific value uses the appropriate default. Enter a value in the Node panel to override that setting for the selected corner. Clear the override field to return to the default; the displayed placeholder shows the inherited value.
For a family of related corners, begin with the defaults and a consistent radius. Override individual corners only where their geometry needs a different treatment. This keeps a later change to the master's normal tension or trap width useful across the design.
Expansion and Export Behavior
While the Smart Corner remains live, the original corner and its settings remain available. For an eligible corner, right-click its blue handle and choose Apply Smart Corner to commit that corner. Remove Smart Corner removes that treatment while retaining the source corner. To resolve the containing filtered construction, use Element > Expand Filters.
Expansion creates the nodes and segments needed to describe the visible result. Rounded corners use boundary nodes around the generated curve, and the construction preserves coincident nodes or zero-length segments in some degenerate and adjacent-corner cases. These details help avoid unnecessary structural changes when a rounded corner shrinks to zero or meets another rounded corner.
Do not assume that every Smart Corner produces exactly two nodes. An ink trap has a different construction, including its notch and curved transitions, and can require additional nodes and handles. Changing between rounding and an ink trap can therefore change the structure of the expanded result.
For a design with several masters:
- Put corresponding Smart Corners on corresponding source nodes.
- Keep the treatment consistent where the masters are meant to interpolate.
- Compare the expanded results on a duplicate or saved version, including zero-radius corners and consecutive corners.
- Check node counts, order, types, and contour direction, then inspect intermediate shapes.
A stable rounded-corner construction helps compatibility; it does not establish compatibility for the entire glyph or guarantee that every combination of Smart Corner settings interpolates correctly.
Native VFC and VFJ files retain the live Smart Corner structure; production-font export resolves it into ordinary outlines. Save the native working file for later editing, and inspect the exported result at both outline and text sizes. Manual expansion is needed when you want to edit the generated contour directly, not simply because the font is ready for export.
For the complete compatibility rule, see Interpolation and Compatibility. Format-specific export handling is covered in The Export Process.