Snap Control Handles to 45 Degrees in FontForge

In FontForge, aligning Bezier control handles to precise angles is essential for creating clean, mathematically sound glyph outlines. This guide explains how to constrain control handles to 45-degree angles using standard keyboard shortcuts, numerical coordinate adjustments, and transformation tools during the glyph editing process.

Using the Shift Key Constraint

The fastest method to snap control handles to a 45-degree angle is using the constraint shortcut while drawing or editing:

  1. Open your glyph in the Outline View window.
  2. Select the Pointer tool from the tool palette (shortcut: V).
  3. Click and hold the Bezier control handle you want to adjust.
  4. Press and hold the Shift key on your keyboard before moving the mouse.
  5. Drag the handle. FontForge will automatically constrain the handle's movement to multiples of 45 degrees (0°, 45°, 90°, 135°, 180°, etc.).
  6. Release the mouse button first to set the handle position, then release the Shift key.

Setting 45-Degree Handles Numerically

For absolute precision, you can set control handles directly via coordinate inputs:

  1. Right-click the on-curve node associated with the handle and select Get Info (or press Ctrl + I / Cmd + I).
  2. Navigate to the control point coordinate fields (labeled Next CP or Prev CP).
  3. To achieve an exact 45-degree angle, set the horizontal distance (\(\Delta X\)) and vertical distance (\(\Delta Y\)) between the base node and the control handle to identical absolute values. For example, if the base node is at (100, 100), placing the control handle at (150, 150) sets it to an exact 45-degree angle pointing up and to the right.
  4. Click OK to apply the changes.

Aligning via the Transform Dialog

If you need to rotate existing handles or point clusters by exactly 45 degrees:

  1. Select the points or handles you want to adjust.
  2. Go to Element in the top menu and select Transform (shortcut: Ctrl + \).
  3. In the dropdown menu, select Rotate.
  4. Enter 45 (or -45) degrees.
  5. Set the origin point to either the selection center or the specific node location, then click OK.