Width Brush Tool Operation

After the Width Brush tool is selected, its size can be changed either in its preferences dialog (see Width Brush: Preferences) or by pressing the keys assigned to Decrease Diameter and Increase Diameter in the native Keyboard Shortcuts dialog (the left and right square bracket keys respectively, by default, for English language keyboards). Its hardness, ranging from 0% to 100%, can only be changed in the preferences dialog.

When at least one path with a variable width stroke (or stroke that can be converted to a variable width stroke) is selected, clicking on it with the brush or dragging the brush across it will widen or narrow the stroke(s). Annotations will dynamically update while the mouse button is down to show the current stroke width:

Width Brush Basic Example

The brush only makes one adjustment per drag; i.e. it does not flow continuously like a Photoshop airbrush. For example, if the adjustment were set to add the fixed amount of 3 pt of width to a stroke, then moving the cursor back and forth over a path will only add 3 pt at most, regardless of how many times the cursor passes over it. However, releasing the mouse button and making a new drag could add up to another 3 pt, and so on.

Width Brush Second Drag

Brush hardness affects the smoothness of the transition between the original stroke width and the adjusted stroke width, as only positions towards the center of the brush get maximum adjustment:

Width Brush Hardness Comparison

Before pressing the mouse button down to click or drag, there are two keypresses which can be used:

Shift: All adjustments will be in the reverse direction. In other words, if the brush were set to add 1.7 mm to all stroke widths, then instead it would subtract 1.7 mm. If it were set to double stroke widths (e.g. make them 200% of their original width), then stroke widths would be instead halved (e.g. make them 50% of their original width).

Option/Alt: Makes the tool act exactly like the Width Eraser tool, which visualizes the width markers on the path(s) and removes those that the tool is passed over (except those at the start and end of the path). Its diameter is taken from that last used in the actual Width Eraser tool, and cannot be changed.

While dragging with the tool, the X key can be pressed to toggle its annotations on and off. This allows you to see the original width of the stroke(s). Annotations are drawn in the same color as that used for the Width Gradient tool.