What does "expand stroke" do?

[jtlapp]

I have played with "expand stroke" in AD, opened help, searched google, and searched the forums, but I have found no description of "expand stroke." In the forums everyone's talking about imprecisions in the expansion. I can't find a user manual.

I have curves that are filled with a color and have no stroke. When I "expand stroke" on one of these curves, I sometimes get a new curve in a new layer having an inside border and an outside border. When I fill this new curve with a color, the area between the two borders fills.

How do I control the width of these fill space? It just seemed to pick a width at random.

In attempting to experiment with "expand stroke," I deleted the layer that was created, clicked on the original curve that I wanted expand, and clicked "expand stroke" again.

Nothing happened this time around. No new curve.

I clearly don't understand this feature. Can someone point me to an explanation, please? Thanks!

(I have drawn insect legs but decided that I made them too thin. I just want to fatten them up a bit. Resizing doesn't change leg proportions.)

[jtlapp]

Ah, I think I figured it out. I think the problem is that it's buggy when you do an expand stroke on a curve that has no stroke set.

When I set a stroke and expand, it roughly creates a curve to encompass the previously-drawn stroke.

That's not quite the behavior I'm looking for. I want to expand my curve. I guess I can accomplish this by deleting the inner curve of the expanded stroke.

[gdenby]

Hi, jtlapp,

AD's vector shapes can have 2 attributes, fill and stroke. (If I've got this right) The built in shapes default to a pale grey fill, and no stroke. The pen and pencil default to a very thin stroke, no fill. 

You just replied. Its not a bug that it doesn't expand stroke when there is no stroke. There is nothing to expand.

What happens w. expand stroke is that the stroke, which is "painted" onto the vector, is turned to a vector by adding connected nodes to the boundary of the painted stroke. So a rectangle, for instance, w. no fill, but a thick stroke, 36 pt perhaps, will be expanded to a 1/2" perimeter. That new object has the fill color of the stroke, but no stroke of its own. One can then add a stroke to the expanded stroke, and expand again, creating a series of perimeter shapes.

Because the strokes can have pressure profiles, on can make pen or pencil curves w. variable thickness. Upon expanding, one gets something like a dynamic ink stroke. 

The routine as it stands can produce immense numbers of nodes if the stroke is highly inflected, very curved w. many width variations. This can make subsequent work doing geometric operations between various curve objects rather messy. Sometimes boolean operations will produce hundreds of objects that are invisible because they are so small, but are comprised of nodes a .001 apart.

[Alfred]

26 minutes ago, jtlapp said:

(I have drawn insect legs but decided that I made them too thin. I just want to fatten them up a bit. Resizing doesn't change leg proportions.)

There’s a ‘Scale’ option in the Stroke panel to control whether or not the stroke width changes when you resize the object.

3 minutes ago, jtlapp said:

Ah, I think I figured it out. I think the problem is that it's buggy when you do an expand stroke on a curve that has no stroke set.

How can you expand a stroke that isn’t there? The ‘Expand Stroke’ command creates (or tries to create!) a closed shape which mimics the selected stroke: if you start with a vertical straight line which is 50 px long and 20 px wide, you should end up with a rectangle which is 50 px high by 20 px wide.

[jtlapp]

Thank you everyone!

The bug is that AD does sometimes "expand" strokes on curves that do not have strokes. It appears to use the stroke width set for the curve, even though the stroke itself is set to none.

And sometimes "expanding" the stroke on a curve without a stroke does nothing.

That's inconsistent behavior and what was inclining me to think I didn't understand something.

My challenge is that I'm not using strokes on any of my curves. Maybe I should.

[jtlapp]

I'd like to see an "expand curve" function that does not require me to (tediously) delete the inner curve of a stroke. 

[Alfred]

I’m confused. In your original post you wrote that you have curves which are filled with a colour but have no stroke: if that is your starting point, what do you want to end up with?

[jtlapp]

5 minutes ago, αℓƒяє∂ said:

I’m confused. In your original post you wrote that you have curves which are filled with a colour but have no stroke: if that is your starting point, what do you want to end up with?

I fattened insect legs. Fortunately, I drew the legs on a separate curve from the insect's body.

Here is before and after, although it looks like the after image is first.

 

[gdenby]

If there is no stroke on a "curve," i.e. a vector, it would be somewhat useful to have the command ghosted for objects that have a stroke set to zero. 

One does not need to expand an object w. no stroke. The vector that defines the perimeter is the fundamental shape. 

Try using the outline view mode. It will show only the geometric shapes, and not the stroke and fill attributes. 

When ever I use the command on a stroke-less vector, there is no new curve object generated. Any object w. an extremely small stroke, .001 pt for instance, will generate a new layer object, but it will be invisible until zoomed way in.