Parts

There are a few parameters shared by many of the parts:

The callback parameter

The callback parameter can take on of the following forms:

• A function (or bound method) that expects one parameter: the number of the side the callback is currently called for.

• A dict with some of the numbers of the sides as keys and functions without parameters as values.

• A list of functions without parameters. The list may contain None as place holder and be shorter than the number of sides.

The callback functions are called with the side of the part at the positive x and y axis. If the edge uses up space this space is below the x axis. You do not have to restore the coordinate settings in the callback.

Instead of functions it can be handy to use a lambda expression calling the one building block function you need (e.g. fingerHolesAt).

For your own parts you can use this helper function:

Boxes.cc(callback, number, x=0.0, y=None, a=0.0)

Call callback from edge of a part

Parameters:

• callback – callback (callable or list of callables)

• number – number of the callback

• x – (Default value = 0.0) x position to be call on

• y – (Default value = None) y position to be called on (default does burn correction)

For finding the right piece to the callback parameter this function is used:

Boxes.getEntry(param, idx)

Get entry from list or items itself

Parameters:

• param – list or item

• idx – index in list

The move parameter

For placing the parts the move parameter can be used. It is string with space separated words - at most one of each of those options:

• left / right

• up / down

• only

If “only” is given the part is not drawn but only the move is done. This can be useful to go in one direction after having placed multiple parts in the other and have returned with .ctx.restore().

For implementing parts the following helper function can be used to implement a move parameter:

Boxes.move(x, y, where, before=False, label='')

Intended to be used by parts where can be combinations of “up” or “down”, “left” or “right”, “only”, “mirror” and “rotated” when “only” is included the move is only done when before is True “mirror” will flip the part along the y-axis “rotated” draws the parts rotated 90 counter clockwise The function returns whether actual drawing of the part should be omitted.

Parameters:

• x – width of part

• y – height of part

• where – which direction to move

• before – (Default value = False) called before or after part being drawn

It needs to be called before and after drawing the actual part with the proper before parameter set.

The edges parameter

The edges parameter needs to be an iterable of Edge instances to be used as edges of the part. Instead of instances it is possible to pass a single character that is looked up in the .edges dict. This allows to pass a string with the desired characters per edge. By default the following character are supported:

• e : straight edge

• E : as above but extended outside by one thickness

• f, F : finger joints

• h : edge with holes for finger joints

• d, D : dove tail joints

Generators can register their own Edges by putting them into the .edges dictionary.

Same applies to the parameters of .surroundingWall although they denominate single edge (types) only.

PartsMatrix

To place a grid of identical parts, partMatrix can used:

Boxes.partsMatrix(n, width, move, part, *l, **kw)

place many of the same part

Parameters:

• n – number of parts

• width – number of parts in a row (0 for same as n)

• move – (Default value = “”)

• part – callable that draws a part and knows move param

• l – params for part

• kw – keyword params for part

It creates one big block of parts. The move param treats this block like one big part.