Manual/Plugins/Scripting/0.9.3

Scripts are in QtScript aka ECMAScript aka JavaScript.

The details of the language are specified in the Qt ECMAScript reference. This page focuses on functions and objects specific to Knotter.

Geometry

Point

A wrapper to QPointF.

Constructors
Name	Type	Description
new Point()	Point	new Point(0,0)
new Point( Point other )	Point	Copy point other
new Point( Number x, Number y )	Point	Create point with given coordinates
External functions
Name	Type	Description
opposite( Point p )	Point	new Point(-p.x,-p.y)
distance(Point a, Point b)	Number	Distance from a and b

Line

A wrapper to QLineF most of the functionality of QLineF is also present in line.

Constructors
Name	Type	Description
new Line()	Line	Empty line
new Line( Line other )	Line	Copy line other_line
new Line( point1, point2 )	Line	Line from point point1 to point2
Properties
Name	Type	Description
p1	Point	Starting point of the line
p2	Point	End point of the line
x1	Number	p1.x
x2	Number	p2.x
y1	Number	p1.y
y2	Number	p2.y
angle	Number	Angle of the line in degrees. An angle of 0° is a horizontal line pointing to the right.
length	Number	Length of the line (distance between p1 and p2
dx	Number	p1.x-p2.x
dy	Number	p1.y-p2.y
Methods
Name	Type	Description
intersect ( Line other )	Point	Return the intersection point between the current line and other
normalVector()	Line	Returns a line that is perpendicular to this line with the same starting point and length.
unitVector()	Line	Returns the unit vector for this line, i.e a line starting at the same point as this line with a length of 1.0.
pointAt(Number t)	Point	Returns the point at the parameterized position specified by t. The function returns the line's start point if t = 0, and its end point if t = 1.
translate(Point offset)	void	Translate the line by offset
translate(Number x,Number y)	void	translate(point(x,y))

Polygon

Name	Type	Description
new Polygon()	Polygon	Create an empty polygon.
new Polygon(vertices)	Polygon	Create a polygon with given vertices.
vertices	Array[Point]	Vertices of the polygon.
contains(point)	Boolean	Whether the point is inside the polygon.
contains(x,y)	Boolean	contains(new Point(x,y)).
add_vertex(point)	void	Appends a vertex to vertices.

Graph

Graph

The graph for a given knot.

Name	Type	Description
new graph()	Graph	Creates an empty graph
nodes	Array[Node]	Nodes in the graph
edges	Array[Edge]	Edges in the graph
selected_nodes	Array[node]	List of the selected nodes
add_node(point)	Node	Creates a new node
add_node(x,y)	Node	Creates a new node
remove_node(node)	void	Remove node from the graph
connect(node1,node2)	Edge	Creates a new edge
node_at(point)	Node	Get the node at the given location
node_at(x,y)	Node	Get the node at the given location

Node

Name	Type	Description
pos	Point	Position of the node.
x	Number	pos.x.
y	Number	pos.y.
selected	Boolean	Whether the node is selected.
edges	Array[Edge]	(Read-Only) Edges with this node as vertex.
has_edge_too(Node other)	Boolean	Whether there is an edge from this to other.
edge_to(Node other)	Edge	Edge connecting this and other.

Edge

Name	Type	Description
vertex1	Node	One of the vertices of the edge
vertex2	Node	One of the vertices of the edge
line	Line	Line from vertex1.pos to vertex2.pos
midpoint	Point	Point at the middle of the edge
is_vertex(node)	Boolean	Whether the node is a vertex of the edge
other(node)	Node	If the given node is one of its vertices, return the other vertex

Interaction with Knotter

knotter

Object with information on Knotter.

Name	Type	Description
version	String	Knotter version
has_version(Number major,Number minor)	Boolean	Whether the current version is greater than major.minor.0

window

Perform some basic operations to Knotter main window.

Name	Type	Description
current_file	String	(Read only) File name of the knot in the active tab
current_tab	Number	Index of the active tab
open_tabs	Number	Number of open tabs
document	Document	Document corresponding to the current tab.
open( String file )	Boolean	Open file, returns true if successful
open()	Boolean	Create an new tab

window.dialog

An object that contains several functions to display simple dialogs to the user

Name	Type	Description
information(message,title="")	void	Display an information dialog
warning(message,title="")	void	Display a warning dialog
critical(message,title="")	void	Display an error dialog
question(message, title="", button_0="OK", button_1="", button_2="")	Number	Display a dialog asking a question. For every non-empty button text a button is shown. Returns the index of the button that the user pressed.
get_open_file(title="",filters="")	String	Show a dialog to open a file. Filters is in the form "Text (.txt);;Image (.svg .png)", Returns the selected file name or an empty string if the user canceled the dialog.
get_number(message, title="", default_value=0, min=MIN, max=MAX)	Number	Asks a dialog for a number. Returns NaN if the user canceled.
get_integer(message, title="", default_value=0, min=MIN, max=MAX)	Number	Just like get_number but only integers values are allowed
get_text(message,title="",default_value=)	String	Ask the user for a line of text.
information(get_item,title="",items=[])	String	Ask the user to select an item from the list. Returns the string representing the value or an empty string if the user canceled the dialog.
load_widget(file_name)	QWidget	Load a widget from a Ui file

Document

(Global object) The document from which the script was called. While window.document may change, the global document object will be the same during the entire script.

Name	Type	Description
filename	String	The name of the file for this document.
graph	Graph	The graph contained by the document.
grid	Grid	The grid used by the document.
insert(graph,message="ScriptInsert")	Boolean	Insert graph in the document. The inserted graph will have to be placed by the user in the desired location. Returns whether insertion has been successful.
begin_macro(message)	void	Wrap following edits to the document in a macro, the message will be the text displayed in the action history. Macros can be nested.
end_macro()	void	End current macro. For each call to begin_macro there should be a call to end_macro.

Grid

The grid displayed by a document object.

Name	Type	Description
size	Number	Size of a grid cell.
origin	Point	Position of the grid origin
enabled	Boolean	Whether the grid is displayed or not.
shape	String	One of SQUARE, TRIANGLE1 or TRIANGLE2.
enable()	void	Shorthand for grid.enabled = true;.
disable()	void	Shorthand for grid.enabled = false;.

Path

Object used in cusp plugins to draw the knot line, wrapper to the Knotter internal Path_Builder class. Cannot be constructed by the user.

Methods
Name	Type	Description
add_line( Point p1, Point p2 )	void	Draw a straight line from p1 to p2
add_quad( Point p1, Point control, Point p2	void	Draw a quadratic curve from p1 to p2 with control point control
add_cubic( Point p1, Point control1, Point control2, Point p2 )	void	Draw a cubic curve from p1 to p2 with control points control1 and control2

Plugin-specific objects

Cusp Plugin

Name	Type	Description
angle	Number	The angle between input and output edge
cusp_angle	Number	Style setting, if angle > cusp_angle , draw a cusp
handle_length	Number	Style setting, "curve" style parameter in the UI
start_handle	Line	Starting point for lines, start_handle.p1 will be connected to the path forming the crossing
finish_handle	Line	Ending point for lines, finish_handle.p1 will be connected to the path forming the crossing
cusp_point	Point	Pre-computed cusp point location
node_point	Point	Position of the node between the two edges
input_edge	Line	Line corresponding to the input edge
output_edge	Line	Line corresponding to the output edge
path	Path	Object used to build the path
direction	Number	-1 or +1 depending on the direction of the angle (clockwise or counter)

Guidelines

A cusp is expected to render a path from start_handle.p1 to finish_handle.p1.

start_handle.p2 and finish_handle.p2 may be used as control points.

If angle > cusp_angle the line should pass through cusp_point

Example

Follows the code to replicate the built-in rounded cusp.

if ( angle > cusp_angle ) 
{
    // Create a "handle" that on cusp_point with size handle_length to determine the control points
    handle = new Line(start_handle.p1,finish_handle.p1);
    handle.translate(cusp_point);
    handle.translate(opposite(start_handle.p1));
    handle.length = handle_length/2;
    h2 = handle.p2;
    handle.length = -handle_length/2;
    h1 = handle.p2;
    // Use the control points to render the cusp
    path.add_cubic ( start_handle.p1, start_handle.p2, h1, cusp_point );
    path.add_cubic ( finish_handle.p1, finish_handle.p2, h2, cusp_point );
}
else
{
    // Don't draw a cusp, just a cubic curve from start_handle to finish_handle
    path.add_cubic(start_handle.p1,start_handle.p2,finish_handle.p2,finish_handle.p1);
}