Overview of Item Types
spline2line command. In addition, it is possible to generate a spline that approximates a multi-segmented line with the line2spline command. A bezier curve is defined using four points - the start and end point for the curve, and two control points that indicate the path that the curve follows. For example:
For a spline made from a single bezier segment, the points are given as follows:
<start-x> <start-y> <c1-x> <c1-y> <c2-x> <c2-y> <end-x> <end-y>
That is, first the start point is given, followed by the first control point, followed by the second control point and finishing with the end point for the curve. For example, you can create a simple spline using:
.pad create spline 0 0 10 10 20 10 30 0
here (0, 0) defines the start of the curve. (10, 10) is the first control point, (20, 10) is the second control point, and the curve ends at (30, 0).
Splines are created with widget commands of the following form:
pathName create spline x1 y1... xn yn [option value option value ...]The arguments x1 through yn give the coordinates for a series of one or more splines. Each point is specified by two coordinates. When specifying a spline made from two or more bezier curves, the end point of the first curve is used as the start point for the second, so the second curve only requires an additional three points (two control points and an end point). In general a spline of N bezier curves requires 3N+1 points (6N+2 coordinates). This represents a start point and then three points for each curve.
For convenience, if the end point of the last curve segment in a spline is omitted, Pad++ assumes that the curve should be 'closed' - it uses the start point of the first curve as the end point for the last curve, creating a closed shape. For closed shapes, therefore, you should provide 3N points (6N coordinates).
After the coordinates there may be any number of option-value pairs, each of which sets one of the configuration options for the item. These same option-value pairs may be used in itemconfigure widget commands to change the item's configuration. The following options are supported for lines:
-arrow [7] Whether to draw arrow heads with this item
-arrowshape [8] The shape of drawn arrow heads
-capstyle [12] Specifies how to draw line ends
-joinstyle [32] Specifies how to draw the joints within multi-point lines
-pen [45] Specifies pen color of item
-penwidth [46] Specifies width of pen
Copyright Computer Science Department, The University of New Mexico