Blend2D-contours

Blend2D extension for extracting contours from a BLPath

This is a little Blend2D extension for extracting the contours of a BLPath. With this extension, you can extract all the contours and the single curves it is made of; Then you can compute the position of each point on these curves, ando also their tangent and normal versors.

You are free to use the the code Get the source code at https://github.com/abu-irrational/Blend2D-contours

These extension introduces a new main class "BLX_Contours", and two inner classes: BLX_Contour and Bcurve.

BLX_Contours: a list of BLX_Contour.
    BLX_Contour: a list of connected Bcurve (Bezier-Curves) of degree 2,3,4
        Bcurve: A Bezier-curve stored in polynomial form for fast evaluation.

Usage:

#include <blend2d.h>
#include "BLX_Contours.h"
...
 // extract the contours from a BLPath
BLX_Contours contours;
contours.init(blPath);

 // get the numbers of contours:
size_t nc = contours.size();
...
 //  get the i-th contour   ( 0 <= i <contours.size() )
BLX_Contour contour = contours[i];
...
 // get the number of basic curves (strokes) on this contour
size_t nStrokes = contour.size();    //  contours[j].size()
...
 // get the j-th curve on this contour ( 0 <= j < contour.size() )
BCurve bCurve = contour[j];          //  contours[i][j]
...
 // get any BLPoint on bCurve for any t ( 0.0 <=t <=1.0 )
BLPoint P = bCurve.at(t);
 // Get the tangent or the normal versor
BLPoint T = bCurve.tangent(t);
BLPoint N = bCurve.normal(t);

 // .. or use a more compact notation ( provided that i,j are in range)
BLPoint P = contours[i][j].at(t)
BLPoint T = contours[i][j].tangent(t)
BLPoint N = contours[i][j].normal(t)