thickLineRgba function

bool thickLineRgba(Pointer<SdlRenderer> renderer, double x1, double y1, double x2, double y2, double width, int r, int g, int b, int a, { int blendMode = SDL_BLENDMODE_BLEND, })

Implementation

bool thickLineRgba(
  Pointer<SdlRenderer> renderer,
  double x1,
  double y1,
  double x2,
  double y2,
  double width,
  int r,
  int g,
  int b,
  int a, {
  int blendMode = SDL_BLENDMODE_BLEND,
}) {
  int wh;
  double dx;
  double dy;
  double dx1;
  double dy1;
  double dx2;
  double dy2;
  double l;
  double wl2;
  double nx;
  double ny;
  double ang;
  double adj;
  final px = calloc<Int16>(4);
  final py = calloc<Int16>(4);

  if (renderer == nullptr) {
    return false;
  }

  if (width < 1) {
    return false;
  }

  /* Special case: thick "point" */
  if ((x1 == x2) && (y1 == y2)) {
    wh = width ~/ 2;
    return boxRgba(
      renderer,
      x1 - wh,
      y1 - wh,
      x2 + width,
      y2 + width,
      r,
      g,
      b,
      a,
    );
  }

  /* Special case: width == 1 */
  if (width == 1) {
    return lineRgba(renderer, x1, y1, x2, y2, r, g, b, a, blendMode: blendMode);
  }

  /* Calculate offsets for sides */
  dx = x2 - x1;
  dy = y2 - y1;
  l = sdlSqrt(dx * dx + dy * dy);
  ang = sdlAtan2(dx, dy);
  adj = 0.1 + 0.9 * sdlFabs(sdlCos(2.0 * ang));
  wl2 = (width - adj) / (2.0 * l);
  nx = dx * wl2;
  ny = dy * wl2;

  /* Build polygon */
  dx1 = x1;
  dy1 = y1;
  dx2 = x2;
  dy2 = y2;
  px[0] = (dx1 + ny).toInt();
  px[1] = (dx1 - ny).toInt();
  px[2] = (dx2 - ny).toInt();
  px[3] = (dx2 + ny).toInt();
  py[0] = (dy1 - nx).toInt();
  py[1] = (dy1 + nx).toInt();
  py[2] = (dy2 + nx).toInt();
  py[3] = (dy2 - nx).toInt();

  /* Draw polygon */
  final result = filledPolygonRgba(
    renderer,
    px,
    py,
    4,
    r,
    g,
    b,
    a,
    blendMode: blendMode,
  );
  calloc
    ..free(px)
    ..free(py);

  return result;
}