diff options
Diffstat (limited to 'src/gdisp/gdisp.c')
| -rw-r--r-- | src/gdisp/gdisp.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/src/gdisp/gdisp.c b/src/gdisp/gdisp.c index 1eb5a41b..b625f8a7 100644 --- a/src/gdisp/gdisp.c +++ b/src/gdisp/gdisp.c @@ -2565,6 +2565,131 @@ void gdispGDrawBox(GDisplay *g, coord_t x, coord_t y, coord_t cx, coord_t cy, co } } } + + static int32_t rounding_div(const int32_t n, const int32_t d) + { + if ((n < 0) != (d < 0)) + return (n - d/2) / d; + else + return (n + d/2) / d; + } + + void gdispGDrawThickLine(GDisplay *g, coord_t x0, coord_t y0, coord_t x1, coord_t y1, color_t color, coord_t width, bool_t round) { + coord_t dx, dy, nx, ny; + + /* Compute the direction vector for the line */ + dx = x1 - x0; + dy = y1 - y0; + + /* Compute vector for the normal of the line */ + nx = dy; + ny = -dx; + + /* Normalize the normal vector to length width. + * This uses Newton-Rhapson to avoid the need for floating point sqrt. + * We try to solve f(div) = div^2 - len/width^2. + */ + { + int32_t div, len, tmp; + uint8_t i; + + len = nx*nx + ny*ny; + div = 100; /* Initial guess for divider; not critical */ + + for (i = 0; i < 5; i++) { + tmp = width * width * div; + div -= (tmp * div - len) / (2 * tmp); + } + + nx = rounding_div(nx, div); + ny = rounding_div(ny, div); + } + + /* Offset the x0,y0 by half the width of the line. This way we + * can keep the width of the line accurate even if it is not evenly + * divisible by 2. + */ + { + x0 -= rounding_div(nx, 2); + y0 -= rounding_div(ny, 2); + } + + /* Fill in the point array */ + if (!round) { + /* We use 4 points for the basic line shape: + * + * pt1 pt2 + * (+n) ------------------------------------ (d+n) + * | | + * (0,0) ----------------------------------- (d) + * pt0 pt3 + */ + point pntarray[4]; + + pntarray[0].x = 0; + pntarray[0].y = 0; + pntarray[1].x = nx; + pntarray[1].y = ny; + pntarray[2].x = dx + nx; + pntarray[2].y = dy + ny; + pntarray[3].x = dx; + pntarray[3].y = dy; + + gdispGFillConvexPoly(g, x0, y0, pntarray, 4, color); + } else { + /* We use 4 points for basic shape, plus 4 extra points for ends: + * + * pt3 ------------------ pt4 + * / \ + * pt2 pt5 + * | | + * pt1 pt6 + * \ / + * pt0 -------------------pt7 + */ + point pntarray[8]; + coord_t nx2, ny2; + + /* Magic numbers: + * 75/256 = sin(45) / (1 + sqrt(2)) diagonal octagon segments + * 106/256 = 1 / (1 + sqrt(2)) octagon side + * 53/256 = 0.5 / (1 + sqrt(2)) half of octagon side + * 150/256 = 1 - 1 / (1 + sqrt(2)) octagon height minus one side + */ + + /* Rotate the normal vector 45 deg counter-clockwise and reduce + * to 1 / (1 + sqrt(2)) length, for forming octagonal ends. */ + nx2 = rounding_div((nx * 75 + ny * 75), 256); + ny2 = rounding_div((-nx * 75 + ny * 75), 256); + + /* Offset and extend the line so that the center of the octagon + * is at the specified points. */ + x0 += ny * 53 / 256; + y0 -= nx * 53 / 256; + dx -= ny * 106 / 256; + dy += nx * 106 / 256; + + /* Now fill in the points by summing the calculated vectors. */ + pntarray[0].x = 0; + pntarray[0].y = 0; + pntarray[1].x = nx2; + pntarray[1].y = ny2; + pntarray[2].x = nx2 + nx * 106/256; + pntarray[2].y = ny2 + ny * 106/256; + pntarray[3].x = nx; + pntarray[3].y = ny; + pntarray[4].x = dx + nx; + pntarray[4].y = dy + ny; + pntarray[5].x = dx + nx - nx2; + pntarray[5].y = dy + ny - ny2; + pntarray[6].x = dx + nx * 150/256 - nx2; + pntarray[6].y = dy + ny * 150/256 - ny2; + pntarray[7].x = dx; + pntarray[7].y = dy; + + gdispGFillConvexPoly(g, x0, y0, pntarray, 8, color); + } + } #endif #if GDISP_NEED_TEXT |