f16d7206f27f0ed5965f791cf4e85dbc846ae31f kate Wed Jan 3 15:28:13 2018 -0800 Preliminary (rough) support for curve drawing -- ellipse and bezier. Code by Zingl Alois, 2016, posted to github and http://members.chello.at/~easyfilter/bresenham.html. refs #17512 diff --git src/hg/lib/hvGfx.c src/hg/lib/hvGfx.c index e9340ea..bb02c58 100644 --- src/hg/lib/hvGfx.c +++ src/hg/lib/hvGfx.c @@ -221,16 +221,304 @@ gfxPolyAddPoint(t1, x+w/2, y+h); gfxPolyAddPoint(t2, x+w/2, y+h/2); gfxPolyAddPoint(t2, x+w, y); gfxPolyAddPoint(t2, x+w, y+h); } /* The two filled triangles. */ vgDrawPoly(hvg->vg, t1, hvgColor, TRUE); vgDrawPoly(hvg->vg, t2, hvgColor, TRUE); /* The two outline triangles. */ vgDrawPoly(hvg->vg, t1, color, FALSE); vgDrawPoly(hvg->vg, t2, color, FALSE); gfxPolyFree(&t1); gfxPolyFree(&t2); } +/* from memgfx.c and vPng.c*/ + +struct memPng +/* Something that handles a PNG. */ + { + struct memGfx mg; /* Memory form. This needs to be first field. */ + char *fileName; /* PNG file name. */ + boolean useTransparency; /* Make background color transparent if TRUE. */ + }; + +#define _mgBpr(mg) ((mg)->width) +#define _mgPixAdr(mg,x,y) ((mg)->pixels+_mgBpr(mg) * (y) + (x)) + +INLINE void mixDot(struct hvGfx *hvg, int x, int y, float frac, Color col) +/* Puts a single dot on the image, mixing it with what is already there + * based on the frac argument. */ +{ +struct memPng *png = (struct memPng *)hvg->vg->data; +struct memGfx *img = (struct memGfx *)png; +if ((x < img->clipMinX) || (x > img->clipMaxX) || (y < img->clipMinY) || (y > img->clipMaxY)) + return; + +Color *pt = _mgPixAdr(img,x,y); +float invFrac = 1 - frac; + +int r = COLOR_32_RED(*pt) * invFrac + COLOR_32_RED(col) * frac; +int g = COLOR_32_GREEN(*pt) * invFrac + COLOR_32_GREEN(col) * frac; +int b = COLOR_32_BLUE(*pt) * invFrac + COLOR_32_BLUE(col) * frac; +hvGfxDot(hvg, x, y, MAKECOLOR_32(r,g,b)); +hvGfxDot(hvg, x, y, MAKECOLOR_32(r,g,b)); +} + +#define fraction(X) (((double)(X))-(double)(int)(X)) +#define invFraction(X) (1.0-fraction(X)) + +void hvGfxCurveSeg(struct hvGfx *hvg, int x0, int y0, int x1, int y1, int x2, int y2, Color color) +/* Draw a segment of a curve within 3 points (quadratic Bezier) + * Adapted trivially from code posted on github and at http://members.chello.at/~easyfilter/bresenham.html */ + /* Thanks to author * @author Zingl Alois + * @date 22.08.2016 */ +{ + int sx = x2-x1, sy = y2-y1; + long xx = x0-x1, yy = y0-y1, xy; /* relative values for checks */ + double dx, dy, err, cur = xx*sy-yy*sx; /* curvature */ + + assert(xx*sx <= 0 && yy*sy <= 0); /* sign of gradient must not change */ + + if (sx*(long)sx+sy*(long)sy > xx*xx+yy*yy) { /* begin with longer part */ + x2 = x0; x0 = sx+x1; y2 = y0; y0 = sy+y1; cur = -cur; /* swap P0 P2 */ + } + if (cur != 0) { /* no straight line */ + xx += sx; xx *= sx = x0 < x2 ? 1 : -1; /* x step direction */ + yy += sy; yy *= sy = y0 < y2 ? 1 : -1; /* y step direction */ + xy = 2*xx*yy; xx *= xx; yy *= yy; /* differences 2nd degree */ + if (cur*sx*sy < 0) { /* negated curvature? */ + xx = -xx; yy = -yy; xy = -xy; cur = -cur; + } + dx = 4.0*sy*cur*(x1-x0)+xx-xy; /* differences 1st degree */ + dy = 4.0*sx*cur*(y0-y1)+yy-xy; + xx += xx; yy += yy; err = dx+dy+xy; /* error 1st step */ + do { + hvGfxDot(hvg, x0, y0, color); /* plot curve */ + if (x0 == x2 && y0 == y2) return; /* last pixel -> curve finished */ + y1 = 2*err < dx; /* save value for test of y step */ + if (2*err > dy) { x0 += sx; dx -= xy; err += dy += yy; } /* x step */ + if ( y1 ) { y0 += sy; dy -= xy; err += dx += xx; } /* y step */ + } while (dy < 0 && dx > 0); /* gradient negates -> algorithm fails */ + } + hvGfxLine(hvg, x0,y0, x2,y2, color); /* plot remaining part to end */ +} + +void hvGfxCurveSegAA(struct hvGfx *hvg, int x0, int y0, int x1, int y1, int x2, int y2, Color color) +/* Draw a segment of an anti-aliased curve within 3 points (quadratic Bezier) + * Adapted trivially from code posted on github and at http://members.chello.at/~easyfilter/bresenham.html */ + /* Thanks to author * @author Zingl Alois + * @date 22.08.2016 */ +{ + int sx = x2-x1, sy = y2-y1; + long xx = x0-x1, yy = y0-y1, xy; /* relative values for checks */ + double dx, dy, err, ed, cur = xx*sy-yy*sx; /* curvature */ + + assert(xx*sx <= 0 && yy*sy <= 0); /* sign of gradient must not change */ + + if (sx*(long)sx+sy*(long)sy > xx*xx+yy*yy) { /* begin with longer part */ + x2 = x0; x0 = sx+x1; y2 = y0; y0 = sy+y1; cur = -cur; /* swap P0 P2 */ + } + if (cur != 0) + { /* no straight line */ + xx += sx; xx *= sx = x0 < x2 ? 1 : -1; /* x step direction */ + yy += sy; yy *= sy = y0 < y2 ? 1 : -1; /* y step direction */ + xy = 2*xx*yy; xx *= xx; yy *= yy; /* differences 2nd degree */ + if (cur*sx*sy < 0) { /* negated curvature? */ + xx = -xx; yy = -yy; xy = -xy; cur = -cur; + } + dx = 4.0*sy*(x1-x0)*cur+xx-xy; /* differences 1st degree */ + dy = 4.0*sx*(y0-y1)*cur+yy-xy; + xx += xx; yy += yy; err = dx+dy+xy; /* error 1st step */ + do { + cur = fmin(dx+xy,-xy-dy); + ed = fmax(dx+xy,-xy-dy); /* approximate error distance */ + ed += 2*ed*cur*cur/(4*ed*ed+cur*cur); + mixDot(hvg, x0,y0, 255*fabs(err-dx-dy-xy)/ed, color); /* plot curve */ + if (x0 == x2 || y0 == y2) break; /* last pixel -> curve finished */ + x1 = x0; cur = dx-err; y1 = 2*err+dy < 0; + if (2*err+dx > 0) { /* x step */ + if (err-dy < ed) mixDot(hvg, x0,y0+sy, 255*fabs(err-dy)/ed, color); + x0 += sx; dx -= xy; err += dy += yy; + } + if (y1) { /* y step */ + if (cur < ed) mixDot(hvg, x1+sx,y0, 255*fabs(cur)/ed, color); + y0 += sy; dy -= xy; err += dx += xx; + } + } while (dy < dx); /* gradient negates -> close curves */ + } + hvGfxLine(hvg, x0,y0, x2,y2, color); /* plot remaining needle to end */ +} + +void hvGfxCurveAA(struct hvGfx *hvg, int x0, int y0, int x1, int y1, int x2, int y2, Color color) +/* Draw a segment of an anti-aliased curve within 3 points (quadratic Bezier) + * Adapted trivially from code posted at http://members.chello.at/~easyfilter/bresenham.html */ +{ + int x = x0-x1, y = y0-y1; + double t = x0-2*x1+x2, r; + + if ((long)x*(x2-x1) > 0) { /* horizontal cut at P4? */ + if ((long)y*(y2-y1) > 0) /* vertical cut at P6 too? */ + if (fabs((y0-2*y1+y2)/t*x) > abs(y)) { /* which first? */ + x0 = x2; x2 = x+x1; y0 = y2; y2 = y+y1; /* swap points */ + } /* now horizontal cut at P4 comes first */ + t = (x0-x1)/t; + r = (1-t)*((1-t)*y0+2.0*t*y1)+t*t*y2; /* By(t=P4) */ + t = (x0*x2-x1*x1)*t/(x0-x1); /* gradient dP4/dx=0 */ + x = floor(t+0.5); y = floor(r+0.5); + r = (y1-y0)*(t-x0)/(x1-x0)+y0; /* intersect P3 | P0 P1 */ + hvGfxCurveSegAA(hvg,x0,y0, x,floor(r+0.5), x,y, color); + r = (y1-y2)*(t-x2)/(x1-x2)+y2; /* intersect P4 | P1 P2 */ + x0 = x1 = x; y0 = y; y1 = floor(r+0.5); /* P0 = P4, P1 = P8 */ + } + if ((long)(y0-y1)*(y2-y1) > 0) { /* vertical cut at P6? */ + t = y0-2*y1+y2; t = (y0-y1)/t; + r = (1-t)*((1-t)*x0+2.0*t*x1)+t*t*x2; /* Bx(t=P6) */ + t = (y0*y2-y1*y1)*t/(y0-y1); /* gradient dP6/dy=0 */ + x = floor(r+0.5); y = floor(t+0.5); + r = (x1-x0)*(t-y0)/(y1-y0)+x0; /* intersect P6 | P0 P1 */ + hvGfxCurveSegAA(hvg,x0,y0, floor(r+0.5),y, x,y, color); + r = (x1-x2)*(t-y2)/(y1-y2)+x2; /* intersect P7 | P1 P2 */ + x0 = x; x1 = floor(r+0.5); y0 = y1 = y; /* P0 = P6, P1 = P7 */ + } + hvGfxCurveSegAA(hvg,x0,y0, x1,y1, x2,y2, color); /* remaining part */ +} + +void hvGfxCurve(struct hvGfx *hvg, int x0, int y0, int x1, int y1, int x2, int y2, Color color) +/* Draw a segment of an anti-aliased curve within 3 points (quadratic Bezier) + * Adapted trivially from code posted at http://members.chello.at/~easyfilter/bresenham.html */ +{ + int x = x0-x1, y = y0-y1; + double t = x0-2*x1+x2, r; + + if ((long)x*(x2-x1) > 0) { /* horizontal cut at P4? */ + if ((long)y*(y2-y1) > 0) /* vertical cut at P6 too? */ + if (fabs((y0-2*y1+y2)/t*x) > abs(y)) { /* which first? */ + x0 = x2; x2 = x+x1; y0 = y2; y2 = y+y1; /* swap points */ + } /* now horizontal cut at P4 comes first */ + t = (x0-x1)/t; + r = (1-t)*((1-t)*y0+2.0*t*y1)+t*t*y2; /* By(t=P4) */ + t = (x0*x2-x1*x1)*t/(x0-x1); /* gradient dP4/dx=0 */ + x = floor(t+0.5); y = floor(r+0.5); + r = (y1-y0)*(t-x0)/(x1-x0)+y0; /* intersect P3 | P0 P1 */ + hvGfxCurveSeg(hvg,x0,y0, x,floor(r+0.5), x,y, color); + r = (y1-y2)*(t-x2)/(x1-x2)+y2; /* intersect P4 | P1 P2 */ + x0 = x1 = x; y0 = y; y1 = floor(r+0.5); /* P0 = P4, P1 = P8 */ + } + if ((long)(y0-y1)*(y2-y1) > 0) { /* vertical cut at P6? */ + t = y0-2*y1+y2; t = (y0-y1)/t; + r = (1-t)*((1-t)*x0+2.0*t*x1)+t*t*x2; /* Bx(t=P6) */ + t = (y0*y2-y1*y1)*t/(y0-y1); /* gradient dP6/dy=0 */ + x = floor(r+0.5); y = floor(t+0.5); + r = (x1-x0)*(t-y0)/(y1-y0)+x0; /* intersect P6 | P0 P1 */ + hvGfxCurveSeg(hvg,x0,y0, floor(r+0.5),y, x,y, color); + r = (x1-x2)*(t-y2)/(y1-y2)+x2; /* intersect P7 | P1 P2 */ + x0 = x; x1 = floor(r+0.5); y0 = y1 = y; /* P0 = P6, P1 = P7 */ + } + hvGfxCurveSeg(hvg,x0,y0, x1,y1, x2,y2, color); /* remaining part */ +} + +#ifdef INFINITE +void hvGfxEllipseAA(struct hvGfx *hvg, int x0, int y0, int x1, int y1, Color color) +/* Draw an anti-aliased ellipse specified by rectangle, using Bresenham algorithm. + * Point 0 is left, point 1 is top of rectangle + * Adapted trivially from code posted at http://members.chello.at/~easyfilter/bresenham.html + */ +{ + long a = abs(x1-x0), b = abs(y1-y0), b1 = b&1; /* diameter */ + float dx = 4*(a-1.0)*b*b, dy = 4*(b1+1)*a*a; /* error increment */ + float ed, i, err = b1*a*a-dx+dy; /* error of 1.step */ + bool f; + + if (a == 0 || b == 0) return hvGfxLine(hvg, x0, y0, x1, y1, color); + if (x0 > x1) { x0 = x1; x1 += a; } /* if called with swapped points */ + if (y0 > y1) y0 = y1; /* .. exchange them */ + y0 += (b+1)/2; y1 = y0-b1; /* starting pixel */ + a = 8*a*a; b1 = 8*b*b; + + int q = 0; + for (q=0; q<1000; q++) { /* approximate ed=sqrt(dx*dx+dy*dy) */ + //for (;;) { /* approximate ed=sqrt(dx*dx+dy*dy) */ + i = min(dx,dy); ed = max(dx,dy); + if (y0 == y1+1 && err > dy && a > b1) ed = 255*4./a; /* x-tip */ + else ed = 255/(ed+2*ed*i*i/(4*ed*ed+i*i)); /* approximation */ + i = ed*fabs(err+dx-dy); /* get intensity value by pixel error */ + mixDot(hvg, x0,y0, i, color); mixDot(hvg, x0,y1, i, color); + mixDot(hvg, x1,y0, i, color); mixDot(hvg, x1,y1, i, color); + + if ((f = 2*err+dy) >= 0) { /* x step, remember condition */ + if (x0 >= x1) break; + i = ed*(err+dx); + if (i < 255) { + mixDot(hvg, x0,y0+1, i, color); mixDot(hvg, x0,y1-1, i, color); + mixDot(hvg, x1,y0+1, i, color); mixDot(hvg, x1,y1-1, i, color); + } /* do error increment later since values are still needed */ + } + if ((2*err) <= dx) { /* y step */ + i = ed*(dy-err); + if (i < 255) { + mixDot(hvg, x0+1,y0, i, color); mixDot(hvg, x1-1,y0, i, color); + mixDot(hvg, x0+1,y1, i, color); mixDot(hvg, x1-1,y1, i, color); + } + y0++; y1--; err += dy += a; + } + if (f) { x0++; x1--; err -= dx -= b1; } /* x error increment */ + } + if (--x0 == x1++) /* too early stop of flat ellipses */ + while (y0-y1 < b) { + i = 255*4*fabs(err+dx)/b1; /* -> finish tip of ellipse */ + mixDot(hvg, x0,++y0, i, color); mixDot(hvg, x1,y0, i, color); + mixDot(hvg, x0,--y1, i, color); mixDot(hvg, x1,y1, i, color); + err += dy += a; + } +} + +#endif + +void hvGfxEllipseDraw(struct hvGfx *hvg, int x0, int y0, int x1, int y1, Color color, int mode) +/* Draw an ellipse (or limit to top or bottom) specified by rectangle, using Bresenham algorithm. + * Point 0 is left, point 1 is top of rectangle + * Adapted trivially from code posted at http://members.chello.at/~easyfilter/bresenham.html + */ +{ + int a = abs(x1-x0), b = abs(y1-y0), b1 = b&1; /* values of diameter */ + long dx = 4*(1-a)*b*b, dy = 4*(b1+1)*a*a; /* error increment */ + long err = dx+dy+b1*a*a, e2; /* error of 1.step */ + + if (x0 > x1) { x0 = x1; x1 += a; } /* if called with swapped points */ + if (y0 > y1) y0 = y1; /* .. exchange them */ + y0 += (b+1)/2; y1 = y0-b1; /* starting pixel */ + a *= 8*a; b1 = 8*b*b; + + do { + if (mode == ELLIPSE_BOTTOM || mode == ELLIPSE_FULL) { + hvGfxDot(hvg, x1, y0, color); /* I. Quadrant */ + hvGfxDot(hvg, x0, y0, color); /* II. Quadrant */ + } + if (mode == ELLIPSE_TOP || mode == ELLIPSE_FULL) { + hvGfxDot(hvg, x0, y1, color); /* III. Quadrant */ + hvGfxDot(hvg, x1, y1, color); /* IV. Quadrant */ + } + e2 = 2*err; + if (e2 <= dy) { y0++; y1--; err += dy += a; } /* y step */ + if (e2 >= dx || 2*err > dy) { x0++; x1--; err += dx += b1; } /* x step */ + } while (x0 <= x1); + + while (y0-y1 < b) { /* too early stop of flat ellipses a=1 */ + hvGfxDot(hvg, x0-1, y0, color); /* -> finish tip of ellipse */ + hvGfxDot(hvg, x1+1, y0++, color); + hvGfxDot(hvg, x0-1, y1, color); + hvGfxDot(hvg, x1+1, y1--, color); + } +} + +void hvGfxEllipse(struct hvGfx *hvg, int x0, int y0, int x1, int y1, Color color) +/* Draw a full ellipse specified by rectangle, using Bresenham algorithm. + * Point 0 is left, point 1 is top of rectangle + * Adapted trivially from code posted at http://members.chello.at/~easyfilter/bresenham.html + */ +{ +hvGfxEllipseDraw(hvg, x0, y0, x1, y1, color, ELLIPSE_FULL); +} +