javascript 常用代码大全（四 ）

//8

一个可以在页面上随意画线、多边形、圆，填充等功能的js （part 2）

function mkOv2D(left, top, width, height)
{
var s = this.stroke;
width += s-1;
height += s-1;
var a = width>>1, b = height>>1,
wod = width&1, hod = (height&1)+1,
cx = left+a, cy = top+b,
x = 0, y = b,
aa = (a*a)<<1, bb = (b*b)<<1,
st = (aa>>1)*(1-(b<<1)) + bb,
tt = (bb>>1) - aa*((b<<1)-1);
if (s-4 < 0 && (!(s-2) || width-51 > 0 && height-51 > 0))
{
var ox = 0, oy = b,
w, h,
pxl, pxr, pxt, pxb, pxw;
while (y > 0)
{
if (st < 0)
{
st += bb*((x<<1)+3);
tt += (bb<<1)*(++x);
}
else if (tt < 0)
{
st += bb*((x<<1)+3) - (aa<<1)*(y-1);
tt += (bb<<1)*(++x) - aa*(((y--)<<1)-3);
w = x-ox;
h = oy-y;
if (w-1)
{
pxw = w+1+(s&1);
h = s;
}
else if (h-1)
{
pxw = s;
h += 1+(s&1);
}
else pxw = h = s;
this.mkOvQds(cx, cy, -x+1, ox-pxw+w+wod, -oy, -h+oy+hod, pxw, h);
ox = x;
oy = y;
}
else
{
tt -= aa*((y<<1)-3);
st -= (aa<<1)*(--y);
}
}
this.mkDiv(cx-a, cy-oy, s, (oy<<1)+hod);
this.mkDiv(cx+a+wod-s+1, cy-oy, s, (oy<<1)+hod);
}
else
{
var _a = (width-((s-1)<<1))>>1,
_b = (height-((s-1)<<1))>>1,
_x = 0, _y = _b,
_aa = (_a*_a)<<1, _bb = (_b*_b)<<1,
_st = (_aa>>1)*(1-(_b<<1)) + _bb,
_tt = (_bb>>1) - _aa*((_b<<1)-1),
pxl = new Array(),
pxt = new Array(),
_pxb = new Array();
pxl[0] = 0;
pxt[0] = b;
_pxb[0] = _b-1;
while (y > 0)
{
if (st < 0)
{
st += bb*((x<<1)+3);
tt += (bb<<1)*(++x);
pxl[pxl.length] = x;
pxt[pxt.length] = y;
}
else if (tt < 0)
{
st += bb*((x<<1)+3) - (aa<<1)*(y-1);
tt += (bb<<1)*(++x) - aa*(((y--)<<1)-3);
pxl[pxl.length] = x;
pxt[pxt.length] = y;
}
else
{
tt -= aa*((y<<1)-3);
st -= (aa<<1)*(--y);
}
if (_y > 0)
{
if (_st < 0)
{
_st += _bb*((_x<<1)+3);
_tt += (_bb<<1)*(++_x);
_pxb[_pxb.length] = _y-1;
}
else if (_tt < 0)
{
_st += _bb*((_x<<1)+3) - (_aa<<1)*(_y-1);
_tt += (_bb<<1)*(++_x) - _aa*(((_y--)<<1)-3);
_pxb[_pxb.length] = _y-1;
}
else
{
_tt -= _aa*((_y<<1)-3);
_st -= (_aa<<1)*(--_y);
_pxb[_pxb.length-1]--;
}
}
}
var ox = 0, oy = b,
_oy = _pxb[0],
l = pxl.length,
w, h;
for (var i = 0; i < l; i++)
{
if (typeof _pxb[i] != "undefined")
{
if (_pxb[i] < _oy || pxt[i] < oy)
{
x = pxl[i];
thi, s.mkOvQds(cx, cy, -x+1, ox+wod, -oy, _oy+hod, x-ox, oy-_oy);
ox = x;
oy = pxt[i];
_oy = _pxb[i];
}
}
else
{
x = pxl[i];
this.mkDiv(cx-x+1, cy-oy, 1, (oy<<1)+hod);
this.mkDiv(cx+ox+wod, cy-oy, 1, (oy<<1)+hod);
ox = x;
oy = pxt[i];
}
}
this.mkDiv(cx-a, cy-oy, 1, (oy<<1)+hod);
this.mkDiv(cx+ox+wod, cy-oy, 1, (oy<<1)+hod);
}
}

function mkOvDott(left, top, width, height)
{
var a = width>>1, b = height>>1,
wod = width&1, hod = height&1,
cx = left+a, cy = top+b,
x = 0, y = b,
aa2 = (a*a)<<1, aa4 = aa2<<1, bb = (b*b)<<1,
st = (aa2>>1)*(1-(b<<1)) + bb,
tt = (bb>>1) - aa2*((b<<1)-1),
drw = true;
while (y > 0)
{
if (st < 0)
{
st += bb*((x<<1)+3);
tt += (bb<<1)*(++x);
}
else if (tt < 0)
{
st += bb*((x<<1)+3) - aa4*(y-1);
tt += (bb<<1)*(++x) - aa2*(((y--)<<1)-3);
}
else
{
tt -= aa2*((y<<1)-3);
st -= aa4*(--y);
}
if (drw) this.mkOvQds(cx, cy, -x, x+wod, -y, y+hod, 1, 1);
drw = !drw;
}
}