一组javascript绘图函数

作者： unknow

<html>
<head>
<title>JavaScript绘图</title>
<script language="JavaScript">
IE4 = ! (navigator.appVersion.charAt(0) < "4" || navigator.appName == "Netscape")

var xo=0
var yo=0
var Ox = -1
var Oy = -1

var rad = Math.PI/180
var maxY = 400
var color = "red"

function print(str) {
  document.write(str)
}

function orgY(y) {
  return maxY-y
}
function outPlot(x,y,w,h) {
  print(@#<span style="position:absolute;left:@#+x+@#;top:@#+y+@#;height:@#+h+@#;width:@#+w+@#;font-size:1px;background-color:@#+color+@#"></span>@#)
}

function Plot(x,y) {
  outPlot(x,y,1,1)
  if(Ox>=0 || Oy>=0) {
    ShowLine(Ox,Oy,x-Ox,y-Oy)
  }
  Ox = x
  Oy = y
}

function ShowLine(x,y,w,h) {
  if(w<0) {
    x += w
    w = Math.abs(w)
  }
  if(h<0) {
    y += h
    h = Math.abs(h)
  }
  if(w<1) w=1
  if(h<1) h=1
  outPlot(x,y,Math.round(w),Math.round(h))
}

function LineTo(x,y) {
  Line(xo,yo,x,y)
}

function sign(n) {
  if(n>0)
    return 1
  if(n<0)
    return -1
  return n
}

function Line(x1,y1,x2,y2) {
  x2 = Math.round(x2)
  y2 = Math.round(y2)
  xo = x2
  yo = y2
  y1 = orgY(y1)
  y2 = orgY(y2)
  var str = ""
  var i=0

  var x = x1
  var y = y1
  dx = Math.abs(x2-x1)
  dy = Math.abs(y2-y1)
  s1 = sign(x2-x1)
  s2 = sign(y2-y1)

  if(dx==0 || dy==0) {
    ShowLine(x1,y1,x2-x1,y2-y1)
    return
  }

  if(dx>dy) {
    temp = dx
    dx = dy
    dy = temp
    key = 1
  }else
    key = 0
  e = 2*dy-dx

  for(i=0;i<dx;i++) {
    px = 0
    py = 0
    Plot(x,y)
    while(e>=0) {
      if(key==1) {
        x += s1
        px += s1
      }else {
        y += s2
        py += s2
      }
      e = e-2*dx
    }
    if(key==1)
      y += s2
    else
      x += s1
    e = e+2*dy
  }
}

function MoveTo(x,y) {
  Ox = Oy = -1
  xo = Math.round(x)
  yo = Math.round(y)
}

// 圆
function Cir(x,y,r) {
  MoveTo(x+r,y)
  for(i=0;i<=360;i+=5) {
    LineTo(r*Math.cos(i*rad)+x,r*Math.sin(i*rad)+y)
  }
}
// 弧形
function Arc(x,y,r,a1,a2) {
  MoveTo(r*Math.cos(a1*rad)+x,r*Math.sin(a1*rad)+y)
  for(i=a1;i<=a2;i++) {
    LineTo(r*Math.cos(i*rad)+x,r*Math.sin(i*rad)+y)
  }
}
// 扇形
function Pei(x,y,r,a1,a2) {
  MoveTo(x,y)
  for(var i=a1;i<=a2;i++) {
    LineTo(r*Math.cos(i*rad)+x,r*Math.sin(i*rad)+y)
  }
  LineTo(x,y)
}
// 弹出扇形
function PopPei(x,y,r,a1,a2) {
  dx = r*Math.cos((a1+(a2-a1)/2)*rad)/10
  dy = r*Math.sin((a1+(a2-a1)/2)*rad)/10
  x += dx
  y += dy
  MoveTo(x,y)
  for(var i=a1;i<=a2;i++) {
    LineTo(r*Math.cos(i*rad)+x,r*Math.sin(i*rad)+y)
  }
  LineTo(x,y)
}

// 矩形
function Rect(x,y,w,h) {
  MoveTo(x,y)
  LineTo(x+w,y)
  LineTo(x+w,y+h)
  LineTo(x,y+h)
  LineTo(x,y)
}

// 准星
function zhunxing(x,y) {
  var ox = xo
  var oy = yo
  var oColor = color
  color = "#000000"
  Line(x-5,y,x+6,y)
  Line(x,y-6,x,y+5)
  print(@#<span style="position:absolute;font-size:10pt;left:@#+(x+5)+@#;top:@#+orgY(y+5)+@#;">[@#+x+@#,@#+y+@#]</span>@#)
  color = oColor
  xo = ox
  yo = oy
}
// 标注
function biaozhuStr(x,y,s) {
  return @#<span style="position:absolute;font-size:10pt;left:@#+x+@#;top:@#+orgY(y)+@#;">@#+s+@#</span>@#
}
function biaozhu(x,y,s,t) {
  var ox = xo
  var oy = yo
  var oColor = color
  point = "p01.gif"
  if(t==1) {
     print(biaozhuStr(x-5,y+6,"·"+s))
  }
  if(t==2) {
    print(biaozhuStr(xo+x*Math.cos(y*rad)-10,yo+x*Math.sin(y*rad),s))
  }
  color = oColor
  xo = ox
  yo = oy
}
</script>
</head>

<body>
<table border="0" width="100%">
  <tr>
    <td width="100%" style="font-family: 方正舒体; font-size: 18pt; color: #FF0000" class="t1">JavaScript绘图</td>
  </tr>
  <tr>
    <td width="100%" style="font-family: 幼圆; font-size: 12pt; color: #008000" class="t2">
      如果需要在网页上提供图形化的资料，通常是将其制作成图片，但这样一来网络上的开销就太大了。有什么办法呢？这里向你提供一组JavaScript函数，来解决这一问题。虽然简单了点，但是对画点线图来说还是绰绰有余的！</td>
  </tr>
</table>

<script>
if(IE4) {

// 基本图形
color = "maroon"
Cir(50,40,20)
Arc(100,40,20,60,120)
Pei(150,60,40,240,300)
Rect(200,20,40,40)

// 折线图
color = "#FF0000"
var jd = new Array(
203,232,277,223,271,234,273,284,276,250,267,280
)
MoveTo(30,jd[0]-40)
biaozhu(xo,yo,jd[0])
for(i=1;i<jd.length;i++) {
  LineTo(i*30+30,jd[i]-40)
  biaozhu(xo,yo,jd[i],1)
}
color = "#C0C0C0"
Line(30,140,i*30+30,140)
Line(30,140,30,260)

// 饼图
color = "#00FF00"
var gc = new Array(
150,120,200,180,180
)
var s = 0
var m = 0
var n = 0
for(i=0;i<gc.length;i++) {
  s +=gc[i]
  if(gc[i] > m) {
    m = gc[i]
    n = i
  }
}
var k = s/360
var mm = 0
var a =0
for(i=0;i<gc.length;i++) {
  b = Math.round((gc[i]+mm)/k)
  if(i==n)
    PopPei(600,150,100,a,b)
  else
    Pei(600,150,100,a,b)
  biaozhu(60,a+(b-a)/2,Math.round(gc[i]/s*100)+"%",2)
  mm = mm+gc[i]
  a = b
}

// 十字标注
MoveTo(280,20)
zhunxing(xo,yo)

}else {
  document.write("<p>  </p><table bgcolor=#FF0000><tr><td><font color=#FFFF00>对不起！您的浏览器不能支持该页的某些功能，请换用IE4.0以上版本的浏览器！谢谢！</font></td></tr></table>")
}
</script>

</body>
</html>

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