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用JavaScript實現使用鼠標畫線的示例代碼
01 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 02 <html xmlns="http://www.w3.org/1999/xhtml"> 03 04 <head> 05 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 06 <title>Untitled 1</title> 07 <style type="text/css"> 08 .style1 { 09 font-size: x-small; 10 } 11 </style> 12 <script type="text/javascript"> 13 /** 14 畫點 15 */ 16 function makedot(x, y){ 17 pointDiv = "<div style='height:1px;position:absolute;left:" + x + 18 "px;top:" + y + "px;width:1px;background:#f00;overflow:hidden'></div>"; 19 return pointDiv; 20 } 21 /** 22 根據兩點坐標畫直線。 23 */ 24 25 function line(x1,y1,x2,y2){ 26 var slope; //斜率 27 var direction;//坐標運動方向 28 var tx = x2 - x1; 29 var ty = y2 - y1; 30 if(tx == 0 && ty == 0)return; 31 var points = ""; 32 var axis;//坐標軸上的坐標 33 if(Math.abs(tx) >= Math.abs(ty)){//在x軸上移動 34 direction = tx > 0 ? 1 : -1; 35 tx = Math.abs(tx); 36 slope = ty / tx; 37 axis = x1; 38 for(i = 0; i < tx; i ++){ 39 points += makedot(axis, y1 + i * slope); 40 axis += direction; 41 } 42 43 }else{//在y軸上移動 44 direction = ty > 0 ? 1 : -1; 45 ty = Math.abs(ty); 46 slope = tx / ty; 47 axis = y1; 48 for(i = 0; i < ty; i ++){ 49 points += makedot(x1 + i * slope, axis); 50 axis += direction; 51 } 52 } 53 var container = document.getElementById("container"); 54 container.innerHTML += points; 55 } 56 var oldPoint = null; 57 //獲取鼠標位置 58 function mousePosition(ev){ 59 ev = ev || window.event; 60 if(ev.pageX || ev.pageY){ 61 return {x:ev.pageX, y:ev.pageY}; 62 } 63 var doc = document.documentElement, body = document.body; 64 var pageX = event.clientX + (doc && doc.scrollLeft || body && body.scrollLeft || 0) - (doc && doc.clientLeft || body && body.clientLeft || 0); 65 var pageY = event.clientY + (doc && doc.scrollTop || body && body.scrollTop || 0) - (doc && doc.clientTop || body && body.clientTop || 0); 66 return {x:pageX, y:pageY}; 67 } 68 69 function recordPoint(ev){ 70 71 var point = mousePosition(ev); 72 if(oldPoint != null){
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