SVG： Scalable Vector Graphics(可伸縮矢量圖形)
它使用XML格式來定義圖形，例如：
<svg>
<rect width="100" height="100" x="0" y="0"
style="fill:red; stroke:black; stroke-width:5">
</svg>
優點：
1、SVG圖檔它在放大或縮小時不會像圖檔一樣失真；
2、SVG圖檔可以被搜尋、索引、加載腳步和壓縮；
3、SVG圖檔它可擴充；
4、SVG是開放的标準；
5、SVG是純XML檔案。
DEMO：
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1、rectangle矩形
<svg>
<rect x="50" y="20" rx="50" ry="50" width="200" height="200"
style="fill:red;stroke:black;stroke-width:5;opacity:0.5" />
</svg>
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2、Circle圓形
<svg>
<circle cx="100" cy="50" r="40" fill="red" stroke="black" stroke-width="20"
fill-opacity="0.8" stroke-opacity="0.5" />
</svg>
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3、Ellipse橢圓
<svg>
<ellipse cx="300" cy="80" rx="100" ry="50" style="fill:yellow; stroke:purple; stroke-width:2" />
</svg>
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4、Line線
<svg>
<line x1="0" y1="0" x2="200" y2="50" stroke-width="5" stroke="black" />
</svg>
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5、Polygon多邊形
<svg>
<polygon points="100,10 40,180 190,60 10,60 160,180" style="fill:lime;stroke:purple;stroke-width:5;fill-rule:evenodd"/>
</svg>
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6、Polyline折線
<svg>
<polyline points="0,40 40,40 40,80 80,80 80,120 120,120 120,160"
style="fill:yellow;stroke:red;stroke-width:4"/>
</svg>
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7、Path路勁
<svg>
<path id="lineAB" d="M 100 350 l 150 -300" stroke="red" stroke-width="3" fill="none" />
<path id="lineBC" d="M 250 50 l 150 300" stroke="red" stroke-width="3" fill="none" />
<path id="lineBC" d="M 175 200 l 150 0" stroke="red" stroke-width="3" fill="none" />
<path id="quadcurveABC" d="M 100 350 q 150 -300 300 0" stroke="blue" stroke-width="5" fill="none" />
<!-- Mark relevant points -->
<g stroke="black" stroke-width="3" fill="black">
<circle id="pointA" cx="100" cy="350" r="3" />
<circle id="pointB" cx="250" cy="50" r="3" />
<circle id="pointC" cx="400" cy="350" r="3" />
</g>
<!-- Label the points -->
<g font-size="30" font="sans-serif" fill="black" stroke="none" text-anchor="middle">
<text x="100" y="350" dx="-30">A</text>
<text x="250" y="50" dy="-10">B</text>
<text x="400" y="350" dx="30">C</text>
</g>
</svg>
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8、Text文字
<svg>
<text x="0" y="15" fill="red" transform="rotate(30 20,40)">I Love SVG</text>
</svg>
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9、Stroke描邊
<svg>
<g fill="none" stroke="black" stroke-width="4">
<path stroke-dasharray="5,5" d="M5 20 l215 0" />
<path stroke-dasharray="10,10" d="M5 40 l215 0" />
<path stroke-dasharray="20,10,5,5,5,10" d="M5 60 l215 0" />
</g>
</svg>
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