HTML--SVG基础

优点:
1.使用编辑器即可编辑图形;
2.基于XML,SVG图形可以被很容易的搜索,脚本化和压缩;
3.缩放不影响图形质量;
4.支持随意打印成需要的尺寸;
5.SVG开源标准;

劣势:
1.比正常格式图片体积大;
2.即使小图片也可能很大;

<svg width="100" height="100">
    <circle cx="50" cy="50" r="45" stroke="orange" stroke-width="10" fill="#ff5" />
</svg>

<svg width="500" height="400">
    <rect x="10" y="10" width="300" height="150" style="fill:#ccc; stroke:orange; stroke-width:5px;" />
    <rect x="10" y="210" rx="50" ry="100" width="300" height="150" style="fill:#ccc; stroke:orange; stroke-width:5px; stroke-opacity:.5; fill-opacity:.9;"  />
</svg>

<svg width="500" height="400">
    <ellipse cx="150" cy="100" rx="90" ry="50" stroke="orange" stroke-width="5" fill="#000" fill-opacity=".5" />
    <text x="110" y="30" font-size="24" font-weight="bold">SVG椭圆</text>
</svg>

<svg width="500" height="400">
    <line x1="5" y1="5" x2="250" y2="200" style="stroke:rgba(255, 0, 0, .5); stroke-width:5px;" />
    <text x="120" y="50" font-size="24" font-weight="bold">SVG直线</text>
</svg>

<svg width="500" height="400">
    <polygon points="150, 75 258, 137.5 258, 262.5 150, 325 42, 262.6 42, 137.5" stroke="orange" stroke-width="5" stroke-opacity=".5" fill="rgba(250, 0, 0, .3)" />
    <text x="95" y="50" font-size="24" font-weight="bold">SVG多边形</text>
</svg>

<svg width="500" height="400">
    <polyline points="150,75 258,137.5 258,262.5 150,325 42,262.6 42,137.5" stroke="orange" stroke-width="5" fill="none"/>
    <text x="103" y="50" font-size="24" font-weight="bold">SVG折线</text>
</svg>

<svg width="500" height="400">
    <path d="M 100 100 L 300 100 L 200 300 z" style="fill:orange; stroke:#666; stroke-width:5px;" />
    <text x="150" y="80" font-size="24" font-weight="bold">SVG路径</text>
</svg>

<svg width="500" height="400">
    <text x="170" y="80" font-size="24" font-weight="bold">SVG文字</text>
    <text x="130" y="120" rotate=" 45" textlength="150" font-size="20" font-weight="bold">文字旋转45度</text>
    <a href="http://www.cnblogs.com/yizihan">
        <text x="30" y="180" fill="orange" textlength="350" font-size="20" font-weight="bold">
            http://www.cnblogs.com/yizihan
        </text>
    </a>
</svg>

<svg width="500" height="400">
    <g>
        <text x="30" y="30" font-size="20" font-weight="bold">stroke例子</text>
        <path stroke="orange" stroke-width="10" d="M 50 50 L 300 50" />
    </g>
    <g>
        <text x="30" y="130" font-size="20" font-weight="bold">stroke linecap</text>
        <path stroke="orange" stroke-linecap="butt" stroke-width="10" d="M 50 150 L 300 150" />
        <path stroke="orange" stroke-linecap="round" stroke-width="10" d="M 50 180 L 300 180" />
        <path stroke="orange" stroke-linecap="square" stroke-width="10" d="M 50 210 L 300 210" />
    </g>
    <g>
        <text x="30" y="280" font-size="20" font-weight="bold">stroke dasharray</text>            
        <path stroke="orange" stroke-dasharray="5, 5" stroke-width="10" d="M 50 300 L 300 300" />
        <path stroke="orange" stroke-dasharray="15, 15" stroke-width="10" d="M 50 330 L 300 330" />
        <path stroke="orange" stroke-dasharray="55, 55" stroke-width="10" d="M 50 360 L 300 360" />
    </g>
</svg>

// 先定义滤镜
<defs>
    <filter id="myfilter" x="0" y="0" >
    // <filter>标签里的id属性可以为滤镜定义一个唯一的名称;
        <feGaussianBlur in="SourceGraphic" stdDeviation="5" />
        // 滤镜效果是通过<feGaussianBlur>标签进行定义的,--高斯模糊;;fe后缀可用于所有的滤镜;
        // <feGaussianBlur>标签的stdDeviation属性可定义模糊的程度;
        // in="SourceGraphic"这个部分定义了由整个图像创建效果;
    </filter>
</defs>
// 应用滤镜到图形
<rect x="30" y="30" width="200" height="100" stroke="green" stroke-width="10" fill="orange" filter="url(#myfilter)" />
// filter:url属性用来把元素链接到滤镜;当链接滤镜id时,必须使用#字符;

<defs>
    <pattern id="mypattern" patternUnits="userSpaceOnUse" x="10" y="10" width="100" height="100">
    // patternUnits:用来定义图案使用的单位;
        <path d="M 0 0 L 100 0 L 50 100 z" fill="#222" stroke="orange" stroke-width="5"  />  
        // 绘制一个倒三角; 
    </pattern>
</defs>
// 应用图案到具体图形;
<rect x="10" y="10" width="300" height="200" stroke="green" stroke-width="5" fill="url(#mypattern)" />

<svg width="500" height="400">
    // 定义线性渐变
    <defs>
        <linearGradient id="linearGradient">
            <stop offset="0%" stop-color="#f00" />
            <stop offset="100" stop-color="#f60" />
        </linearGradient>
    </defs>
    // 应用线性渐变
    <rect x="10" y="10" width="300" height="100" stroke="orange" stroke-width="5" fill="url(#linearGradient)" />

    // 定义径向渐变
    <defs>
        <radialGradient id="radialGradient">
            <stop offset="0%" stop-color="#f00" />
            <stop offset="100%" stop-color="#f60" />
        </radialGradient>
    </defs>
    // 应用径向渐变
    <rect x="10" y="150" width="100" height="100" stroke="orange" stroke-width="5" fill="url(#radialGradient)" />
</svg>

// 定义矩形
<svg width="500" height="400">
    <rect id="myrect" x="50" y="50" width="200" height="200" fill="orange" onClick="showcolor()" />
</svg>
<script>
// 针对SVG图形定义JS方法;
function showcolor(){
    var color = document.getElementById(‘myrect‘).getAttributeNS(null,‘fill‘);
    // getAttributeNS():通过命名空间URI和名称来获取属性值;
    alert(‘矩形填充色为:‘ + color);
}
</script>

<svg width="500" height="400">
    <a xlink:href="http://www.cnblogs.com/yizihan/" >
        <rect x="10" y="10" width="200" height="200" style="fill:orange; stroke-width:5; stroke:rgb(222, 0, 0)" />   
    </a>
</svg>