SVG <feOffset>
示例1
<svg height="120" width="120">
<defs>
<filter id="f1" x="0" y="0" width="200%" height="200%">
<feOffset result="offOut" in="SourceGraphic" dx="20" dy="20" />
<feBlend in="SourceGraphic" in2="offOut" mode="normal" />
</filter>
</defs>
<rect width="90" height="90" stroke="green" stroke-width="3"
fill="yellow" filter="url(#f1)" />
</svg>
代码解释：
- 该元素的id属性定义了滤镜的唯一名称
- 该元件的滤镜属性链接到了“f1”滤镜
示例2
加上了 <feGaussianBlur>
<svg height="140" width="140">
<defs>
<filter id="f2" x="0" y="0" width="200%" height="200%">
<feOffset result="offOut" in="SourceGraphic" dx="20" dy="20" />
<feGaussianBlur result="blurOut" in="offOut" stdDeviation="10" />
<feBlend in="SourceGraphic" in2="blurOut" mode="normal" />
</filter>
</defs>
<rect width="90" height="90" stroke="green" stroke-width="3"
fill="yellow" filter="url(#f2)" />
</svg>
示例3
<svg height="140" width="140">
<defs>
<filter id="f3" x="0" y="0" width="200%" height="200%">
<feOffset result="offOut" in="SourceAlpha" dx="20" dy="20" />
<feGaussianBlur result="blurOut" in="offOut" stdDeviation="10" />
<feBlend in="SourceGraphic" in2="blurOut" mode="normal" />
</filter>
</defs>
<rect width="90" height="90" stroke="green" stroke-width="3"
fill="yellow" filter="url(#f3)" />
</svg>
代码解释：
- <feOffset> 元素改成了"SourceAlpha"虚化中的Alpha通道代替了RGBA像素
示例4
<svg height="140" width="140">
<defs>
<filter id="f4" x="0" y="0" width="200%" height="200%">
<feOffset result="offOut" in="SourceGraphic" dx="20" dy="20" />
<feColorMatrix result="matrixOut" in="offOut" type="matrix"
values="0.2 0 0 0 0 0 0.2 0 0 0 0 0 0.2 0 0 0 0 0 1 0" />
<feGaussianBlur result="blurOut" in="matrixOut" stdDeviation="10" />
<feBlend in="SourceGraphic" in2="blurOut" mode="normal" />
</filter>
</defs>
<rect width="90" height="90" stroke="green" stroke-width="3"
fill="yellow" filter="url(#f4)" />
</svg>
代码解释：
- <feColorMatrix> 转换颜色，使偏移图片的颜色值接近空（0）
- 矩阵中三个'0.2'是获取了red、green、blue 通道
