<filter>

The <filter> tag is used in an SVG document to apply graphical effects, such as blurs, drop shadows, or color blending, to SVG elements (not with the <svg> tag).

It serves as a container for various filter effects, allowing you to apply complex visual effects to your SVG elements.

Structure and syntax of the <filter> tag

Structure

Here is a basic example of syntax:

<svg width="200" height="200" xmlns="http://www.w3.org/2000/svg">
    <defs>
        <filter id="blurFilter">
            <feGaussianBlur in="SourceGraphic" stdDeviation="5" />
        </filter>
   </defs>

    <circle cx="100" cy="100" r="50" fill="blue" filter="url(#blurFilter)" />
</svg>

In this example:

• A filter (<filter>) is defined within <defs> with an id (#blurFilter);
• The filter is then applied to the circle using filter="url(#blurFilter)".

Here is the result of this example:

Example

Here is an example using multiple filters to create a drop shadow effect:

<svg width="300" height="200" xmlns="http://www.w3.org/2000/svg">
    <defs>
        <filter id="dropShadow">
            <feOffset dx="5" dy="5" result="offset" />
            <feGaussianBlur in="offset" stdDeviation="3" result="blur" />
            <feBlend in="SourceGraphic" in2="blur" mode="normal" />
        </filter>
    </defs>

    <text x="50" y="100" font-size="40" fill="black" filter="url(#dropShadow)">
        Shadowed Text
    </text>
</svg>

In this example:

• <feOffset> offsets the text to create the shadow effect.
• <feGaussianBlur> blurs the shadow.
• <feBlend> combines the original text with the blurred shadow.

Here is the result:

Attributes of the <filter> tag

The <filter> tag accepts several attributes to customize its behavior:

Best practices

Here are some tips for effectively using <filter>:

• Always place your filters in a <defs> container to centralize their definition (your code will be simpler).
• Use clear and meaningful ids for the filters defined.
• Combine <filter> with CSS attributes or transformations to efficiently reuse graphical resources.

Browser compatibility

The <filter> tag is supported by all modern browsers: