feComposite 滤镜元素#

feComposite Filter Element

参见

http://www.w3.org/TR/SVG11/filters.html#feCompositeElement

此滤镜执行两个输入图像在图像空间中的像素级组合，使用 Porter-Duff 合成操作之一： over、 in、 atop、 out、 xor。此外，还可以应用分量级的算术操作（结果被限制在 [0..1] 之间）。

算术操作对于将 feDiffuseLighting 和 feSpecularLighting 滤镜的输出与纹理数据结合非常有用。它还可以用于实现溶解效果。如果选择算术操作，则每个结果像素使用以下公式计算：

result = k1 * i1 * i2 + k2 * i1 + k3 * i2 + k4

对于此滤镜原语，结果图像的范围可能会扩展，如描述滤镜原语子区域的部分所述。

有关常见属性，请参见： 滤镜原语概述

This filter performs the combination of the two input images pixel-wise in image space using one of the Porter-Duff compositing operations: over, in, atop, out, xor. Additionally, a component-wise arithmetic operation (with the result clamped between [0..1]) can be applied.

The arithmetic operation is useful for combining the output from the feDiffuseLighting and feSpecularLighting filters with texture data. It is also useful for implementing dissolve. If the arithmetic operation is chosen, each result pixel is computed using the following formula:

result = k1*i1*i2 + k2*i1 + k3*i2 + k4

For this filter primitive, the extent of the resulting image might grow as described in the section that describes the filter primitive subregion.

For common properties see: 滤镜原语概述

SVG Attributes#

  • in – (请参阅 in 属性)

  • operator – 'over | in | out | atop | xor | arithmetic'

    要执行的合成操作。除算术运算符外，所有 operator 类型都对应 [PORTERDUFF] 中描述的操作。算术运算符如上所述。如果未指定 operator 属性，则效果相当于指定了值 'over'。

  • k1, k2, k3, k4 – <number>

    仅在 operator = 'arithmetic' 时适用。如果未指定此属性，则效果相当于指定了值 0。

  • in2 – (请参阅 in 属性)

    用于合成操作的第二个输入图像。此属性可以采用与 in 属性相同的值。

  • in – (see in attribute)

  • operator – 'over | in | out | atop | xor | arithmetic

    The compositing operation that is to be performed. All of the operator types except arithmetic match the correspond operation as described in [PORTERDUFF]. The arithmetic operator is described above. If attribute operator is not specified, then the effect is as if a value of 'over' were specified.

  • k1, k2, k3, k4 – <number>

    Only applicable if operator = 'arithmetic'. If the attribute is not specified, the effect is as if a value of 0 were specified.

  • in2 – (see in attribute)

    The second input image to the compositing operation. This attribute can take on the same values as the in attribute.