feDisplacementMap 滤镜元素#

feDisplacementMap Filter Element

参见

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

该滤镜原语使用来自 in2 图像的像素值来空间地位移 in 图像。

此滤镜可能对输入图像产生任意的非本地化效果，这可能需要在处理管道中进行大量缓冲。然而，通过这种方式，任何中间缓冲需求都可以通过 scale 来确定， scale 代表了 x 或 y 方向的最大位移范围。

在应用此滤镜时，源像素位置通常会位于几个源像素之间。在这种情况下，建议高质量的查看器对周围像素应用插值，例如双线性或三次插值，而不仅仅是选择最近的源像素。根据可用插值器的速度，这一选择可能会受到 image-rendering 属性设置的影响。

color-interpolation-filters 属性仅适用于 in2 源图像，而不适用于 in 源图像。in 源图像必须保持其当前的颜色空间。

有关常见属性，请参见：滤镜原语概述

This filter primitive uses the pixels values from the image from in2 to spatially displace the image from in.

This filter can have arbitrary non-localized effect on the input which might require substantial buffering in the processing pipeline. However with this formulation, any intermediate buffering needs can be determined by scale which represents the maximum range of displacement in either x or y.

When applying this filter, the source pixel location will often lie between several source pixels. In this case it is recommended that high quality viewers apply an interpolent on the surrounding pixels, for example bilinear or bicubic, rather than simply selecting the nearest source pixel. Depending on the speed of the available interpolents, this choice may be affected by the image-rendering property setting.

The color-interpolation-filters property only applies to the in2 source image and does not apply to the in source image. The ‘in’ source image must remain in its current color space.

For common properties see: 滤镜原语概述

SVG Attributes#

  • in – (见 in 属性)

  • in2 – (见 in 属性)

    第二个输入图像，用于在 in 图像中位移像素。此属性可以具有与 in 属性相同的值。

  • scale – <number>

    位移缩放因子。该值以 filter 元素上的 primitiveUnits 属性所定义的坐标系统来表示。

    当此属性的值为 '0' 时，此操作对源图像没有任何影响。

    如果未指定此属性，则效果等同于指定值为 '0'。

  • xChannelSelector – 'R | G | B | A'

    指定使用 in2 中的哪个通道来沿 x 轴位移 in 图像的像素。如果未指定 xChannelSelector 属性，则效果等同于指定值为 'A'。

  • yChannelSelector – 'R | G | B | A'

    指定使用 in2 中的哪个通道来沿 y 轴位移 in 图像的像素。如果未指定 yChannelSelector 属性，则效果等同于指定值为 'A'。

  • in – (see in attribute)

  • in2 – (see in attribute)

    The second input image, which is used to displace the pixels in the image from attribute in. This attribute can take on the same values as the in attribute.

  • scale – <number>

    Displacement scale factor. The amount is expressed in the coordinate system established by attribute primitiveUnits on the filter element.

    When the value of this attribute is '0', this operation has no effect on the source image.

    If the attribute is not specified, then the effect is as if a value of '0' were specified.

  • xChannelSelector – 'R | G | B | A'

    Indicates which channel from in2 to use to displace the pixels in in along the x-axis. If attribute xChannelSelector is not specified, then the effect is as if a value of 'A' were specified.

  • yChannelSelector – 'R | G | B | A'

    Indicates which channel from in2 to use to displace the pixels in in along the y-axis. If attribute yChannelSelector is not specified, then the effect is as if a value of 'A' were specified.