Layer Filters - Core Animation - page 95

LISTING 6-10

Continued

return [ NSArray arrayWithObjects :
blurFilter,
hueFilter,
colorFilter,
nil ];

}

This code creates three filters: blurFilter , hueFilter , and colorFilter . The latter,
colorFilter , enables us to alter three different values: saturation, contrast, and bright-
ness. Each filter has a set of default values that we can take advantage of by calling
-setDefaults . Notice also that we have given each filter a name; these names are used to
access filter values with bindings and KVC.

With the filters added to the layer, we can access each filter's parameters using a key-path.
The full key-paths for each slider are shown in Table 6-1.

TABLE 6-1

Filter Key-Paths
Filter

Filter Name Parameter Name Key-Path

blur inputRadius imageLayer.filters.blur.inputRadius

hue inputAngle imageLayer.filters.hue.inputAngle

color inputSaturation imageLayer.filters.color.inputSaturation

color inputContrast imageLayer.filters.color.inputContrast

color inputBrightness imageLayer.filters.color.inputBrightnes

If you look at the bindings menu in the slider inspector in Interface Builder, you can see
how these key-paths are applied. Figure 6-6 shows the key path for the hue filter.

FIGURE 6-6 Bindings for the Hue Filter Slider