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Modify the Description Property List

For executable filters, only the version number, filter class, and filter name are read from the Description.plist file. You provide a list of attributes for the filter in your code (see “Write a Custom Attributes Method”). You need to check the Description.plist file provided in the image unit template to make sure the filter name is correct and to enter the version number.

For CPU–nonexecutable filters, the image unit host reads the Description.plist file to obtain information about the filter attributes listed inTable 4-1. You need to modify the Description.plist file so that it contains the appropriate information. (For information about filter keys, see also Core Image Reference Collection.)

Table 4-1  Keys in the filter description property list

Key

Associated values

CIPlugInFilterList

A dictionary of filter dictionaries. If this key is present, it indicates that there is at least one Core Image filter defined in the image unit.

CIFilterDisplayName

The localized filter name available in the Description.strings file.

CIFilterClass

The class name in the binary that contains the filter implementation, if available.

CIKernelFile

The filename of the filter kernel in the bundle, if available. Use this key to define a nonexecutable filter.

CIFilterAttributes

A dictionary of attributes that describe the filter. This is the same as the attributes dictionary that you provided when you wrote the filter.

CIInputs

An array of input keys and associated attributes. The input keys must be in the same order as the parameters of the kernel function. Each attribute must contain its parameter class (see Table 4-2) and name.

CIOutputs

Reserved for future use.

CIHasCustomInterface

None. Use this key to specify that the filter has a custom user interface. The host provides a view for the user interface.

CIPlugInVersion

The version of the CIPlugIn architecture, which is 1.0.

Table 4-2 lists the input parameter classes and the value associated with each class. For a nonexecutable filter, you provide the parameter class for each input and output parameter.

Table 4-2  Input parameter classes and expected values

Input parameter class

Associated value

CIColor

A string that specifies a color.

CIVector

A string that specifies a vector. See vectorWithString:.

CIImage

An NSString object that describes either the relative path of the image to the bundle or the absolute path of the image.

All scalar types

An NSNumber value.

Figure 4-4 shows the contents of a description.plist file for a color generator filter. You may want to use the Property List Editor to modify a description.plist file. The Property List Editor application is located in Developer/Applications/Utilities/.


Figure 4-4  A description property list for a sample filter

A description property list for a sample filter



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Last updated: 2008-06-09

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