Retrieves a specified series of bytes from the specified descriptor.
SDK
- macOS 10.2+
Framework
- Core Services
Declaration
OSStatus AEGetDescDataRange(const AEDesc *dataDesc, void *buffer, Size offset, Size length);
Parameters
dataDescA pointer to the descriptor to get the data from. See
AEDesc.bufferA pointer to a buffer, local variable, or other storage location created and disposed of by your application. The size in bytes should be at least as large as the value you pass in the
lengthparameter. On return, contains the specified data from the descriptor.offsetThe zero-based offset to the data to be retrieved from the descriptor.
lengthThe number of bytes of contiguous data to retrieve.
Return Value
A result code. If the requested offset and length are such that they do not fit entirely within the descriptor’s data, AEGet returns err. See also Result Codes.
Discussion
This function is valid only for value type descriptors (such astype). You can use this function when you know the precise location of a subset of data within the descriptor. For example, if the descriptor contains a block of your private data, you might retrieve just a particular chunk you need at a known offset, representing an image, a string, or some other data type. Or if a descriptor contains an RGB color, you can access just the blue field.
When used in conjunction with AECreate, AEGet can provide greatly improved performance, especially when working with large blocks of data.