Struct CIPDF417CodeDescriptor

Source

#[repr(C)]
pub struct CIPDF417CodeDescriptor { /* private fields */ }

Available on crate feature CIBarcodeDescriptor only.

Expand description

CIPDF417CodeDescriptor is a concrete subclass of CIBarcodeDescriptor that defines an abstract representation of a PDF417 code symbol.

Refer to the ISO/IEC 15438:2006(E) for the PDF417 symbol specification.

Implementations§

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impl CIPDF417CodeDescriptor

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pub unsafe fn errorCorrectedPayload(&self) -> Retained<NSData>

The error-corrected codewords which comprise the PDF417 symbol. The first codeword indicates the number of data codewords in the errorCorrectedPayload.

PDF417 codes are comprised of a start character on the left and a stop character on the right. Each row begins and ends with special characters indicating the current row as well as information about the dimensions of the PDF417 symbol. The errorCorrectedPayload represents the sequence of PDF417 codewords that make up the body of the message. The first codeword indicates the number of codewords in the message. This count includes the “count” codeword and any padding codewords, but does not include the error correction codewords. Each codeword is a 16-bit value in the range of 0…928. The sequence is to be interpreted as described in the PDF417 bar code symbology specification – ISO/IEC 15438:2006(E).

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pub unsafe fn isCompact(&self) -> bool

A BOOL indicating whether the symbol is compact.

Compact PDF417 symbols have abbreviated right-side guard bars.

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pub unsafe fn rowCount(&self) -> NSInteger

Indicates the number of rows in the rectangular matrix.

rowCount values range from 3 to 90.

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pub unsafe fn columnCount(&self) -> NSInteger

Indicates the number of columns in the rectangular matrix, excluding the columns used to indicate the symbol structure.

columnCount values range from 1 to 30.

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pub unsafe fn initWithPayload_isCompact_rowCount_columnCount( this: Allocated<Self>, error_corrected_payload: &NSData, is_compact: bool, row_count: NSInteger, column_count: NSInteger, ) -> Option<Retained<Self>>

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pub unsafe fn descriptorWithPayload_isCompact_rowCount_columnCount( error_corrected_payload: &NSData, is_compact: bool, row_count: NSInteger, column_count: NSInteger, ) -> Option<Retained<Self>>

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impl CIPDF417CodeDescriptor

Methods declared on superclass NSObject.

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pub unsafe fn init(this: Allocated<Self>) -> Retained<Self>

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pub unsafe fn new() -> Retained<Self>

Methods from Deref<Target = NSObject>§

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pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

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pub fn class(&self) -> &'static AnyClass

Dynamically find the class of this object.

§Panics

May panic if the object is invalid (which may be the case for objects returned from unavailable init/new methods).

§Example

Check that an instance of NSObject has the precise class NSObject.

use objc2::ClassType;
use objc2::runtime::NSObject;

let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());

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pub unsafe fn get_ivar<T>(&self, name: &str) -> &T
where T: Encode,

👎Deprecated: this is difficult to use correctly, use Ivar::load instead.

Use Ivar::load instead.

§Safety

The object must have an instance variable with the given name, and it must be of type T.

See Ivar::load_ptr for details surrounding this.

Source

pub fn downcast_ref<T>(&self) -> Option<&T>
where T: DowncastTarget,

Attempt to downcast the object to a class of type T.

This is the reference-variant. Use Retained::downcast if you want to convert a retained object to another type.

§Mutable classes

Some classes have immutable and mutable variants, such as NSString and NSMutableString.

When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.

So using this method to convert a NSString to a NSMutableString, while not unsound, is generally frowned upon unless you created the string yourself, or the API explicitly documents the string to be mutable.

See Apple’s documentation on mutability and on isKindOfClass: for more details.

§Generic classes

Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.

You can, however, safely downcast to generic collections where all the type-parameters are AnyObject.

§Panics

This works internally by calling isKindOfClass:. That means that the object must have the instance method of that name, and an exception will be thrown (if CoreFoundation is linked) or the process will abort if that is not the case. In the vast majority of cases, you don’t need to worry about this, since both root objects NSObject and NSProxy implement this method.

§Examples

Cast an NSString back and forth from NSObject.

use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};

let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();

Try (and fail) to cast an NSObject to an NSString.

use objc2_foundation::{NSObject, NSString};

let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());

Try to cast to an array of strings.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();

This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.

Downcast when processing each element instead.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);

for elem in arr {
    if let Some(data) = elem.downcast_ref::<NSString>() {
        // handle `data`
    }
}