Struct QLThumbnailGenerator

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pub struct QLThumbnailGenerator { /* private fields */ }

Available on crate feature QLThumbnailGenerator only.

Expand description

Apple’s documentation

Implementations§

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impl QLThumbnailGenerator

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pub unsafe fn sharedGenerator() -> Retained<QLThumbnailGenerator>

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pub unsafe fn generateBestRepresentationForRequest_completionHandler( &self, request: &QLThumbnailGenerationRequest, completion_handler: &DynBlock<dyn Fn(mut QLThumbnailRepresentation, mut NSError)>, )

Available on crate features QLThumbnailGenerationRequest and QLThumbnailRepresentation and block2 only.

Parameter completionHandler: Always called when the thumbnail generation is over. The thumbnail passed to this handler is the most representative version of the thumbnail that was successfully generated (if any). If set, the error contains information about the issue that occurred while trying to generate the thumbnail. QLThumbnail error codes can be found in <QuickLookThumbnailing /QLThumbnailErrors.h>.

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pub unsafe fn generateRepresentationsForRequest_updateHandler( &self, request: &QLThumbnailGenerationRequest, update_handler: Option<&DynBlock<dyn Fn(mut QLThumbnailRepresentation, QLThumbnailRepresentationType, mut NSError)>>, )

Available on crate features QLThumbnailGenerationRequest and QLThumbnailRepresentation and block2 only.

Parameter updateHandler: Called for the successive requested representations of a thumbnail. If a representation was not successfully generated, this may be called with a nil representation. If a requested more representative version was successfully generated before a less representative one, this handler will be called only for the more representative version, skipping the less representative one. This handler is guaranteed to be called at least once, for the requested most representative version, whether a representation could be successfully generated or not. If set, the error contains information about the issue that occurred while trying to generate the representation of the given type. QLThumbnail error codes can be found in <QuickLookThumbnailing /QLThumbnailErrors.h>.

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pub unsafe fn cancelRequest(&self, request: &QLThumbnailGenerationRequest)

Available on crate feature QLThumbnailGenerationRequest only.

Cancels the given QLThumbnailGenerationRequest.

Parameter request: The request that should be cancelled.

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pub unsafe fn saveBestRepresentationForRequest_toFileAtURL_asContentType_completionHandler( &self, request: &QLThumbnailGenerationRequest, file_url: &NSURL, content_type: &UTType, completion_handler: &DynBlock<dyn Fn(*mut NSError)>, )

Available on crate features QLThumbnailGenerationRequest and block2 and objc2-uniform-type-identifiers only.

Saves a thumbnail for the request on disk at fileURL. The file saved at fileURL has to be deleted when it is not used anymore. This is primarily intended for file provider extensions which need to upload thumbnails and have a small memory limit.

Parameter contentType: An image content type to save the thumbnail as, supported by CGImageDestination, such as UTTypePNG or UTTypeJPEG

Parameter completionHandler: Always called when the thumbnail generation is over. Will contain an error if the thumbnail could not be successfully saved to disk at fileURL.

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pub unsafe fn saveBestRepresentationForRequest_toFileAtURL_withContentType_completionHandler( &self, request: &QLThumbnailGenerationRequest, file_url: &NSURL, content_type: &NSString, completion_handler: &DynBlock<dyn Fn(*mut NSError)>, )

👎Deprecated

Available on crate features QLThumbnailGenerationRequest and block2 only.

Saves a thumbnail for the request on disk at fileURL. The file saved at fileURL has to be deleted when it is not used anymore. This is primarily intended for file provider extensions which need to upload thumbnails and have a small memory limit.

Parameter contentType: An image content type to save the thumbnail as, supported by CGImageDestination, such as kUTTypePNG or kUTTypeJPEG

Parameter completionHandler: Always called when the thumbnail generation is over. Will contain an error if the thumbnail could not be successfully saved to disk at fileURL.

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impl QLThumbnailGenerator

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.

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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`
    }
}