3b50f82094
Adds blurhash and image dimensions. This is an alternative and backwards compatible version of NIP94 for images in kind1 notes. Changelog-Added: Add image metadata to image uploads
46 lines
2.0 KiB
Markdown
46 lines
2.0 KiB
Markdown
# BlurHash for iOS, in Swift
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## Standalone decoder and encoder
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[BlurHashDecode.swift](BlurHashDecode.swift) and [BlurHashEncode.swift](BlurHashEncode.swift) contain a decoder
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and encoder for BlurHash to and from `UIImage`. Both files are completeiy standalone, and can simply be copied into your
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project directly.
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### Decoding
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[BlurHashDecode.swift](BlurHashDecode.swift) implements the following extension on `UIImage`:
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public convenience init?(blurHash: String, size: CGSize, punch: Float = 1)
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This creates a UIImage containing the placeholder image decoded from the BlurHash string, or returns nil if decoding failed.
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The parameters are:
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* `blurHash` - A string containing the BlurHash.
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* `size` - The requested output size. You should keep this small, and let UIKit scale it up for you. 32 pixels wide is plenty.
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* `punch` - Adjusts the contrast of the output image. Tweak it if you want a different look for your placeholders.
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### Encoding
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[BlurHashEncode.swift](BlurHashEncode.swift) implements the following extension on `UIImage`:
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public func blurHash(numberOfComponents components: (Int, Int)) -> String?
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This returns a string containing the BlurHash for the image, or nil if the image was in a weird format that is not supported.
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The parameters are:
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* `numberOfComponents` - a Tuple of integers specifying the number of components in the X and Y directions. Both must be
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between 1 and 9 inclusive, or the function will return nil. 3 to 5 is usually a good range.
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## BlurHashKit
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This is a more advanced library, currently in development. It will let you do more advanced operations using BlurHashes,
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such testing whether various parts of an image are dark and light, or generating BlurHashes as gradients from corner colours.
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It is currently not documented or finalised, but feel free to look into the different files and what they implement, or look at
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how it is used by the test app.
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## BlurHashTest.app
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This is a simple test app that shows how to use the various pieces of BlurHash functionality, and lets you play with the
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algorithm.
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