Created
February 9, 2017 00:34
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Resizing CGImage in Swift 3
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| func resize(_ image: CGImage) -> CGImage? { | |
| var ratio: Float = 0.0 | |
| let imageWidth = Float(image.width) | |
| let imageHeight = Float(image.height) | |
| let maxWidth: Float = 1024.0 | |
| let maxHeight: Float = 768.0 | |
| // Get ratio (landscape or portrait) | |
| if (imageWidth > imageHeight) { | |
| ratio = maxWidth / imageWidth | |
| } else { | |
| ratio = maxHeight / imageHeight | |
| } | |
| // Calculate new size based on the ratio | |
| if ratio > 1 { | |
| ratio = 1 | |
| } | |
| let width = imageWidth * ratio | |
| let height = imageHeight * ratio | |
| guard let colorSpace = image.colorSpace else { return nil } | |
| guard let context = CGContext(data: nil, width: Int(width), height: Int(height), bitsPerComponent: image.bitsPerComponent, bytesPerRow: image.bytesPerRow, space: colorSpace, bitmapInfo: image.alphaInfo.rawValue) else { return nil } | |
| // draw image to context (resizing it) | |
| context.interpolationQuality = .high | |
| context.draw(image, in: CGRect(x: 0, y: 0, width: Int(width), height: Int(height))) | |
| // extract resulting image from context | |
| return context.makeImage() | |
| } |
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| let ciImage = CIImage(cgImage: image) | |
| let filter = CIFilter(name: "CILanczosScaleTransform")! | |
| filter.setValue(ciImage, forKey: "inputImage") | |
| filter.setValue(ratio, forKey: "inputScale") | |
| filter.setValue(1.0, forKey: "inputAspectRatio") | |
| let outputImage = filter.value(forKey: "outputImage") as! CIImage | |
| let context = CIContext(options: [kCIContextUseSoftwareRenderer: false]) | |
| return context.createCGImage(outputImage, from: outputImage.extent) |
Same issue here
Why are you passing alphaInfo as bitmapInfo?
if ratio > 1 {
ratio = 1
}
what if ratio needed to be > 1?
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Just had a look at your resize function, but for me the CGContext (line 24) is always nil?!? Any ideas? I am running it on macOS