Here I have a MTKView and running a simple CIFilter live on camera feed. This works fine.
On older devices' selfie camera's, such as iPhone 5, iPad Air, the feed gets drawn on a smaller area. UPDATE: As I found out, those older devices' selfie cameras produce smaller CMSampleBuffer's. How would I scale the drawing accordingly?
import UIKit
import MetalPerformanceShaders
import MetalKit
import AVFoundation
final class MetalObject: NSObject, MTKViewDelegate {
private var metalBufferView : MTKView?
private var metalDevice = MTLCreateSystemDefaultDevice()
private var metalCommandQueue : MTLCommandQueue!
private var metalSourceTexture : MTLTexture?
private var context : CIContext?
private var filter : CIFilter?
init(with frame: CGRect, filterType: Int, scaledUp: Bool) {
super.init()
self.metalCommandQueue = self.metalDevice!.makeCommandQueue()
self.metalBufferView = MTKView(frame: frame, device: self.metalDevice)
self.metalBufferView!.framebufferOnly = false
self.metalBufferView!.isPaused = true
self.metalBufferView!.contentScaleFactor = UIScreen.main.nativeScale
self.metalBufferView!.delegate = self
self.context = CIContext()
}
final func update (sampleBuffer: CMSampleBuffer) {
var textureCache : CVMetalTextureCache?
CVMetalTextureCacheCreate(kCFAllocatorDefault, nil, self.metalDevice!, nil, &textureCache)
var cameraTexture: CVMetalTexture?
guard
let cameraTextureCache = textureCache,
let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
return
}
let cameraTextureWidth = CVPixelBufferGetWidthOfPlane(pixelBuffer, 0)
let cameraTextureHeight = CVPixelBufferGetHeightOfPlane(pixelBuffer, 0)
CVMetalTextureCacheCreateTextureFromImage(kCFAllocatorDefault,
cameraTextureCache,
pixelBuffer,
nil,
MTLPixelFormat.bgra8Unorm,
cameraTextureWidth,
cameraTextureHeight,
0,
&cameraTexture)
if let cameraTexture = cameraTexture,
let metalTexture = CVMetalTextureGetTexture(cameraTexture) {
self.metalSourceTexture = metalTexture
self.metalBufferView!.draw()
}
}
//MARK: - Metal View Delegate
final func draw(in view: MTKView) {
guard let currentDrawable = self.metalBufferView!.currentDrawable,
let sourceTexture = self.metalSourceTexture
else { return }
let commandBuffer = self.metalCommandQueue!.makeCommandBuffer()
var inputImage = CIImage(mtlTexture: sourceTexture)!.applyingOrientation(self.orientationNumber)
if self.showFilter {
self.filter!.setValue(inputImage, forKey: kCIInputImageKey)
inputImage = filter!.outputImage!
}
self.context!.render(inputImage, to: currentDrawable.texture, commandBuffer: commandBuffer, bounds: inputImage.extent, colorSpace: self.colorSpace!)
commandBuffer.present(currentDrawable)
commandBuffer.commit()
}
final func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {
}
}- Only happens on selfie cameras of older devices
- Selfie cameras on newer devices are fine when the issue occurs, new content gets drawn in a smaller area (gravitated towards top left), with old content from back camera is still remaining outside of new content.
- Constraints and the sizing/placement of Metal View is fine.
- self.metalBufferView!.contentScaleFactor = UIScreen.main.nativeScale solves the weird scaling issue on Plus devices.
