hezhk3

use this https://github.com/chenkaijie4ever/Single-hand-Sticker

I used OpenCV. cv::findContours() cv::boundingRect()

I put ACEDrawingView inside a UIScrollView and set scrollView.panGestureRecognizer.minimumNumberOfTouches = 2, it is able to zoom, but still draw a little before it zooms.

Use AVVideoCompositionCoreAnimationTool to export CAKeyFrameAnimation with keypath contents. https://www.raywenderlich.com/2734-avfoundation-tutorial-adding-overlays-and-animations-to-videos

GPUImageUIElement renders the CALayer into a bitmap context. `[layer renderInContext:imageContext];` But GPUImageView's layer is a CAEAGLLayer, which won't render it's content to the context.

https://github.com/HarrisonJackson/HJImagesToVideo

see https://github.com/felixturner/bad-tv-shader

But why you can't add NSCameraUsageDescription? The access request alert view won't show up until you use the camera.

That's because GPUImageUIElement is using layer.contentsScale to calculate the size in pixels. ``` - (CGSize)layerSizeInPixels; { CGSize pointSize = layer.bounds.size; return CGSizeMake(layer.contentsScale * pointSize.width, layer.contentsScale * pointSize.height); } ``` so...

maybe you should set completion block before you start processing?