1

我想将我的画布保存到相册，但是当我返回相册时我的子视图不可见。我只有画布和我的画。

我应该改变什么？

  struct Home : View {
        @State var canvas = PKCanvasView()
        @State var showingAlert = false
        var body: some View{
            
            NavigationView{
                MyCanvas(canvasView: canvas)
                    .navigationBarTitleDisplayMode(.inline)
                    .navigationBarItems(
                        leading:
                            HStack{
                                Button(action: { SaveImage()  }, label: { Image(systemName: "square.and.arrow.down.fill").padding() })
                            })
            }
        }

我将图像保存到相册的功能：

        func SaveImage(){
            
            // getting image from canvas....
            
            let image = canvas.drawing.image(from: canvas.drawing.bounds, scale: 1)
            
            // saving to albums....
            
            UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)
            showingAlert = true
        }
    }

我的画布，我在其中添加背景图片：

    struct MyCanvas: UIViewRepresentable {
        var canvasView: PKCanvasView
        let picker = PKToolPicker.init()
        
        func makeUIView(context: Context) -> PKCanvasView {
            self.canvasView.tool = PKInkingTool(.pen, color: .black, width: 15)
            self.canvasView.isOpaque = false
            self.canvasView.backgroundColor = UIColor.clear
            self.canvasView.becomeFirstResponder()
    
           let imageView = UIImageView(image: UIImage(named: "badmintoncourt"))
            let subView = self.canvasView.subviews[0]
                subView.addSubview(imageView)
                subView.sendSubviewToBack(imageView)
            return canvasView
        }
        
        func updateUIView(_ uiView: PKCanvasView, context: Context) {
            picker.addObserver(canvasView)
            picker.setVisible(true, forFirstResponder: uiView)
            DispatchQueue.main.async {
                uiView.becomeFirstResponder()
            }
        }
    }
4

2 回答 2

0

这实际上并没有回答这个问题，但我这样保存我的绘图以处理暗模式：

let drawing = canvasView.drawing
let frameForImage = canvasView.bounds
let darkImage = thumbnail(drawing: drawing, thumbnailRect: frameForImage, traitCollection: UITraitCollection(userInterfaceStyle: .light))

带有缩略图功能：

func thumbnail(drawing: PKDrawing, thumbnailRect: CGRect, traitCollection: UITraitCollection) -> UIImage {
    var image = UIImage()
    traitCollection.performAsCurrent {
        image = drawing.image(from: thumbnailRect, scale: 1.0)
    }
    return image
}
于 2021-02-18T11:26:27.267 回答
0

您需要挂钩特定约束的出口（它可能是垂直/水平/高度），您需要将其设置为 0 并需要管理您的 UI。

隐藏：

self.viewYourConstraint.constant = 0
self.yourView.hidden = true
self.view.layoutIfNeeded()

以显示：

self.viewYourConstraint.constant = 100//your constant value
self.yourView.hidden = false
self.view.layoutIfNeeded()

注意：如果上述约束的更新会影响到其他约束，还必须调用以下语句：

 self.yourView.setNeedsUpdateConstraints()
于 2020-12-12T10:34:47.250 回答