SwiftUI缩放状态下ScrollView内图片无法平移，如何同时支持缩放和平移？

scaleEffect仅会修改视图的渲染效果，不会改变视图的实际布局尺寸，因此ScrollView的可滚动区域始终等于原图大小，放大后超出屏幕的部分不会被识别为可滚动内容，就无法平移。

缩放时同步更新图片的实际布局尺寸，让ScrollView的可滚动区域跟随缩放比例动态变化，ScrollView本身会自动适配内容尺寸实现平移，不需要额外添加拖动手势。

struct TestView: View {
    let image = UIImage(named: "test")!
    @State private var scale: CGFloat = 1.0
    @State private var lastScaleValue: CGFloat = 1.0
    // 缩放上下限可根据需求自行调整
    private let minScale: CGFloat = 1.0
    private let maxScale: CGFloat = 5.0

    var body: some View {
        GeometryReader { geo in
            // 按原图比例计算基础展示尺寸
            let baseWidth = geo.size.width
            let baseHeight = baseWidth * image.size.height / image.size.width
            ScrollView([.vertical, .horizontal], showsIndicators: false) {
                Image(uiImage: image)
                    .resizable()
                    .aspectRatio(contentMode: .fit)
                    // 直接用缩放比例修改图片实际布局尺寸
                    .frame(width: baseWidth * scale, height: baseHeight * scale)
                    .gesture(
                        MagnificationGesture()
                            .onChanged { val in
                                let delta = val / lastScaleValue
                                lastScaleValue = val
                                let newScale = scale * delta
                                // 限制缩放范围
                                scale = max(minScale, min(newScale, maxScale))
                            }
                            .onEnded { _ in
                                lastScaleValue = 1.0
                                // 可选：小于最小比例时自动回弹
                                if scale < minScale {
                                    withAnimation { scale = minScale }
                                }
                            }
                    )
            }
            .frame(width: geo.size.width, height: geo.size.height)
            .border(Color.red)
            .background(Color.systemBackground.edgesIgnoringSafeArea(.all))
        }
    }
}

内容的提问来源于stack exchange，提问作者zumzum