如何修改拖放预览SwiftUI的背景颜色和形状？

struct ContentView: View {
    @State private var isDragging = false
    
    var body: some View {
        VStack {
            // 拖放预览视图
            Rectangle()
                .fill(Color.blue)
                .frame(width: 100, height: 100)
                .opacity(isDragging ? 0.5 : 1.0)
                .onDrag {
                    self.isDragging = true
                    let itemProvider = NSItemProvider(object: "拖放数据" as NSString)
                    return itemProvider
                }
            
            // 其他内容
            Text("拖放目标区域")
                .font(.title)
                .padding()
                .background(Color.gray)
                .cornerRadius(10)
        }
    }
}