SwiftUI 复杂视图中的字体缩放

Question

My goal is to make sure Text in a container to scale according to its parent. It works well when the container only contains one Text view, as following:

import SwiftUI

struct FontScalingExperiment: View {
    var body: some View {
        Text("Hello World ~!")
            .font(.system(size: 500))
            .minimumScaleFactor(0.01)
            .lineLimit(1)
            .padding()
            .background(
                RoundedRectangle(cornerRadius: 20)
                    .fill(Color.yellow)
                    .scaledToFill()  
        )
    }
}

struct FontScalingExperiment_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            FontScalingExperiment()
                .previewLayout(.fixed(width: 100, height: 100))
            FontScalingExperiment()
                .previewLayout(.fixed(width: 200, height: 200))
            FontScalingExperiment()
                .previewLayout(.fixed(width: 300, height: 300))
            FontScalingExperiment()
                .previewLayout(.fixed(width: 400, height: 400))
        }

    }
}

the result:

However, when we have more complex View, we cant use same approach to automatically scale the text based on its parent size, for example:

import SwiftUI

struct IndicatorExperiment: View {
    var body: some View {
        VStack {
            HStack {
                Text("Line 1")
                Spacer()
            }
            Spacer()
            VStack {
                Text("Line 2")
                Text("Line 3")
            }
            Spacer()
            Text("Line 4")
        }
        .padding()
        .background(
            RoundedRectangle(cornerRadius: 20)
                .fill(Color.yellow)
        )
            .aspectRatio(1, contentMode: .fit)
    }
}

struct IndicatorExperiment_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            IndicatorExperiment()
                .previewLayout(.fixed(width: 100, height: 100))
            IndicatorExperiment()
                .previewLayout(.fixed(width: 200, height: 200))
            IndicatorExperiment()
                .previewLayout(.fixed(width: 300, height: 300))
            IndicatorExperiment()
                .previewLayout(.fixed(width: 400, height: 400))
        }
    }
}

Simply adding these 3 modifiers:

.font(.system(size: 500)) .minimumScaleFactor(0.01) .lineLimit(1)

wont produce result like the first example; Text enlarged beyond the frame. I did successfully, produce the result that I want by using GeometryReader then scale the font size based on geometry.size.width . Is this the only approach for achieving the desired result in SwiftUI?

Answer 1

Using GeometryReader and a .minimumScaleFactor modifier would probably the only way to scale text in a view. To have more control on sizing, one possible way is to provde the .frame size from the parent view.

Scalable Text View

    GeometryReader { geo in
        Text("Foo")
            .font(
                .system(size: min(geo.size.height, geo.size.width) * 0.95))
            .minimumScaleFactor(0.05)
            .lineLimit(1)
    }

Parent View that uses the Scalable Text View

    GeometryReader { geo in
        ScaleableText()
            .frame(width: geo.size.width, height: geo.size.height)
    }