使用 SwiftUI 构建高级图形效果

4:18 - Cover art image

Image("CoverArt")

4:24 - Blurred cover art image

Image("CoverArt")
    .blur(radius: 30)

7:09 - Applying layer effect in SwiftUI

GeometryReader { proxy in
    CoverArtView()
        .layerEffect(
            ShaderLibrary.backgroundWarp(),
            maxSampleOffset: .zero
        )
}
.ignoresSafeArea()

7:21 - Writing layer effect shader in Metal

[[stitchable]] half4 backgroundWarp(
    float2 position, SwiftUI::Layer layer
) {
    return layer.sample(position);
}

7:39 - Metal shader with offset parameter

[[stitchable]] half4 backgroundWarp(
    float2 position, SwiftUI::Layer layer,
    float2 offset
) {
    return layer.sample(position + offset);
}

7:55 - SwiftUI layer effect with offset parameter

GeometryReader { proxy in
    CoverArtView()
        .layerEffect(
            ShaderLibrary.backgroundWarp(
               .float2(.init(x: 0, y: 0))
            ),
            maxSampleOffset: .zero
        )
}
.ignoresSafeArea()

8:04 - SwiftUI layer effect with full-width offset

GeometryReader { proxy in
    CoverArtView()
        .layerEffect(
            ShaderLibrary.backgroundWarp(
               .float2(.init(x: proxy.size.width, y: 0))
            ),
            maxSampleOffset: .zero
        )
}
.ignoresSafeArea()

8:37 - SwiftUI layer effect with noise sampling

GeometryReader { proxy in
    CoverArtView()
        .layerEffect(
            ShaderLibrary.backgroundWarp(
                .float2(proxy.size),
                .image(Image("NoiseTexture"))
            ),
            maxSampleOffset: .zero
        )
}
.ignoresSafeArea()

8:55 - Metal shader with noise sampling

[[stitchable]] half4 backgroundWarp(
    float2 position, SwiftUI::Layer layer,
    float2 size, texture2d<half> noiseTex
) {
    constexpr sampler s(address::repeat, filter::linear);
    float2 uv = position / size;

    half4 n = noiseTex.sample(s, uv);
    float2 offset = (float2(n.r, n.g) - 0.5) * 200.0;

    return layer.sample(position + offset);
}

10:22 - Metal shader with domain warping

[[stitchable]] half4 backgroundWarp(
    float2 position, SwiftUI::Layer layer,
    float2 size, texture2d<half> noiseTex
) {
    constexpr sampler s(address::repeat, filter::linear);
    float2 uv = position / size;

    half4 n = noiseTex.sample(s, uv);

    float2 q = float2(n.r, n.g);
    n = noiseTex.sample(s, uv + q);

    float2 offset = (float2(n.r, n.g) - 0.5) * 200.0;

    return layer.sample(position + offset);
}

11:16 - SwiftUI layer effect with static visual

GeometryReader { proxy in
    CoverArtView()
        .layerEffect(
            ShaderLibrary.backgroundWarp(
                .float2(proxy.size),
                .image(Image("NoiseTexture"))
            ),
            maxSampleOffset: .zero
        )
}
.ignoresSafeArea()

11:37 - SwiftUI layer effect with animated visual

@State private var startDate = Date.now

TimelineView(.animation) { timeline in
    let elapsed = timeline.date.timeIntervalSince(
        startDate
    )
    CoverArtView()
        .layerEffect(
            ShaderLibrary.backgroundWarp(
                .float2(proxy.size),
                .image(Image("NoiseTexture")),
                .float(elapsed)
            ),
            maxSampleOffset: .zero
        )
}

12:15 - Basic transcript view

ScrollView {
    LazyVStack(alignment: .leading, spacing: 12) {
        ForEach(sampleTranscript) { line in
                .font(.title)
                .fontWeight(.bold)
        }
    }
}

12:33 - Time-synced transcript view

@State private var playback = PlaybackState()

ScrollViewReader { scrollProxy in
    ScrollView {
        LazyVStack(alignment: .leading, spacing: 12) {
            ForEach(sampleTranscript) { line in
                Text(line.text)
                    .transcriptLineStyle(isCurrent: 
                        line.id == playback.currentLineIndex
                    )
            }
        }
    }
    .onChange(of: playback.currentLineIndex, { _, i in
        scrollProxy.scrollTo(i, anchor: .center)
    })
}

13:53 - Overlay with center alignment

Text(line.text)
     .overlay {
          Text(line.formattedTimestamp)
     }

14:06 - Overlay with bottom leading alignment

Text(line.text)
     .overlay(alignment: .bottomLeading) {
          Text(line.formattedTimestamp)
     }

14:32 - Overlay with alignment guide override

Text(line.text)
     .overlay(alignment: .bottomLeading) {
          Text(line.formattedTimestamp)
              .alignmentGuide(.bottom) { $0[.top] }
     }