disabling digital crown scrolling in ScrollView when using .digitalCrownRotation() modifier - swiftui

Question

I'm working on a SwiftUI modifier (ZoomableModifier) that will be predominantly used for making images zoomable. I want this to work on both iOS and watchOS, but particularly on watchOS. I want it to be possible to use the digital crown to zoom in and out, and to achieve this I'm using the .digitalCrownRotation() modifier to read the rotation of the digital crown and use that to determine the scale factor.
Here's the code for the modifier:
//
// ZoomableModifier.swift
//
// Created by jasu on 2022/01/26.
// Modified by Toni Sucic on 2023/01/08.
// Copyright (c) 2022 jasu All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is furnished
// to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
// CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
// OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
import SwiftUI
public struct ZoomableModifier: ViewModifier {
private enum ZoomState {
case inactive
case active(scale: CGFloat)
var scale: CGFloat {
switch self {
case .active(let scale):
return scale
default:
return 1.0
}
}
}
/// The content size of the views.
let contentSize: CGSize
/// The minimum value that can be zoom out.
let min: CGFloat
/// The maximum value that can be zoom in.
let max: CGFloat
/// A value that indicates whether the scroll view displays the scrollable component of the content offset, in a way that’s suitable for the platform.
let showsIndicators: Bool
#if os(iOS)
#GestureState private var zoomState = ZoomState.inactive
#endif
#State private var currentScale: CGFloat = 1.0
var scale: CGFloat {
#if os(iOS)
currentScale * zoomState.scale
#elseif os(watchOS)
currentScale
#endif
}
#if os(iOS)
var zoomGesture: some Gesture {
MagnificationGesture()
.updating($zoomState) { value, state, transaction in
state = .active(scale: value)
}
.onEnded { value in
var new = currentScale * value
if new <= min { new = min }
if new >= max { new = max }
currentScale = new
}
}
#endif
var doubleTapGesture: some Gesture {
TapGesture(count: 2).onEnded {
if scale <= min { currentScale = max } else
if scale >= max { currentScale = min } else {
currentScale = ((max - min) * 0.5 + min) < scale ? max : min
}
}
}
public func body(content: Content) -> some View {
ScrollView([.vertical, .horizontal], showsIndicators: showsIndicators) {
content
.frame(width: contentSize.width * scale, height: contentSize.height * scale, alignment: .center)
.scaleEffect(scale, anchor: .center)
#if os(watchOS)
.focusable(true)
.digitalCrownRotation(detent: $currentScale,
from: min,
through: max,
by: 0.1,
sensitivity: .low,
isContinuous: false,
isHapticFeedbackEnabled: true)
#endif
}
#if os(iOS)
.gesture(ExclusiveGesture(zoomGesture, doubleTapGesture))
#elseif os(watchOS)
.gesture(doubleTapGesture)
#endif
.animation(.easeInOut, value: scale)
}
}
extension View {
func zoomable(contentSize: CGSize,
min: CGFloat = 1.0,
max: CGFloat = 3.0,
showsIndicators: Bool = false) -> some View {
modifier(ZoomableModifier(contentSize: contentSize, min: min, max: max, showsIndicators: showsIndicators))
}
}
I'm using the modifier in this view:
struct FullscreenImage: View {
let imageURL: URL
#Environment(\.dismiss) var dismiss
var body: some View {
GeometryReader { proxy in
AsyncImage(url: imageURL) { imagePhase in
Group {
switch imagePhase {
case .success(let image):
image
.resizable()
.aspectRatio(contentMode: .fit)
.frame(width: proxy.size.width, height: proxy.size.height)
.zoomable(contentSize: proxy.size)
case .failure(let error):
Text(error.localizedDescription)
.font(.caption)
.padding()
default:
Rectangle()
.fill(Color.white.opacity(0.2))
}
}
.animation(.easeInOut, value: imagePhase)
}
}
}
}
I would expect there to be a way to disable digital crown scrolling for the scroll view when using the .digitalCrownRotation() modifier, but I haven't found one. Thus, when I rotate the digital crown, it tries to scroll the scroll view instead of changing the scale factor to get the zoom effect I'm looking for.