64 lines
2.1 KiB
Swift
64 lines
2.1 KiB
Swift
//
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// Copyright 2022 New Vector Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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import Foundation
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import SwiftUI
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extension View {
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/// Reads the frame of the view and store it in `frame` binding.
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/// - Parameters:
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/// - frame: a `CGRect` binding
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/// - coordinateSpace: the coordinate space of the frame.
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func readFrame(_ frame: Binding<CGRect>, in coordinateSpace: CoordinateSpace = .local) -> some View {
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background(ViewFrameReader(frame: frame, coordinateSpace: coordinateSpace))
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}
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}
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/// Used to calculate the frame of a view.
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///
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/// Useful in situations as with `ZStack` where you might want to layout views using alignment guides.
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/// ```
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/// @State private var frame: CGRect = CGRect.zero
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/// ...
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/// SomeView()
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/// .background(ViewFrameReader(frame: $frame))
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/// ```
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private struct ViewFrameReader: View {
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@Binding var frame: CGRect
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var coordinateSpace: CoordinateSpace = .local
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var body: some View {
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GeometryReader { geometry in
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Color.clear
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.preference(key: FramePreferenceKey.self,
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value: geometry.frame(in: coordinateSpace))
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}
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.onPreferenceChange(FramePreferenceKey.self) { newValue in
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guard frame != newValue else { return }
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frame = newValue
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}
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}
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}
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/// A SwiftUI `PreferenceKey` for `CGRect` values such as a view's frame.
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private struct FramePreferenceKey: PreferenceKey {
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static var defaultValue: CGRect = .zero
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static func reduce(value: inout CGRect, nextValue: () -> CGRect) {
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value = nextValue()
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}
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}
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