87 lines
3.4 KiB
Swift
87 lines
3.4 KiB
Swift
//
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// Copyright 2023 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 SwiftUI
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/// A view modifier that applies a shimmering effect to the view.
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struct ShimmerModifier: ViewModifier {
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/// A boolean which is toggled to trigger the animation.
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@State private var animationTrigger = false
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/// The start and end points of a gradient.
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private struct GradientPoints {
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/// The start point of the gradient.
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let start: UnitPoint
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/// The end point of the gradient.
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let end: UnitPoint
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}
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/// The initial points used by the gradient before animation occurs.
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private let initialPoints = GradientPoints(start: UnitPoint(x: -5, y: 0), end: UnitPoint(x: 0, y: 0))
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/// The final points used by the gradient once the animation has completed.
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private let finalPoints = GradientPoints(start: UnitPoint(x: 1, y: 0), end: UnitPoint(x: 5, y: 0))
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/// The colour that causes a highlight to be shown.
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private let highlightColor = Color.white.opacity(0.5)
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/// The colour that causes the view to remain unchanged.
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private let regularColor = Color.white
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func body(content: Content) -> some View {
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content
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.mask { gradient }
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.task {
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withAnimation(.linear(duration: 1.75).delay(0.5).repeatForever(autoreverses: false)) {
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animationTrigger.toggle()
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}
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}
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}
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/// The gradient used to create the shimmer.
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var gradient: LinearGradient {
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LinearGradient(stops: [.init(color: regularColor, location: 0),
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.init(color: regularColor, location: 0.3),
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.init(color: highlightColor, location: 0.45),
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.init(color: highlightColor, location: 0.55),
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.init(color: regularColor, location: 0.7),
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.init(color: regularColor, location: 1)],
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startPoint: animationTrigger ? finalPoints.start : initialPoints.start,
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endPoint: animationTrigger ? finalPoints.end : initialPoints.end)
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}
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}
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extension View {
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/// Applies a shimmering effect to the view.
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func shimmer() -> some View {
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modifier(ShimmerModifier())
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}
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}
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struct ShimmerOverlay_Previews: PreviewProvider {
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static let viewModel = HomeScreenViewModel(userSession: MockUserSession(clientProxy: MockClientProxy(userID: ""),
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mediaProvider: MockMediaProvider()),
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attributedStringBuilder: AttributedStringBuilder())
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static var previews: some View {
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VStack {
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ForEach(0...8, id: \.self) { _ in
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HomeScreenRoomCell(room: .placeholder(), context: viewModel.context)
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}
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}
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.redacted(reason: .placeholder)
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.shimmer()
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}
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}
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