Using a more trick but smart solution for cases when WebImage is used during transition state, like scaleEffect. In this time, we does not trigger a actualy image loading, only query the memory cache for quickly placeholder

This commit is contained in:
DreamPiggy 2020-03-31 17:24:47 +08:00
parent 0b11cceaaa
commit d9fd4726ea
3 changed files with 30 additions and 11 deletions

View File

@ -38,7 +38,7 @@ struct DetailView: View {
let url: String
let animated: Bool
@State var isAnimating: Bool = true
@State var lastScaleValue: CGFloat = 1.0
@State var lastScale: CGFloat = 1.0
@State var scale: CGFloat = 1.0
@Environment(\.presentationMode) var presentationMode
@EnvironmentObject var settings: UserSettings
@ -75,12 +75,12 @@ struct DetailView: View {
return contentView()
.scaleEffect(self.scale)
.gesture(MagnificationGesture(minimumScaleDelta: 0.1).onChanged { value in
let delta = value / self.lastScaleValue
self.lastScaleValue = value
let delta = value / self.lastScale
self.lastScale = value
let newScale = self.scale * delta
self.scale = min(max(newScale, 0.5), 2)
}.onEnded { value in
self.lastScaleValue = 1.0
self.lastScale = 1.0
})
#endif
#if os(tvOS)

View File

@ -106,6 +106,23 @@ public final class ImageManager : ObservableObject {
}
}
/// Prefetch the initial state of image
internal func prefetch() {
let key = manager.cacheKey(for: url)
if let imageCache = manager.imageCache as? SDImageCache {
self.image = imageCache.imageFromMemoryCache(forKey: key)
} else {
// generic API
manager.imageCache.containsImage(forKey: key, cacheType: .memory) { [unowned self] (cacheType) in
if cacheType == .memory {
self.manager.imageCache.queryImage(forKey: key, options: self.options, context: self.context) { [unowned self] (image, data, cacheType) in
self.image = image
}
}
}
}
}
}
// Completion Handler

View File

@ -57,16 +57,13 @@ public struct WebImage : View {
}
}
self.imageManager = ImageManager(url: url, options: options, context: context)
// this prefetch the memory cache of image, to immediately render it on screen
// this solve the cause when `onAppear` not been called, for example, some transaction indetermite state :)
self.imageManager.prefetch()
}
public var body: some View {
// load remote image when first called `body`, SwiftUI sometimes will create a new View struct without calling `onAppear` (like enter EditMode) :)
// this can ensure we load the image, and display image synchronously when memory cache hit to avoid flashing
// called once per struct, SDWebImage take care of the duplicated query
if imageManager.isFirstLoad {
imageManager.load()
}
return Group {
Group {
if imageManager.image != nil {
if isAnimating && !self.imageManager.isIncremental {
if currentFrame != nil {
@ -109,6 +106,11 @@ public struct WebImage : View {
setupPlaceholder()
.frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity)
.onAppear {
// load remote image when first appear
if self.imageManager.isFirstLoad {
self.imageManager.load()
return
}
guard self.retryOnAppear else { return }
// When using prorgessive loading, the new partial image will cause onAppear. Filter this case
if self.imageManager.image == nil && !self.imageManager.isIncremental {