fix: snap to replied-to UX lag issue

Mastodon/Scene/Compose/ComposeViewController.swift

@@ -860,20 +860,45 @@ extension ComposeViewController {
 
         let repliedToCellFrame = viewModel.repliedToCellFrame.value
         guard repliedToCellFrame != .zero else { return }
-        let throttle = viewModel.repliedToCellFrame.value.height - scrollView.adjustedContentInset.top
-        // print("\(throttle) - \(scrollView.contentOffset.y)")
+
+         // try to find some patterns:
+         // print("""
+         // repliedToCellFrame: \(viewModel.repliedToCellFrame.value.height)
+         // scrollView.contentOffset.y: \(scrollView.contentOffset.y)
+         // scrollView.contentSize.height: \(scrollView.contentSize.height)
+         // scrollView.frame: \(scrollView.frame)
+         // scrollView.adjustedContentInset.top: \(scrollView.adjustedContentInset.top)
+         // scrollView.adjustedContentInset.bottom: \(scrollView.adjustedContentInset.bottom)
+         // """)
 
         switch viewModel.collectionViewState.value {
         case .fold:
-            if scrollView.contentOffset.y < throttle {
+            os_log("%{public}s[%{public}ld], %{public}s: fold", ((#file as NSString).lastPathComponent), #line, #function)
+            guard velocity.y < 0 else { return }
+            let offsetY = scrollView.contentOffset.y + scrollView.adjustedContentInset.top
+            if offsetY < -44 {
+                tableView.contentInset.top = 0
+                targetContentOffset.pointee = CGPoint(x: 0, y: -scrollView.adjustedContentInset.top)
                 viewModel.collectionViewState.value = .expand
             }
-            os_log("%{public}s[%{public}ld], %{public}s: fold", ((#file as NSString).lastPathComponent), #line, #function)
 
         case .expand:
-            if scrollView.contentOffset.y > -44 {
+            os_log("%{public}s[%{public}ld], %{public}s: expand", ((#file as NSString).lastPathComponent), #line, #function)
+            guard velocity.y > 0 else { return }
+            // check if top across
+            let topOffset = (scrollView.contentOffset.y + scrollView.adjustedContentInset.top) - repliedToCellFrame.height
+
+            // check if bottom bounce
+            let bottomOffsetY = scrollView.contentOffset.y + (scrollView.frame.height - scrollView.adjustedContentInset.bottom)
+            let bottomOffset = bottomOffsetY - scrollView.contentSize.height
+
+            if topOffset > 44 {
+                // do not interrupt user scrolling
+                viewModel.collectionViewState.value = .fold
+            } else if bottomOffset > 44 {
+                tableView.contentInset.top = -repliedToCellFrame.height
+                targetContentOffset.pointee = CGPoint(x: 0, y: -repliedToCellFrame.height)
                 viewModel.collectionViewState.value = .fold
-                os_log("%{public}s[%{public}ld], %{public}s: expand", ((#file as NSString).lastPathComponent), #line, #function)
             }
         }
     }
@@ -910,7 +935,8 @@ extension ComposeViewController: UICollectionViewDelegate {
 extension ComposeViewController: UIAdaptivePresentationControllerDelegate {
     
     func adaptivePresentationStyle(for controller: UIPresentationController, traitCollection: UITraitCollection) -> UIModalPresentationStyle {
-        return traitCollection.userInterfaceIdiom == .pad ? .formSheet : .automatic
+        return .fullScreen
+        //return traitCollection.userInterfaceIdiom == .pad ? .formSheet : .automatic
     }
 
     func presentationControllerShouldDismiss(_ presentationController: UIPresentationController) -> Bool {

Mastodon/Scene/Compose/ComposeViewModel+Diffable.swift

@@ -253,6 +253,8 @@ extension ComposeViewModel: UITableViewDataSource {
                     cell.statusContentWarningEditorView.alpha = 0
                     UIView.animate(withDuration: 0.33, delay: 0, options: [.curveEaseOut]) {
                         cell.statusContentWarningEditorView.alpha = 1
+                        tableView.beginUpdates()
+                        tableView.endUpdates()
                     } completion: { _ in
                         // do nothing
                     }

Mastodon/Scene/Compose/ComposeViewModel.swift

@@ -29,7 +29,7 @@ final class ComposeViewModel: NSObject {
     let selectedStatusVisibility: CurrentValueSubject<ComposeToolbarView.VisibilitySelectionType, Never>
     let activeAuthentication: CurrentValueSubject<MastodonAuthentication?, Never>
     let activeAuthenticationBox: CurrentValueSubject<AuthenticationService.MastodonAuthenticationBox?, Never>
-    let traitCollectionDidChangePublisher = CurrentValueSubject<Void, Never>(Void())      // use CurrentValueSubject to make intial event emit
+    let traitCollectionDidChangePublisher = CurrentValueSubject<Void, Never>(Void())      // use CurrentValueSubject to make initial event emit
     let repliedToCellFrame = CurrentValueSubject<CGRect, Never>(.zero)
     let autoCompleteRetryLayoutTimes = CurrentValueSubject<Int, Never>(0)
     let autoCompleteInfo = CurrentValueSubject<ComposeViewController.AutoCompleteInfo?, Never>(nil)

Mastodon/Scene/Compose/View/StatusContentWarningEditorView.swift

@@ -57,29 +57,43 @@ extension StatusContentWarningEditorView {
             containerBackgroundView.trailingAnchor.constraint(equalTo: trailingAnchor, constant: 1024),
             containerBackgroundView.bottomAnchor.constraint(equalTo: bottomAnchor),
         ])
-        
-        iconImageView.translatesAutoresizingMaskIntoConstraints = false
-        addSubview(iconImageView)
+
+        let containerStackView = UIStackView()
+        containerStackView.axis = .horizontal
+        containerStackView.translatesAutoresizingMaskIntoConstraints = false
+        addSubview(containerStackView)
         NSLayoutConstraint.activate([
-            iconImageView.centerYAnchor.constraint(equalTo: centerYAnchor),
-            iconImageView.leadingAnchor.constraint(equalTo: layoutMarginsGuide.leadingAnchor),
-            iconImageView.widthAnchor.constraint(equalToConstant: StatusView.avatarImageSize.width).priority(.defaultHigh),    // center alignment to avatar
-        ])
-        iconImageView.setContentHuggingPriority(.required - 2, for: .horizontal)
-        
-        textView.translatesAutoresizingMaskIntoConstraints = false
-        addSubview(textView)
-        NSLayoutConstraint.activate([
-            textView.centerYAnchor.constraint(equalTo: centerYAnchor),
-            textView.topAnchor.constraint(greaterThanOrEqualTo: topAnchor, constant: 6).priority(.required - 1),
-            textView.leadingAnchor.constraint(equalTo: iconImageView.trailingAnchor, constant: StatusView.avatarToLabelSpacing - 4),    // align to name label. minus magic 4pt to remove addition inset
-            textView.trailingAnchor.constraint(equalTo: layoutMarginsGuide.trailingAnchor),
-            bottomAnchor.constraint(greaterThanOrEqualTo: textView.bottomAnchor, constant: 6).priority(.required - 1),
-            //textView.heightAnchor.constraint(greaterThanOrEqualToConstant: 44).priority(.defaultHigh),
+            containerStackView.topAnchor.constraint(equalTo: topAnchor, constant: 6),
+            containerStackView.leadingAnchor.constraint(equalTo: layoutMarginsGuide.leadingAnchor),
+            containerStackView.trailingAnchor.constraint(equalTo: layoutMarginsGuide.trailingAnchor),
+            bottomAnchor.constraint(equalTo: containerStackView.bottomAnchor, constant: 6),
         ])
 
-        textView.setContentHuggingPriority(.required - 1, for: .vertical)
-        textView.setContentCompressionResistancePriority(.required - 1, for: .vertical)
+        containerStackView.addArrangedSubview(iconImageView)
+        iconImageView.setContentHuggingPriority(.required - 1, for: .horizontal)
+        containerStackView.addArrangedSubview(textView)
+        
+//        iconImageView.translatesAutoresizingMaskIntoConstraints = false
+//        addSubview(iconImageView)
+//        NSLayoutConstraint.activate([
+//            iconImageView.leadingAnchor.constraint(equalTo: layoutMarginsGuide.leadingAnchor),
+//            iconImageView.widthAnchor.constraint(equalToConstant: StatusView.avatarImageSize.width).priority(.defaultHigh),    // center alignment to avatar
+//        ])
+//        iconImageView.setContentHuggingPriority(.required - 2, for: .horizontal)
+//
+//        textView.translatesAutoresizingMaskIntoConstraints = false
+//        addSubview(textView)
+//        NSLayoutConstraint.activate([
+//            textView.centerYAnchor.constraint(equalTo: centerYAnchor),
+//            textView.topAnchor.constraint(equalTo: topAnchor, constant: 6),
+//            textView.leadingAnchor.constraint(equalTo: iconImageView.trailingAnchor, constant: StatusView.avatarToLabelSpacing - 4),    // align to name label. minus magic 4pt to remove addition inset
+//            textView.trailingAnchor.constraint(equalTo: layoutMarginsGuide.trailingAnchor),
+//            bottomAnchor.constraint(equalTo: textView.bottomAnchor, constant: 6),
+//            textView.heightAnchor.constraint(greaterThanOrEqualToConstant: 44).priority(.defaultHigh),
+//        ])
+//
+//        textView.setContentHuggingPriority(.required - 1, for: .vertical)
+//        textView.setContentCompressionResistancePriority(.required - 1, for: .vertical)
     }
 }