From c62f0f0f6d84dc5cea05b8397030fd3f7cebbdea Mon Sep 17 00:00:00 2001
From: Roopesh Chander <roop@roopc.net>
Date: Mon, 1 Apr 2019 22:36:16 +0530
Subject: [PATCH] macOS: Log view: Fix autoscroll to end of log

Looks like the tableview doesn't know how much to scroll to get to the
end when we use usesAutomaticRowHeights. So we wait for the tableview
to realize its frame has changed and then scroll to the bottom of the
frame explicitly.

Also, we keep track of whether the scroll view is scrolled to the end or
not every time scrolling happens, not just when we add log entries to
the table.
---
 .../ViewController/LogViewController.swift    | 25 +++++++++++++------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/WireGuard/WireGuard/UI/macOS/ViewController/LogViewController.swift b/WireGuard/WireGuard/UI/macOS/ViewController/LogViewController.swift
index ddc8c31..3f3a14b 100644
--- a/WireGuard/WireGuard/UI/macOS/ViewController/LogViewController.swift
+++ b/WireGuard/WireGuard/UI/macOS/ViewController/LogViewController.swift
@@ -76,6 +76,7 @@ class LogViewController: NSViewController {
     let logViewHelper: LogViewHelper?
     var logEntries = [LogViewHelper.LogEntry]()
     var isFetchingLogEntries = false
+    var isInScrolledToEndMode = true
 
     private var updateLogEntriesTimer: Timer?
 
@@ -103,6 +104,21 @@ class LogViewController: NSViewController {
         clipView.documentView = tableView
         scrollView.contentView = clipView
 
+        _ = NotificationCenter.default.addObserver(forName: NSView.boundsDidChangeNotification, object: clipView, queue: OperationQueue.main) { [weak self] _ in
+            guard let self = self else { return }
+            let lastVisibleRowIndex = self.tableView.row(at: NSPoint(x: 0, y: self.scrollView.contentView.documentVisibleRect.maxY - 1))
+            self.isInScrolledToEndMode = lastVisibleRowIndex < 0 || lastVisibleRowIndex == self.logEntries.count - 1
+        }
+
+        _ = NotificationCenter.default.addObserver(forName: NSView.frameDidChangeNotification, object: tableView, queue: OperationQueue.main) { [weak self] _ in
+            guard let self = self else { return }
+            if self.isInScrolledToEndMode {
+                DispatchQueue.main.async {
+                    self.tableView.scroll(NSPoint(x: 0, y: self.tableView.frame.maxY - clipView.documentVisibleRect.height))
+                }
+            }
+        }
+
         let margin: CGFloat = 20
         let internalSpacing: CGFloat = 10
 
@@ -155,14 +171,9 @@ class LogViewController: NSViewController {
                 self.saveButton.isEnabled = true
             }
             guard !fetchedLogEntries.isEmpty else { return }
-            let numOfEntries = self.logEntries.count
-            let lastVisibleRowIndex = self.tableView.row(at: NSPoint(x: 0, y: self.scrollView.contentView.documentVisibleRect.maxY - 1))
-            let isScrolledToEnd = lastVisibleRowIndex == numOfEntries - 1
+            let oldCount = self.logEntries.count
             self.logEntries.append(contentsOf: fetchedLogEntries)
-            self.tableView.insertRows(at: IndexSet(integersIn: numOfEntries ..< numOfEntries + fetchedLogEntries.count), withAnimation: .slideDown)
-            if isScrolledToEnd {
-                self.tableView.scrollRowToVisible(self.logEntries.count - 1)
-            }
+            self.tableView.insertRows(at: IndexSet(integersIn: oldCount ..< oldCount + fetchedLogEntries.count), withAnimation: .slideDown)
         }
     }