REOPEN-F7: a hidden sidebar icon button makes its image when it first shows

Packages/macOS/CmuxNext/Sources/CmuxNextSidebar/Views/SidebarIconButton.swift

@@ -60,7 +60,7 @@ final class SidebarIconButton: ClickableButton {
         self.label = label
         self.pointSize = pointSize
         super.init(frame: .zero)
-        renderIcon()
+        // The image comes when the button first shows (``renderIcon()``): a row's hover controls stay hidden.
         imagePosition = .imageOnly
         // An image-only button: no "Button" title for VoiceOver and hint mode (they read the label).
         title = ""
@@ -79,8 +79,6 @@ final class SidebarIconButton: ClickableButton {
     convenience init(symbol: String, pointSize: @escaping () -> CGFloat = { Metrics.smallIconSize }, label: String) {
         self.init(icon: IconName(symbol), pointSize: pointSize, label: label)
         self.symbol = symbol
-        renderedSize = 0
-        renderIcon()
     }
 
     @available(*, unavailable)
@@ -132,7 +130,11 @@ final class SidebarIconButton: ClickableButton {
         onMenuOpenChange?(false)
     }
 
+    /// Makes the icon image for the current point size, once the button shows: a hidden button, or one in a
+    /// hidden row, has none yet (REOPEN-F7: each workspace row's 5 hover-only buttons made theirs before the
+    /// window's first frame, about 4 ms of it). Showing, joining a window, a layout and a size read make it.
     private func renderIcon() {
+        guard !isHiddenOrHasHiddenAncestor else { return }
         let size = pointSize()
         guard size != renderedSize else { return }
         renderedSize = size
@@ -147,6 +149,13 @@ final class SidebarIconButton: ClickableButton {
         renderIcon()
     }
 
+    /// Sized by its icon, as an image-only button is. `renderedSize` (0: no icon yet), not `image`: AppKit answers a
+    /// button with no image of its own with a shared 1 x 1 placeholder, so `image` is never nil here.
+    override var intrinsicContentSize: NSSize {
+        if renderedSize == 0 { renderIcon() }
+        return super.intrinsicContentSize
+    }
+
     nonisolated override var wantsUpdateLayer: Bool { true }
 
     override var acceptsFirstResponder: Bool {
@@ -169,6 +178,7 @@ final class SidebarIconButton: ClickableButton {
 
     override func viewDidMoveToWindow() {
         super.viewDidMoveToWindow()
+        if window != nil { renderIcon() }
         if takesKeyFocus { keyRepaint.track() }
     }
 
@@ -212,6 +222,7 @@ final class SidebarIconButton: ClickableButton {
 
     override func viewDidUnhide() {
         super.viewDidUnhide()
+        renderIcon()
         hover.pointer?.refresh()
     }
 }

Packages/macOS/CmuxNext/Sources/CmuxNextSidebar/Views/WorkspaceRowView.swift

@@ -167,6 +167,7 @@ final class WorkspaceRowView: SidebarRowView {
         layer?.addSublayer(progressTrack)
         closeButton.isHidden = true
         audioButton.isHidden = true
+        pinButton.isHidden = true // hover only (layoutPin shows it), so it makes no image before then
         placeholderBar.wantsLayer = true
         placeholderBar.layer?.cornerRadius = Metrics.chipCornerRadius(height: SidebarStyle.placeholderBarHeight)
         placeholderBar.isHidden = true

Packages/macOS/CmuxNext/Tests/CmuxNextAppTests/SidebarIconButtonLazyImageTests.swift

@@ -0,0 +1,84 @@
+import AppKit
+import CmuxNextIcons
+@testable import CmuxNextSidebar
+import Testing
+import CmuxNextTestSupport
+
+/// REOPEN-F7: a reopened window's sidebar makes 5 icon buttons per workspace row (close, audio, pin, tree fold,
+/// more) and they stay hidden until the pointer is on the row. Each made its icon image when it was made: about
+/// 4 ms of the profiled window build before the first frame (`SidebarIconButton.renderIcon`). A hidden button
+/// needs no image; it makes it when it first shows.
+@MainActor @Suite(.closesItsWindows, .serialized) struct SidebarIconButtonLazyImageTests {
+    /// The button's icon image: AppKit answers a button with no image of its own with a shared 1 x 1
+    /// placeholder, so "no icon yet" is no image at least 2 points wide.
+    private static func icon(of button: SidebarIconButton) -> NSImage? {
+        button.image.flatMap { $0.size.width > 1 ? $0 : nil }
+    }
+
+    private static func window() -> NSWindow {
+        NSWindow(contentRect: NSRect(x: 200, y: 400, width: 300, height: 200), styleMask: [.titled], backing: .buffered, defer: false)
+    }
+
+    @Test func aHiddenButtonMakesNoImageUntilItShows() throws {
+        let window = Self.window()
+        let button = SidebarIconButton(icon: .actionClose, label: "Close Workspace")
+        button.isHidden = true
+        button.frame = NSRect(x: 20, y: 20, width: 20, height: 20)
+        let content = try #require(window.contentView)
+        content.addSubview(button)
+        content.layoutSubtreeIfNeeded()
+        #expect(Self.icon(of: button) == nil, "a hidden button made its icon image")
+        button.isHidden = false
+        let image = try #require(Self.icon(of: button), "a shown button has no icon image")
+        #expect(image.isTemplate)
+        #expect(image.size.width > 0)
+    }
+
+    @Test func aButtonInAHiddenRowMakesNoImageUntilTheRowShows() throws {
+        let window = Self.window()
+        let row = NSView(frame: NSRect(x: 0, y: 0, width: 200, height: 30))
+        row.isHidden = true
+        let button = SidebarIconButton(icon: .actionClose, label: "Close Workspace")
+        button.frame = NSRect(x: 160, y: 5, width: 20, height: 20)
+        row.addSubview(button)
+        let content = try #require(window.contentView)
+        content.addSubview(row)
+        content.layoutSubtreeIfNeeded()
+        #expect(Self.icon(of: button) == nil, "a button in a hidden row made its icon image")
+        row.isHidden = false
+        #expect(Self.icon(of: button) != nil, "the button of a shown row has no icon image")
+    }
+
+    @Test func aShownButtonHasItsImageInAWindowAndWithoutOne() throws {
+        let window = Self.window()
+        let shown = SidebarIconButton(icon: .actionClose, label: "Close Workspace")
+        try #require(window.contentView).addSubview(shown)
+        #expect(Self.icon(of: shown) != nil, "a button shown in a window has no icon image")
+        // Sized by its image outside a window too (a stack or constraints read its intrinsic size).
+        let loose = SidebarIconButton(icon: .actionClose, label: "Close Workspace")
+        #expect(loose.intrinsicContentSize.width > 0)
+        #expect(Self.icon(of: loose) != nil)
+    }
+
+    @Test func aNewIconOnAHiddenButtonWaitsToo() throws {
+        let window = Self.window()
+        let button = SidebarIconButton(icon: .disclosureExpanded, label: "Collapse")
+        button.isHidden = true
+        try #require(window.contentView).addSubview(button)
+        button.icon = .disclosureCollapsed
+        #expect(Self.icon(of: button) == nil)
+        button.isHidden = false
+        #expect(Self.icon(of: button) != nil)
+    }
+
+    /// Review of #33112 (P3): a workspace row's Unpin button was not hidden at init, so it made its image when the row
+    /// joined the window, before the row's first layout hid it. Every hover-only control starts hidden.
+    @Test func aNewRowsHoverControlsStartHidden() throws {
+        let row = WorkspaceRowView(key: .workspace(WorkspaceID("lazy-controls")))
+        for (name, button) in [("close", row.closeButton), ("pin", row.pinButton), ("audio", row.audioButton),
+                               ("tree fold", row.treeFoldButton)] {
+            #expect(button.isHidden, "a new row's \(name) button starts shown")
+            #expect(Self.icon(of: button) == nil, "a new row's \(name) button made its image")
+        }
+    }
+}