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Pre-composite backdrop #86

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Merged
lawrencecchen merged 1 commit into from
Mar 30, 2026
Merged

Pre-composite backdrop #86

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40 changes: 22 additions & 18 deletions Sources/Bonsplit/Internal/Views/TabBarView.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -187,24 +187,7 @@ struct TabBarView: View {
.overlay(alignment: .trailing) {
if showSplitButtons {
let shouldShow = presentationMode != "minimal" || isHoveringTabBar
// Pre-composite: produce the flat opaque color that
// matches what .background(barFill) looks like over the
// window background. Avoids double-compositing mismatch.
let bg: Color = {
let chrome = TabBarColors.nsColorPaneBackground(for: appearance)
let winBg = NSColor.windowBackgroundColor
guard let fg = chrome.usingColorSpace(.sRGB),
let bk = winBg.usingColorSpace(.sRGB) else {
return Color(nsColor: chrome.withAlphaComponent(1.0))
}
let a = isFocused ? fg.alphaComponent : fg.alphaComponent * 0.95
return Color(nsColor: NSColor(
sRGBRed: fg.redComponent * a + bk.redComponent * (1 - a),
green: fg.greenComponent * a + bk.greenComponent * (1 - a),
blue: fg.blueComponent * a + bk.blueComponent * (1 - a),
alpha: 1.0
))
}()
let bg = Color(nsColor: Self.precompositedPaneBackground(for: appearance, focused: isFocused))
ZStack(alignment: .trailing) {
// Backdrop: fade gradient then solid
HStack(spacing: 0) {
Expand Down Expand Up @@ -542,6 +525,27 @@ struct TabBarView: View {
}


/// Pre-composite the pane background over the window background to produce
/// a flat opaque color that matches what .background(barFill) looks like
/// after compositing. Avoids double-compositing mismatch on overlays.
private static func precompositedPaneBackground(
for appearance: BonsplitConfiguration.Appearance,
focused: Bool
) -> NSColor {
let chrome = TabBarColors.nsColorPaneBackground(for: appearance)
let winBg = NSColor.windowBackgroundColor
guard let fg = chrome.usingColorSpace(.sRGB),
let bk = winBg.usingColorSpace(.sRGB) else {
return chrome.withAlphaComponent(1.0)
}
let a: CGFloat = focused ? fg.alphaComponent : fg.alphaComponent * 0.95
let oneMinusA = 1.0 - a
let r = fg.redComponent * a + bk.redComponent * oneMinusA
let g = fg.greenComponent * a + bk.greenComponent * oneMinusA
let b = fg.blueComponent * a + bk.blueComponent * oneMinusA
return NSColor(red: r, green: g, blue: b, alpha: 1.0)
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@greptile-apps greptile-apps bot Mar 30, 2026

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P1 Wrong NSColor initializer changes color space from sRGB to calibratedRGB

The extracted function blends components after converting both inputs to .sRGB (lines 537–538), so r, g, and b are sRGB-space values. The original inline code used NSColor(sRGBRed:green:blue:alpha:) to correctly wrap those values back into the sRGB color space.

The new code uses NSColor(red:green:blue:alpha:), which creates an NSCalibratedRGBColorSpace color — a different color space. The same numeric component values interpreted in calibrated RGB will render at a slightly different color than intended, reintroducing the compositing mismatch the PR aims to fix.

Suggested change
return NSColor(red: r, green: g, blue: b, alpha: 1.0)
return NSColor(sRGBRed: r, green: g, blue: b, alpha: 1.0)

}

// MARK: - Fade Overlays

/// Mask that fades scroll content at the edges instead of overlaying
Expand Down
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