fix(menubar): 修正预览位图缩放

Packages/XStatsKit/Sources/XStatsUI/AppKit/MenuBarRenderer.swift

@@ -294,9 +294,9 @@ enum MenuBarRenderer {
         return image
     }
 
-    /// 设置页预览：按指定外观绘制到不透明底色上。
+    /// 设置页预览：按指定外观栅格化，透明区域由界面叠加底色。
     /// 绘制回调型图像每次布局或重绘都会重跑文字排版，因此栅格化一次，SwiftUI 之后只复用位图。
-    static func preview(_ image: NSImage, dark: Bool) -> NSImage {
+    static func preview(_ image: NSImage, dark: Bool, backingScale: CGFloat? = nil) -> NSImage {
         let appearance = NSAppearance(named: dark ? .darkAqua : .aqua)
         let draw = { (rect: NSRect) in
             let content = {
@@ -308,16 +308,19 @@ enum MenuBarRenderer {
             }
             if let appearance { appearance.performAsCurrentDrawingAppearance(content) } else { content() }
         }
-        let scale = NSScreen.main?.backingScaleFactor ?? 2
+        let scale = backingScale ?? NSScreen.main?.backingScaleFactor ?? 2
         guard let rep = NSBitmapImageRep(bitmapDataPlanes: nil,
                                          pixelsWide: Int(ceil(image.size.width * scale)),
                                          pixelsHigh: Int(ceil(image.size.height * scale)),
                                          bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true, isPlanar: false,
-                                         colorSpaceName: .deviceRGB, bytesPerRow: 0, bitsPerPixel: 0),
-              let context = NSGraphicsContext(bitmapImageRep: rep) else {
+                                         colorSpaceName: .deviceRGB, bytesPerRow: 0, bitsPerPixel: 0) else {
             return NSImage(size: image.size, flipped: false) { draw($0); return true }
         }
+        // 逻辑尺寸决定上下文的点到像素缩放，必须在创建上下文前设置。
         rep.size = image.size
+        guard let context = NSGraphicsContext(bitmapImageRep: rep) else {
+            return NSImage(size: image.size, flipped: false) { draw($0); return true }
+        }
         NSGraphicsContext.saveGraphicsState()
         NSGraphicsContext.current = context
         draw(NSRect(origin: .zero, size: image.size))

Packages/XStatsKit/Tests/XStatsUITests/XStatsUITests.swift

@@ -202,8 +202,8 @@ private func isolatedDefaults() -> UserDefaults {
 
 @MainActor
 @Suite struct SettingsTests {
-    @Test(arguments: [false, true])
-    func settingsPreviewRasterizesOnceAndKeepsAppearanceColors(dark: Bool) throws {
+    @Test(arguments: [false, true], [CGFloat(1), CGFloat(2)])
+    func settingsPreviewRasterizesOnceAndKeepsAppearanceColors(dark: Bool, scale: CGFloat) throws {
         var draws = 0
         let source = NSImage(size: NSSize(width: 40, height: 18), flipped: false) { rect in
             draws += 1
@@ -212,7 +212,7 @@ private func isolatedDefaults() -> UserDefaults {
             return true
         }
         source.isTemplate = true
-        let preview = MenuBarRenderer.preview(source, dark: dark)
+        let preview = MenuBarRenderer.preview(source, dark: dark, backingScale: scale)
         let drawsAfterRender = draws
         #expect(drawsAfterRender >= 1)
         // 反复读取预览（布局、重绘）不能再触发源图的绘制回调。
@@ -222,9 +222,16 @@ private func isolatedDefaults() -> UserDefaults {
         #expect(preview.representations.contains { $0 is NSBitmapImageRep })
         // 模板图按外观着色：浅色外观为黑，深色外观为白。
         let rep = try #require(preview.representations.compactMap { $0 as? NSBitmapImageRep }.first)
+        #expect(rep.pixelsWide == Int(source.size.width * scale))
+        #expect(rep.pixelsHigh == Int(source.size.height * scale))
         let center = try #require(rep.colorAt(x: rep.pixelsWide / 2, y: rep.pixelsHigh / 2)?.usingColorSpace(.deviceRGB))
         #expect(center.alphaComponent > 0.99)
         #expect((center.redComponent > 0.5) == dark)
+        for (x, y) in [(0, 0), (rep.pixelsWide - 1, 0), (0, rep.pixelsHigh - 1), (rep.pixelsWide - 1, rep.pixelsHigh - 1)] {
+            let corner = try #require(rep.colorAt(x: x, y: y)?.usingColorSpace(.deviceRGB))
+            #expect(corner.alphaComponent > 0.99)
+            #expect((corner.redComponent > 0.5) == dark)
+        }
     }
 
     @Test func stackedCenteredStyleRendersDifferentPlacementAtSameWidth() {