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iccery-v2-mac/Sources/ICCery/Print/TargetPageCanvasView.swift
gronod ddb9245f44
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fix(print): anchor raster at page top in bottom-up canvas space (#211)
226e7b2 un-flipped the canvas but left destinationRect anchored at
pageRect.minY — the page's BOTTOM edge in bottom-up space — so
sub-page targets printed at the foot of the sheet and oversize
targets clipped their top rows. Anchor at pageRect.maxY - height,
restoring the spec'd top-left anchor (docs/14 §6, D9).

Adds the missing regression coverage: the geometry test now asserts
the top anchor with a sub-page raster, and the PDF harness gains a
banded (red-over-blue) fixture that fails on either a mirrored draw
or a bottom anchor — solid fills could catch neither.
2026-09-17 21:53:17 +01:00

89 lines
3.2 KiB
Swift

import AppKit
/// Headless print canvas (#201, docs/14 §6). Never installed in a
/// window; `NSPrintOperation` is its only client.
@MainActor
final class TargetPageCanvasView: NSView {
private let pages: [TargetPageRaster]
private let paperSize: NSSize
/// Test probe — invoked once per drawn page with the live context
/// so the interpolation/antialias contract is assertable without a
/// printer.
var drawProbe: ((NSGraphicsContext, Int, NSRect) -> Void)?
init(pages: [TargetPageRaster], paperSize: NSSize) {
self.pages = pages
self.paperSize = paperSize
super.init(frame: NSRect(
x: 0, y: 0,
width: paperSize.width,
height: paperSize.height * CGFloat(pages.count)))
}
@available(*, unavailable)
required init?(coder: NSCoder) {
fatalError("TargetPageCanvasView is code-only")
}
/// Bottom-up CoreGraphics space: `CGContext.draw(_:in:)` renders
/// the raster upright — a flipped view prints mirrored (#211).
/// Page 1 is the BOTTOM band of the frame, the non-flipped
/// pagination convention.
override var isFlipped: Bool { false }
override var isOpaque: Bool { true }
override func knowsPageRange(_ range: NSRangePointer) -> Bool {
range.pointee = NSRange(location: 1, length: pages.count)
return true
}
/// 1-based page → its paper-sized rect, stacked bottom-up.
override func rectForPage(_ page: Int) -> NSRect {
NSRect(x: 0,
y: CGFloat(page - 1) * paperSize.height,
width: paperSize.width,
height: paperSize.height)
}
/// Where page `page`'s image lands: top-left anchored inside
/// `rectForPage`, sized `raster.pointSize`, origin snapped to
/// 0.001 pt (docs/14 §6) so a fractional origin cannot trigger
/// device resampling. `internal` for unit tests.
func destinationRect(forPage page: Int) -> NSRect {
let pageRect = rectForPage(page)
let size = pages[page - 1].pointSize
return NSRect(x: Self.snap(pageRect.minX),
y: Self.snap(pageRect.maxY - size.height),
width: size.width,
height: size.height)
}
override func draw(_ dirtyRect: NSRect) {
guard let ctx = NSGraphicsContext.current else { return }
ctx.imageInterpolation = .none
ctx.shouldAntialias = false
let cg = ctx.cgContext
cg.interpolationQuality = .none
cg.setShouldAntialias(false)
cg.setAllowsAntialiasing(false)
cg.setShouldSmoothFonts(false)
for index in pages.indices {
let pageRect = rectForPage(index + 1)
guard pageRect.intersects(dirtyRect) else { continue }
cg.saveGState() // page N never inherits N-1's CTM
NSColor.white.setFill()
pageRect.fill()
cg.draw(pages[index].cgImage,
in: destinationRect(forPage: index + 1))
cg.restoreGState()
drawProbe?(ctx, index + 1, destinationRect(forPage: index + 1))
}
}
private static func snap(_ value: CGFloat) -> CGFloat {
(value * 1000).rounded() / 1000
}
}