14.19: Filter › Scanlines, its own filter, on Swift's cdde327 kernel

src/Document/Scanlines.h

@@ -0,0 +1,42 @@
+#pragma once
+#include "Document/Dither.h"
+
+// Filter › Scanlines: the picture as a CRT draws it.
+struct ScanlinesSettings {
+    static constexpr double lineSpacingLow = 2, lineSpacingHigh = 32;
+    static constexpr double wobbleLow = 0, wobbleHigh = 64;
+    static constexpr double displaceLow = -100, displaceHigh = 100;
+    static constexpr double splitLow = 0, splitHigh = 16;
+    // How far apart the lines are, in layer pixels.
+    double lineSpacing = 4;
+    // How much of the gap a bright line fills, 5–100%.
+    double thickness = 70;
+    // 0–100%: light blooming round the lines.
+    double glow = 0;
+    // 0–100%: darker tones bead the lines into dots.
+    double dots = 0;
+    // Pixels the lines waver sideways, down the screen.
+    double wobble = 0;
+    // Pixels a line rises over brightness; negative, falls.
+    double displace = 0;
+    // 0–100%: how far brightness is smoothed before displacing.
+    double smoothness = 50;
+    // 0–100%: darker tones draw no line.
+    double threshold = 0;
+    // Pixels the red and blue move apart.
+    double split = 0;
+    // −100…100: darker or lighter, flatter or punchier.
+    double density = 0;
+    double contrast = 0;
+    // 0–100%: the lines' brightness over black.
+    double blackLevel = 0;
+    DitherColors colors = DitherColors::blackWhite;
+    AdjustmentColor dark = AdjustmentColor(0, 0, 0);
+    AdjustmentColor light = AdjustmentColor(1, 1, 1);
+    ScanlinesSettings normalized() const;
+    QImage apply(const QImage &image) const;
+    friend bool operator==(const ScanlinesSettings &, const ScanlinesSettings &) = default;
+
+private:
+    QImage glowing(const QImage &image) const;
+};