The document's own pixel budget, marching ants at screen resolution (12.11a)

src/Document/DocumentLimits.h

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+#pragma once
+#include <QString>
+#include <QtGlobal>
+
+// Swift's DocumentLimits: one surface, and a whole document's raster.
+namespace DocumentLimits {
+// Longest side of any canvas, layer, mask or generated surface.
+inline constexpr int maxSide = 30'000;
+// Largest single surface; both ceilings stay under maxSide squared.
+inline constexpr qint64 maxSurfacePixels = 200'000'000;
+// All layers and masks: a quarter of memory, capped.
+qint64 documentPixelBudget();
+// The budget for this much memory, in bytes.
+qint64 budgetFor(qint64 memory);
+qint64 maxSurfaceMegapixels();
+qint64 documentBudgetMegapixels();
+// The side limit as Swift's `formatted()` prints it: 30,000.
+QString maxSideText();
+}