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

src/Document/DocumentLimits.cpp

@@ -0,0 +1,31 @@
+#include "Document/DocumentLimits.h"
+#include <QLocale>
+#include <algorithm>
+#include <unistd.h>
+
+// Swift's physicalMemory / 16, read once as a static let.
+qint64 DocumentLimits::documentPixelBudget()
+{
+    static const qint64 budget = budgetFor(qint64(sysconf(_SC_PHYS_PAGES)) * qint64(sysconf(_SC_PAGE_SIZE)));
+    return budget;
+}
+
+qint64 DocumentLimits::budgetFor(qint64 memory)
+{
+    return std::min<qint64>(800'000'000, std::max(maxSurfacePixels, memory / 16));
+}
+
+qint64 DocumentLimits::maxSurfaceMegapixels()
+{
+    return maxSurfacePixels / 1'000'000;
+}
+
+qint64 DocumentLimits::documentBudgetMegapixels()
+{
+    return documentPixelBudget() / 1'000'000;
+}
+
+QString DocumentLimits::maxSideText()
+{
+    return QLocale(QLocale::English).toString(maxSide);
+}