OmaPhoto 1.0.0: the Linux port of Compositor

A layered image editor for Linux and Omarchy, ported from Compositor
(github.com/robbietilton/Compositor), whose Swift source is its
specification. It reads and writes Compositor's .comp projects.

Packages for Ubuntu, Fedora and Arch come from the release workflow;
scripts/install/ holds one install script per distribution family,
and flake.nix serves NixOS.

Co-Authored-By: Claude <noreply@anthropic.com>

src/IO/ProjectStore.h

@@ -0,0 +1,95 @@
+#pragma once
+#include "Document/LayerAdjustment.h"
+#include "Document/LayerAppearance.h"
+#include "Document/LayerEffects.h"
+#include "Document/LayerTransform.h"
+#include "Document/ShapeTool.h"
+#include "Document/TypeTool.h"
+#include "IO/ImageImporter.h"
+#include <QByteArray>
+#include <QString>
+#include <QUuid>
+#include <map>
+#include <optional>
+#include <stdexcept>
+#include <utility>
+#include <vector>
+
+struct LayerMask;
+
+// Absent optionals stay out of the manifest.
+struct ProjectLayerRecord {
+    QUuid id;
+    QString name;
+    bool isVisible;
+    LayerTransform transform;
+    std::optional<QString> imageFile;
+    std::optional<QUuid> parentID = std::nullopt;
+    std::optional<bool> isGroup = std::nullopt;
+    std::optional<double> opacity = std::nullopt;
+    std::optional<LayerBlendMode> blendMode = std::nullopt;
+    std::optional<QString> maskFile = std::nullopt;
+    std::optional<bool> maskEnabled = std::nullopt;
+    std::optional<QUuid> maskSourceID = std::nullopt;
+    std::optional<LayerAdjustment> adjustment = std::nullopt;
+    std::optional<LayerTransform> maskPlacement = std::nullopt;
+    // Absent in older projects, which means linked.
+    std::optional<bool> maskLinked = std::nullopt;
+    // A shape layer's shape; older versions keep the pixels alone.
+    std::optional<LayerShapeStyle> shape = std::nullopt;
+    // What the layer draws round itself; its pixels stay.
+    std::optional<LayerEffects> effects = std::nullopt;
+    std::optional<LayerTextStyle> text = std::nullopt;
+};
+
+// A UUID as Swift writes it: upper case, no braces.
+QString uuidString(const QUuid &id);
+
+struct ProjectManifest {
+    QString format = QStringLiteral("com.compositor.project");
+    // Swift's Int: a wild number must reach validation whole.
+    qint64 version = 7;
+    QString colorSpace = QStringLiteral("sRGB");
+    // Version-1 projects carry none: 72 pixels per inch.
+    std::optional<double> resolution = std::nullopt;
+    QUuid documentID;
+    qint64 width;
+    qint64 height;
+    std::optional<QUuid> activeLayerID;
+    std::vector<ProjectLayerRecord> layers;
+
+    // Pretty JSON with sorted keys; absent optionals are left out.
+    QByteArray encoded() const;
+    // Throws ProjectError(invalid) on anything Swift's decoder refuses.
+    static ProjectManifest decoded(const QByteArray &data);
+    // Format and version alone: newer files may not decode.
+    static std::pair<QString, qint64> header(const QByteArray &data);
+};
+
+struct ProjectSnapshot {
+    ProjectManifest manifest;
+    std::map<QUuid, ImportedImage> images;
+    std::map<QUuid, ImportedImage> masks = {};
+    // A record's mask, from its mask file and fields.
+    std::optional<LayerMask> mask(const ProjectLayerRecord &layer) const;
+};
+
+class ProjectError : public std::runtime_error {
+public:
+    enum class Kind { invalid, version, missingImage, tooLarge, encode };
+    explicit ProjectError(Kind kind);
+    static ProjectError unsupportedVersion(qint64 version);
+    const Kind kind;
+    // Set only for Kind::version.
+    const std::optional<qint64> version;
+
+private:
+    ProjectError(Kind kind, std::optional<qint64> version, const QString &description);
+};
+
+// A .comp project: a directory holding manifest.json and images/.
+namespace ProjectStore {
+// Replaces the project in one step or leaves it untouched.
+void save(const ProjectSnapshot &snapshot, const QString &path);
+ProjectSnapshot load(const QString &path);
+}