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/Document/EditorSession+Model.h

@@ -0,0 +1,85 @@
+#pragma once
+#include "Document/LayerAdjustment.h"
+#include "Document/LayerAppearance.h"
+#include "Document/LayerGroups.h"
+#include "Document/LayerMask.h"
+#include "Document/LayerTransform.h"
+#include "Document/Selection.h"
+#include "Document/ShapeTool.h"
+#include "Document/TypeTool.h"
+#include "IO/ImageImporter.h"
+#include <QString>
+#include <QUuid>
+#include <optional>
+#include <vector>
+
+struct ImageLayer {
+    QUuid id;
+    std::optional<ImportedImage> asset;
+    LayerTransform transform;
+    QString name;
+    bool isVisible = true;
+    std::optional<QUuid> parentID;
+    bool isGroup = false;
+    double opacity = 1;
+    LayerBlendMode blendMode = LayerBlendMode::normal;
+    std::optional<QUuid> maskSourceID;
+    std::optional<LayerMask> mask;
+    std::optional<LayerAdjustment> adjustment;
+    // Set on layers the Shape tool made; see `liveShape`.
+    std::optional<LayerShape> shape;
+    // A stroke, shadows or overlay drawn round the pixels.
+    std::optional<LayerEffects> effects;
+    std::optional<LayerText> text;
+
+    ImageLayer(ImportedImage imported, QPointF origin);
+    ImageLayer(QString name, QSizeF blankSize);
+    // A layer as a project records it.
+    ImageLayer(const ProjectLayerRecord &record, std::optional<ImportedImage> asset, std::optional<LayerMask> mask);
+
+    QPointF origin() const { return transform.origin; }
+    QSizeF size() const { return transform.size; }
+    ProjectLayerRecord hierarchyRecord() const;
+    LayerTransform maskTransform() const;
+    // The shape this layer still is: none once repainted otherwise.
+    std::optional<LayerShape> liveShape() const;
+    // The text this layer still is: none once repainted otherwise.
+    std::optional<LayerText> liveText() const;
+    friend bool operator==(const ImageLayer &lhs, const ImageLayer &rhs);
+};
+
+// The layer's place in the list, or -1.
+int indexOf(const std::vector<ImageLayer> &layers, std::optional<QUuid> id);
+
+struct ProjectSnapshot;
+
+struct CanvasDocument {
+    QUuid id;
+    int width;
+    int height;
+    double resolution = 72;
+    std::vector<ImageLayer> layers; // Bottom to top.
+    // Part of the document so undo covers it; never saved.
+    std::optional<DocumentSelection> selection;
+
+    CanvasDocument(int width, int height);
+    // The canvas a project holds, each layer as recorded.
+    explicit CanvasDocument(const ProjectSnapshot &snapshot);
+
+    QSizeF size() const { return QSizeF(width, height); }
+    static std::optional<int> validDimension(const QString &value);
+    std::vector<LayerHierarchy::Entry> hierarchyEntries() const;
+    QSet<QUuid> effectiveVisibleIDs() const;
+    std::vector<ImageLayer> renderLayers() const;
+    friend bool operator==(const CanvasDocument &lhs, const CanvasDocument &rhs) = default;
+};
+
+enum class NavigationTool {
+    move, marquee, lasso, wand, crop, brush, spotHealing, cloneStamp, blur,
+    gradient, shape, type, eyedropper, hand, zoom, idle
+};
+
+// The rail's tooltip: the tool's name and its key.
+QString label(NavigationTool tool);
+bool isBrushTool(NavigationTool tool);
+bool isSelectionTool(NavigationTool tool);