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/UI/GradientControls.h

@@ -0,0 +1,49 @@
+#pragma once
+#include "UI/ToolHeaderStyle.h"
+#include <functional>
+
+class EditorSession;
+class QButtonGroup;
+class QCheckBox;
+class QComboBox;
+class QPushButton;
+class QSlider;
+class QToolButton;
+class SelectionAmountField;
+
+// Swift's gradient swatch: the colours over a checkerboard.
+class GradientSwatch : public QWidget {
+public:
+    GradientSwatch(const EditorSession &session, QWidget *parent);
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+
+private:
+    const EditorSession &m_session;
+};
+
+// Swift's GradientControls: shape, colours, reverse, opacity, apply.
+class GradientControls : public ToolHeaderBar {
+    Q_OBJECT
+public:
+    explicit GradientControls(EditorSession &session, QWidget *parent = nullptr);
+
+private:
+    QToolButton *shape(const QString &name, const QString &text, bool radial);
+    void synchronize();
+
+    EditorSession &m_session;
+    QButtonGroup *const m_shapes;
+    QToolButton *const m_linear;
+    QToolButton *const m_radial;
+    GradientSwatch *const m_swatch;
+    QComboBox *const m_style;
+    QCheckBox *const m_reverse;
+    // The slider steps in thousandths, the field in whole percents.
+    QSlider *const m_opacitySlider;
+    SelectionAmountField *const m_opacity;
+    QLabel *const m_mask;
+    QPushButton *const m_cancel;
+    QPushButton *const m_apply;
+};