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/FloatingPanel.cpp

@@ -0,0 +1,118 @@
+#include "UI/FloatingPanel.h"
+#include "Rendering/EditorCanvas.h"
+#include <QApplication>
+#include <QCloseEvent>
+#include <QDialog>
+#include <QHash>
+#include <QVBoxLayout>
+
+namespace {
+// Top-left corners by panel, for this run of the app.
+QHash<QString, QPoint> &positions()
+{
+    static QHash<QString, QPoint> positions;
+    return positions;
+}
+}
+
+// Swift's NSPanel: a tool window whose close is Cancel.
+class PanelWindow : public QDialog {
+public:
+    PanelWindow(FloatingPanel &owner, QWidget *parent) : QDialog(parent), m_owner(owner)
+    {
+        // A dialog is non-modal unless asked: Swift's panel.
+        setWindowFlag(Qt::Tool);
+        auto *layout = new QVBoxLayout(this);
+        layout->setContentsMargins(0, 0, 0, 0);
+        layout->setSizeConstraint(QLayout::SetFixedSize);
+    }
+
+protected:
+    // QDialog's own would reject, and so close, again.
+    void closeEvent(QCloseEvent *event) override
+    {
+        m_owner.closed();
+        QWidget::closeEvent(event);
+    }
+    // Escape closes as the close button does.
+    void reject() override { close(); }
+    void moveEvent(QMoveEvent *event) override
+    {
+        QDialog::moveEvent(event);
+        if (isVisible())
+            m_owner.remember();
+    }
+
+private:
+    FloatingPanel &m_owner;
+};
+
+FloatingPanel::FloatingPanel(const QString &name, QWidget &owner) : m_name(name), m_owner(owner) {}
+
+FloatingPanel::~FloatingPanel()
+{
+    delete m_panel;
+}
+
+void FloatingPanel::show(const QString &title, QWidget *content)
+{
+    if (!m_panel) {
+        m_panel = new PanelWindow(*this, m_owner.window());
+        m_panel->setObjectName(m_name);
+    }
+    const bool wasVisible = m_panel->isVisible();
+    m_panel->setWindowTitle(title);
+    // Later: a signal from the old content may still run.
+    if (m_content) {
+        m_content->hide();
+        m_content->deleteLater();
+    }
+    m_content = content;
+    m_panel->layout()->addWidget(content);
+    // Shown now: layouts show late children from the event loop.
+    content->show();
+    m_panel->adjustSize();
+    // A shown panel stays; without a canvas QDialog centres itself.
+    if (!wasVisible) {
+        const CanvasView *canvas = m_owner.window()->findChild<CanvasView *>();
+        if (positions().contains(m_name))
+            m_panel->move(positions().value(m_name));
+        else if (canvas)
+            m_panel->move(canvas->mapToGlobal(canvas->rect().center()) - QPoint(m_panel->width() / 2, m_panel->height() / 2));
+    }
+    m_panel->show();
+    m_panel->raise();
+    m_panel->activateWindow();
+    remember();
+}
+
+// Moves were remembered as they came; hide sends no close.
+void FloatingPanel::close()
+{
+    if (m_panel)
+        m_panel->hide();
+}
+
+bool FloatingPanel::isVisible() const
+{
+    return m_panel && m_panel->isVisible();
+}
+
+void FloatingPanel::refocus(const QString &name)
+{
+    for (QWidget *widget : QApplication::topLevelWidgets()) {
+        if (widget->objectName() == name && widget->isVisible())
+            widget->activateWindow();
+    }
+}
+
+void FloatingPanel::remember()
+{
+    positions().insert(m_name, m_panel->pos());
+}
+
+void FloatingPanel::closed()
+{
+    if (onClose)
+        onClose();
+}