12.3b: rulers, the grid and guides on the canvas, guide drags (Compositor 1.1.7)

src/UI/CanvasRulers.h

@@ -0,0 +1,43 @@
+#pragma once
+#include "Document/EditorSession.h"
+#include <QWidget>
+
+class CanvasView;
+
+namespace CanvasRuler {
+inline constexpr int thickness = 18;
+}
+
+// The square where the two rulers meet.
+class CanvasRulerCorner : public QWidget {
+    Q_OBJECT
+public:
+    explicit CanvasRulerCorner(QWidget *parent = nullptr);
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+};
+
+// Swift's CanvasRulerNSView: ticks in document pixels; drag out a guide.
+class CanvasRulerView : public QWidget {
+    Q_OBJECT
+public:
+    CanvasRulerView(EditorSession &session, CanvasGuide::Axis axis, CanvasView &canvas, QWidget *parent = nullptr);
+    // Numbered ticks about 70 points apart, 1-2-5 steps.
+    static double majorStep(double pointsPerPixel);
+    static QString label(double value);
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+    void mousePressEvent(QMouseEvent *event) override;
+    void mouseMoveEvent(QMouseEvent *event) override;
+    void mouseReleaseEvent(QMouseEvent *event) override;
+
+private:
+    QPointF inCanvas(QPointF point) const;
+    std::optional<double> documentPosition(QPointF point) const;
+
+    EditorSession &m_session;
+    const CanvasGuide::Axis m_axis;
+    CanvasView &m_canvas;
+};