Make parallel lines

And make TODO for P2P

Canvas.h

@@ -2,33 +2,65 @@
 
 #include <QWidget>
 #include <QMouseEvent>
+#include <QPointF>
+#include <QMessageBox>
+
 #ifdef _DEBUG
 #include <QDebug>
 #endif
 
+// GCS — ãåîìåòðè÷åñêèé ñîëâåð èç FreeCAD
 #include "GCS/Geo.h"
+#include "GCS/GCS.h"
 using namespace GCS;
 
-enum Mode {
-	None,
-	DrawingLine
+enum class Mode : int
+{
+    None = 0,
+    DrawingLine = 1,
+    Parallel = 2
 };
 
+// Óäîáíûé òèï äëÿ õðàíåíèÿ ïàðû ïàðàëëåëüíûõ ëèíèé (ïîðÿäîê íå âàæåí)
+using LinePair = std::pair<Line*, Line*>;
+
+// ===================================================================
+// Îñíîâíîé êëàññ õîëñòà
+// ===================================================================
 
 class Canvas : public QWidget
 {
-	Q_OBJECT
-private:
-	void changeMode(Mode);
-	Mode mode = Mode::None;
-	QVector<Line*> lines;
-	QVector<Point> points;
-	QVector<double*> params;
-	Line* current_line;
-protected:
-	void mousePressEvent(QMouseEvent*) override;
-public:
-	Canvas(QWidget *parent);
-	~Canvas();
-};
+    Q_OBJECT
 
+public:
+    explicit Canvas(QWidget* parent = nullptr);
+    ~Canvas() override;
+
+    void changeMode(Mode newMode);
+
+protected:
+    void mousePressEvent(QMouseEvent* event) override;
+    void paintEvent(QPaintEvent* event) override;
+
+private:
+    // ====================== Ïîèñê è âûáîð ======================
+    Line* findAt(QPointF&);                    // èùåò ëèíèþ ïîä êóðñîðîì
+
+    // ====================== Ïàðàëëåëüíîñòü ======================
+    LinePair makeOrderedPair(Line* l1, Line* l2);
+    bool areAlreadyParallel(Line* l1, Line* l2);           // ïðîâåðêà íà äóáëèêàò
+
+    // ====================== Äàííûå ñöåíû ======================
+    System               sys;                     // ãåîìåòðè÷åñêèé ñîëâåð
+    QVector<Line*>       lines;                   // çàâåðø¸ííûå ëèíèè
+    QVector<Point>       points;                  // âñå òî÷êè (äëÿ óäîáíîãî äîñòóïà)
+    std::vector<double*> params;                  // âñå ïàðàìåòðû, ïåðåäàâàåìûå â ñîëâåð
+
+    std::set<LinePair> parallelPairs;           // óæå çàïàðàëëåëåííûå ïàðû (çàùèòà îò äóáëåé)
+
+    Line* current_line{ nullptr };
+    Mode mode{ Mode::None };
+
+    int obj_count{ 0 };            // òåã äëÿ íîâûõ îáúåêòîâ
+    int constraints_count{ 0 };    // òåã äëÿ íîâûõ îãðàíè÷åíèé
+};