Release v0.6.5: preserve caption links and connect arrows to other objects

src/screenshot.h

@@ -17,6 +17,10 @@ enum class LineStyle { Solid, Dotted, Dashed, DashDot };
 enum class LineEnds { End, Start, Both, None };
 enum class ScreenshotShape { None, Rectangle, Circle, Ellipse };
 struct ScreenshotOffset { double x, y; };
+struct ScreenshotLink {
+    unsigned long long target{};
+    double u{}, v{}; // Relative boundary position, or fractional position along a path.
+};
 struct ScreenshotMark {
     POINT from, to; int number; int radius = 15; int thickness = 3;
     int fromNumber = 0, toNumber = 0;
@@ -33,6 +37,8 @@ struct ScreenshotMark {
     std::wstring label;
     ScreenshotOffset labelOffset{0,-24}; // Along the line and perpendicular to it, in image pixels.
     bool labelRotationManual=false;
+    unsigned long long id{};
+    ScreenshotLink fromLink, toLink;
     bool isText() const { return !text.empty(); }
     bool isHighlight() const { return !points.empty() && !freehand; }
     bool isLine() const { return !number && !isText() && !isHighlight() && shape==ScreenshotShape::None; }
@@ -48,7 +54,7 @@ class ScreenshotHistory {
 };
 void resolveScreenshotLinks(std::vector<ScreenshotMark> &);
 void linkScreenshotEndpoint(ScreenshotMark &, bool start, POINT drop,
-                            const std::vector<ScreenshotMark> &, double tolerance);
+                            std::vector<ScreenshotMark> &, double tolerance);
 enum class MarkPart { None, Body, Start, End, Radius, Thickness, Rotation, Label };
 POINT screenshotThicknessHandle(const ScreenshotMark &, double clearance = 16);
 ScreenshotMark cloneScreenshotMark(const ScreenshotMark &, const std::vector<ScreenshotMark> &, int width, int height);