ProEssentials v10 WinForms .NET 8 — log-log scientific scatter chart with intelligent decade-based axis restructuring on zoom, plus a left-drag quick annotation measurement tool that overlays a live measurement rectangle with X/Y delta labels. Direct2D.

• Log-log axes (ScaleControl.Log on both X and Y) with automatic decade-based grid numbers as you zoom through several decades.
• Quick annotation drag tool — left-drag builds six quick annotations (negated Graph.Type → CacheBmp2 overlay) forming a measurement rectangle with geometric-mean-centered delta labels. No full chart rebuild per frame.
• DataCross cursor snapped to nearest data point.
• Code-built UI — chart + 3 mouse handlers in MainForm.cs; no .Designer.cs / .resx.

Chart config and the quick-annotation math are identical to the WPF version. Host changes: the three mouse handlers use WinForms MouseEventArgs (MouseDown/Up gated on e.Button == MouseButtons.Left); LastMouseMove/GetRectGraph return System.Drawing.Point/Rectangle (int, no casts); colors are System.Drawing.Color.

➡️ WPF version: wpf-chart-log-log-axes-drag-measure-quick-annotations-proessentials

1. Clone, open LogLogDragMeasure.sln in Visual Studio 2022
2. Build → Rebuild Solution; press F5. Left-drag to measure; wheel to zoom.

References ProEssentials.Chart.Net80.x64.Winforms (>= 10.0.0.28).

Example code is MIT licensed. ProEssentials requires a commercial license for continued use.