ProEssentials WinUI — Log-Log Axes & Quick Annotation Drag Measure

A ProEssentials v11 WinUI 3 .NET 10 demonstration of two advanced PesgoWinUI features: intelligent logarithmic axes that restructure intelligently on zoom, and a live drag measurement tool built with the Quick Annotation mechanism.

➡️ gigasoft.com/examples

Both axes use ScaleControl.Log. ProEssentials selects intelligent logarithmic grid numbers automatically at any zoom level, always landing on clean powers of ten and their subdivisions:

Pesgo1.PeGrid.Configure.XAxisScaleControl = ScaleControl.Log;
Pesgo1.PeGrid.Configure.YAxisScaleControl = ScaleControl.Log;

Mouse wheel zooms both axes simultaneously:

Pesgo1.PeUserInterface.Allow.Zooming = AllowZooming.None; // left-drag reserved for measurement
Pesgo1.PeUserInterface.Scrollbar.MouseWheelFunction = MouseWheelFunction.HorizontalVerticalZoom;
Pesgo1.PeUserInterface.Scrollbar.MouseWheelZoomSmoothness = 8;

Quick annotations are graph annotations that render via an optimized overlay path, avoiding full chart rebuilds. They are ideal for transient UI that updates on every pointer move.

In WinUI, PesgoWinUI automatically manages the CacheBmp2 secondary buffer and improved cursor rendering — CacheBmp2 is not exposed on the WinUI interface at all and requires no explicit setup.

The only mouse wheel zoom requirement is pairing MouseWheelFunction with the matching scrollbar flags:

Pesgo1.PeUserInterface.Scrollbar.ScrollingHorzZoom  = true;
Pesgo1.PeUserInterface.Scrollbar.ScrollingVertZoom  = true;
Pesgo1.PeUserInterface.Scrollbar.MouseWheelFunction = MouseWheelFunction.HorizontalVerticalZoom;

MouseWheelFunction.HorizontalVerticalZoom requires both flags set explicitly — without them the wheel cannot zoom out and only one axis responds.

Any GraphAnnotationType value becomes a quick annotation by negating it:

// Normal annotation — baked into cached image, requires ResetImage to change:
Graph.Type[i] = (int)GraphAnnotationType.TopLeft;

// Quick annotation — overlay only, no chart rebuild needed:
Graph.Type[i] = ((int)GraphAnnotationType.TopLeft + 1) * -1;

When ShowingQuickAnnotations = true, only negative-type annotations are rendered, drawn on top of the primary cached chart image.

// PointerMoved — trigger overlay redraw (no chart rebuild):
Pesgo1.PeAnnotation.ShowingQuickAnnotations = true;
Pesgo1.Invalidate();
Pesgo1.UpdateLayout();

// PointerReleased — clear overlay:
Pesgo1.PeAnnotation.ShowingQuickAnnotations = false;
Pesgo1.PeAnnotation.HidingQuickAnnotations  = true;
Pesgo1.Invalidate();
Pesgo1.UpdateLayout();

The WPF twin calls Refresh() where this sample calls UpdateLayout() — Invalidate() is what schedules the WinUI repaint.

On log axes the visual center of a span is the geometric mean, not the arithmetic mean. Delta labels use geometric centering so they appear visually centered within the selection at any zoom level:

double centeredXLog = (Math.Log10(fX) + Math.Log10(_dragStartX)) / 2.0;
double centeredX    = Math.Pow(10.0, centeredXLog);

Pointer pixel positions are converted to data-unit coordinates using ConvPixelToGraph, then clamped to the visible axis extents:

int nA = 0, nX = (int)pt.X, nY = (int)pt.Y;
double fX = 0, fY = 0;
Pesgo1.PeFunction.ConvPixelToGraph(ref nA, ref nX, ref nY,
                                    ref fX, ref fY, false, false, false);

// Clamp to current visible range
fX = Math.Max(Pesgo1.PeGrid.Configure.ManualMinX,
     Math.Min(Pesgo1.PeGrid.Configure.ManualMaxX, fX));

ManualMinX/MaxX/MinY/MaxY are only valid after the chart has rendered its first image — never read them during initialization.

PesgoWinUI forwards pointer input to the native engine in its own PointerPressed / PointerMoved / PointerReleased handlers and then marks the event handled. Attach with AddHandler(..., handledEventsToo: true) so your handlers still run — the control's handler runs first, so PeUserInterface.Cursor.LastMouseMove is already current when you read it:

Pesgo1.AddHandler(UIElement.PointerPressedEvent,
                  new PointerEventHandler(Pesgo1_MouseDown), true);

System.Windows.Point / Rect become Windows.Foundation.Point / Rect, and System.Windows.Media.Color becomes Windows.UI.Color — the FromArgb signature is unchanged.

• Visual Studio 2026 with the .NET desktop development and Windows application development workloads
• .NET 10 SDK
• Internet connection for NuGet restore

No XAML designer: Visual Studio has no XAML designer for WinUI 3 in any edition, so the chart is declared in markup rather than dragged from the Toolbox. That is a Windows App SDK limitation, not a ProEssentials one. Nothing needs to be installed beyond the NuGet packages for this project to build and run.

1. Clone this repository
2. Open LogLogDragMeasureWinUI.sln in Visual Studio 2026
3. Build → Rebuild Solution (NuGet restore is automatic)
4. Press F5

References ProEssentials.Chart.Net10.WinUI. Package restore is automatic on build.

The AnyCpu package embeds the native rendering engines inside the assembly and unpacks the one matching the running process at run time, so there is no native DLL to copy or deploy alongside your app. It also carries the control's .pri, whose resources are merged into your app's own .pri at build time.

The nuget.org package is the evaluation build and draws an "Evaluating ProEssentials" watermark across the chart. A licensed installation replaces the assembly and the watermark goes away — performance and behavior are identical.

WinUI deploys differently than WPF and WinForms:

• A .NET app is not a single exe — ship the entire build or publish output folder, never a hand-picked subset.
• The target machine needs two runtimes: the .NET 10 Desktop Runtime and the Windows App SDK Runtime. Or publish self-contained with -p:WindowsAppSDKSelfContained=true.
• Your development machine already has both, so it will run from an under-filled folder. Always validate on a clean machine.

• WPF version — wpf-chart-log-log-axes-drag-measure-quick-annotations-proessentials
• WinUI Chart Quickstart
• All Examples — GigasoftInc on GitHub
• Full Evaluation Download
• gigasoft.com

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