ProEssentials WPF Real-Time Circular Buffer — 4 x 2 Million Points

A ProEssentials v10 WPF .NET 8 demonstration of the highest-performance real-time line charting pattern using PesgoWpf — combining local-memory UseDataAtLocation, v10 CircularBuffers, GPU ComputeShader with StagingBuffers, and Filter2D3D data reduction to sustain a continuous 8 million float real-time update at 15ms intervals without frame drops.

Extends the base example 146 pattern with a custom right-click Zoom Mode menu that lets you switch live between two zooming behaviors — demonstrating the single-line timer tick difference between examples 145 and 146.

➡️ gigasoft.com/examples/146

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What This Demonstrates

4 subsets × 2,000,000 points = 8,000,000 floats updated continuously at 150 new samples per subset every 15ms. The chart never allocates new memory, never shifts existing data, and the GPU never waits on a CPU copy — achieving the maximum throughput possible in a .NET WPF application.

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The Two Zoom Modes (right-click → Zoom Mode)

This repo combines examples 145 and 146 into a single app, toggling between their zoom behaviors via the custom right-click menu. The subtitle updates to reflect the active mode.

Stationary (default — example 146 behavior)

Zoom in → zoom window stays fixed
New data streams past behind it

When zoomed in, the zoom window does not advance. New data continuously appends to the ring buffer and updates the full axis extents, but the zoomed viewport is anchored in time. Use this to study a feature in detail while the live stream keeps running.

Scrolling (example 145 behavior)

Zoom in → zoom window follows the latest samples

When zoomed in, Zoom.MaxX and Zoom.MinX are each advanced by nNewSamplesPerTick every frame. The viewport "follows" the data stream, always showing the most recent 150 samples per tick.

The Entire Code Difference

// In Timer_Tick — the only difference between 145 and 146:

if (_zoomScrolls && Pesgo1.PeGrid.Zoom.Mode)  // Scrolling mode (145)
{
    Pesgo1.PeGrid.Zoom.MaxX += nNew;
    Pesgo1.PeGrid.Zoom.MinX += nNew;
}
// Comment out the block above = Stationary mode (146)

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ProEssentials Features Demonstrated

UseDataAtLocation — Zero-Copy Local Memory

// App owns these arrays — chart holds a pointer, never copies them
private readonly float[] _xData = new float[2_000_000];
private readonly float[] _yData = new float[8_000_000];

// Give the chart direct access — no transfer, no allocation
Pesgo1.PeData.X.UseDataAtLocation(_xData, 2_000_000);
Pesgo1.PeData.Y.UseDataAtLocation(_yData, 8_000_000);

Compare to example 145 which uses FastCopyFrom — that copies 8M floats into chart-internal circular buffers at init time. UseDataAtLocation is faster because the GPU staging buffers read from your memory directly. No copy ever happens between app memory and chart memory.

CircularBuffers (v10)

Pesgo1.PeData.CircularBuffers = true;  // set before UseDataAtLocation

AppendData writes into a ring buffer rather than shifting all existing data left. With 2M points per subset, shifting without CircularBuffers would move 8M floats every 15ms. With it, append is O(1) — only the new samples are written. ComputeShader rendering reads the ring in-order with no penalty.

DuplicateDataX — Single X Array for All Subsets

Pesgo1.PeData.DuplicateDataX = DuplicateData.PointIncrement;
// ...
Pesgo1.PeData.X.UseDataAtLocation(_xData, 2_000_000);  // one array, not four

One shared X array instead of 4 × 2M = 8M floats of redundant X data. The chart uses _xData[p] for all subsets automatically. AppendData on X sends only 150 values per tick instead of 600.

GPU Pipeline — ComputeShader + StagingBuffers + Filter2D3D

Pesgo1.PeConfigure.RenderEngine = RenderEngine.Direct3D;
Pesgo1.PeData.ComputeShader     = true;  // geometry built on GPU
Pesgo1.PeData.StagingBufferX    = true;  // DX CPU→GPU transfer path for X
Pesgo1.PeData.StagingBufferY    = true;  // DX CPU→GPU transfer path for Y
Pesgo1.PeData.Filter2D3D        = true;  // lossless pixel-level reduction
Pesgo1.PeSpecial.AutoImageReset = false; // suppress intermediate redraws

At 2M points per subset, only ~1000 points are visible per pixel-column at any zoom level. Filter2D3D applies a lossless min/max reduction before GPU transfer — the GPU only processes the visible data density, not the full 2M. AutoImageReset = false suppresses WPF's intermediate invalidation path, preventing tearing at 67fps update rates.

Manual Axis Scaling — Skip the Min/Max Scan

Pesgo1.PeGrid.Configure.ManualScaleControlY = ManualScaleControl.MinMax;
Pesgo1.PeGrid.Configure.ManualMinY          = -110;
Pesgo1.PeGrid.Configure.ManualMaxY          =  220;

Pesgo1.PeGrid.Configure.ManualScaleControlX = ManualScaleControl.MinMax;
Pesgo1.PeGrid.Configure.ManualMinX          = 0;
Pesgo1.PeGrid.Configure.ManualMaxX          = 2_000_000;

Without manual scaling the chart scans all 8M floats every tick to find min/max. With manual scaling that scan is skipped entirely — the axis extents are updated manually in the timer tick as the counter advances.

Custom Right-Click Menu — PeCustomMenu Event (example 127 pattern)

// Define menu items — "|" prefix = separator, "Title|Sub1|Sub2" = submenu
Pesgo1.PeUserInterface.Menu.CustomMenuText[0] = "|";
Pesgo1.PeUserInterface.Menu.CustomMenuText[1] = "Zoom Mode|Stationary|Scrolling";

// Default: Stationary checked
Pesgo1.PeUserInterface.Menu.CustomMenuState[1, 1] = CustomMenuState.Checked;
Pesgo1.PeUserInterface.Menu.CustomMenuState[1, 2] = CustomMenuState.UnChecked;

// Both items placed at bottom of built-in menu
Pesgo1.PeUserInterface.Menu.CustomMenuLocation[0] = CustomMenuLocation.Bottom;
Pesgo1.PeUserInterface.Menu.CustomMenuLocation[1] = CustomMenuLocation.Bottom;

// Wire the event:
Pesgo1.PeCustomMenu += Pesgo1_PeCustomMenu;

// Handler — radio-style mutual exclusion:
private void Pesgo1_PeCustomMenu(object sender,
    Gigasoft.ProEssentials.EventArg.CustomMenuEventArgs e)
{
    if (e.MenuIndex != 1) return;

    Pesgo1.PeUserInterface.Menu.CustomMenuState[1, 1] = CustomMenuState.UnChecked;
    Pesgo1.PeUserInterface.Menu.CustomMenuState[1, 2] = CustomMenuState.UnChecked;
    Pesgo1.PeUserInterface.Menu.CustomMenuState[1, e.SubmenuIndex] = CustomMenuState.Checked;

    _zoomScrolls = (e.SubmenuIndex == 2);
}

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Y Data Memory Layout

The _yData array is a flat interleaved block, subset-major order:

[0       .. 1999999]   subset 0  (red)
[2000000 .. 3999999]   subset 1  (green)
[4000000 .. 5999999]   subset 2  (yellow)
[6000000 .. 7999999]   subset 3  (cyan)

UseDataAtLocation(_yData, 8_000_000) passes the total element count. AppendData(_newY, 150) appends 150 samples per subset per tick, laid out the same way: [s0p0..s0p149 | s1p0..s1p149 | s2.. | s3..].

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Controls

Input	Action
Mouse wheel	Horizontal zoom in / out
Right-click	Context menu
Right-click → Zoom Mode → Stationary	Zoom window fixed (default)
Right-click → Zoom Mode → Scrolling	Zoom window follows data

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Prerequisites

• Visual Studio 2022
• .NET 8 SDK
• Internet connection for NuGet restore
• Discrete GPU recommended (integrated GPU will work but may throttle)

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How to Run

1. Clone this repository
2. Open RealTimeCircularBuffer.sln in Visual Studio 2022
3. Build → Rebuild Solution (NuGet restore is automatic)
4. Press F5
5. Mouse-wheel to zoom in, then right-click → Zoom Mode to switch behaviors

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NuGet Package

References ProEssentials.Chart.Net80.x64.Wpf. Package restore is automatic on build.

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Related Examples

• WPF Delaunay 2D Contour — Example 147
• WPF 3D Delaunay Heightmap — Example 414
• WPF Heatmap Spectrogram — Example 139
• WPF Quickstart — Simple Scientific Graph
• All Examples — GigasoftInc on GitHub
• Full Evaluation Download
• gigasoft.com

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License

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