Trend¶

Real-Time Trend Visualization¶

The Trend EWO is a full-featured chart widget for real-time and historical data visualization. It supports multiple curves with independent Y-axes, crosshair inspection, zoom/pan, statistical analysis, and a tabular data view — all rendered in a custom-painted C++ component optimized for continuous data streams.

Trend statistics demo — Animated demo of the Trend widget with statistics panel, showing real-time data and per-curve metrics.

Crosshair hover — The crosshair tracking mouse position, showing real-time values for each curve at the selected timestamp.

Trend table demo — Animated demo switching between chart view and table view.

Trend overview — The Trend widget showing multiple curves with real-time data, legend, and time axis.

Key Features¶

Multi-Curve Display¶

Multiple trends plotted simultaneously with independent colors, line widths, and visibility toggles. Curves can share a Y-axis or be grouped by unit.

Interactive Crosshair¶

Hover to inspect exact values at any timestamp — a vertical crosshair follows the mouse with tooltips showing per-curve values.

Statistical Analysis Panel¶

A collapsible statistics panel shows MIN, MAX, AVG, and other aggregations for the visible time range:

Trend statistics — Statistics panel below the chart showing per-curve metrics: minimum, maximum, average, and current value.

Trend Analysis¶

Tabular Data View¶

Switch between chart and table view to inspect raw data values:

Trend table — Tabular view showing timestamped data for all curves in a sortable, scrollable table.

Auto-Scroll Mode¶

Real-time mode with a configurable time window that automatically scrolls to keep the latest data visible.

Zoom & Pan¶

Mouse wheel zoom on both axes, click-drag to pan, and double-click to reset view. Zoom can be restricted to X-axis only for time-based analysis.

Main Properties¶

Property	Type	Description
`Color_Background`	`QVariant`	Chart background color
`Color_Grid`	`QVariant`	Grid line color
`Color_Axis`	`QVariant`	Axis line and label color
`Color_Text`	`QVariant`	General text color
`Color_Crosshair`	`QVariant`	Crosshair line color
`Color_TooltipBackground`	`QVariant`	Tooltip background
`Grid_Visible`	`bool`	Show grid lines
`Grid_HorizontalLines`	`int`	Number of horizontal grid lines
`Grid_VerticalLines`	`int`	Number of vertical grid lines
`Axis_AutoScale`	`bool`	Auto-fit Y-axis to data range
`Axis_YMin`	`double`	Fixed Y-axis minimum
`Axis_YMax`	`double`	Fixed Y-axis maximum
`UI_CrosshairEnabled`	`bool`	Enable crosshair inspection
`UI_ZoomEnabled`	`bool`	Enable mouse wheel zoom
`UI_PanEnabled`	`bool`	Enable click-drag panning
`Line_DefaultWidth`	`int`	Default curve line width
`Line_ShowPoints`	`bool`	Show data point markers
`AutoScroll_Enabled`	`bool`	Real-time auto-scroll mode
`AutoScroll_WindowSeconds`	`int`	Visible time window (seconds)
`Statistics_Visible`	`bool`	Show statistics panel
`Statistics_Height`	`int`	Statistics panel height
`Table_Visible`	`bool`	Show tabular data view
`Legend_Position`	`int`	Legend placement
`Focus_Mode`	`bool`	Highlight hovered curve
`Measurement_Mode`	`bool`	Enable measurement cursors

Note: This widget exposes 66 configurable properties. The table above covers only a selection — dozens more are available for fine-tuned control over colors, fonts, margins, axis formatting, and behavior.

Usage Example in WinCC OA¶

CTRL Initialization Script¶

main()
{
  // Configure trend display
  EWO.AutoScroll_Enabled = true;
  EWO.AutoScroll_WindowSeconds = 3600; // 1 hour window
  EWO.Statistics_Visible = true;
  EWO.UI_CrosshairEnabled = true;

  // Add curves
  EWO.setGraphData(curvesJson);

  // Set time range
  time tEnd = getCurrentTime();
  time tStart = tEnd - 3600;
  EWO.setGraphTimeRange(tStart, tEnd);
}

// Handle range change (user zoom/pan)
void rangeChanged(long startMs, long endMs)
{
  // Request historical data for new range
  EWO.requestHistoricalData(startMs, endMs);
}

Available Signals¶

Signal	Parameters	Description
`pointHovered`	`trendName`, `timestamp`, `value`	Crosshair over a data point
`rangeChanged`	`startMs`, `endMs`	Visible time range changed
`trendClicked`	`trendName`, `timestamp`, `value`	Click on a curve
`legendClicked`	`trendName`, `visible`	Legend item toggled
`legendHovered`	`trendName`	Mouse over legend item
`requestHistoricalData`	`startMs`, `endMs`	Request data for new range
`statisticsVisibilityChanged`	`visible`	Stats panel toggled
`tableViewVisibilityChanged`	`visible`	Table view toggled