You can customize the graph plot area of intensity graphs, mixed signal graphs, and waveform graphs by drawing a background image, middle image, or foreground image in the plot area.

Figure 20. Sample Plot Area Drawing depicts an example of a drawing that includes the following:

  • Foreground circles to annotate data points
  • A middle envelope to designate a defined tolerance for the data
Figure 20. Sample Plot Area Drawing
Graph with data points annotated by circles and a blue tolerance envelope.
  • Background image—Resides behind both the plot data and the grid lines. Use the Plot Images:Back property to set this image for mixed signal and waveform graphs.
  • Middle image—Resides between the grid lines and the plot data. Use the Plot Images:Middle property to set this image for mixed signal and waveform graphs.
  • Foreground image—Resides in front of both the plot data and the grid lines. Use the Plot Images:Front property to set this image for intensity, mixed signal, and waveform graphs.

    • The canvas for drawing plot images uses a coordinate system. The origin (0, 0) for the coordinate system is always located at the top, leftmost corner of the graph plot area. By default, the properties you use to create plot images use this coordinate system to place the plot images.

    To draw to the graph plot area of intensity graphs, mixed signal graphs, and waveform graphs, complete the following steps.

    1. Depending on your graph type, use the Plot Images properties of the following classes to create custom grids in the background, create data envelopes in the middle, or use shapes to annotate data points in the foreground of the graph plot area.
      Graph TypeDescription
      Intensity graph
      • Plot Images property class: IntensityGraph
      • Supported images: foreground
      Mixed signal graph
      • Plot Images properties: MixedSignalGraph
      • Supported images: background, middle, foreground
      Waveform graph
      • Plot Images properties: WaveformGraph
      • Supported images: background, middle, foreground
      Note By default, these properties use the top, leftmost corner of the graph plot area as the origin (0, 0) for the drawing.
    2. Optional: If you want to use graph data points as references for drawings, rather than the plot area origin, use the Map XY To Coordinates method to map the graph coordinates of the data points to coordinates on the front panel.
      Note Using splitter bars on the front panel creates multiple panes. When you use Map XY To Coordinates, you must account for the offset of the plot area of the graph from the origin of the owning pane on the front panel.

      Figure 21. Sample Block Diagram: Map XY To Coordinates displays one option you can use to find the correct location in which to draw.

      Figure 21. Sample Block Diagram: Map XY To Coordinates
      Block diagram using Map XY To Coords method to find graph coordinates.
    3. If you resize or copy a graph that has custom annotations or envelopes, rerun the VI to redraw the image.
    4. Optional: To remove a drawing, do either of the following:
      • Wire an empty image to the appropriate property
      • Make the image transparent
    Refer to labview\examples\Controls and Indicators\Graphs and Charts\Graphs - General\Graphs - General.lvproj for examples of using the Plot Images properties and the Map XY To Coordinates method.