Hello mael15,
Sorry for the delay in my response. I was recently able to look at the issue you have raised with another colleague, and I have another suggestion for you. Hopefully it will be a little more helpful.
A possiblity would be for you to maintain your own internal bitmap, and draw the plots to this bitmap, instead of to the internal, private, bitmap the ScatterGraph maintains. This would allow you to use the PlotXY method instead of the eventually slower PlotXYAppend method. By never clearing your internal bitmap, the PlotXY method will be sufficient to fake a PlotXYAppend method with an infinite history capacity.
The implementation of this would be something similar to the following:
- Create your own internal bitmap, and graphis object from this bitmap using Graphics.FromImage()
- Handle the BeforeDrawPlot event
-- in this event, create a ComponentDrawArgs object from your graphics object and the Bounds property of the EventArgs
-- call ScatterPlot.Draw(args) with your newly created ComponentDrawArgs
-- call e.Cancel, signifying that you will be responsible for drawing the plot
- Handle the AfterDrawPlotArea event
-- in this event, call e.Graphics.DrawImage(), passing in your own internal bitmap that now has a plot drawn to it
There are of course many other considerations you may wish to make, such as resizing the internal bitmap if the graph size changes, and perhaps checking a boolean flag set in the PlotDataChanged event of the graph - so that you only redraw if the plot data has been updated.
The relevant pieces of code can be found below, and a complete example (minus the aforementioned sanity checking) can be found attached:
private Bitmap bmp;
private Graphics graphics;
public Form1()
{
InitializeComponent();
bmp = new Bitmap(GetPlotGraphicsWidth(scatterGraph1, 0), GetPlotGraphicsHeight(scatterGraph1, 0));
graphics = Graphics.FromImage(bmp);
}
private void scatterGraph1_BeforeDrawPlot(object sender, BeforeDrawXYPlotEventArgs e)
{
ComponentDrawArgs args = new ComponentDrawArgs(graphics, e.Bounds);
scatterPlot1.Draw(args);
e.Cancel = true;
}
private void scatterGraph1_AfterDrawPlotArea(object sender, AfterDrawEventArgs e)
{
e.Graphics.DrawImage(bmp, 0f, 0f);
}
I haven't been able to extensively test the performance of this, but it looks to be faster than PlotXYAppend with a very large history capacity. Please let me know if it does not meet your performance requirements, or other requirements I may not have thought of.
Thanks!
NickB
National Instruments
