Cookbook: add recipe showing frameless heatmap

[itsmygam3]

Question: For further processing, I need to save the heatmap plot as an image, but when trying to save, white fields are always formed at the edges. How can I fix the code so that I can get an image containing only a graph of a heatmap without extraneous elements?

UPD. At the moment, I found out that the DataBackground field from BackgroundStyle class is responsible for this frame. I was able to change its color, but I need to completely exclude it.

ScottPlot Version: 5.0.34

Code Sample:

double[,] data = { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };

formsPlot1.Plot.HideGrid();
formsPlot1.Plot.Layout.Frameless();
formsPlot1.Plot.Add.Heatmap(data);
formsPlot1.Plot.SaveJpeg("bord.jpg", 400, 400);

panel1.Controls.Add(formsPlot1);

[swharden]

Thanks for reporting this @itsmygam3! I suspect this issue relates to axes taking several pixels even though frameless is enabled, but an not 100% sure yet. I'll take a look at this eventually, but if someone from the open source community is able to take a closer look first and creates a PR to fix the problem, I will be happy to review and merge it in good time 👍

[swharden]

I confirmed this is a heatmap issue (not an axis padding issue) because setting the data area background color shows the heatmap is not filling the whole data area

double[,] data = { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };

ScottPlot.Plot plot = new();
plot.DataBackground.Color = ScottPlot.Colors.Magenta;
plot.Add.Heatmap(data);
plot.Layout.Frameless();
plot.SaveJpeg("bord.jpg", 400, 400).LaunchFile();

[swharden]

Actually, I figured it out! Plots have a little bit of padding (margins) around the data area by deafault. Disabling this gets the functionality you're seeking:

double[,] data = { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };

ScottPlot.Plot plot = new();
plot.DataBackground.Color = ScottPlot.Colors.Magenta;
plot.Axes.Margins(0, 0); // <------ SET MARGIN TO ZERO
plot.Add.Heatmap(data);
plot.Layout.Frameless();
plot.SaveJpeg("bord.jpg", 400, 400).LaunchFile();

I'll leave this issue open to track adding an example to the cookbook