Plot: add figure and data border (ScottPlot#5024)

* Plot: Use the Render() method of the Sync object to uniformly call RenderManager.Render().

* PixelRect: Added a conversion method from SKRectI to PixelRect.

* Plot: Update rendering boundaries

The boundary of the Render(IMultiplot, SKSurface) method has been changed from LocalClipBounds to DeviceClipBounds to ensure that the rendered content fits within the device's clipping range

* Plot: Add border styles and rendering features (ScottPlot#4854)

* Plot: FigureBorder and DataBorder

* Update CHANGELOG.md

---------

Co-authored-by: Scott W Harden <swharden@gmail.com>

Author: CoderPM2011

CHANGELOG.md

@@ -23,6 +23,7 @@ _Not yet on NuGet..._
 * Legend: Added the ability to customize default marker shape for legend items (#5005, #5006) @aespitia
 * Pie: Added a `Radius` property (instead of forcing `1.0`) and improved rendering and SVG export (#5020) @CoderPM2011 @aespitia
 * Data Streamer: Added `FillY` and related properties so streaming plots support filled ares (#4948, #5023) @manaruto @Stephanowicz
+* Plot: Added `FigureBorder` and `DataBorder` for displaying custom borders on plots and subplots (#4854, #5024) @CoderPM2011
 
 ## ScottPlot 5.0.55
 _Published on [NuGet](https://www.nuget.org/profiles/ScottPlot) on 2025-03-22_

src/ScottPlot5/ScottPlot5 Cookbook/Recipes/General/Styling.cs

@@ -354,6 +354,36 @@ public override void Execute()
         }
     }
 
+    public class PlotBorder : RecipeBase
+    {
+        public override string Name => "Plot Border";
+        public override string Description => "Plots can be assigned borders to draw around the figure or data area.";
+
+        [Test]
+        public override void Execute()
+        {
+            myPlot.Add.Signal(Generate.Sin());
+            myPlot.Add.Signal(Generate.Cos());
+
+            myPlot.FigureBorder = new()
+            {
+                Color = Colors.Magenta,
+                Width = 3,
+                Pattern = LinePattern.Dotted,
+            };
+
+            myPlot.DataBorder = new()
+            {
+                Color = Colors.Green,
+                Width = 3,
+                Pattern = LinePattern.DenselyDashed,
+            };
+
+            // the hide axis frame lines so our custom border is the only one
+            myPlot.Axes.Frame(false);
+        }
+    }
+
     public class SetFontName : RecipeBase
     {
         public override string Name => "Set Font by Name";

src/ScottPlot5/ScottPlot5/Interfaces/IMultiplot.cs

@@ -65,7 +65,7 @@ public static Image Render(this IMultiplot multiplot, int width, int height)
     /// </summary>
     public static void Render(this IMultiplot multiplot, SKSurface surface)
     {
-        multiplot.Render(surface.Canvas, surface.Canvas.LocalClipBounds.ToPixelRect());
+        multiplot.Render(surface.Canvas, surface.Canvas.DeviceClipBounds.ToPixelRect());
     }
 
     /// <summary>

src/ScottPlot5/ScottPlot5/Plot.cs

@@ -23,6 +23,9 @@ public class Plot : IDisposable
     /// </summary>
     public BackgroundStyle DataBackground = new() { Color = Colors.Transparent };
 
+    public LineStyle FigureBorder { get; set; } = LineStyle.None;
+    public LineStyle DataBorder { get; set; } = LineStyle.None;
+
     public IZoomRectangle ZoomRectangle { get; set; }
     public double ScaleFactor { get => ScaleFactorF; set => ScaleFactorF = (float)value; }
     internal float ScaleFactorF { get; private set; } = 1.0f;
@@ -253,7 +256,7 @@ public void Render(SKCanvas canvas, PixelRect rect)
     /// </summary>
     public void Render(SKSurface surface)
     {
-        RenderManager.Render(surface.Canvas, surface.Canvas.LocalClipBounds.ToPixelRect());
+        Render(surface.Canvas, surface.Canvas.LocalClipBounds.ToPixelRect());
     }
 
     public Image GetImage(int width, int height)

src/ScottPlot5/ScottPlot5/Primitives/LineStyle.cs

@@ -126,11 +126,14 @@ public void Render(SKCanvas canvas, PixelLine line, SKPaint paint)
         Drawing.DrawLine(canvas, paint, line, this);
     }
 
-    public void Render(SKCanvas canvas, PixelRect rect, SKPaint paint)
+    public void Render(SKCanvas canvas, PixelRect rect, SKPaint paint, bool contract = false)
     {
         if (!IsVisible)
             return;
 
+        if (contract)
+            rect = rect.Contract(Width / 2);
+
         Pixel[] pixels =
         [
             rect.BottomLeft,

src/ScottPlot5/ScottPlot5/Primitives/PixelRect.cs

@@ -422,4 +422,9 @@ public static PixelRect ToPixelRect(this SKRect rect)
     {
         return new PixelRect(rect.Left, rect.Right, rect.Bottom, rect.Top);
     }
+
+    public static PixelRect ToPixelRect(this SKRectI rect)
+    {
+        return new PixelRect(rect.Left, rect.Right, rect.Bottom, rect.Top);
+    }
 }

src/ScottPlot5/ScottPlot5/Rendering/RenderActions/RenderBorders.cs

@@ -0,0 +1,10 @@
+namespace ScottPlot.Rendering.RenderActions;
+
+public class RenderBorders : IRenderAction
+{
+    public void Render(RenderPack rp)
+    {
+        rp.Plot.FigureBorder.Render(rp.Canvas, rp.FigureRect, rp.Paint, contract: true);
+        rp.Plot.DataBorder.Render(rp.Canvas, rp.DataRect, rp.Paint);
+    }
+}

src/ScottPlot5/ScottPlot5/Rendering/RenderManager.cs

@@ -27,6 +27,7 @@ public class RenderManager(Plot plot)
         new RenderActions.RenderGridsAbovePlottables(),
         new RenderActions.RenderLegends(),
         new RenderActions.RenderPanels(),
+        new RenderActions.RenderBorders(),
         new RenderActions.RenderZoomRectangle(),
         new RenderActions.SyncGLPlottables(),
         new RenderActions.RenderPlottablesLast(),