Cookbook: demoinstrate Heatmap.CellAlignment

resolves #3806

CHANGELOG.md

@@ -9,7 +9,8 @@
 * Rendering: Added `Plot.RenderManager.RemoveAction<T>()` for easily removing specific actions from the render sequence
 * SVG: Fixed issue where plots would have a black outline in some browsers (#3709) @sproott @KennyTK @aespitia
 * Controls: Add "open in new window" to right-click menu for WinForms and WPF controls (#3730)
-* Cookbook: Demonstrated how to achieve a frameless heatmap (#3828) @itsmygam3
+* Cookbook: Demonstrate how to achieve a frameless heatmap (#3828) @itsmygam3
+* Cookbook: Demonstrate `Heatmap.CellAlignment` to achieve heatmaps that do not extend past their boundaries (#3806) @FengQingYangDad
 
 ## ScottPlot 5.0.34
 _Published on [NuGet](https://www.nuget.org/profiles/ScottPlot) on 2024-05-05_

src/ScottPlot5/ScottPlot5 Cookbook/Recipes/PlotTypes/Heatmap.cs

@@ -275,4 +275,26 @@ public override void Execute()
             myPlot.Axes.Margins(0, 0);
         }
     }
+
+    public class HeatmapCellAlignment : RecipeBase
+    {
+        public override string Name => "HeatmapCellAlignment";
+        public override string Description => "Heatmap cells are aligned in their centers by default. " +
+            "This means that the bottom left cell will be centered at (0, 0), and its lower left corner will be " +
+            "to the lower left of the origin. Setting sell alignment to lower left causes the lower left of the " +
+            "heatmap to be exactly at (0, 0).";
+
+        [Test]
+        public override void Execute()
+        {
+            double[,] data = {
+                { 1, 2, 3 },
+                { 4, 5, 6 },
+                { 7, 8, 9 },
+            };
+
+            var hm = myPlot.Add.Heatmap(data);
+            hm.CellAlignment = Alignment.LowerLeft;
+        }
+    }
 }