Add Plot Profile command

src/ImageJCsharp.App/Form1.cs

@@ -68,6 +68,7 @@ private void BuildUi()
         var analyze = AddMenu(menu, "&Analyze");
         AddActiveImageItem(analyze, "&Measure", MeasureCurrentRoi, Keys.Control | Keys.M);
         AddActiveImageItem(analyze, "&Histogram", ShowHistogram, shortcutKeyDisplayString: "H");
+        AddActiveImageItem(analyze, "Plot &Profile", ShowProfile);
         AddActiveImageItem(analyze, "Set &Scale...", SetScale);
         AddItem(analyze, "Set &Measurements...", SetMeasurements);
         AddResultsItem(analyze, "Export &Results...", ExportResults, Keys.Control | Keys.E);
@@ -445,6 +446,21 @@ private void ShowHistogram()
         form.Show(this);
     }
 
+    private void ShowProfile()
+    {
+        if (_document is null)
+        {
+            return;
+        }
+
+        var profile = _roi is null
+            ? Profile.HorizontalCenterLine(_document.Image)
+            : Profile.HorizontalCenterLine(_document.Image, _roi.Value);
+
+        var form = new ProfileForm(_document.DisplayName, profile);
+        form.Show(this);
+    }
+
     private void ExportResults()
     {
         using var dialog = new SaveFileDialog

src/ImageJCsharp.App/ProfileForm.cs

@@ -0,0 +1,63 @@
+using System;
+using System.Drawing;
+using System.Linq;
+using System.Windows.Forms;
+using ImageJCsharp.Core;
+
+namespace ImageJCsharp.App;
+
+public sealed class ProfileForm : Form
+{
+    private readonly ProfileResult _profile;
+    private readonly Panel _plotPanel = new Panel();
+
+    public ProfileForm(string imageName, ProfileResult profile)
+    {
+        _profile = profile ?? throw new ArgumentNullException(nameof(profile));
+        Text = "Plot Profile of " + imageName;
+        Width = 640;
+        Height = 360;
+        BuildUi();
+    }
+
+    private void BuildUi()
+    {
+        _plotPanel.Dock = DockStyle.Fill;
+        _plotPanel.BackColor = Color.White;
+        _plotPanel.Paint += PlotPanelPaint;
+        Controls.Add(_plotPanel);
+    }
+
+    private void PlotPanelPaint(object? sender, PaintEventArgs e)
+    {
+        e.Graphics.Clear(Color.White);
+        if (_profile.Values.Length == 0)
+        {
+            return;
+        }
+
+        var bounds = _plotPanel.ClientRectangle;
+        bounds.Inflate(-32, -24);
+        e.Graphics.DrawRectangle(Pens.LightGray, bounds);
+
+        var max = Math.Max(1, (int)_profile.Values.Max());
+        PointF Map(int index, ushort value)
+        {
+            var x = bounds.Left + (bounds.Width * (index / (float)Math.Max(1, _profile.Values.Length - 1)));
+            var y = bounds.Bottom - (bounds.Height * (value / (float)max));
+            return new PointF(x, y);
+        }
+
+        if (_profile.Values.Length == 1)
+        {
+            var point = Map(0, _profile.Values[0]);
+            e.Graphics.FillEllipse(Brushes.RoyalBlue, point.X - 2, point.Y - 2, 4, 4);
+            return;
+        }
+
+        var points = _profile.Values
+            .Select((value, index) => Map(index, value))
+            .ToArray();
+        e.Graphics.DrawLines(Pens.RoyalBlue, points);
+    }
+}

src/ImageJCsharp.Core/Profile.cs

@@ -0,0 +1,53 @@
+using System;
+using System.Linq;
+
+namespace ImageJCsharp.Core;
+
+public sealed class ProfileResult
+{
+    public ProfileResult(ushort[] values)
+    {
+        Values = values?.ToArray() ?? throw new ArgumentNullException(nameof(values));
+    }
+
+    public ushort[] Values { get; }
+}
+
+public static class Profile
+{
+    public static ProfileResult HorizontalCenterLine(GrayImage image)
+    {
+        if (image is null)
+        {
+            throw new ArgumentNullException(nameof(image));
+        }
+
+        return HorizontalCenterLine(image, new RectRoi(0, 0, image.Width, image.Height));
+    }
+
+    public static ProfileResult HorizontalCenterLine(GrayImage image, RectRoi roi)
+    {
+        if (image is null)
+        {
+            throw new ArgumentNullException(nameof(image));
+        }
+
+        var startX = Math.Max(0, roi.X);
+        var endX = Math.Min(image.Width, roi.Right);
+        var startY = Math.Max(0, roi.Y);
+        var endY = Math.Min(image.Height, roi.Bottom);
+        if (startX >= endX || startY >= endY)
+        {
+            throw new ArgumentException("ROI does not intersect the image.", nameof(roi));
+        }
+
+        var y = startY + ((endY - startY) / 2);
+        var values = new ushort[endX - startX];
+        for (var x = startX; x < endX; x++)
+        {
+            values[x - startX] = image[x, y];
+        }
+
+        return new ProfileResult(values);
+    }
+}

tests/ImageJCsharp.Core.Tests/CoreImageTests.cs

@@ -240,4 +240,35 @@ public void HistogramRejectsValuesOutsideEightBitRange()
 
         Assert.Contains("8-bit", exception.Message);
     }
+
+    [Fact]
+    public void ProfileUsesHorizontalCenterLineOfImage()
+    {
+        var image = GrayImage.FromPixels(3, 3, new ushort[]
+        {
+            1, 2, 3,
+            4, 5, 6,
+            7, 8, 9
+        });
+
+        var profile = Profile.HorizontalCenterLine(image);
+
+        Assert.Equal(new ushort[] { 4, 5, 6 }, profile.Values);
+    }
+
+    [Fact]
+    public void ProfileUsesHorizontalCenterLineOfRectRoi()
+    {
+        var image = GrayImage.FromPixels(4, 4, new ushort[]
+        {
+            1, 2, 3, 4,
+            5, 6, 7, 8,
+            9, 10, 11, 12,
+            13, 14, 15, 16
+        });
+
+        var profile = Profile.HorizontalCenterLine(image, new RectRoi(1, 1, 2, 2));
+
+        Assert.Equal(new ushort[] { 10, 11 }, profile.Values);
+    }
 }