add clipping rectangles

Author: brettfo

src/IxMilia.Pdf.Test/IxMilia.Pdf.Test.csproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>net8.0</TargetFramework>
-    <LangVersion>10</LangVersion>
+    <LangVersion>11</LangVersion>
     <Nullable>enable</Nullable>
   </PropertyGroup>
 

src/IxMilia.Pdf.Test/PdfWriterTests.cs

@@ -532,5 +532,55 @@ 400.00 0.00 0.00 400.00 100.00 100.00 cm
 ";
             AssertPageContains(page, expectedImageData);
         }
+
+        [Fact]
+        public void ClipTest()
+        {
+            var path = new PdfPath();
+            var builder = new PdfPathBuilder()
+            {
+                new PdfLine(
+                    new PdfPoint(PdfMeasurement.Zero, PageHeight / 2.0), // left middle
+                    new PdfPoint(PageWidth / 2.0, PageHeight)), // top middle
+                new PdfLine(
+                    new PdfPoint(PageWidth / 2.0, PageHeight), // top middle
+                    new PdfPoint(PageWidth, PageHeight / 2.0)), // right middle
+                new PdfLine(
+                    new PdfPoint(PageWidth, PageHeight / 2.0), // right middle
+                    new PdfPoint(PageWidth / 2.0, PdfMeasurement.Zero)), // bottom middle
+                new PdfLine(
+                    new PdfPoint(PageWidth / 2.0, PdfMeasurement.Zero), // bottom middle
+                    new PdfPoint(PdfMeasurement.Zero, PageHeight / 2.0)), // left middle
+            };
+
+            path.Commands.Add(new PdfClip(
+                new PdfMeasurement(0.25, PdfMeasurementType.Inch),
+                new PdfMeasurement(0.25, PdfMeasurementType.Inch),
+                PageWidth - new PdfMeasurement(0.5, PdfMeasurementType.Inch),
+                PageHeight - new PdfMeasurement(0.5, PdfMeasurementType.Inch)));
+            path.Commands.AddRange(builder.ToPath().Commands);
+
+            var page = PdfPage.NewLetter();
+            page.Items.Add(path);
+            var file = new PdfFile();
+            file.Pages.Add(page);
+
+            // first 4 lines are the clipping rectable; remaining are the lines
+            AssertPageContains(page, """
+                n
+                18.00 18.00 576.00 756.00 re
+                W
+                n
+                0.00 396.00 m
+                306.00 792.00 l
+                306.00 792.00 m
+                612.00 396.00 l
+                612.00 396.00 m
+                306.00 0.00 l
+                306.00 0.00 m
+                0.00 396.00 l
+                S
+                """);
+        }
     }
 }

src/IxMilia.Pdf/PdfClip.cs

@@ -0,0 +1,28 @@
+using IxMilia.Pdf.Extensions;
+
+namespace IxMilia.Pdf
+{
+    public class PdfClip : PdfPathCommand
+    {
+        public PdfMeasurement X { get; set; }
+        public PdfMeasurement Y { get; set; }
+        public PdfMeasurement Width { get; set; }
+        public PdfMeasurement Height { get; set; }
+
+        public PdfClip(PdfMeasurement x, PdfMeasurement y, PdfMeasurement width, PdfMeasurement height)
+        {
+            X = x;
+            Y = y;
+            Width = width;
+            Height = height;
+        }
+
+        internal override void Write(PdfStreamWriter writer)
+        {
+            writer.WriteLine("n"); // end previous path
+            writer.WriteLine($"{X.AsPoints().AsFixed()} {Y.AsPoints().AsFixed()} {Width.AsPoints().AsFixed()} {Height.AsPoints().AsFixed()} re");
+            writer.WriteLine("W"); // clip
+            writer.WriteLine("n"); // end this path
+        }
+    }
+}

src/IxMilia.Pdf/PdfPath.cs

@@ -4,7 +4,7 @@ namespace IxMilia.Pdf
 {
     public class PdfPath : PdfStreamItem
     {
-        public IList<PdfPathCommand> Commands { get; } = new List<PdfPathCommand>();
+        public List<PdfPathCommand> Commands { get; } = new List<PdfPathCommand>();
 
         internal override void Write(PdfStreamWriter writer)
         {