Merge pull request #420 from MeVitae/writer-text-mode

Add `SetTextRenderingMode` method to `PdfPageBuilder`

src/UglyToad.PdfPig.Core/TextRenderingMode.cs

@@ -1,4 +1,4 @@
-namespace UglyToad.PdfPig.Graphics.Core
+namespace UglyToad.PdfPig.Core
 {
     /// <summary>
     /// The text rendering mode determines whether showing text causes glyph outlines to be stroked, filled, used as a clipping boundary,
@@ -45,4 +45,4 @@
         /// </summary>
         NeitherClip = 7
     }
-}
+}

src/UglyToad.PdfPig.Tests/Writer/PdfDocumentBuilderTests.cs

@@ -189,6 +189,62 @@
             }
         }
 
+        [Fact]
+        public void CanWriteSinglePageInvisibleHelloWorld()
+        {
+            var builder = new PdfDocumentBuilder();
+
+            PdfPageBuilder page = builder.AddPage(PageSize.A4);
+
+            PdfDocumentBuilder.AddedFont font = builder.AddStandard14Font(Standard14Font.Helvetica);
+
+            page.SetTextRenderingMode(TextRenderingMode.Neither);
+
+            page.AddText("Hello World!", 12, new PdfPoint(25, 520), font);
+
+            var b = builder.Build();
+
+            WriteFile(nameof(CanWriteSinglePageInvisibleHelloWorld), b);
+
+            using (var document = PdfDocument.Open(b))
+            {
+                var page1 = document.GetPage(1);
+
+                Assert.Equal(new[] { "Hello", "World!" }, page1.GetWords().Select(x => x.Text));
+            }
+        }
+
+        [Fact]
+        public void CanWriteSinglePageMixedRenderingMode()
+        {
+            var builder = new PdfDocumentBuilder();
+
+            PdfPageBuilder page = builder.AddPage(PageSize.A4);
+
+            PdfDocumentBuilder.AddedFont font = builder.AddStandard14Font(Standard14Font.Helvetica);
+
+            page.AddText("Hello World!", 12, new PdfPoint(25, 520), font);
+
+            page.SetTextRenderingMode(TextRenderingMode.Neither);
+
+            page.AddText("Invisible!", 12, new PdfPoint(25, 500), font);
+
+            page.SetTextRenderingMode(TextRenderingMode.Fill);
+
+            page.AddText("Filled again!", 12, new PdfPoint(25, 480), font);
+
+            var b = builder.Build();
+
+            WriteFile(nameof(CanWriteSinglePageMixedRenderingMode), b);
+
+            using (var document = PdfDocument.Open(b))
+            {
+                var page1 = document.GetPage(1);
+
+                Assert.Equal(new[] { "Hello", "World!", "Invisible!", "Filled", "again!" }, page1.GetWords().Select(x => x.Text));
+            }
+        }
+
         [Fact]
         public void CanWriteSinglePageHelloWorld()
         {

src/UglyToad.PdfPig/Graphics/Core/RenderingModeExtensions.cs

@@ -1,5 +1,7 @@
 namespace UglyToad.PdfPig.Graphics.Core
 {
+    using UglyToad.PdfPig.Core;
+
     internal static class RenderingModeExtensions
     {
         public static bool IsFill(this TextRenderingMode mode)
@@ -26,4 +28,4 @@
                    || mode == TextRenderingMode.NeitherClip;
         }
     }
-}
+}

src/UglyToad.PdfPig/Graphics/Operations/TextState/SetTextRenderingMode.cs

@@ -1,6 +1,7 @@
 namespace UglyToad.PdfPig.Graphics.Operations.TextState
 {
     using System.IO;
+    using PdfPig.Core;
     using Core;
 
     /// <inheritdoc />
@@ -22,6 +23,14 @@
         /// </summary>
         public TextRenderingMode Mode { get; }
 
+        /// <summary>
+        /// Create a new <see cref="SetTextRenderingMode"/>.
+        /// </summary>
+        public SetTextRenderingMode(TextRenderingMode mode)
+        {
+            Mode = mode;
+        }
+
         /// <summary>
         /// Create a new <see cref="SetTextRenderingMode"/>.
         /// </summary>
@@ -48,4 +57,4 @@
             return $"{Mode} {Symbol}";
         }
     }
-}
+}

src/UglyToad.PdfPig/Writer/PdfPageBuilder.cs

@@ -340,6 +340,17 @@
             return letters;
         }
 
+        /// <summary>
+        /// Set the text rendering mode. This will apply to all future calls to AddText until called again.
+        ///
+        /// To insert invisible text, for example output of OCR, use <c>TextRenderingMode.Neither</c>.
+        /// </summary>
+        /// <param name="mode">Text rendering mode to set.</param>
+        public void SetTextRenderingMode(TextRenderingMode mode)
+        {
+            currentStream.Add(new SetTextRenderingMode(mode));
+        }
+
         private NameToken GetAddedFont(PdfDocumentBuilder.AddedFont font)
         {
             if (!documentFonts.TryGetValue(font.Id, out NameToken value))