Feature/image buffer (#95)

* #93 (#94) Added the result byte array as parameter for polling the arrays. * update write to buffer API * fix spacing --------- Co-authored-by: Hafman08 <Hafman08@users.noreply.github.com>
GowenGit · Sep 4, 2023 · 03191d3 · 03191d3
1 parent 67fdf5c
commit 03191d3
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Showing 5 changed files with 133 additions and 21 deletions.
diff --git a/src/Docnet.Core/Converters/IImageBytesConverter.cs b/src/Docnet.Core/Converters/IImageBytesConverter.cs
@@ -6,6 +6,6 @@ public interface IImageBytesConverter
         /// Input is in B-G-R-A format.
         /// </summary>
         /// <param name="bytes">Image bytes.</param>
-        byte[] Convert(byte[] bytes);
+        void Convert(byte[] bytes);
     }
 }
diff --git a/src/Docnet.Core/Converters/NaiveTransparencyRemover.cs b/src/Docnet.Core/Converters/NaiveTransparencyRemover.cs
@@ -23,7 +23,7 @@ public NaiveTransparencyRemover(byte red, byte green, byte blue)
         /// </summary>
         /// <param name="bytes">Image bytes.</param>
         /// <returns>Same B-G-R-A array with alpha filled with white color.</returns>
-        public byte[] Convert(byte[] bytes)
+        public void Convert(byte[] bytes)
         {
             for (var i = 0; i < bytes.Length / 4; i++)
             {
@@ -39,8 +39,6 @@ public byte[] Convert(byte[] bytes)
                 bytes[j + 2] = (byte)((red * alpha + _backgroundRed * (255 - alpha)) >> 8);
                 bytes[j + 3] = byte.MaxValue;
             }
-
-            return bytes;
         }
     }
 }
diff --git a/src/Docnet.Core/Readers/IPageReader.cs b/src/Docnet.Core/Readers/IPageReader.cs
@@ -70,6 +70,26 @@ public interface IPageReader : IDisposable
         /// </summary>
         byte[] GetImage(IImageBytesConverter converter, RenderFlags flags);
 
+        /// <summary>
+        /// Return a byte representation
+        /// of the page image.
+        /// Byte array is formatted as
+        /// B-G-R-A ordered list.
+        /// Use result if you create the array before
+        /// </summary>
+        void WriteImageToBuffer(RenderFlags flags, byte[] result);
+
+        /// <summary>
+        /// Return a byte representation
+        /// of the page image.
+        /// Byte array is formatted as
+        /// B-G-R-A ordered list. Then it
+        /// applies a predefined byte transformation
+        /// to modify the image.
+        /// Use result if you create the array before
+        /// </summary>
+        void WriteImageToBuffer(IImageBytesConverter converter, RenderFlags flags, byte[] result);
+
         /// <summary>
         /// Renders the page onto a device context.
         /// </summary>

diff --git a/src/Docnet.Core/Readers/PageReader.cs b/src/Docnet.Core/Readers/PageReader.cs
@@ -177,10 +177,39 @@ private static int AdjustToRange(int coord, int range)
         }
 
         /// <inheritdoc />
-        public byte[] GetImage() => GetImage(0);
+        public byte[] GetImage() => WriteImageToBufferInternal(0);
 
         /// <inheritdoc />
-        public byte[] GetImage(RenderFlags flags)
+        public byte[] GetImage(RenderFlags flags) => WriteImageToBufferInternal(flags);
+
+        /// <inheritdoc />
+        public byte[] GetImage(IImageBytesConverter converter) => GetImage(converter, 0);
+
+        /// <inheritdoc />
+        public byte[] GetImage(IImageBytesConverter converter, RenderFlags flags)
+        {
+            var bytes = WriteImageToBufferInternal(flags);
+
+            converter.Convert(bytes);
+
+            return bytes;
+        }
+
+        /// <inheritdoc />
+        public void WriteImageToBuffer(RenderFlags flags, byte[] result)
+        {
+            WriteImageToBufferInternal(flags, result: result);
+        }
+
+        /// <inheritdoc />
+        public void WriteImageToBuffer(IImageBytesConverter converter, RenderFlags flags, byte[] result)
+        {
+            WriteImageToBufferInternal(flags, result: result);
+
+            converter.Convert(result);
+        }
+
+        private byte[] WriteImageToBufferInternal(RenderFlags flags, byte[] result = null)
         {
             lock (DocLib.Lock)
             {
@@ -195,8 +224,14 @@ public byte[] GetImage(RenderFlags flags)
                 }
 
                 var stride = fpdf_view.FPDFBitmapGetStride(bitmap);
+                var length = stride * height;
+
+                result = result ?? new byte[length];
 
-                var result = new byte[stride * height];
+                if (result.Length < length)
+                {
+                    throw new DocnetException($"result array length should be greater or equal than {length}");
+                }
 
                 try
                 {
@@ -234,7 +269,7 @@ public byte[] GetImage(RenderFlags flags)
 
                         var buffer = fpdf_view.FPDFBitmapGetBuffer(bitmap);
 
-                        Marshal.Copy(buffer, result, 0, result.Length);
+                        Marshal.Copy(buffer, result, 0, length);
                     }
                 }
                 catch (Exception ex)
@@ -245,20 +280,9 @@ public byte[] GetImage(RenderFlags flags)
                 {
                     fpdf_view.FPDFBitmapDestroy(bitmap);
                 }
-
-                return result;
             }
-        }
 
-        /// <inheritdoc />
-        public byte[] GetImage(IImageBytesConverter converter) => GetImage(converter, 0);
-
-        /// <inheritdoc />
-        public byte[] GetImage(IImageBytesConverter converter, RenderFlags flags)
-        {
-            var bytes = GetImage(flags);
-
-            return converter.Convert(bytes);
+            return result;
         }
 
         public void RenderDeviceContext(IntPtr deviceContext, Rectangle bounds) =>
@@ -295,4 +319,4 @@ public void Dispose()
             }
         }
     }
-}
+}
diff --git a/src/Docnet.Tests.Integration/PageReaderTests.cs b/src/Docnet.Tests.Integration/PageReaderTests.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Buffers;
 using System.Linq;
 using System.Threading.Tasks;
 using Docnet.Core.Converters;
@@ -339,6 +340,75 @@ public void GetImage_WhenAnnotationsRendered_ShouldHaveDifferentBytes(string fil
             });
         }
 
+        [Theory]
+        [InlineData(Input.FromFile, "Docs/simple_3.pdf", null, 1)]
+        [InlineData(Input.FromFile, "Docs/simple_0.pdf", null, 18)]
+        [InlineData(Input.FromFile, "Docs/protected_0.pdf", "password", 0)]
+        [InlineData(Input.FromBytes, "Docs/simple_3.pdf", null, 1)]
+        [InlineData(Input.FromBytes, "Docs/simple_0.pdf", null, 18)]
+        [InlineData(Input.FromBytes, "Docs/protected_0.pdf", "password", 0)]
+        public void WriteImageToBufferWithResultByteAndNoRenderFlags_WhenCalled_ShouldReturnNonZeroRawByteArray(Input type, string filePath, string password, int pageIndex)
+        {
+            ExecuteForDocument(type, filePath, password, 1, pageIndex, pageReader =>
+            {
+
+                var height = pageReader.GetPageHeight();
+                var stride = 4 * pageReader.GetPageWidth(); //4 is for B-G-R-A format
+
+                var bytes = new byte[stride * height];
+
+                pageReader.WriteImageToBuffer(0, bytes);
+
+                Assert.True(bytes.Length > 0);
+                Assert.NotEmpty(bytes.Where(x => x != 0));
+            });
+        }
+
+        [Theory]
+        [InlineData(Input.FromFile, "Docs/simple_3.pdf", null, 1)]
+        [InlineData(Input.FromFile, "Docs/simple_0.pdf", null, 18)]
+        [InlineData(Input.FromFile, "Docs/protected_0.pdf", "password", 0)]
+        [InlineData(Input.FromBytes, "Docs/simple_3.pdf", null, 1)]
+        [InlineData(Input.FromBytes, "Docs/simple_0.pdf", null, 18)]
+        [InlineData(Input.FromBytes, "Docs/protected_0.pdf", "password", 0)]
+        public void WriteImageToBufferWithResultByteWithLowerLengthAndNoRenderFlags_WhenCalled_ShouldReturnException(Input type, string filePath, string password, int pageIndex)
+        {
+            ExecuteForDocument(type, filePath, password, 1, pageIndex, pageReader =>
+            {
+                var height = pageReader.GetPageHeight();
+                var stride = 4 * pageReader.GetPageWidth(); //4 is for B-G-R-A format
+
+                var bytes = new byte[stride * height - 1];
+
+
+                Assert.Throws<DocnetException>(() => pageReader.WriteImageToBuffer(0, bytes));
+            });
+        }
+
+        [Theory]
+        [InlineData(Input.FromFile, "Docs/simple_3.pdf", null, 1)]
+        [InlineData(Input.FromFile, "Docs/simple_0.pdf", null, 18)]
+        [InlineData(Input.FromFile, "Docs/protected_0.pdf", "password", 0)]
+        [InlineData(Input.FromBytes, "Docs/simple_3.pdf", null, 1)]
+        [InlineData(Input.FromBytes, "Docs/simple_0.pdf", null, 18)]
+        [InlineData(Input.FromBytes, "Docs/protected_0.pdf", "password", 0)]
+        public void WriteImageToBufferWithResultFromArrayPoolNoRenderFlags_WhenCalled_ShouldReturnNonZeroRawByteArray(Input type, string filePath, string password, int pageIndex)
+        {
+            ExecuteForDocument(type, filePath, password, 1, pageIndex, pageReader =>
+            {
+                var height = pageReader.GetPageHeight();
+                var stride = 4 * pageReader.GetPageWidth(); //4 is for B-G-R-A format
+                var arrayPool = ArrayPool<byte>.Shared;
+                var bytes = arrayPool.Rent(stride * height);
+
+                pageReader.WriteImageToBuffer(0, bytes);
+
+                Assert.True(bytes.Length > 0);
+                Assert.NotEmpty(bytes.Where(x => x != 0));
+                arrayPool.Return(bytes);
+            });
+        }
+
         private static int GetNonZeroByteCount(Input type, string filePath, LibFixture fixture)
         {
             using (var reader = fixture.GetDocReader(type, filePath, null, 1000, 1000))