add lzw filter support

2025-10-15 19:54:52 +08:00 · 2019-05-18 12:25:47 +01:00
parent 9a8becde3e
commit f3bc3a37b9
4 changed files with 310 additions and 1 deletions
--- a/src/UglyToad.PdfPig.Tests/Filters/BitStreamTests.cs
+++ b/src/UglyToad.PdfPig.Tests/Filters/BitStreamTests.cs
@@ -0,0 +1,84 @@
+namespace UglyToad.PdfPig.Tests.Filters
+{
+    using PdfPig.Filters;
+    using Xunit;
+
+    public class BitStreamTests
+    {
+        private readonly byte[] data = {
+            0b00101001,
+            0b11011100,
+            0b01000110,
+            0b11111011,
+            0b00101010,
+            0b11010111,
+            0b10010001,
+            0b11011011,
+            0b11110000,
+            0b00010111,
+            0b10101011
+        };
+
+        [Fact]
+        public void GetNumbers()
+        {
+            var bitStream = new BitStream(data);
+
+            var first = bitStream.Get(9);
+            var second = bitStream.Get(9);
+            var third = bitStream.Get(11);
+            var fourth = bitStream.Get(5);
+            var fifth = bitStream.Get(17);
+
+            Assert.Equal(0b001010011, first);
+            Assert.Equal(0b101110001, second);
+            Assert.Equal(0b00011011111, third);
+            Assert.Equal(0b01100, fourth);
+            Assert.Equal(0b10101011010111100, fifth);
+        }
+
+        [Fact]
+        public void GetNumbersCrossingBoundaries()
+        {
+            var bitStream = new BitStream(data);
+
+            var first = bitStream.Get(13);
+            var second = bitStream.Get(15);
+            var third = bitStream.Get(13);
+
+            Assert.Equal(0b0010100111011, first);
+            Assert.Equal(0b100010001101111, second);
+            Assert.Equal(0b1011001010101, third);
+        }
+
+        [Fact]
+        public void GetNumbersUntilOffsetResets()
+        {
+            var bitStream = new BitStream(data);
+
+            var first = bitStream.Get(9);
+            var second = bitStream.Get(9);
+            var third = bitStream.Get(9);
+            var fourth = bitStream.Get(9);
+            var fifth = bitStream.Get(9);
+            var sixth = bitStream.Get(9);
+            var seventh = bitStream.Get(9);
+            var eighth = bitStream.Get(9);
+            var ninth = bitStream.Get(9);
+
+            var end = bitStream.Get(7);
+
+            Assert.Equal(0b001010011, first);
+            Assert.Equal(0b101110001, second);
+            Assert.Equal(0b000110111, third);
+            Assert.Equal(0b110110010, fourth);
+            Assert.Equal(0b101011010, fifth);
+            Assert.Equal(0b111100100, sixth);
+            Assert.Equal(0b011101101, seventh);
+            Assert.Equal(0b111110000, eighth);
+            Assert.Equal(0b000101111, ninth);
+
+            Assert.Equal(0b0101011, end);
+        }
+    }
+}