From 18c4a7fef050d81df501b1dec3ac6b3081eb7e2f Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Tue, 14 Aug 2018 10:40:33 +0100
Subject: [PATCH] Fix 1 bit bmp decoding and add extra test images.

---
 src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs  |   4 +---
 .../Formats/Bmp/BmpDecoderTests.cs            |   5 +----
 tests/ImageSharp.Tests/TestImages.cs          |  20 +++++++++++++++++-
 tests/Images/Input/Bmp/pal1.bmp               | Bin 0 -> 1086 bytes
 tests/Images/Input/Bmp/pal1p1.bmp             | Bin 0 -> 1082 bytes
 tests/Images/Input/Bmp/pal4.bmp               | Bin 0 -> 4198 bytes
 6 files changed, 21 insertions(+), 8 deletions(-)
 create mode 100644 tests/Images/Input/Bmp/pal1.bmp
 create mode 100644 tests/Images/Input/Bmp/pal1p1.bmp
 create mode 100644 tests/Images/Input/Bmp/pal4.bmp

diff --git a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
index 128ae08542..d67beb0368 100644
--- a/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
+++ b/src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs
@@ -373,11 +373,9 @@ private void ReadRgbPalette<TPixel>(Buffer2D<TPixel> pixels, byte[] colors, int
                     for (int x = 0; x < arrayWidth; x++)
                     {
                         int colOffset = x * ppb;
-
-                        for (int shift = 0; shift < ppb && (x + shift) < width; shift++)
+                        for (int shift = 0, newX = colOffset; shift < ppb && newX < width; shift++, newX++)
                         {
                             int colorIndex = ((rowSpan[offset] >> (8 - bits - (shift * bits))) & mask) * 4;
-                            int newX = colOffset + shift;
 
                             // Stored in b-> g-> r order.
                             rgba.Bgr = Unsafe.As<byte, Bgr24>(ref colors[colorIndex]);
diff --git a/tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs
index 09c3d1545f..5f2de9f51e 100644
--- a/tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs
@@ -17,10 +17,7 @@ public class BmpDecoderTests
     {
         public const PixelTypes CommonNonDefaultPixelTypes = PixelTypes.Rgba32 | PixelTypes.Bgra32 | PixelTypes.RgbaVector;
 
-        public static readonly string[] AllBmpFiles =
-        {
-            Car, F, NegHeight, CoreHeader, V5Header, RLE, RLEInverted, Bit8, Bit8Inverted, Bit16, Bit16Inverted
-        };
+        public static readonly string[] AllBmpFiles = All;
 
         public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
         new TheoryData<string, int, int, PixelResolutionUnit>
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index 142b923ed1..5eb70117e3 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -165,12 +165,30 @@ public static class Bmp
             public const string V5Header = "Bmp/BITMAPV5HEADER.bmp";
             public const string RLE = "Bmp/RunLengthEncoded.bmp";
             public const string RLEInverted = "Bmp/RunLengthEncoded-inverted.bmp";
+            public const string Bit1 = "Bmp/pal1.bmp";
+            public const string Bit1Pal1 = "Bmp/pal1p1.bmp";
+            public const string Bit4 = "Bmp/pal4.bmp";
             public const string Bit8 = "Bmp/test8.bmp";
             public const string Bit8Inverted = "Bmp/test8-inverted.bmp";
             public const string Bit16 = "Bmp/test16.bmp";
             public const string Bit16Inverted = "Bmp/test16-inverted.bmp";
 
-            public static readonly string[] All = { Car, F, NegHeight, CoreHeader, V5Header, RLE, RLEInverted, Bit8, Bit8Inverted, Bit16, Bit16Inverted };
+            public static readonly string[] All
+            = {
+                Car,
+                F,
+                NegHeight,
+                CoreHeader,
+                V5Header, RLE,
+                RLEInverted,
+                Bit1,
+                Bit1Pal1,
+                Bit4,
+                Bit8,
+                Bit8Inverted,
+                Bit16,
+                Bit16Inverted
+            };
         }
 
         public static class Gif
diff --git a/tests/Images/Input/Bmp/pal1.bmp b/tests/Images/Input/Bmp/pal1.bmp
new file mode 100644
index 0000000000000000000000000000000000000000..4776f827786ad054037baa9ae27e211332a5c596
GIT binary patch
literal 1086
zcmbW0&uZI15XQ%nY(#59jS;9P7a2;cQ+vxPm{dOI(8H2bsB4<%ka{V?PvD+hY$#?8
z$piEv3I)GFjzW2Y)VJi2vi)XON=yGx=$PGs{ruZ+XLfaXbl{Q10p=$dDaHt+g`WiU
z{(U<fyCSnO2Dx=?ms*SwIa*_ikv9>7$a`h=w#_+oKc7*q&vL|{`AAd5{BjBY#PVJx
z8GM%I8od5H@96*bkNEu7e~I|jAJ#g{|Kab%;;#{P{pg^r-_LbMl*QybP5rh!s{0q|
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zcW&(e;92k8@e%g#uHZkRd)7askok#hkJ1-rw|bgwQ**gquW^3^vvd1Jk(wR<gZXgv
zcmjUE;k$148Tb$~c=!*)5dNX)J@$Xz#rauhUVj`;JE(sydh(t+FTS|NY1Q!58P48r
zv7hMekoNikpKl*HTE8&2QA~$8kLcrpxfv<EYI6xapK<>`Xdf>RPZjsmLkTaT+rag2
zuq^LSGL5SwQ6(Xd5a1<n4`)^n(q5qO4YZ~IQC#y)W`2AEzFm1ql7JTueK>D;r4-me
zc-;AK{_3JM><>J_^K1A!e|4Nfw><V_euF;PeY|m1metQZ`(EK3wZBTQulYj`(g%o|
W|MaNg6J^S8tXu!JX71{1bN=t4fKZ13

literal 0
HcmV?d00001

diff --git a/tests/Images/Input/Bmp/pal1p1.bmp b/tests/Images/Input/Bmp/pal1p1.bmp
new file mode 100644
index 0000000000000000000000000000000000000000..b68321c4c1e216498056df1221362442f1735404
GIT binary patch
literal 1082
xcmZ?rwPIla11lh@0mSt{>;S}!KnMmvd0}n{hKex!cL1pv1*0J_8UiCV1OO{s1F--A

literal 0
HcmV?d00001

diff --git a/tests/Images/Input/Bmp/pal4.bmp b/tests/Images/Input/Bmp/pal4.bmp
new file mode 100644
index 0000000000000000000000000000000000000000..7fd36303caea2b0aaf12469efee44ecd3cdbb5fa
GIT binary patch
literal 4198
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literal 0
HcmV?d00001