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Fix #2467 bmp encoding issue for BMP with 1 bit per pixel and more pixels per row than divisible by 8. #2471

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merged 2 commits into from
Jun 8, 2023
Merged

Fix #2467 bmp encoding issue for BMP with 1 bit per pixel and more pixels per row than divisible by 8. #2471

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b4ad3c3
Added test that shows the issue
synercoder Jun 7, 2023
b29cd27
Fixed bug in Write1BitPixelData that wrote too many bits to the byte
synercoder Jun 7, 2023
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2 changes: 1 addition & 1 deletion src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -668,7 +668,7 @@ private void Write1BitPixelData<TPixel>(Configuration configuration, Stream stre

if (quantizedPixelRow.Length % 8 != 0)
{
int startIdx = quantizedPixelRow.Length - 7;
int startIdx = quantizedPixelRow.Length - (quantizedPixelRow.Length % 8);
endIdx = quantizedPixelRow.Length;
Write1BitPalette(stream, startIdx, endIdx, quantizedPixelRow);
}
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24 changes: 24 additions & 0 deletions tests/ImageSharp.Tests/Formats/Bmp/BmpEncoderTests.cs
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Expand Up @@ -370,6 +370,30 @@ public void Encode_WorksWithDiscontiguousBuffers<TPixel>(TestImageProvider<TPixe
TestBmpEncoderCore(provider, bitsPerPixel);
}

[Theory]
[WithFile(BlackWhitePalletDataMatrix, PixelTypes.Rgb24, BmpBitsPerPixel.Pixel1)]
public void Encode_Issue2467<TPixel>(TestImageProvider<TPixel> provider, BmpBitsPerPixel bitsPerPixel)
where TPixel : unmanaged, IPixel<TPixel>
{
using Image<TPixel> image = provider.GetImage();

using var reencodedStream = new MemoryStream();
var encoder = new BmpEncoder
{
BitsPerPixel = bitsPerPixel,
SupportTransparency = false,
Quantizer = KnownQuantizers.Octree
};
image.SaveAsBmp(reencodedStream, encoder);
reencodedStream.Seek(0, SeekOrigin.Begin);

using Image<TPixel> reencodedImage = Image.Load<TPixel>(reencodedStream);

reencodedImage.DebugSave(provider);

reencodedImage.CompareToOriginal(provider);
}

private static void TestBmpEncoderCore<TPixel>(
TestImageProvider<TPixel> provider,
BmpBitsPerPixel bitsPerPixel,
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2 changes: 2 additions & 0 deletions tests/ImageSharp.Tests/TestImages.cs
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Expand Up @@ -407,6 +407,8 @@ public static class Bmp
public const string Rgba321010102 = "Bmp/rgba32-1010102.bmp";
public const string RgbaAlphaBitfields = "Bmp/rgba32abf.bmp";

public const string BlackWhitePalletDataMatrix = "Bmp/bit1datamatrix.bmp";

public static readonly string[] BitFields =
{
Rgb32bfdef,
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3 changes: 3 additions & 0 deletions tests/Images/Input/Bmp/bit1datamatrix.bmp
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