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Fix marker skipping bug when decoding certain images

af/merge-core
James Jackson-South 9 years ago
parent
acb7982a88
commit
8b9c0af322
2 changed files with 50 additions and 56 deletions
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  1. 102
      src/ImageSharp/Formats/Png/PngDecoderCore.cs
  2. 4
      tests/ImageSharp.Tests/FileTestBase.cs

102
src/ImageSharp/Formats/Png/PngDecoderCore.cs
View File

@ -267,41 +267,35 @@ namespace ImageSharp.Formats
/// <param name="source">The bytes to convert from. Cannot be null.</param>
/// <param name="bytesPerScanline">The number of bytes per scanline</param>
/// <param name="bits">The number of bits per value.</param>
/// <returns>The resulting <see cref="T:byte[]"/> array. Is never null.</returns>
/// <returns>The resulting <see cref="Span{Byte}"/> array. Is never null.</returns>
/// <exception cref="System.ArgumentNullException"><paramref name="source"/> is null.</exception>
/// <exception cref="System.ArgumentException"><paramref name="bits"/> is less than or equals than zero.</exception>
private static byte[] ToArrayByBitsLength(byte[] source, int bytesPerScanline, int bits)
private static Span<byte> ToArrayByBitsLength(Span<byte> source, int bytesPerScanline, int bits)
{
Guard.NotNull(source, nameof(source));
Guard.MustBeGreaterThan(bits, 0, nameof(bits));
byte[] result;
if (bits < 8)
if (bits >= 8)
{
result = new byte[bytesPerScanline * 8 / bits];
int mask = 0xFF >> (8 - bits);
int resultOffset = 0;
return source;
}
// ReSharper disable once ForCanBeConvertedToForeach
// First byte is the marker so skip.
for (int i = 1; i < bytesPerScanline; i++)
byte[] result = new byte[bytesPerScanline * 8 / bits];
int mask = 0xFF >> (8 - bits);
int resultOffset = 0;
for (int i = 0; i < bytesPerScanline; i++)
{
byte b = source[i];
for (int shift = 0; shift < 8; shift += bits)
{
byte b = source[i];
for (int shift = 0; shift < 8; shift += bits)
{
int colorIndex = (b >> (8 - bits - shift)) & mask;
int colorIndex = (b >> (8 - bits - shift)) & mask;
result[resultOffset] = (byte)colorIndex;
result[resultOffset] = (byte)colorIndex;
resultOffset++;
}
resultOffset++;
}
}
else
{
result = source;
}
return result;
}
@ -584,13 +578,15 @@ namespace ImageSharp.Formats
{
var color = default(TPixel);
Span<TPixel> rowSpan = pixels.GetRowSpan(this.currentRow);
// Trim the first marker byte from the buffer
var scanlineBuffer = new Span<byte>(defilteredScanline, 1);
switch (this.pngColorType)
{
case PngColorType.Grayscale:
int factor = 255 / ((int)Math.Pow(2, this.header.BitDepth) - 1);
byte[] newScanline1 = ToArrayByBitsLength(defilteredScanline, this.bytesPerScanline, this.header.BitDepth);
Span<byte> newScanline1 = ToArrayByBitsLength(scanlineBuffer, this.bytesPerScanline, this.header.BitDepth);
for (int x = 0; x < this.header.Width; x++)
{
byte intensity = (byte)(newScanline1[x] * factor);
@ -604,10 +600,10 @@ namespace ImageSharp.Formats
for (int x = 0; x < this.header.Width; x++)
{
int offset = 1 + (x * this.bytesPerPixel);
int offset = x * this.bytesPerPixel;
byte intensity = defilteredScanline[offset];
byte alpha = defilteredScanline[offset + this.bytesPerSample];
byte intensity = scanlineBuffer[offset];
byte alpha = scanlineBuffer[offset + this.bytesPerSample];
color.PackFromRgba32(new Rgba32(intensity, intensity, intensity, alpha));
rowSpan[x] = color;
@ -617,7 +613,7 @@ namespace ImageSharp.Formats
case PngColorType.Palette:
this.ProcessScanlineFromPalette(defilteredScanline, rowSpan);
this.ProcessScanlineFromPalette(scanlineBuffer, rowSpan);
break;
@ -682,10 +678,10 @@ namespace ImageSharp.Formats
/// <typeparam name="TPixel">The type of pixel we are expanding to</typeparam>
/// <param name="defilteredScanline">The scanline</param>
/// <param name="row">Thecurrent output image row</param>
private void ProcessScanlineFromPalette<TPixel>(byte[] defilteredScanline, Span<TPixel> row)
private void ProcessScanlineFromPalette<TPixel>(Span<byte> defilteredScanline, Span<TPixel> row)
where TPixel : struct, IPixel<TPixel>
{
byte[] newScanline = ToArrayByBitsLength(defilteredScanline, this.bytesPerScanline, this.header.BitDepth);
Span<byte> newScanline = ToArrayByBitsLength(defilteredScanline, this.bytesPerScanline, this.header.BitDepth);
byte[] pal = this.palette;
var color = default(TPixel);
@ -737,15 +733,15 @@ namespace ImageSharp.Formats
{
var color = default(TPixel);
// Trim the first marker byte from the buffer
var scanlineBuffer = new Span<byte>(defilteredScanline, 1);
switch (this.pngColorType)
{
case PngColorType.Grayscale:
int factor = 255 / ((int)Math.Pow(2, this.header.BitDepth) - 1);
byte[] newScanline1 = ToArrayByBitsLength(
defilteredScanline,
this.bytesPerScanline,
this.header.BitDepth);
for (int x = pixelOffset, o = 1; x < this.header.Width; x += increment, o++)
Span<byte> newScanline1 = ToArrayByBitsLength(scanlineBuffer, this.bytesPerScanline, this.header.BitDepth);
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
{
byte intensity = (byte)(newScanline1[o] * factor);
color.PackFromRgba32(new Rgba32(intensity, intensity, intensity));
@ -756,10 +752,10 @@ namespace ImageSharp.Formats
case PngColorType.GrayscaleWithAlpha:
for (int x = pixelOffset, o = 1; x < this.header.Width; x += increment, o += this.bytesPerPixel)
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += this.bytesPerPixel)
{
byte intensity = defilteredScanline[o];
byte alpha = defilteredScanline[o + this.bytesPerSample];
byte intensity = scanlineBuffer[o];
byte alpha = scanlineBuffer[o + this.bytesPerSample];
color.PackFromRgba32(new Rgba32(intensity, intensity, intensity, alpha));
rowSpan[x] = color;
}
@ -768,14 +764,14 @@ namespace ImageSharp.Formats
case PngColorType.Palette:
byte[] newScanline = ToArrayByBitsLength(defilteredScanline, this.bytesPerScanline, this.header.BitDepth);
Span<byte> newScanline = ToArrayByBitsLength(scanlineBuffer, this.bytesPerScanline, this.header.BitDepth);
var rgba = default(Rgba32);
if (this.paletteAlpha != null && this.paletteAlpha.Length > 0)
{
// If the alpha palette is not null and has one or more entries, this means, that the image contains an alpha
// channel and we should try to read it.
for (int x = pixelOffset, o = 1; x < this.header.Width; x += increment, o++)
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
{
int index = newScanline[o];
int offset = index * 3;
@ -791,7 +787,7 @@ namespace ImageSharp.Formats
{
rgba.A = 255;
for (int x = pixelOffset, o = 1; x < this.header.Width; x += increment, o++)
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
{
int index = newScanline[o];
int offset = index * 3;
@ -815,10 +811,8 @@ namespace ImageSharp.Formats
using (var compressed = new Buffer<byte>(length))
{
// TODO: Should we use pack from vector here instead?
this.From16BitTo8Bit(new Span<byte>(defilteredScanline, 1), compressed, length);
for (int x = pixelOffset, o = 0;
x < this.header.Width;
x += increment, o += 3)
this.From16BitTo8Bit(scanlineBuffer, compressed, length);
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 3)
{
rgba.R = compressed[o];
rgba.G = compressed[o + 1];
@ -831,11 +825,11 @@ namespace ImageSharp.Formats
}
else
{
for (int x = pixelOffset, o = 1; x < this.header.Width; x += increment, o += this.bytesPerPixel)
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += this.bytesPerPixel)
{
rgba.R = defilteredScanline[o];
rgba.G = defilteredScanline[o + this.bytesPerSample];
rgba.B = defilteredScanline[o + (2 * this.bytesPerSample)];
rgba.R = scanlineBuffer[o];
rgba.G = scanlineBuffer[o + this.bytesPerSample];
rgba.B = scanlineBuffer[o + (2 * this.bytesPerSample)];
color.PackFromRgba32(rgba);
rowSpan[x] = color;
@ -852,7 +846,7 @@ namespace ImageSharp.Formats
using (var compressed = new Buffer<byte>(length))
{
// TODO: Should we use pack from vector here instead?
this.From16BitTo8Bit(new Span<byte>(defilteredScanline, 1), compressed, length);
this.From16BitTo8Bit(scanlineBuffer, compressed, length);
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 4)
{
rgba.R = compressed[o];
@ -867,12 +861,12 @@ namespace ImageSharp.Formats
}
else
{
for (int x = pixelOffset, o = 1; x < this.header.Width; x += increment, o += this.bytesPerPixel)
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += this.bytesPerPixel)
{
rgba.R = defilteredScanline[o];
rgba.G = defilteredScanline[o + this.bytesPerSample];
rgba.B = defilteredScanline[o + (2 * this.bytesPerSample)];
rgba.A = defilteredScanline[o + (3 * this.bytesPerSample)];
rgba.R = scanlineBuffer[o];
rgba.G = scanlineBuffer[o + this.bytesPerSample];
rgba.B = scanlineBuffer[o + (2 * this.bytesPerSample)];
rgba.A = scanlineBuffer[o + (3 * this.bytesPerSample)];
color.PackFromRgba32(rgba);
rowSpan[x] = color;

4
tests/ImageSharp.Tests/FileTestBase.cs
View File

@ -79,8 +79,8 @@ namespace ImageSharp.Tests
// TestFile.Create(TestImages.Bmp.NegHeight), // Perf: Enable for local testing only
TestFile.Create(TestImages.Png.Splash),
// TestFile.Create(TestImages.Png.Cross), // Perf: Enable for local testing only
// TestFile.Create(TestImages.Png.ChunkLength1), // Perf: Enable for local testing only
// TestFile.Create(TestImages.Png.ChunkLength2), // Perf: Enable for local testing only
// TestFile.Create(TestImages.Png.Bad.ChunkLength1), // Perf: Enable for local testing only
// TestFile.Create(TestImages.Png.Bad.ChunkLength2), // Perf: Enable for local testing only
// TestFile.Create(TestImages.Png.Powerpoint), // Perf: Enable for local testing only
// TestFile.Create(TestImages.Png.Blur), // Perf: Enable for local testing only
// TestFile.Create(TestImages.Png.Indexed), // Perf: Enable for local testing only

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