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Remove Marshalling code during Color Translation, reduce allocations (#…
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…9330)

* replace heap allocs with stackallocs, get rid of unnecessary marshalling code

* use Span<float> in the call chain and stackalloc small temp arrays of 3 floats

* improve codegen/performance further (not included in benchmark)

* remove redundant array initializations to zero
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@h3xds1nz
h3xds1nz authored Oct 19, 2024
1 parent b340d5c commit e733ef2
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Showing 2 changed files with 32 additions and 62 deletions.
15 changes: 5 additions & 10 deletions src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/Color.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -431,7 +431,7 @@ public float[] GetNativeColorValues()
c2.context = new ColorContext(PixelFormats.Bgra32);

ColorTransform colorTransform = new ColorTransform(c1.context, c2.context);
float[] sRGBValue = new float[3];
Span<float> sRGBValue = stackalloc float[3];

colorTransform.Translate(c1.nativeColorValue, sRGBValue);

Expand Down Expand Up @@ -550,7 +550,7 @@ public static Color Add(Color color1, Color color2)
c2.context = new ColorContext(PixelFormats.Bgra32);

ColorTransform colorTransform = new ColorTransform(c1.context, c2.context);
float[] sRGBValue = new float[3];
Span<float> sRGBValue = stackalloc float[3];

colorTransform.Translate(c1.nativeColorValue, sRGBValue);

Expand Down Expand Up @@ -1097,7 +1097,7 @@ private void ComputeScRgbValues()
c2.context = new ColorContext(PixelFormats.Bgra32);

ColorTransform colorTransform = new ColorTransform(this.context, c2.context);
float[] scRGBValue = new float[3];
Span<float> scRGBValue = stackalloc float[3];

colorTransform.Translate(this.nativeColorValue, scRGBValue);

Expand All @@ -1110,16 +1110,11 @@ private void ComputeScRgbValues()
private void ComputeNativeValues(int numChannels)
{
this.nativeColorValue = new float[numChannels];
if (this.nativeColorValue.GetLength(0) > 0)
if (this.nativeColorValue.Length > 0)
{
float[] sRGBValue = new float[3];

sRGBValue[0] = this.sRgbColor.r / 255.0f;
sRGBValue[1] = this.sRgbColor.g / 255.0f;
sRGBValue[2] = this.sRgbColor.b / 255.0f;
Span<float> sRGBValue = [this.sRgbColor.r / 255.0f, this.sRgbColor.g / 255.0f, this.sRgbColor.b / 255.0f];

ColorTransform colorTransform = new ColorTransform(this.context, new ColorContext(PixelFormats.Bgra32));

colorTransform.Translate(sRGBValue, this.nativeColorValue);
}
}
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79 changes: 27 additions & 52 deletions src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/ColorTransform.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -106,52 +106,30 @@ internal ColorTransform(SafeMILHandle bitmapSource, ColorContext srcContext, Col

#region Internal Methods

internal void Translate(float[] srcValue, float[] dstValue)
internal unsafe void Translate(Span<float> srcValue, Span<float> dstValue)
{
// 3. create Win32 unmanaged profile handle from memory source profile using OpenColorProfileW
IntPtr[] pProfiles = new IntPtr[2];
// Transform colors using TranslateColors
const UInt32 NumColors = 1;

IntPtr paInputColors = IntPtr.Zero;
IntPtr paOutputColors = IntPtr.Zero;
// There's no SkipLocalsInit, will be all zeroes
long* paInputColors = stackalloc long[64 / sizeof(long)];
long* paOutputColors = stackalloc long[64 / sizeof(long)];

try
{
// 6. transform colors using TranslateColors
UInt32 numColors = 1;
long inputColor = ICM2Color(srcValue);
paInputColors = Marshal.AllocHGlobal(64);

Marshal.WriteInt64(paInputColors, inputColor);

paOutputColors = Marshal.AllocHGlobal(64);
long outputColor = 0;

Marshal.WriteInt64(paOutputColors, outputColor);

_colorTransformHelper.TranslateColors(
(IntPtr)paInputColors,
numColors,
_inputColorType,
(IntPtr)paOutputColors,
_outputColorType
);
long inputColor = ICM2Color(srcValue);
paInputColors[0] = inputColor;

outputColor = Marshal.ReadInt64(paOutputColors);
for (int i = 0; i < dstValue.GetLength(0); i++)
{
UInt32 result = 0x0000ffff & (UInt32)(outputColor >> (16 * i));
float a = (result & 0x7fffffff) / (float)(0x10000);
_colorTransformHelper.TranslateColors((nint)paInputColors, NumColors, _inputColorType, (nint)paOutputColors, _outputColorType);

if (result < 0)
dstValue[i] = -a;
else
dstValue[i] = a;
}
}
finally
long outputColor = paOutputColors[0];
for (int i = 0; i < dstValue.Length; i++)
{
Marshal.FreeHGlobal(paInputColors);
Marshal.FreeHGlobal(paOutputColors);
UInt32 result = 0x0000ffff & (UInt32)(outputColor >> (16 * i));
float a = (result & 0x7fffffff) / (float)0x10000;

if (result < 0)
dstValue[i] = -a;
else
dstValue[i] = a;
}
}

Expand All @@ -170,21 +148,20 @@ private void InitializeICM()
_colorTransformHelper = new ColorTransformHelper();
}

private long ICM2Color(float[] srcValue)
private long ICM2Color(Span<float> srcValue)
{
long colorValue;

if (srcValue.GetLength(0) < 3 || srcValue.GetLength(0) > 8)
if (srcValue.Length < 3 || srcValue.Length > 8)
{
throw new NotSupportedException(); // Only support color spaces with 3,4,5,6,7,8 channels
}

if (srcValue.GetLength(0) <= 4)
if (srcValue.Length <= 4)
{
UInt16[] channel = new UInt16[4];
Span<UInt16> channel = stackalloc UInt16[4];

channel[0] = channel[1] = channel[2] = channel[3] = 0;
for (int i = 0; i < srcValue.GetLength(0); i++)
for (int i = 0; i < srcValue.Length; i++)
{
if (srcValue[i] >= 1.0)// this fails for values above 1.0 and below 0.0
{
Expand All @@ -204,11 +181,9 @@ private long ICM2Color(float[] srcValue)
}
else
{
byte[] channel = new byte[8];
Span<byte> channel = stackalloc byte[8];

channel[0] = channel[1] = channel[2] = channel[3] =
channel[4] = channel[5] = channel[6] = channel[7] = 0;
for (int i = 0; i < srcValue.GetLength(0); i++)
for (int i = 0; i < srcValue.Length; i++)
{
if (srcValue[i] >= 1.0)// this fails for values above 1.0 and below 0.0
{
Expand Down Expand Up @@ -244,9 +219,9 @@ private long ICM2Color(float[] srcValue)

private ColorTransformHelper _colorTransformHelper;

private UInt32 _inputColorType;
private readonly UInt32 _inputColorType;

private UInt32 _outputColorType;
private readonly UInt32 _outputColorType;

#endregion
}
Expand Down

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