mirror of https://github.com/SixLabors/ImageSharp
Vicente Penades
8 years ago
11 changed files with 6706 additions and 575 deletions
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// Copyright (c) Six Labors and contributors.
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// Copyright (c) Six Labors and contributors.
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// Licensed under the Apache License, Version 2.0.
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// Licensed under the Apache License, Version 2.0.
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using System; |
using System; |
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using System.Numerics; |
using System.Numerics; |
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using System.Runtime.CompilerServices; |
using System.Runtime.CompilerServices; |
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namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders |
namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders |
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{ |
{ |
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/// <summary>
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/// <summary>
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/// Collection of Porter Duff alpha blending functions applying an the 'Over' composition model.
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/// Collection of Porter Duff alpha blending functions applying an the 'Over' composition model.
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/// </summary>
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/// </summary>
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/// <remarks>
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/// <remarks>
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/// These functions are designed to be a general solution for all color cases,
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/// These functions are designed to be a general solution for all color cases,
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/// that is, they take in account the alpha value of both the backdrop
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/// that is, they take in account the alpha value of both the backdrop
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/// and source, and there's no need to alpha-premultiply neither the backdrop
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/// and source, and there's no need to alpha-premultiply neither the backdrop
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/// nor the source.
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/// nor the source.
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/// Note there are faster functions for when the backdrop color is known
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/// Note there are faster functions for when the backdrop color is known
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/// to be opaque
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/// to be opaque
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/// </remarks>
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/// </remarks>
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internal static partial class PorterDuffFunctions |
internal static partial class PorterDuffFunctions |
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{ |
{ |
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/// <summary>
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/// <summary>
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/// Source over backdrop
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/// Source over backdrop
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/// </summary>
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/// </summary>
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/// <param name="backdrop">Backdrop color</param>
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/// <param name="backdrop">Backdrop color</param>
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/// <param name="source">Source color</param>
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/// <param name="source">Source color</param>
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/// <param name="opacity">Opacity applied to Source Alpha</param>
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/// <returns>Output color</returns>
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/// <returns>Output color</returns>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
public static Vector4 Normal(Vector4 backdrop, Vector4 source) |
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public static Vector4 Normal(Vector4 backdrop, Vector4 source, float opacity) |
{ |
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{ |
return source; |
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source.W *= opacity; |
} |
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return Compose(backdrop, source, source); |
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} |
/// <summary>
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/// Source multiplied by backdrop
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/// <summary>
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/// </summary>
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/// Source multiplied by backdrop
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/// <param name="backdrop">Backdrop color</param>
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/// </summary>
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/// <param name="source">Source color</param>
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/// <param name="backdrop">Backdrop color</param>
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/// <returns>Output color</returns>
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/// <param name="source">Source color</param>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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/// <param name="opacity">Opacity applied to Source Alpha</param>
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public static Vector4 Multiply(Vector4 backdrop, Vector4 source) |
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/// <returns>Output color</returns>
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{ |
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
return backdrop * source; |
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public static Vector4 Multiply(Vector4 backdrop, Vector4 source, float opacity) |
} |
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{ |
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source.W *= opacity; |
/// <summary>
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return Compose(backdrop, source, backdrop * source); |
/// Source added to backdrop
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} |
/// </summary>
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/// <param name="backdrop">Backdrop color</param>
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/// <summary>
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/// <param name="source">Source color</param>
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/// Source added to backdrop
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/// <returns>Output color</returns>
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/// </summary>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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/// <param name="backdrop">Backdrop color</param>
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public static Vector4 Add(Vector4 backdrop, Vector4 source) |
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/// <param name="source">Source color</param>
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{ |
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/// <param name="opacity">Opacity applied to Source Alpha</param>
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return Vector4.Min(Vector4.One, backdrop + source); |
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/// <returns>Output color</returns>
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} |
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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public static Vector4 Add(Vector4 backdrop, Vector4 source, float opacity) |
/// <summary>
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{ |
/// Source subtracted from backdrop
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source.W *= opacity; |
/// </summary>
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return Compose(backdrop, source, Vector4.Min(Vector4.One, backdrop + source)); |
/// <param name="backdrop">Backdrop color</param>
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} |
/// <param name="source">Source color</param>
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/// <returns>Output color</returns>
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/// <summary>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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/// Source subtracted from backdrop
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public static Vector4 Subtract(Vector4 backdrop, Vector4 source) |
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/// </summary>
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{ |
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/// <param name="backdrop">Backdrop color</param>
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return Vector4.Max(Vector4.Zero, backdrop - source); |
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/// <param name="source">Source color</param>
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} |
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/// <param name="opacity">Opacity applied to Source Alpha</param>
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/// <returns>Output color</returns>
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/// <summary>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
/// Complement of source multiplied by the complement of backdrop
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public static Vector4 Subtract(Vector4 backdrop, Vector4 source, float opacity) |
/// </summary>
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{ |
/// <param name="backdrop">Backdrop color</param>
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source.W *= opacity; |
/// <param name="source">Source color</param>
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return Compose(backdrop, source, Vector4.Max(Vector4.Zero, backdrop - source)); |
/// <returns>Output color</returns>
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} |
[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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public static Vector4 Screen(Vector4 backdrop, Vector4 source) |
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/// <summary>
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{ |
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/// Complement of source multiplied by the complement of backdrop
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return Vector4.One - ((Vector4.One - backdrop) * (Vector4.One - source)); |
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/// </summary>
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} |
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/// <param name="backdrop">Backdrop color</param>
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/// <param name="source">Source color</param>
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/// <summary>
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/// <param name="opacity">Opacity applied to Source Alpha</param>
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/// Per element, chooses the smallest value of source and backdrop
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/// <returns>Output color</returns>
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/// </summary>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
/// <param name="backdrop">Backdrop color</param>
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public static Vector4 Screen(Vector4 backdrop, Vector4 source, float opacity) |
/// <param name="source">Source color</param>
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{ |
/// <returns>Output color</returns>
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source.W *= opacity; |
[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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return Compose(backdrop, source, Vector4.One - ((Vector4.One - backdrop) * (Vector4.One - source))); |
public static Vector4 Darken(Vector4 backdrop, Vector4 source) |
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} |
{ |
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return Vector4.Min(backdrop, source); |
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/// <summary>
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} |
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/// Per element, chooses the smallest value of source and backdrop
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/// </summary>
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/// <summary>
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/// <param name="backdrop">Backdrop color</param>
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/// Per element, chooses the largest value of source and backdrop
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/// <param name="source">Source color</param>
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/// </summary>
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/// <param name="opacity">Opacity applied to Source Alpha</param>
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/// <param name="backdrop">Backdrop color</param>
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/// <returns>Output color</returns>
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/// <param name="source">Source color</param>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
/// <returns>Output color</returns>
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public static Vector4 Darken(Vector4 backdrop, Vector4 source, float opacity) |
[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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{ |
public static Vector4 Lighten(Vector4 backdrop, Vector4 source) |
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source.W *= opacity; |
{ |
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return Compose(backdrop, source, Vector4.Min(backdrop, source)); |
return Vector4.Max(backdrop, source); |
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} |
} |
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/// <summary>
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/// <summary>
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/// Per element, chooses the largest value of source and backdrop
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/// Overlays source over backdrop
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/// </summary>
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/// </summary>
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/// <param name="backdrop">Backdrop color</param>
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/// <param name="backdrop">Backdrop color</param>
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/// <param name="source">Source color</param>
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/// <param name="source">Source color</param>
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/// <param name="opacity">Opacity applied to Source Alpha</param>
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/// <returns>Output color</returns>
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/// <returns>Output color</returns>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
public static Vector4 Overlay(Vector4 backdrop, Vector4 source) |
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public static Vector4 Lighten(Vector4 backdrop, Vector4 source, float opacity) |
{ |
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{ |
float cr = OverlayValueFunction(backdrop.X, source.X); |
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source.W *= opacity; |
float cg = OverlayValueFunction(backdrop.Y, source.Y); |
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return Compose(backdrop, source, Vector4.Max(backdrop, source)); |
float cb = OverlayValueFunction(backdrop.Z, source.Z); |
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} |
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return Vector4.Min(Vector4.One, new Vector4(cr, cg, cb, 0)); |
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/// <summary>
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} |
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/// Overlays source over backdrop
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/// </summary>
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/// <summary>
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/// <param name="backdrop">Backdrop color</param>
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/// Hard light effect
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/// <param name="source">Source color</param>
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/// </summary>
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/// <param name="opacity">Opacity applied to Source Alpha</param>
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/// <param name="backdrop">Backdrop color</param>
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/// <returns>Output color</returns>
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/// <param name="source">Source color</param>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
/// <returns>Output color</returns>
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public static Vector4 Overlay(Vector4 backdrop, Vector4 source, float opacity) |
[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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{ |
public static Vector4 HardLight(Vector4 backdrop, Vector4 source) |
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source.W *= opacity; |
{ |
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float cr = OverlayValueFunction(backdrop.X, source.X); |
float cr = OverlayValueFunction(source.X, backdrop.X); |
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float cg = OverlayValueFunction(backdrop.Y, source.Y); |
float cg = OverlayValueFunction(source.Y, backdrop.Y); |
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float cb = OverlayValueFunction(backdrop.Z, source.Z); |
float cb = OverlayValueFunction(source.Z, backdrop.Z); |
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return Compose(backdrop, source, Vector4.Min(Vector4.One, new Vector4(cr, cg, cb, 0))); |
return Vector4.Min(Vector4.One, new Vector4(cr, cg, cb, 0)); |
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} |
} |
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/// <summary>
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/// <summary>
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/// Hard light effect
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/// Helper function for Overlay andHardLight modes
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/// </summary>
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/// </summary>
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/// <param name="backdrop">Backdrop color</param>
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/// <param name="backdrop">Backdrop color element</param>
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/// <param name="source">Source color</param>
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/// <param name="source">Source color element</param>
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/// <param name="opacity">Opacity applied to Source Alpha</param>
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/// <returns>Overlay value</returns>
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/// <returns>Output color</returns>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
private static float OverlayValueFunction(float backdrop, float source) |
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public static Vector4 HardLight(Vector4 backdrop, Vector4 source, float opacity) |
{ |
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{ |
return backdrop <= 0.5f ? (2 * backdrop * source) : 1 - ((2 * (1 - source)) * (1 - backdrop)); |
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source.W *= opacity; |
} |
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float cr = OverlayValueFunction(source.X, backdrop.X); |
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float cg = OverlayValueFunction(source.Y, backdrop.Y); |
/// <summary>
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float cb = OverlayValueFunction(source.Z, backdrop.Z); |
/// General composition function for all modes, with a general solution for alpha channel
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/// </summary>
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return Compose(backdrop, source, Vector4.Min(Vector4.One, new Vector4(cr, cg, cb, 0))); |
/// <param name="backdrop">Original Backdrop color</param>
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} |
/// <param name="source">Original source color</param>
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/// <param name="xform">Desired transformed color, without taking Alpha channel in account</param>
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/// <summary>
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/// <returns>The final color</returns>
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/// Helper function for Overlay andHardLight modes
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/// <remarks>
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/// </summary>
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/// This is the default compositor for "normal" alpha blending, which matches the generated SrcOver compositor.
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/// <param name="backdrop">Backdrop color element</param>
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/// </remarks>
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/// <param name="source">Source color element</param>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
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/// <returns>Overlay value</returns>
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private static Vector4 Compose(Vector4 backdrop, Vector4 source, Vector4 xform) |
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
{ |
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private static float OverlayValueFunction(float backdrop, float source) |
// calculate weights
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{ |
float xw = backdrop.W * source.W; |
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return backdrop <= 0.5f ? (2 * backdrop * source) : 1 - ((2 * (1 - source)) * (1 - backdrop)); |
float bw = backdrop.W - xw; |
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} |
float sw = source.W - xw; |
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/// <summary>
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// calculate final alpha
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/// General composition function for all modes, with a general solution for alpha channel
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float a = xw + bw + sw; |
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/// </summary>
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/// <param name="backdrop">Original Backdrop color</param>
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// calculate final value
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/// <param name="source">Original source color</param>
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xform = ((xform * xw) + (backdrop * bw) + (source * sw)) / MathF.Max(a, Constants.Epsilon); |
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/// <param name="xform">Desired transformed color, without taking Alpha channel in account</param>
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xform.W = a; |
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/// <returns>The final color</returns>
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[MethodImpl(MethodImplOptions.AggressiveInlining)] |
return xform; |
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private static Vector4 Compose(Vector4 backdrop, Vector4 source, Vector4 xform) |
} |
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{ |
} |
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// calculate weights
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float xw = backdrop.W * source.W; |
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float bw = backdrop.W - xw; |
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float sw = source.W - xw; |
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// calculate final alpha
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float a = xw + bw + sw; |
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// calculate final value
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xform = ((xform * xw) + (backdrop * bw) + (source * sw)) / MathF.Max(a, Constants.Epsilon); |
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xform.W = a; |
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return xform; |
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} |
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} |
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} |
} |
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