UWP Composition Api 是否支持颜色替换？

我一直在尝试寻找与颜色替换相关的示例，这是一个使用 Photoshop 的示例，例如，它可以采用蓝色阴影并将其替换为红色阴影：

BEFORE:

AFTER:

使用最新版本的 Composition Api 中的 Composition Effects 是否可以实现这一点？

我看过与色调旋转、温度和色调相关的示例：

https://xamlbrewer.wordpress.com/2016/04/08/uwp-composition-effects-hue-rotation/ https://xamlbrewer.wordpress.com/2016/04/08/uwp-composition-effects-hue-rotation/

https://xamlbrewer.wordpress.com/2016/04/19/uwp-composition-effects-Temperature-and-tint/ https://xamlbrewer.wordpress.com/2016/04/19/uwp-composition-effects-temperature-and-tint/

但我想知道 api 是否能够使用效果来切换图像中的颜色范围？

我有一个你可能会喜欢的解决方案。示例如下所示：

为了实现这一点，我使用了 3 个连锁效果：PixelShaderEffect, GaussianBlurEffect and BlendEffect from Win2d API.

XAML 有CanvasAnimatedControl绘制结果加上一些助手，例如源（我们要替换的颜色）并替换颜色选择器和阈值滑块。

<Grid>
    <xaml:CanvasAnimatedControl x:Name="AnimatedControl"
                            CreateResources="AnimatedControl_OnCreateResources"
                            Draw="AnimatedControl_OnDraw"/>

    <StackPanel HorizontalAlignment="Left" VerticalAlignment="Bottom">
        <TextBlock Text="Source Color" FontSize="32" Foreground="White" TextAlignment="Center"/>

        <ColorSpectrum Width="256" Height="256" ColorChanged="ColorSpectrum_OnColorChanged"/>
    </StackPanel>

    <StackPanel HorizontalAlignment="Right" VerticalAlignment="Bottom">
        <TextBlock Text="Replace Color" FontSize="32" Foreground="White" TextAlignment="Center"/>

        <ColorSpectrum Width="256" Height="256" ColorChanged="ColorSpectrum_OnColorChanged1"/>
    </StackPanel>

    <Slider Width="512" ValueChanged="RangeBase_OnValueChanged" VerticalAlignment="Center"/>
</Grid>

背后代码：

    private PixelShaderEffect _textureShader;
    private GaussianBlurEffect _blur;
    private BlendEffect _blend;

    private void AnimatedControl_OnCreateResources(CanvasAnimatedControl sender, CanvasCreateResourcesEventArgs args)
    {
        args.TrackAsyncAction(CreateResourcesAsync(sender).AsAsyncAction());
    }

    private async Task CreateResourcesAsync(CanvasAnimatedControl sender)
    {
        var file = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/Shaders/TextureTest.bin"));
        var buffer = await FileIO.ReadBufferAsync(file);

        var sourceImage = await CanvasBitmap.LoadAsync(sender, new Uri("ms-appx:///Assets/image.jpg"));

        _textureShader = new PixelShaderEffect(buffer.ToArray())
        {
            Source1 = sourceImage
        };

        _blur = new GaussianBlurEffect
        {
            BlurAmount = 4,
            Source = _textureShader
        };

        _blend = new BlendEffect
        {
            Foreground = _blur,
            Background = sourceImage,
            Mode = BlendEffectMode.Color
        };
    }

    private void AnimatedControl_OnDraw(ICanvasAnimatedControl sender, CanvasAnimatedDrawEventArgs args)
    {
        args.DrawingSession.DrawImage(_blend);
    }

    private void RangeBase_OnValueChanged(object sender, RangeBaseValueChangedEventArgs e)
    {
        _textureShader.Properties["threshold"] = (float)e.NewValue / 100;
    }

    private void ColorSpectrum_OnColorChanged(ColorSpectrum sender, ColorChangedEventArgs args)
    {
        _textureShader.Properties["sourceColor"] = new Vector3((float)args.NewColor.R / 255, (float)args.NewColor.G / 255, (float)args.NewColor.B / 255);
    }

    private void ColorSpectrum_OnColorChanged1(ColorSpectrum sender, ColorChangedEventArgs args)
    {
        _textureShader.Properties["replaceColor"] = new Vector3((float)args.NewColor.R / 255, (float)args.NewColor.G / 255, (float)args.NewColor.B / 255);
    }

最令人兴奋的是像素着色器：

#define D2D_INPUT_COUNT 1
#define D2D_INPUT0_SIMPLE

#include "d2d1effecthelpers.hlsli"

float3 sourceColor;
float3 replaceColor;
float threshold;

D2D_PS_ENTRY(main)
{
    float3 color = D2DGetInput(0).rgb;

    if (abs(color.r - sourceColor.r) < threshold && abs(color.g - sourceColor.g) < threshold && abs(color.b - sourceColor.b) < threshold) 
    {
        float3 newColor = color - sourceColor + replaceColor;
        return float4(newColor.r, newColor.g, newColor.b, 1);
    }
    else 
    {
        return float4(0, 0, 0, 0);
    }
}

要编译它，您应该访问这里：https://github.com/Microsoft/Win2D-Samples/tree/master/ExampleGallery/Shared/Shaders https://github.com/Microsoft/Win2D-Samples/tree/master/ExampleGallery/Shared/Shaders

有一个 cmd 文件可以编译 hlsl 着色器。如果您需要一些帮助 - 评论它。玩得开心！