如何在画布上绘制具有径向渐变的圆？ [英] How to draw a circle with a radial gradient on the canvas?

问题描述

我需要在自定义控件（XAML）中的画布上绘制一个带有径向渐变的圆。但是 Windows :: UI :: Xaml :: Media 仅包含 LinearGradientBrush 。我了解设计指南，但我的控件需要这样做，以便用户可以看到伽玛颜色。

在下面，我需要获取：



PS 我问至少在没有XAML的情况下如何以编程方式绘制它。

PPS 我知道我可以画一幅画在某些具有径向渐变的编辑器中，然后将其绘制在画布上，但对于自适应设计而言似乎不是一个好的解决方案。

I need to draw a circle with a radial gradient on the canvas in my custom control (XAML). But Windows::UI::Xaml::Media contains LinearGradientBrush only. I know about design guids but my control requires so feature to the user can see the color gamma.
Below that I need to get:

P.S. I ask how to draw it at least programmaticaly without XAML.
P.P.S. I know that I can draw a picture in some editor with radial gradient and after draw it on the canvas but it seems not good solution for the adaptive design.

推荐答案

您可以检查 RenderColorPickerHueRing（） 方法的示例，说明如何在 WriteableBitmap 中的CPU上执行此操作。它并不是超级快（至少在C＃版本中），但是至少它可以避免您将图像与应用程序打包在一起或使用DirectX，这对于正确设置和稳定它来说比较棘手。

You can check the RenderColorPickerHueRing() method for a sample of how you could do it on a CPU in a WriteableBitmap. It's not super fast (at least in the C# version), but at least it saves you from packaging another image with your app or from using DirectX, which is a bit more tricky to get set up correctly and stabilize.

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