用渐变绘制线条 [英] Drawing a line with gradient

问题描述

我需要在我的C＃/ WPF应用程序中绘制线条，其中线条跟随鼠标光标移动。



我能够跟踪鼠标光标并显示蓝色路径。



如何使用渐变来创建线条？由于我不知道线的长度，我无法预设渐变的各个颜色。有没有办法我可以说逐渐改变蓝黄 - 红 - 蓝的线条颜色，然后重复？



谢谢！

Hi,

I need to draw lines in my C#/WPF application, where the lines follow the mouse cursor movement.

I am able to trace the mouse cursor and show a blue-colored path.

How can I use gradient to create the line? Since I don't know the length of the line, I can't preset the individual colors of the gradient. Is there a way I can say "Change the line color from blue-yellow-red-blue gradually,and then repeat"?

Thanks!

推荐答案

请参阅 http：// msdn.microsoft.com/en-us/library/aa970904(v=vs.110).aspx [ ^ ]。

那样的东西呢？

Something like this then?

System.Windows.Threading.DispatcherTimer timer = new System.Windows.Threading.DispatcherTimer();
Line gradientLine;
LinearGradientBrush gradBrush = new LinearGradientBrush();

        void Window_Loaded(object sender, RoutedEventArgs e)
        {
            gradBrush.GradientStops.Add(new GradientStop(Colors.Red, 0));
            gradBrush.GradientStops.Add(new GradientStop(Colors.Orange, 0.5));
            gradBrush.GradientStops.Add(new GradientStop(Colors.Yellow, 1));
            gradBrush.GradientStops.Add(new GradientStop(Colors.Green, 1.5));
            gradBrush.GradientStops.Add(new GradientStop(Colors.Blue, 2));
            gradBrush.GradientStops.Add(new GradientStop(Colors.Indigo, 2.5));
            gradBrush.GradientStops.Add(new GradientStop(Colors.Violet, 3));
            gradBrush.GradientStops.Add(new GradientStop(Colors.Purple, 3.5));
            gradientLine =  new Line() { X1 = 0, Y1 = 0, X2 = 100, Y2 = 100, StrokeThickness = 1, Stroke = gradBrush  };
            cnvCanvas.Children.Add(gradientLine);

            timer.Tick += timer_Tick;
            timer.Interval = new TimeSpan(0, 0, 0, 0, 1000/30);
            timer.Start();
        }

        void timer_Tick(object sender, EventArgs e)
        {
            for (int i = 0; i < gradBrush.GradientStops.Count; ++i)
            {
                gradBrush.GradientStops[i].Offset = gradBrush.GradientStops[i].Offset - 0.01;
                if (gradBrush.GradientStops[i].Offset < -1) gradBrush.GradientStops[i].Offset += 4;
            }

        }

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