C#里尝试用Canvas画坐标轴为什么不显示

            //x-y坐标刻度
            for (int i = 0; i < 4; i++)
            {
                TimeStr[i] = i * 10 + "s";
            }

            PictureFlow.Width = 49.5/1.5;
            PictureFlow.Height = Picture1.Height;
            PictureTime.Height = 49.5/1.5;
            PictureTime.Width = Picture1.Width;

            PictureTime.Children.Clear();
            PictureFlow.Children.Clear();

            PictureTime.Children.Add(new Line()
            {
                X1 = 0,
                Y1 = 0,
                X2 = PictureTime.Width,
                Y2 = 0,
                StrokeThickness = 2,
                Stroke = new SolidColorBrush(white)
            }); //x轴

            for (int i = 0; i < 40; i++) //秒刻度
            {
                PictureTime.Children.Add(new Line()
                {
                    X1 = PictureFlow.Width - 1.5/1.5 + i * 30/1.5,
                    Y1 = 10/1.5,
                    X2 = PictureFlow.Width - 1.5/1.5 + i * 30/1.5,
                    Y2 = 0,
                    StrokeThickness = 2,
                    Stroke = new SolidColorBrush(white)
                }); //时间刻度线
            }

            for (int i = 0; i < 4; i++) //秒刻度
            {
                PictureTime.Children.Add(new Line()
                {
                    X1 = PictureFlow.Width - 1.5/1.5 + i * 30/1.5,
                    Y1 = 20/1.5,
                    X2 = PictureFlow.Width - 1.5/1.5 + i * 30/1.5,
                    Y2 = 0,
                    StrokeThickness = 2,
                    Stroke = new SolidColorBrush(white)
                }); //时间刻度线
                drawText(PictureFlow.Width + i * 30/1.5 - 25/1.5, 20/1.5, TimeStr[i], white, PictureTime);
            }

            PictureFlow.Children.Add(new Line() //y轴
            {
                X1 = PictureFlow.Width - 1.5/1.5,
                Y1 = 0,
                X2 = PictureFlow.Width - 1.5/1.5,
                Y2 = PictureFlow.Height,
                Stroke = new SolidColorBrush(white)
            });

            for (int i = 1; i < 9; i++) //100ml刻度
            {
                PictureFlow.Children.Add(new Line()
                {
                    X1 = PictureFlow.Width - 19.5/1.5,
                    Y1 = i * 50/1.5,
                    X2 = PictureFlow.Width - 1.5/1.5,
                    Y2 = i * 50/1.5,
                    StrokeThickness = 2,
                    Stroke = new SolidColorBrush(white)
                }); //时间刻度线
            }

            for (int i = 5; i < 55; i++) //20ml刻度
            {
                PictureFlow.Children.Add(new Line()
                {
                    X1 = PictureFlow.Width - 10.5/1.5,
                    Y1 = i * 10/1.5,
                    X2 = PictureFlow.Width - 1.5/1.5,
                    Y2 = i * 10/1.5,
                    StrokeThickness = 2,
                    Stroke = new SolidColorBrush(white)
                });
                //drawText(PictureFlow.Width + i * 75/1.5 - 10/1.5, 15/1.5, TimeStr[i], white, PictureFlow);
            }

            drawText(10/1.5, 20/1.5, "ml", white, PictureFlow);

            for (int i = 1; i < 9; i++)
            {
                drawText(2/1.5, 500/1.5 - i * 50/1.5, i * 50/1.5 + "", white, PictureFlow);
            }

大佬们好，我在尝试把一个VB程序翻译成C#，用的是Visual Studio里面的WPF，以上是画坐标轴的代码，Picture1是大的Canvas，PictureTime和PictureFlow是分别用来画x轴和y轴的Canvas，运行以后只有Picture1一个黑色的大Canvas显示了，不知道是什么原因

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