通过将省略号添加为 children，在 canvas 上不显示，但在 XAML 中添加时显示

Question

如标题所述，我的应用程序中有一个 wiimote，它提供了需要显示椭圆的像素坐标。然而，问题是当我用 Canvas.Children.Add() 添加它们时，它们不会出现在 canvas 上。

但是，如果我在 canvas 中添加省略号 XAML，然后在每次遥控器提供新的 x,y 坐标时修改它们的坐标，那么省略号会出现在 canvas 并且似乎正在改变位置。

   if (remote == service.wiimote1_info)
        {
            Action action = () =>
            {
                WM1Status_Lbl.Content = remote.Astatus.ToString();
                WM1_Accel_X.Content = remote.Accelerometer[0].ToString();
                WM1_Accel_Y.Content = remote.Accelerometer[1].ToString();
                WM1_Accel_Z.Content = remote.Accelerometer[2].ToString();
                WM1_IR1.Content = String.Concat(" X = ", remote.IRState[0, 0]/10, "; Y = ", remote.IRState[0, 1]/10, "; Size = ", remote.IRState[0, 2]);
                WM1_IR2.Content = String.Concat(" X = ", remote.IRState[1, 0]/10, "; Y = ", remote.IRState[1, 1]/10, "; Size = ", remote.IRState[1, 2]);
                WM1_IR3.Content = String.Concat(" X = ", remote.IRState[2, 0]/10, "; Y = ", remote.IRState[2, 1]/10, "; Size = ", remote.IRState[2, 2]);
                WM1_IR4.Content = String.Concat(" X = ", remote.IRState[3, 0]/10, "; Y = ", remote.IRState[3, 1]/10, "; Size = ", remote.IRState[3, 2]);
                wm1_progressbar.Value = remote.battery;
                //IRImage.Children.Clear();
                Canvas.SetLeft(IRSensor1, remote.IRState[0, 0] ) ; Canvas.SetBottom(IRSensor1, remote.IRState[0, 1]);
                Canvas.SetLeft(IRSensor2, remote.IRState[1, 0]); Canvas.SetBottom(IRSensor2, remote.IRState[1, 1]);
                Canvas.SetLeft(IRSensor3, remote.IRState[2, 0] ); Canvas.SetBottom(IRSensor3, remote.IRState[2, 1] );
                Canvas.SetLeft(IRSensor4, remote.IRState[3, 0]); Canvas.SetBottom(IRSensor4, remote.IRState[3, 1]);

                //At first I tryed to add the sensors with my DrawSensor() method , but it did not work . So then I have decided to modify already existing sensors instead of continuousely creating new ones .   

                DrawSensor(System.Drawing.Color.Blue, remote.IRState[0, 0]/10, remote.IRState[0,1]/10, (int)remote.IRState[0, 2]+1);
                DrawSensor(System.Drawing.Color.Red, remote.IRState[1, 0]/10, remote.IRState[1, 1]/10, (int)remote.IRState[1, 2]+1);
                DrawSensor(System.Drawing.Color.Yellow, remote.IRState[2, 0]/10, remote.IRState[2, 1]/10, (int)remote.IRState[2, 2]+1);
                DrawSensor(System.Drawing.Color.Green, remote.IRState[3, 0]/10, remote.IRState[3, 1]/10, (int)remote.IRState[3, 2]+1);

            };
            Dispatcher.Invoke(action);
            updated = true;
        }



  public void DrawSensor(System.Drawing.Color color , double x , double y , int Size )
    {
        Ellipse sensor = new Ellipse();
        sensor.Width = Size + 1;
        sensor.Height = Size + 1;
        sensor.Opacity = 100;
        Canvas.SetTop(sensor , x);
        Canvas.SetBottom(sensor , y);
        Canvas.SetLeft(sensor, y);
        IRImage.Children.Add(sensor);
        Console.WriteLine("Point drawn");

    }

Answer 1

我发现您忘记在 DrawSensorMethod

中为椭圆传感器添加填充属性

sensor.Fill = new SolidColorBrush(color);

但更重要的是，我鼓励您不要每次都创建新的椭圆，只需创建 4 个或您需要的数量，然后使用 TranslateTransform 移动它们，它使用 GPU 而不是 CPU，效果是顺利

通过将省略号添加为 children，在 canvas 上不显示，但在 XAML 中添加时显示

Ellipses not shown on canvas by adding them as children but do when added in XAML

c#

wpf

xaml

canvas

ellipse