C# WPF，根据虚拟屏幕分辨率查找坐标

Question

我正在使用 kinect SDK 和 OpenCV 开发一个 wpf 项目， 我需要做的是创建一个框，跟随在 kinect 相机中显示的斑点，并检查该斑点是否位于通过选择 4 个点（矩形的角）添加的矩形内

MCvBox2D box = contours.GetMinAreaRect();
openCVImg.Draw(box, new Bgr(System.Drawing.Color.Red), 2);

POINT p = new POINT { x = (int)box.center.X, y = (int)box.center.Y };

double minX = Math.Min(Canvas.GetLeft(dot1), Math.Min(Canvas.GetLeft(dot2), Math.Min(Canvas.GetLeft(dot3), Canvas.GetLeft(dot4))));
double minY = Math.Min(Canvas.GetTop(dot1), Math.Min(Canvas.GetTop(dot2), Math.Min(Canvas.GetTop(dot3), Canvas.GetTop(dot4))));
double maxX = Math.Max(Canvas.GetLeft(dot1), Math.Max(Canvas.GetLeft(dot2), Math.Max(Canvas.GetLeft(dot3), Canvas.GetLeft(dot4))));
double maxY = Math.Max(Canvas.GetTop(dot1), Math.Max(Canvas.GetTop(dot2), Math.Max(Canvas.GetTop(dot3), Canvas.GetTop(dot4))));
if (p.x >= minX && p.x <= maxX && p.y >= minY && p.y <= maxY)
{
...
}

盒子是围绕斑点创建的，点1，..，点4是矩形的角，点p是盒子的中心。 if 语句检查是否在矩形内找到了框

问题是当我检查 Dots 的坐标时，它们显示的坐标与点 p 不同。 例如当 box.X 超过 minX 时，它显示 box.X = 125 的坐标和 maxX=634 的坐标。

我非常乐意了解我在这里做错了什么以及如何解决它。

谢谢

Answer 1

您可以使用

Visual.PointFromScreen

将以屏幕坐标表示的点转换为

Visual

的坐标系（在您的情况下为托管

Canvas

元素）。

您还应该避免混合

System.Drawing

和

System.Windows

命名空间。因为这是一个 WPF 应用程序，您应该立即将从 OpenCV API 返回的所有

System.Drawing

类型转换为

System.Windows

类型。

您可以通过使用

Rect.Contains

来测试

Point

是否包含在

Rect

定义的矩形内，进一步改进代码。处理

Rect

而不是“松散”坐标点至少可以提高代码的可读性。

private void HandleTrackingBox(Contour<PointF> contour)
{
  MCvBox2D box = contour.GetMinAreaRect();
  openCVImg.Draw(box, new Bgr(System.Drawing.Color.Red), 2);
  var testPointFromScreen = new System.Windows.Point(box.center.X, box.center.Y);

  System.Windows.Rect referenceBounds = CreateReferenceBounds();
  bool isTestPointValid = IsScreenTestPointWithinBounds(referenceBounds, testPointFromScreen);
  if (isTestPointValid)
  {
    // TODO::Handle test point is within the bounds
  }
}

private System.Windows.Rect CreateReferenceBounds()
{
  double minX = Math.Min(Canvas.GetLeft(dot1), Math.Min(Canvas.GetLeft(dot2), Math.Min(Canvas.GetLeft(dot3), Canvas.GetLeft(dot4))));
  double minY = Math.Min(Canvas.GetTop(dot1), Math.Min(Canvas.GetTop(dot2), Math.Min(Canvas.GetTop(dot3), Canvas.GetTop(dot4))));
  double maxX = Math.Max(Canvas.GetLeft(dot1), Math.Max(Canvas.GetLeft(dot2), Math.Max(Canvas.GetLeft(dot3), Canvas.GetLeft(dot4))));
  double maxY = Math.Max(Canvas.GetTop(dot1), Math.Max(Canvas.GetTop(dot2), Math.Max(Canvas.GetTop(dot3), Canvas.GetTop(dot4))));

  double boundsWidth = maxX - minX;
  double boundsHeight = maxY - minY;
  var boundsSize = new System.Windows.Size(boundsWidth, boundsHeight);
  var boundsLocation = new System.Windows.Point(minX, minY);
  var referenceBounds = new System.Windows.Rect(boundsLocation, boundsSize);

  return referenceBounds;
}

private bool IsScreenTestPointWithinBounds(Rect referenceBounds, System.Windows.Point screenTestPoint)
{
  // Use the hosting Canvas to transform the screen point 
  // to a point relative to the Canvas element
  var relativeTestPoint = this.HostingCanvas.PointFromScreen(testPointFromScreen);
  return referenceBounds.Contains(relativeTestPoint);
}