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WPF How to check if in canvas is empty spaces

I am adding rectangles on a Canvas using Random because I don't know the width and height.

Code

  HProDataContext db = new HProDataContext();

        var RoomX = (from d in db.rooms select d.sizex).ToList();
        var RoomY = (from d in db.rooms select d.sizey).ToList();
        var ran开发者_开发问答dom = new Random();
        for (int i = 0; i < RoomX.Count; i++)
        {

            RoomX[i] = (Convert.ToDouble(RoomX[i]) * 10).ToString();
            RoomY[i] = (Convert.ToDouble(RoomY[i]) * 10).ToString();

            var rectangle = new Rectangle()
            {
                Stroke = Brushes.Black,
                Fill = Brushes.SkyBlue,
                Width = Convert.ToDouble(RoomX[i]),
                Height = Convert.ToDouble(RoomY[i]),
                Margin = new Thickness(
                    left: random.NextDouble() * 300,
                    top: random.NextDouble() * 150,
                    right: 0,
                    bottom: 0),
                HorizontalAlignment = HorizontalAlignment.Left,
                VerticalAlignment = VerticalAlignment.Top
            };
            mainCanvas.Children.Add(rectangle);
        }
    }

It works good, but some rectangles are drawing over another rectangles.

How to draw rectangles there where is empty space?

WPF How to check if in canvas is empty spaces


You can calculate a Rect for each WPF Rectangle and use IntersectsWith method found in Rect to test if the code can a draw a new Rectangle without overlaps. I also recommend using rectangle properties Canvas.Left and Canvas.Top instead of adjusting the Margin.

I've included a simple example that you test to get you started.

Here is some XAML containing 4 Rectangles:

<Window x:Class="OverlapRectangeTest.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
  <Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="*"/>
        <RowDefinition Height="60"/>
    </Grid.RowDefinitions>
    <Canvas x:Name="c" Grid.Row="0">
        <Rectangle x:Name="b1" Fill="Aqua" Canvas.Left="0" Canvas.Top="0" Width="100" Height="200"/>
        <Rectangle x:Name="b2" Fill="Bisque" Canvas.Left="0" Canvas.Top="0" Width="200" Height="100"/>
        <Rectangle x:Name="b3" Fill="BlueViolet"  Canvas.Left="250" Canvas.Top="0" Width="100" Height="200"/>
        <Rectangle x:Name="b4" Fill="Cornsilk"  Canvas.Left="111" Canvas.Top="0" Width="100" Height="200"/>
    </Canvas>
    <Button Grid.Row="1" Click="Button_Click"/>
  </Grid>
</Window>

Here is a button click event handler where I test the IntersectsWith method:

private void Button_Click(object sender, RoutedEventArgs e)
{
  double top1 = (double)b1.GetValue(Canvas.TopProperty);
  double left1 = (double)b1.GetValue(Canvas.LeftProperty);
  Rect rect1 = new Rect(left1, top1, b1.Width, b1.Height);

  double top2 = (double)b2.GetValue(Canvas.TopProperty);
  double left2 = (double)b2.GetValue(Canvas.LeftProperty);
  Rect rect2 = new Rect(left2, top2, b2.Width, b2.Height);

  double top3 = (double)b3.GetValue(Canvas.TopProperty);
  double left3 = (double)b3.GetValue(Canvas.LeftProperty);
  Rect rect3 = new Rect(left3, top3, b3.Width, b3.Height);

  double top4 = (double)b4.GetValue(Canvas.TopProperty);
  double left4 = (double)b4.GetValue(Canvas.LeftProperty);
  Rect rect4 = new Rect(left4, top4, b4.Width, b4.Height);

  bool rc0 = rect1.IntersectsWith(rect4);
  bool rc1 = rect1.IntersectsWith(rect2);
  bool rc2 = rect2.IntersectsWith(rect3);
  bool rc3 = rect3.IntersectsWith(rect1);
  bool rc4 = rect2.IntersectsWith(rect4);
}
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