CODEWITHSUNDEEP
c#.netwpfcanvas
M.Farrukh
M.Farrukh

Reputation: 45

Add more then 10 child's to a canvas in wpf then software become slow

I am using canvas for drawing some shapes in WPF. XAML code: 

<Canvas x:Name="canvas1" 
    Background="Transparent" 
    Margin="0,40,0,0"  
    MouseDown="canvas1_MouseDown" 
    MouseMove="canvas1_MouseMove" 
    MouseUp="canvas1_MouseUp" 
    KeyUp="canvas1_KeyUp" >

</Canvas>

In it I have three canvas events: "Down", "Move", "Up". I use them to draw a shape and then add it to canvas child. When i add multiple children it becomes slow.
Here is some sample code for adding a child:

Rectangle rect;

public void canvas1_MouseDown(object sender, MouseButtonEventArgs e)
{ 
    rect = new Rectangle
    {                            
        StrokeDashArray = { 2,2 },
        StrokeThickness = 1
    }; 
    Canvas.SetTop(rect, startPoint.Y);
}

public void canvas1_MouseMove(object sender, MouseButtonEventArgs e)
{ if(boolVariable){        canvas1.Children.Add(rect);
   boolVariable=false}
    rect.Width = w;
    rect.Height = h;
    Canvas.SetLeft(rect, x);
    Canvas.SetTop(rect, y);
}

public void canvas1_Mouseup(object sender, MouseButtonEventArgs e)
{ 
    rect = null;
}

Thats code which i use for adding different shapes.Kindly help me how i handle the speed issues. Thanks.

Upvotes: 0

Views: 578

Answers (1)

dymanoid
dymanoid

Reputation: 15197

Your error is located here:

public void canvas1_MouseMove(object sender, MouseButtonEventArgs e)
{ 
    canvas1.Children.Add(rect);
    // ...
}

On each mouse movement, you add a new visual child to the Canvas. Of course, at some point it will be slow because you probably add thousands of visual children.

Move this line to the canvas1_MouseDown event handler.

Upvotes: 2

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