Question

I am having some issues rendering a window, I was wondering if there is a way I can set all or a subset of these properties and only redraw/render the window once.

My problem is that I am rendering 2 windows and making them “attached” so they move and resize in unison. This means that when I am resizing/moving one window, I end up making 4 calls to render when I should only need at most 2.

As an example, the “Move_Click” method is attached to a button on my window. When clicked, this ends up calling “OnRender” twice.

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }
    protected override void OnRender(DrawingContext drawingContext)
    {
        Console.Error.WriteLine("On rendering...");
        base.OnRender(drawingContext);
    }

    private void Move_Click(object sender, RoutedEventArgs e)
    {
        this.Left--;
        this.Top--;
        this.Width--;
        this.Height--;
    }
}

Answer 1

You could just store a flag that states whether to render or not:

public partial class MainWindow : Window
{
    private bool suspended;

    public MainWindow()
    {
        this.InitializeComponent();
    }

    protected override void OnRender(DrawingContext drawingContext)
    {
        if (suspended)
            return;

        base.OnRender(drawingContext);
    }

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        suspended = true;

        Left = 0;
        Top = 0;
        Width = 100;
        Height = 100;

        suspended = false;

        this.InvalidateVisual();
    }
}

You could wrap it with public methods such as SuspendRender() and ResumeRender().