CODEWITHSUNDEEP
silverlightcanvascontrolssize
Dave W
Dave W

Reputation: 1125

Determining silverlight control's size

I'm an experienced programmer, but completely new to the world of Silverlight. I've been tasked with fixing a problem in a Silverlight application, and am struggling to find the information I need.

The app contains a custom control, upon which pop-up tooltips can be displayed near the mouse cursor. I need to ensure the tooltips get positioned in such a way that they don't exceed the bounds of the control. Easy, in theory, however I can't figure out how to get the size of the control.

It's declared in some XAML, like this (main control name changed to 'XXX' for privacy):

<client:XxxHost x:Class="Project.Client.Banana"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:xxx="clr-namespace:Project.Controls;assembly=Project.Controls.Xxx"
    xmlns:ui="clr-namespace:Project.Controls.UI;assembly=Project.Controls.UI"
    xmlns:client="clr-namespace:Project.Client"
    mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">
<xxx:XxxControl x:Name="XxxControl">
    <xxx:XxxControl.UI>
        <ui:Banana DataContext="{Binding}" View="{Binding View}" />
    </xxx:XxxControl.UI>
    <xxx:XxxControl.TooltipDisplay>
        <xxx:MultiTooltipDisplay></xxx:MultiTooltipDisplay>
    </xxx:XxxControl.TooltipDisplay>
</xxx:XxxControl>
</client:XxxHost>

In the code, MultiTooltipDisplay is a class derived from Canvas. In its method to display a tooltip, it has this code:

    public void DisplayTooltips(System.Collections.Generic.List<UIElement> tooltips, Point screenAnchor)
    {
        ClearTooltips();

        if (tooltips.Count > 0)
        {
            StackPanel ttStack = new StackPanel();
            ttStack.Orientation = Orientation.Vertical;
            for (int i = 0; i < tooltips.Count; i++)
            {
                UIElement ttip = tooltips[ i ];
                UserControl ttipWrapper = new UserControl();
                ttipWrapper.Content = ttip;
                ttStack.Children.Add(ttipWrapper);
            }
            ttStack.SetValue(Canvas.TopProperty, screenAnchor.Y);
            ttStack.SetValue(Canvas.LeftProperty, screenAnchor.X + 24.0); 
            this.Children.Add(ttStack);
         }
    }

If I put a breakpoint in towards the end of this method, and I inspect ttStack's Width/Height/ActualWidth/ActualHeight/DesiredSize, I find they're all 0 or NaN. After some reading and trial & error I found out that by putting in a call to ttStack.UpdateLayout() those values would get populated. I'm not sure if that's the correct way, but the numbers seem reasonable. Great!

However, I need to know the size of the control upon which the tooltip would be displayed, but I get the same issue. this.Width/Height/etc all return 0 or NaN. A call to this.UpdateLayout() doesn't change those properties.

How can I determine the dimensions of the contol?

Upvotes: 2

Views: 1765

Answers (2)

Alobidat
Alobidat

Reputation: 462

I used ActualWidth and ActualHeight, it worked for me.

Upvotes: 0

AnthonyWJones
AnthonyWJones

Reputation: 189525

Try calling the Measure method on ttStack before reading is DesiredSize.

Upvotes: 1

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