CODEWITHSUNDEEP
wpftextbox
markltx
markltx

Reputation: 709

Updating WPF TextBox properties after setting Text

When setting the Text property of a WPF TextBox control, other properties that should also change (as a side effect) do not change. In particular, I would like to check the value of the ExtentWidth property after setting Text, but it does not change. I've tried calling UpdateLayout() to no avail. In Windows.Forms, I would call DoEvents().

OK, here's some code. I put this in the Window_Loaded() event handler. The problem is that textBox.ExtentWidth doesn't change when textBox.Text changes. That doesn't really surprise me. I figure I need to call something like textBox.UpdateLayout() to make it recalculate ExtentWidth, but that didn't help. ExtentWidth does vary depending on what I initialize textBox.Text to in the Window's constructor, but that doesn't help me. I need to set several different Text values and get the corresponding ExtentWidth for each. 

   string initText = textBox.Text;   // "textBox"
   double extentWidth = textBox.ExtentWidth; // 39.3

   textBox.Text = "short text";
   extentWidth = textBox.ExtentWidth;  // 39.3

   textBox.Text = "Long enough to make a difference, eh?";
   extentWidth = textBox.ExtentWidth;  // 39.3

Upvotes: 1

Views: 1067

Answers (1)

markltx
markltx

Reputation: 709

I found a solution to the specific problem of getting TextBox.ExtentWidth to change after setting Text. Setting Text will raise the LayoutUpdated event, and you can get the new value of ExtentWidth in a handler for LayoutUpdated.

I used this fact to create a subclass of WPF TextBox that displays an ellipsis when the text is too long for the visible area. I wrote a CodeProject article about it here.

Upvotes: 1

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