WPF with MVVM: How to insert the text in a textbox based on the caret position(not in code behind)

Question

I have a textbox which is binded to a property “display” of Viewmodel class

My current logic:
I have a keyboard whenever key is pressed the key is appending at the end of existing string text box.

What I want: when key is pressed, based on the cursor position my key should be appended(not at the end) EX: “Stack” is a string. My current cursor position is after “S”, if I press the key “G”, property “display” of Viewmodel class should have “SGtack” (textbox shows “SGtack” but “Display” is still StackG)

score 0 · Accepted Answer · answered Oct 17 '13 at 15:11

0

in your ViewModel you must have :

display Property to keep the text of textbox

CurrentPosition to bind the SelectionStart of textbox

and newChar which is the new character you wanna add to the textbox

when you click a button you should have something like this

    String newDisplay = display.substring(0,CurrentPosition) + newChar +
 display.substring(CurrentPosition,display.lenght - CurrentPosition);

answered Oct 17 '13 at 15:11

mohammad jannesary

1,811
1
26
27

Hi mohammad jannesary, – user2890924 Oct 17 '13 at 15:25
Thanks for your answer, but I am getting error : A 'Binding' cannot be set on the 'SelectionStart' property of type 'TextBox'. A 'Binding' can only be set on a DependencyProperty of a DependencyObject – user2890924 Oct 17 '13 at 15:26
Hi; do you have problem? – mohammad jannesary Oct 17 '13 at 15:26
yes..in Xaml to SelectionStart property binding is not happening with CurrentPosition (A 'Binding' cannot be set on the 'SelectionStart' property of type 'TextBox'. A 'Binding' can only be set on a DependencyProperty of a DependencyObject) – user2890924 Oct 17 '13 at 15:29
you right; because SelectionStart isn't a DependencyProperty please see : [link](http://stackoverflow.com/questions/1175618/how-to-bind-selectionstart-property-of-text-box) – mohammad jannesary Oct 17 '13 at 15:44
Glade I Could Help :) – mohammad jannesary Jan 24 '14 at 16:23

WPF with MVVM: How to insert the text in a textbox based on the caret position(not in code behind)

1 Answers1