KeyEvent or DataBinding

Question

1.00/5 (1 vote)

See more:

Hi everyone!

I have a RichTextBox wich can be used for calculations in my program.
Now I want to Add a Listbox which should display shortcuts from the shortcut[](sin, cos, tan,log,ln.....) array.
Actually the same as Visual Studio, it helps you to find variable names/methods/funktions etc

I have a solution with an KeyEvent, but i think its a bad(confusing) solution..
I read something about DataBindings, could be this the right way?
If it is, i need a good explanation or an example, please!

Thanks

Posted 22-Jul-13 8:01am

SubbZer

Add a Solution

Comments

Jason Gleim 22-Jul-13 14:18pm

Do you want the user to pick something from the listbox and have that function appear in the richtextbox? If so, data binding is not a good solution unless you know that the user will only ever pick a single function and it will always appear at the same place in the rich text box.

Data bindings allow you to have a backing variable in the data context of the control that is automatically updated on the UI. Meaning if you bind the class property MyCheckMark to the Checked property of a check box control, then when you set MyCheckMark = true; in code, the checkbox will change to be checked. (assuming the property and the data context class implement INotifyPropertyChanged)

It would seem to me that you want flexibility... the user should be able to select multiple functions and have them inserted at the current cursor position. There would be value binding the combobox to a property on a ViewModel but I'm guessing if you are asking about databinding, you aren't doing MVVM anyway. In that case I would say, no... data binding is not a good solution for you.

SubbZer 22-Jul-13 14:59pm

1st: fexibility sounds good!
2nd: thats exactly what i want - "the user should be able to select multiple functions and have them inserted at the current cursor position"

thats what my private void Calc_PreviewKeyDown(object sender, KeyEventArgs)-event does, the user can choose the function and the code insered them at the current position
however, it makes the program much slower.. (many declarations of keys what should'nt be pressed..)

ONE of the next problems is that i also can write normal text in the textbox wich also should be observed because the text can contain the shortcut names, then it should'nt be selectable

Jason Gleim 22-Jul-13 15:17pm

You should only insert the function when the user picks it from the combobox... right? So hook the SelectionChanging and SelectionCompleted events. When the user drops the box down, the selection changing event will fire. Set a flag so you know the user dropped the box down. In the selection completed event, check the flag and if set, insert the function into the text runs collection of the rich text box at the current cursor position.

Also, you don't need to process all the keypresses that can't be pressed... why would you do that? Just check for the ones you are interested in intercepting. Make sure you set the Handled property to true so the keypress doesn't bubble up the event chain. For keys you aren't interested in, just do nothing. They will bubble up and be handled by something else.

CHill60 22-Jul-13 18:08pm

OP likes this - paraphrase your comments and post as the solution!

SubbZer 22-Jul-13 16:12pm

Thanks! This was the answer what i was searching for.
I think this would work. Thank you

Jason Gleim 23-Jul-13 10:15am

Posted as a solution. If you would mark it as the answer good karma will come your way! :-)

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Jason Gleim · Accepted Answer · 2013-07-23T04:14:00

You should only insert the function when the user picks it from the combobox... right? So hook the SelectionChanging and SelectionCompleted events. When the user drops the box down, the selection changing event will fire. Set a flag so you know the user dropped the box down. In the selection completed event, check the flag and if set, insert the function into the text runs collection of the rich text box at the current cursor position.

Also, you don't need to process all the keypresses that can't be pressed... why would you do that? Just check for the ones you are interested in intercepting. Make sure you set the Handled property to true so the keypress doesn't bubble up the event chain. For keys you aren't interested in, just do nothing. They will bubble up and be handled by something else.