Re: WPF CheckBox state - WPF Discussion Boards

Re: WPF CheckBox state [modified]

31-Aug-09 9:47

Is there a simple way to set the IsChecked state of a CheckBox without invoking any Checked event handlers? I want to set the initial state of a checkbox without invoking the Checked handler unnecessarily.

I know it's as simple as having a flag that the event handler looks at, or unhooking the event handler while I'm initializing the check box state, but that just seems clumsy.

Software Zen: delete this;

Super Lloyd31-Aug-09 14:43

Super Lloyd

31-Aug-09 14:43

How about:
<CheckBox Content="I'm Checked!" IsChecked="True"/>

or, in code:
theCheckbox.IsChecked = true;

Now, I'm a bit puzzle by what you mean "in the event handler"
You don't set it in the event handler (that would be pointless and against the normal behavior of a checkbox), you get the new value!

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_________________________________________________________
My programs never have bugs, they just develop random features.

modified on Monday, August 31, 2009 9:00 PM

Gary Wheeler1-Sep-09 0:55

1-Sep-09 0:55

Super Lloyd wrote:
<CheckBox Content="I'm Checked!" IsChecked="True"/>

I can't set the initial state of the checkbox in the XAML, since the initial state is determined programmatically during the Loaded() event handler for the dialog.

Super Lloyd wrote:
Now, I'm a bit puzzle by what you mean "in the event handler"

I'm referring to something like this, where a flag tells the CheckBox Checked() handler whether or not to do its thing:

bool _SettingInitialState = true;
//...
_SettingInitialState = true;
_Checkbox.IsChecked = initial_state;
_SettingInitialState = false;
//...
private void _CheckedHandler(...)
{
  if (!_SettingInitialState)
  {
     // normal Checked() handling
  }
}

Software Zen: delete this;

Super Lloyd1-Sep-09 0:58

Super Lloyd

1-Sep-09 0:58

why don't you set it in the Loaded event handler then, if it's when it is decided?

Gary Wheeler1-Sep-09 1:11

1-Sep-09 1:11

That's where I want to set it. I'd just like the act of setting the initial state to not trigger the Checked handler when I do so.

Software Zen: delete this;

Super Lloyd1-Sep-09 1:27

Super Lloyd

1-Sep-09 1:27

Mmm, strange, why is it you can't decide of the checked state before, maybe you are not doing something the elegant way perhaps?

Anyway, to suggest an other unelegant workaround, why don't you register the event handler by code in the Loaded event handler (after setting the value), instead of registering it in XAML?

Gary Wheeler1-Sep-09 1:35

1-Sep-09 1:35

Super Lloyd wrote:
Mmm, strange, why is it you can't decide of the checked state before, maybe you are not doing something the elegant way perhaps?

Setting the state depends upon communications with an external process, which may take a significant amount of time. Until that communication completes, I don't know the state.

I may simply connect the event handler when the communication completes, instead of in the Loaded() handler.

Thanks for the suggestions Rose | [Rose]

Software Zen: delete this;

Dynamic enumlist

ProgrammerWPF31-Aug-09 8:43

ProgrammerWPF

31-Aug-09 8:43

Hi I have an enum set say tiger=0,
lion=1,
deer=2,
snake=4
These enums are to be displayed in a list box which is dependent on a combo box. The combo box will have values like carnivores,herbivores,repltiles.
So when I change my selectedindex the value in the list box(ie the animal names) should also change. So if I have carnivores, I get lion and tiger. If i have reptiles , I have snake.
Please suggest the respective xaml and the necessary code required. Its very urgent.
Thanks

Not Active31-Aug-09 9:54

Not Active

31-Aug-09 9:54

So how do you tell from the enum whether the animal is a carnivore? You can't, so you have to..."Its very urgent.". Of course it's urgent to you, but not to everyone else here who volunteer their time. Don't be rude.

only two letters away from being an asset

ProgrammerWPF31-Aug-09 9:57

ProgrammerWPF

31-Aug-09 9:57

Am not being rude... Smile | :)

neways.. lion = animal.carnivore
snake = animal.reptile
and so on..
hope this helps... Smile | :)

Not Active31-Aug-09 10:10

Not Active

31-Aug-09 10:10

To be clear, when you ask for an urgent response here you are being rude. Everyone here volunteers their time and to ask for an urgent response you are failing to recognize this, and thus being rude and inconsiderate. We don't have to answer your question immediately, or at all, do demand it.

You have your answer already if you think about it. Based on the selection from one dropdown you need to populate a second. How would you do this? How do you populate the first dropdown?

only two letters away from being an asset

ProgrammerWPF31-Aug-09 10:19

ProgrammerWPF

31-Aug-09 10:19

Ok ok... am sorrry... not familiar with the "Posting" standards.

I got ur point, but the problem is with the enums.... if it was a normal list, it was simple... but the enums are creating a problem..
Please do help

Not Active31-Aug-09 10:44

Not Active

31-Aug-09 10:44

ProgrammerWPF wrote:
if it was a normal list, it was simple

An enum can be treated like a "normal" list, Enum.GetNames[^] returns an array of the enum names. Enum.GetValues[^] returns an array values. You can either use one of these methods or create a collection that combines them into name/value pairs and bind your dropdown to it.

only two letters away from being an asset