The scenario is like that;
I need to disable textbox to take input from user by keyboard. But textbox should take inputs using kind of devices like barcode reader. I thought to hold a timer and take the timespan between two key strokes (not clear yet). But maybe there is a property or smarter algorithm for that ?
p.s. it is a windows forms application.
You said you'll need to support any barcode reader, which usually emulate a keyboard, therefore there probably isn't an easy way to programmatically distinguish between input from a keyboard and a barcode reader.
Your idea about using timing is a good one, although I'd do something slightly differently. I'd add a Timer to the Form and start it when the first character is entered into the TextBox. The timer should be set to a very short time span and should have auto-restart disabled. When the timer goes off, check if the TextBox has a valid barcode, and if does, process it. Either way, clear the text box afterwards.
It would then appear to anyone attempting to use the keyboard that their typed text simply disappears, while a barcode scanner (which 'types' very fast) would still work.
Maybe you need to track 'keyboard press' event?
I don't think what automatically pasting something will trigger 'keyboard press' event.
Related
The scenario is like that;
I need to disable textbox to take input from user by keyboard. But textbox should take inputs using kind of devices like barcode reader. I thought to hold a timer and take the timespan between two key strokes (not clear yet). But maybe there is a property or smarter algorithm for that ?
p.s. it is a windows forms application.
You said you'll need to support any barcode reader, which usually emulate a keyboard, therefore there probably isn't an easy way to programmatically distinguish between input from a keyboard and a barcode reader.
Your idea about using timing is a good one, although I'd do something slightly differently. I'd add a Timer to the Form and start it when the first character is entered into the TextBox. The timer should be set to a very short time span and should have auto-restart disabled. When the timer goes off, check if the TextBox has a valid barcode, and if does, process it. Either way, clear the text box afterwards.
It would then appear to anyone attempting to use the keyboard that their typed text simply disappears, while a barcode scanner (which 'types' very fast) would still work.
Maybe you need to track 'keyboard press' event?
I don't think what automatically pasting something will trigger 'keyboard press' event.
I have a Windows 10 mobile uwp app and I am having two issues.
First, I set focus to controls in the app. I do this by using the common call successfully
Control.Focus(FocusState.Programmatic);
However, there are some cases where this does not work. Most times it does but for example, when my page loads, I am trying to set an initial focus in one of the fields and it does not work. I have tried this call in two places. First, in the constructor for the page, after InitializeComponenets and also in the override onNavigatedTo method. Where is the best place to call this and what are some reasons why it may not appear to work, particularly when a new page is instantiated?
Second, related to setting focus. I have a text box on my UI that I set control to with the same Programmatic focus call I listed above. However, the soft (on screen)keyboard shows when this happens. I dont want it to show up when I set focus Programmatically but then have it show if the user selects the field. The scenario is I have a barcode scanner. When the page loads, I set focus in code to the text box and it is therefore ready for me to set the text in the text box from code, based on the barcode scanner result. There is hardly ever a need for the user to type into this field. Therefore, I dont need or want to have the keyboard showing and taking up real estate. There is a rare case when I do allow them to still type the text in manually, for example, in the case the barcode does not read. They would then select the control (even though it may already have focus programmatically) which should set focus again but instead as cursor, touch or something and then I want to show the soft keyboard.
What is the best way to do this?
Thanks!
as far as focusing anything else than the TextBox did not work for me anyway, I found a good solution:
I called:
using Windows.UI.ViewManagement;
InputPane.GetForCurrentView().TryHide();
and the Keyboard gets hidden.
I think the best place to call Focus() is in Loaded event handler of the same control which you trying to focus. When this control is fully loaded, it means it's ready for interaction, including focusing.
As for preventing on-screen keyboard to appear, the TextBox class has PreventKeyboardDisplayOnProgrammaticFocus property. Try to set it to true, this should solve your issue.
I'm wondering how to filter the input of a .NET textbox.
I already know that I could listen for the KeyDown event and intercept the key, but that won't filter pasted strings by a right-click menu or a CTRL+V.
I also don't wan't to completely disable the possibility of pasting of characters in the textbox. The paste action should be cancelled whenever it contains one or more invalid characters.
Finally, I'd like to display a notification balloon whenever invalid characters are either entered or pasted.
μTorrent already has this exact behavior:
How can I achieve this functionality in C# ?
TextChanged event - Seems like a good call.
You can spawn your own baloon or ToolTip on any control you want to show a detailed feedback to the user
It seems like a combination of KeyPress, TextChanged, Validating, and Validated events should work for your purposes.
This supposedly easy task gave me some headache. I simply want to let the user enter any text that succeeds float.TryParse into a Textboxish control.
I could use a normal TextBox and check the Text in some btnOK_Click, but this is obviously lame. Also, there is a nice built-in MaskedTextBox control, but I failed to set it's mask to be equal to float.TryParse. Also, it seems to check for validity only when a focus change occurs.
Digging around on the net brought some interesting ideas, but none of them as nice as I would like.
How did you solve this problem? Did I simply miss an obvious solution, or do I have to implement this functionality myself?
I'm aware of a few similar threads on SO, but there was no feasible solution to be found.
Update: Yes, WinForms.
Edit
Well that makes it alot easier... Just add a Validating Event Handler to your textbox
and do the TryParse in the code behind. If its invalid, prompt the user as such.
Validating will fire when the user is finished typing and moves focus from the TextBox so if you need to do on the fly checking, you could handle the TextChanged or on of the KeyPress/KeyUp Event handlers instead
Original
Is this in asp.net or winforms/wpf
If its asp.net, you could use a combination of RegularExpressionValidator (to account for comma seperation, 1 decimal point, etc...) and a RangeValidator to set the min/max values for a float.
Aside from that, the only way to guarantee it would be to wrap the textbox in an updatepanel, stick a CustomServerValidator on it, and in the server validate function, do a TryParse on the TextBox.Text value, if it succeeds, IS VALID, if it fails, NOT VALID
Be careful using Validating and validating to false. You might find that, unless you enter valid data, you can't move focus off the textbox which is a really big usability pain.
I solve this by simply trying a TryParse() on LostFocus and if the TryParse fails I color the textbox background a reddish tint to make it obvious that something is wrong.
I have a UserControl that consists of three TextBoxes. On a form I can have one or more or my UserControl. I want to implement my own tab behavior so if the user presses Tab in the second TextBox I should only move to the third TextBox if the the second TextBox has anything entered. If nothing is entered in the second TextBox the next control of the form should get focus as per the normal tab behavior. If the user hasn't entered anything in the first or second TextBox and the presses tab there is this special case where a control on the form should be skipped.
By using the ProcessDialogKey I have managed to get it work kind of ok but I still have one problem. My question is if there is a way to detect how a WinForms control got focus since I would also like to know if the my UserControl got focus from a Tab or Shift-Tab and then do my weird stuff but if the user clicks the control I don't want to do anything special.
As a general rule, I would say overriding the standard behavior of the TAB key would be a bad idea. Maybe you can do something like disabling the 3rd text box until a valid entry is made in the 2nd text box.
Now, having said this, I've also broken this rule at the request of the customer. We made the enter key function like the tab key, where the enter key would save the value in a text field, and advance the cursor to the next field.
I don't think there's a built-in way that you could do it. All of the WinForms focus events (GotFocus,LostFocus,Enter,Leave) are called with empty EventArgs parameters, which will not give you any additional information.
Personally, I would disable the third textbox, as Rob Thomas said. If you're determined to do this, though, it wouldn't be difficult to set up a manual (read: hackish) solution. Once the tab key is pressed (if the focus is on the second textbox), set a variable inside your form. If the next object focused is then the third textbox, then you know exactly how it happened.
The reason for this odd tab behavior is all about speed in the input process. It was really good to get some input, I hadn't thought about disabling a textbox but that could actually work. But using the Enter key to accept the input hadn't even crossed my mind. That will work so much better. The user can enter the numbers and then press enter to accept the input and the next possible textbox will be the active one. It's like having the cake and eating it too, The speed factor is there since when using the enter key no unnecessary tabing must be done to get to the correct field and using the enter key next to the numeric keyboard makes it really smooth.
Thanks for the input!
I agree with DannySmurf. Messing with the tab order might give you hell later on if the requirements for the application change.
Another thing that you could do is to implement some kind of wizard for the user to go through.
Better than disabling controls, try monkeying around with TabStop - if this is false, the control will be simply skipped when tabbing.
I'd also suggest that the Changed event of the TextBox is the place to be updating TabStop on the other controls.
I've done something similar to this with a login control, where users could enter either a username or an email address (in separate fields), plus their password, and tabStop is what I used to get the job done.