I'm trying to bind a Textbox.Text to Form.Text (which sets the title of the form).
The binding itself works. But, the title isn't updated until I move the entire form.
How can I achieve Form.Text being updated without moving the form? I'd like Form.Text being updated directly when I type something in the Textbox.
Edit; I set the title of the Form in a TextChanged event which is fired by a ToolStripTextbox:
public partial class ProjectForm : Form
{
public ProjectForm()
{
// my code contains all sorts of code here,
// but nothing that has something to do with the text.
}
}
private void projectName_TextChanged_1(object sender, EventArgs e)
{
this.Text = projectName.TextBox.Text;
}
And the Databinding version:
public partial class ProjectForm : Form
{
public ProjectForm()
{
this.projectName.TextBox.DataBindings.Add("Text", this, "Text", true, DataSourceUpdateMode.OnValidation);
}
}
Edit 2: I see I forgot to mention something. Don't know if it adds anything, but my apllication is a MDI application. The part of the title that changes is:
ApplicationName [THIS CHANGES, BUT ONLY AFTER MOVING/RESIZING]
Classic problem, you're not updating the existing form's Text property but a new one that is not visible. Call the Show() method after you change the Text.
Source
You can also try invalidating your form in the TextChanged event so it will force a re-paint.
Edit 1: This StackOverflow question may provide an answer for you since you are a MDI application
Edit 2: It could be that this operation is not thread-safe and therefore the UI thread is blocking. Therefore, you need to invoke another function in order to cause it to update. I had a similar problem with StatusBar Labels a while back. Here is some example code if you do not know how to use delegates:
public delegate void updateFormTextD(string text);
private void formText(string text)
{
this.Text = text;
}
private void updateFormText(string text)
{
Invoke(new updateFormTextD(formText), text);
}
What about using the TextChanged event of the TextBox, like this:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
this.Text = this.textBox1.Text;
}
}
I had the same problem that almost freaks me out. Eventually I found that my form title update request by "this.text = " was blocked by the method "WndProc(ref Message message)". At the end of WndProc method I added "base.WndProc(ref message)", which passes along all messages to the base also. After that I could update successfully my form title by "this.text = ".
Therefore, I suggest you to look for a method that blocking your form title for being updated.
None of the traditional items worked (invalidate & refresh); nor was I able to readily determine where the message might have been blocked. However, sleeping the thread took care of this.
fForm1->Text = Title;
Thread::Sleep(0); //Allow release for title to update
Related
I am having a problem controlling a textbox. I need to change a value from outside of Form1.cs where the textbox is located for this I have found this snippet.
public void UpdateText(string newValue)
{
torrent_name0.Text = newValue;
}
this allows me in theory to control the textbox outside of Form1.cs, but here comes the problem, every time I want to access it I create a new instance of Form1 instead of using the old one and refreshing it.
Form1 frm = new Form1();
frm.UpdateText("aaaaaaaaaaaa");
frm.Show();
am I missing something? is there a better way to do this? I have tried multiple ways to update the new form but got nowhere.
Bokker,
You will have to have a reference to the singular form1 to which all things refer.
If this is a child form, then as Aybe commented, create a public member of your mainform and name it something.
Public Form myForm1;
You probably have some Event by which you would like Form1 be launched...
A Button click, menu item, toolbar item, etc. In that event you will have to check if the form exists and create if required.
private SomeEvent() {
if (myForm1 == null)
{
myForm1 = new Form1();
myForm1.Show(this);
}
myForm1.UpdateText("some text");
}
Alternatively, you could create the form in the Form Load event, just so long as you create the form prior to attempting the myForm1.UpdateText()
If you follow this paradigm, you are creating myForm1 as part of the main form, best practice says you should also dispose of the form in your main form Closing Event.
private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
{
if (myForm1 != null)
{
myForm1.Close();
myForm1.Dispose();
}
}
This is all off the top of my head, so it might not be perfect.
In that case you can pass the instance of form in the method as argument and make the changes like
public void UpdateText(string newValue, Form1 frm)
{
frm.torrent_name0.Text = newValue;
}
I have a button and hidden textbox on my main form. When I press the button it will hide the main form and show the second form. When I press the button on the second form I want to show the main form again but this time I need to show the hidden textbox. I know how to pass the text from a textbox to another form but not just the reference of the textbox.
You better pass the complete main form instance for the second form, and create a public function to set the textbox to visible, or create a property around it.
Something like:
//form1
Form2 second = new Form2(this);
}....
public void ShowTextBox()
{
textbox1.Visible=true;
}
//form2
Form parent;
public Form2(Form _parent)
{
parent=_parent;
}
///later
parent.Show();
parent.ShowTextBox();
Sounds to me like a custom event would be a better approach. Have the secondary form expose an event, which is raised at whatever appropriate time (your button press). In your main form, when you create your instance of your second form, subscribe to that event. Then run your "unhide" code from within the mainform's event subscription.
This keeps the coupling down on the two forms and results in much more easily maintainable and extensible code (for best effect, use interfaces, but events are a good middle ground for learning).
Something like this:
(it's been a long time since I worked with winforms, or events even, so if this needs refining let me know)
// your secondary/popup form's class
public partial class Form2 : Form
{
// add a custom event
public EventHandler<EventArgs> MyCustomEvent;
// link up your button click event
void InitializeComponent() {
myButton.Click += myButtonClick;
}
// when your button is clicked, raise your custom event
void myButtonClick(object sender, EventArgs, e) {
onMyCustomEvent();
}
// this "broadcasts" the event
void onMyCustomEvent() {
EventHandler<EventArgs> h = MyCustomEvent;
if (h != null) {
h(this, new EventArgs());
}
}
}
// your main form's class
public partial class MainForm
{
void InitializeComponent() {
// ...
}
void showForm2() {
var form2 = new Form2();
form2.MyCustomEvent += form2CustomEvent;
form2.Show();
}
void form2CustomEvent(object sender, EventArgs e) {
myHiddenTextBox.Visible = true;
}
}
All in all this is a much better approach in terms of code architecture. Now the popup doesn't care who opens it (it has no reference to the main form), and the custom event (which is really what you're after) can be managed to any level of control you need, without interfering how other thing work (for example, perhaps later you may want to have a different action that fires this same custom event...)
Food for thought.
Is there any way to have a messagebox immediately pop up when a form opens? I just want to display a short message about how to use the form when it opens. I tried
private void myForm_Load(object sender, EventArgs e)
{
DialogResult dialogOpen = MessageBox.Show("Use the navigation menu to get started.", "Welcome!", MessageBoxButtons.OK);
}
but it doesn't work.
Showing a MessageBox during Form_Load works just fine for me. I literally copy/pasted the code from your original post, and it worked. I'm on .NET Framework 4.5 on Windows 8.1.
Are you sure your Load event handler is getting called? Perhaps the it's not hooked up to the Load event properly.
I don't see why it wouldn't work in Form_Load. Definitely try doing as others have pointed out by putting it beneath form initialization.
Though, given that you're just showing a message box, I don't think there is any reason to store the result, so a simple MessageBox.Show(message); Should do the trick.
As #s.m. said, from a UX point of view, having a notification thrown in your face as soon as the app starts would be very obnoxious, at least if you have it EVERY time. Personally, I would create a boolean Settings variable, set it to true the first time the message is displayed, and only display it when the setting is false, i.e. the first time the message is displayed.
private boolean splashShown = Properties.Settings.Default.splashShown;
private void Form_Load(object sender, EventArgs e)
{
if (!splashShown)
{
MessageBox.Show("message");
myForm.Properties.Settings.Default.splashShown = true;
myForm.Properties.Settings.Default.Save();
}
}
And set up the splashShown Setting in your form properties.
If the problem is that your Form_Load() method isn't actually attached to your Form.Load() event, you can double click the form window in the designer and it will automatically created the Form_Load() base method for you and attach it to the Form.Load() event
Is there a reason to use the Load method of the form? If not you could to it in the constructor of form. If you want it to show up immediately after your form loads, you should do it in the constructor after the form is initialized. It should look something like this:
public partial class myForm : Form
{
public myForm()
{
InitializeComponent();
DialogResult dialogOpen = MessageBox.Show("Use the navigation menu to get started.", "Welcome!", MessageBoxButtons.OK);
}
}
The constructor (public myForm()) and the InitializeComponent(); should be automatically added to the form by Visual Studio after creating it.
Form_Load event occurs before the form is really visible.
I use:
static private bool splashShown = false;
private void Form1_Activated(object sender, System.EventArgs e)
{
if (!splashShown)
{
MessageBox.Show("message");
splashShown = true;
}
}
I have used this and it works fine. App start brings up messagebox first before all else.
InitializeComponent();
MessageBox.Show("put your message here");
I have a CheckBox that has it's Checked property bound to a bool value. During the CheckedChanged event, some logic runs which uses the bool property on the data source.
My problem is the first time the CheckBox gets checked by the user, the bound data source does not get updated. Subsequent updates work fine though.
Here's some sample code for testing the problem. Just create a blank form and add a CheckBox to it.
public partial class Form1 : Form
{
private bool _testBool;
public bool TestBool
{
get { return _testBool; }
set { _testBool = value; }
}
public Form1()
{
InitializeComponent();
checkBox1.DataBindings.Add(new Binding("Checked", this, "TestBool"));
checkBox1.CheckedChanged += new EventHandler(checkBox1_CheckedChanged);
}
void checkBox1_CheckedChanged(object sender, EventArgs e)
{
checkBox1.BindingContext[this].EndCurrentEdit();
Debug.WriteLine(TestBool.ToString());
}
}
The first time I check the box, the TestBool property remains at false, even though checkBox1.Checked is set to true. Subsequent changes do correctly update the TestBool property to match checkBox1.Checked though.
If I add a breakpoint to the CheckedChanged event and check out checkBox1.BindingContext[this].Bindings[0] from the immediate window, I can see that modified = false the first time it runs, which is probably why EndCurrentEdit() is not correctly updating the data source.
The same thing also occurs with using a TextBox and the TextChanged event, so this isn't limited to just CheckBox.Checked.
Why is this? And is there a generic common way of fixing the problem?
Edit: I know of a few workarounds so far, although none are ideal since they are not generic and need to be remembered everytime we want to use a Changed event.
setting the property on the datasource directly from the CheckedChanged event
finding the binding and calling WriteValue()
hooking up the bindings after the control has been loaded
I am more concerned with learning why this is happening, although if someone knows of a standard generic solution to prevent it from happening that does not rely on any special coding in the Changed event, I'd be happy with that too.
Controls usually want to go through their validation first before writing to the data source, so the writing of the value usually won't happen until you try to leave the control.
You can force the writing of the value yourself:
void checkBox1_CheckedChanged(object sender, EventArgs e) {
Binding b = checkBox1.DataBindings["Checked"];
if (b != null) {
b.WriteValue();
}
Debug.WriteLine(TestBool.ToString());
}
Apparently, the CheckedChanged event is too early in the process.
But you can leverage BindingComplete:
public partial class Form1 : Form
{
private Boolean _testBool;
public Boolean TestBool
{
get { return _testBool; }
set { _testBool = value; }
}
public Form1()
{
InitializeComponent();
checkBox1.DataBindings.Add(new Binding("Checked", this, "TestBool", true, DataSourceUpdateMode.OnPropertyChanged));
checkBox1.DataBindings[0].BindingComplete += Form1_BindingComplete;
}
private void Form1_BindingComplete(Object sender, BindingCompleteEventArgs e)
{
Debug.WriteLine("BindingComplete: " + TestBool.ToString());
}
}
Note that the event will fire at startup as the initial bind linkage occurs. You will have to deal with that possible unintended consequence, but otherwise, it works on the first click and every click.
Also note that the true (format) is required in the Binding constructor to make the event fire.
The closest I can find for an explanation to this behavior is this 3rd party explanation
Basically, this is an issue of timing. The way binding works in DotNet
is actually very simple. There's no magic in the DotNet framework that
tells the BindingManager when something changes. What it does is, when
you bind to a property (such as CheckedValue) The BindingManager looks
for an event on the control called propertynameChanged (e.g.
"CheckedValueChanged"). This is the same event your code is hooking
into on your sample form.
When the control fires the event, the order in which the listeners
receive the event is arbitrary. There's no reliable way to tell
whether the BindingManager will get the event first or the Form will.
My CheckBox1_CheckChanged event is running before the BindingManager handles the changed event, so the data source hasn't been updated at this time.
My best guess as to why this only happens the first time is that the control isn't visible yet, so some code doesn't get run that should fix the order events get handled in. I've seen other posts about not being able to bind to non-visible items due to the handle not being created yet, and one answer states
Until the control is visible for the first time some back-end initialization never happens, and part of that initialization is enabling the data binding.
So I suspect that this is somehow related.
I can verify that if I attach the Changed handler later on such as during the Load event, it works as I would expect.
public partial class Form1 : Form
{
private bool _testBool;
public bool TestBool
{
get { return _testBool; }
set { _testBool = value; }
}
public Form1()
{
InitializeComponent();
checkBox1.DataBindings.Add(new Binding("Checked", this, "TestBool"));
Load += new EventHandler(Form1_Load);
}
void Form1_Load(object sender, EventArgs e)
{
checkBox1.CheckedChanged += new EventHandler(checkBox1_CheckedChanged);
}
void checkBox1_CheckedChanged(object sender, EventArgs e)
{
// Not needed anymore
//checkBox1.BindingContext[this].EndCurrentEdit();
Debug.WriteLine(TestBool.ToString());
}
}
...in Silverlight. No tags in the title, and all that. I'm using Silverlight 4 on Chrome, though I've tried it on IE too. I've tried:
System.Windows.Browser.HtmlPage.Plugin.Focus();
this.Focus();
Dispatcher.BeginInvoke(() => { textBox_username.Focus(); });
And various combinations thereof (as suggested by a similar thread), as well as a separate method that was attached to the form loaded event. The above gets me the closest, since clicking anywhere on the page gives my textbox focus, like the plugin isn't getting focus still. Could be because this is the first window viewed?
I dont think that was because the first window viewed. try to put this.Focus(); after your Dispatcher you set it false;
Change your code similar to below
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
this.Loaded += MainPage_Loaded;
}
void MainPage_Loaded(object sender, RoutedEventArgs e)
{
System.Windows.Browser.HtmlPage.Plugin.Focus();
txtBox.UpdateLayout();
txtBox.Focus();
}
}