Develop Reference

Unity preventing editing of variable through script

I'm trying to make a tooltip pop up when I hover my mouse over a button. I had some issues calling the main thread from a separate thread, since the main thread is the only thread you can edit game objects from. So I decided to use a boolean and an update function to get the desired result. However, I ran into an issue I have never seen before. I am setting my boolean showToolTip to true, which is supposed to trigger the create pop-up function. However, by the time my update function runs, showTooltip is always false. I know when I set it to true, it becomes true, because I used debug statements in the requestShowTooltip function to see this. However, it is always false when the update function runs. I did some tests by changing showToolTip and removeToolTip to public booleans. I can change them in the editor while running the application, and when I manually change them through the editor they work 100% as expected, and the tooltip will appear and hide as I change the correlating booleans. However when they are changed from the script they are retained as false. I have also tried leaving them unitialized and initializing them to false in the start, and I was still having the same problem. I even tried taking "showTooltip = true;" out of the thread and just having the function do it immediately, and I was still having the same issue. showTooltip is always false when the update function is called. I have determined this by adding a debug statement in the update function that reports the value of the showTootip and removeTooltip booleans. Furthermore, no matter what, "Calling create tooltip" never appears in the console. Except for when I made the booleans public and changed them through the editor.
Some further explanation on how I set this up. I made a Tooltip Game Object that is a child of the canvas that contains the buttons I want the tooltip for. I added the Tooltips script to the tooltip object. I created event triggers in the button Game Objects. the Pointer Enter trigger calls the requestShowTooltip() function, and the Pointer Exit trigger calls the requestHideTooltip() function.
The Tooltip Background and Tooltip Text Game Objects are also children of this same canvas.
public class Tooltips : MonoBehaviour
{
private GameObject toolTipBackground;
private GameObject toolTipText;
private GameObject inButtonObject;
private bool showTooltip = false;
private bool removeTooltip = false;
void Start()
{
toolTipBackground = GameObject.Find("Tooltip background");
toolTipText = GameObject.Find("Tooltip Text");
//inButton = GameObject.Find("Aft Button");
toolTipBackground.SetActive(false);
toolTipText.SetActive(false);
//Debug.Log("Tool Tip Start");
}
void Update()
{
// show the tooltip when the appropriate boolean has been set
// to true
if(removeTooltip)
{
hideTooltip();
}
// this if statement is always false, because showTooltip is
// always false when the update function is called??
if(showTooltip)
{
Debug.Log("Calling create tooltip");
createTooltip();
}
}
// A timed request for a tooltip to show. The tooltip should
// currently show one second after the request has been made. The
// text of the tooltip will be equal to the passed object's name
public void requestShowTooltip(GameObject inButtonObject)
{
Thread thread = new Thread(delegate ()
{
System.Threading.Thread.Sleep(1000);
this.inButtonObject = inButtonObject;
// I know this runs, but showTooltip is always returning
// to false when the update function is called??
showTooltip = true;
removeTooltip = false;
Debug.Log("Request function completed");
});
thread.start();
}
public void createTooltip()
{
toolTipText.SetActive(true);
toolTipBackground.SetActive(true);
string labelString = inButtonObject.name;
Button inButton = inButtonObject.GetComponent<Button>();
int width = labelString.Length * 10;
int height = 35;
Vector2 size = new Vector2(width, height);
Vector3 position = new Vector3(inButton.transform.x,
inButton.transform.position.y,
inButton.transform.position.z + 1);
toolTipBackground.GetComponent<RectTransform>().
sizeDelta = size;
toolTipText.GetComponent<RectTransform>().sizeDelta = size;
toolTipBackground.transform.position = position;
toolTipText.transform.position = position;
toolTipText.GetComponent<Text>().text = labelString;
showTooltip = false;
}
public void requestHideTooltip()
{
removeTooltip = true;
showTooltip = false;
}
public void hideTooltip()
{
Vector2 hide = new Vector2(0, 0);
toolTipBackground.GetComponent<RectTransform>().
sizeDelta = hide;
toolTipText.GetComponent<RectTransform>().sizeDelta = hide;
toolTipText.setActive(false);
toolTopBackground.SetActive(false);
removeTooltip = false;
showTooltip = false;
}
}

Since basically everything in Unity needs to be called in the main Thread (with very few exceptions) I would suggest to change your code using a ConcurrentQueue<Action> and TryDequeue to let the main thread work through all the responses from any thread.
// a queue for storing actions that shall be handled by the main thread
// a ConcurrentQueue in specific is thread-save
private ConcurrentQueue<Action> actions = new ConcurrentQueue<Action>();
private void Update()
{
// invoke all actions from the threads in the main thread
while(!actions.IsEmpty)
{
// TryDequeue writes the first entry to currentAction
// and at the same time removes it from the queue
// if it was successfull invoke the action otherwise do nothing
if(actions.TryDequeue(out var currentAction))
{
currentAction?.Invoke();
}
}
if(removeTooltip)
{
hideTooltip();
}
if(showTooltip)
{
Debug.Log("Calling create tooltip");
createTooltip();
}
}
Then in your Thread instead of making the thread directly execute the stuff itself rather pass it back to the main thread using the actions queue and add a new Action to the end using Enqueue
public void requestShowTooltip(GameObject inButtonObject)
{
Thread thread = new Thread(delegate()
{
System.Threading.Thread.Sleep(1000);
// add an Action to the end of the queue
// e.g. as lambda-expression
actions.Enqueue(()=>
{
this.inButtonObject = inButtonObject;
// I know this runs, but showTooltip is always returning
// to false when the update function is called??
showTooltip = true;
removeTooltip = false;
Debug.Log("Request function completed");
});
});
thread.start();
}
You might want to consider btw to make inButtonObject of type Button - first in order to make sure the passed object always has a/is a Button and second you can get rid of the performance intense GetComponent call.
The same way I would rather store
RectTransform toolTipBackgroundRectTransform;
Text toolTipText;
RectTransform toolTipTextrectTransform;
since those are the components you can get already once in Start and then you can re-use always the same references and get rid of all further GetComponent calls.

Pause the while loop until the button is pressed w/o using event handler C#

I am struggling to workout how to create something that essentially pauses my while loop until my button1 is pressed, I know about the event handler button1_Click but I don't think that will work in this situation as I have lots of loops nested in each other on my form_load.
Any help would be highly appreciated!
This is a snipped of my code where I want the loop to be 'paused' with the notes:
while (reader2.Read())
{
QuestionSpace = Convert.ToString(reader2["Question Space"]);
label1.Text = QuestionSpace;
if (button1.Click = true) // if the button is clicked)
{
// continue with the while loop (I am going to add an INSERT SQL query in here later)
}
else
{
// pause until the button is pressed
}
}
My whole code for the form:
public partial class CurrentlySetTestForm : Form
{
private int QuestionID { get; set; }
private string QuestionSpace { get; set; }
public CurrentlySetTestForm()
{
InitializeComponent();
}
private void CurrentlySetTestForm_Load(object sender, EventArgs e)
{
string y = GlobalVariableClass.Signedinteacher;
MessageBox.Show(y);
Convert.ToInt32(y);
string connectionString = ConfigurationManager.ConnectionStrings["myconnectionstring"].ConnectionString;
SqlConnection connect = new SqlConnection(connectionString);
connect.Open();
SqlCommand command18 = new SqlCommand("SELECT [QuestionID] FROM QuestionStudentAssociation WHERE ( [StudentID]=#Signedinstudent)", connect);
command18.Parameters.AddWithValue("#Signedinstudent", y);
var reader = command18.ExecuteReader();
while (reader.Read())
{
QuestionID = Convert.ToInt32(reader["QuestionID"]);
SqlCommand command19 = new SqlCommand(#"SELECT [Question Space] FROM Questions WHERE ( [QuestionID] = #currentQID )", connect);
command19.Parameters.AddWithValue("#currentQID", QuestionID);
try
{
var reader2 = command19.ExecuteReader();
while (reader2.Read())
{
QuestionSpace = Convert.ToString(reader2["Question Space"]);
label1.Text = QuestionSpace;
if (button1.Click = true) // if the button is clicked)
{
// continue with the while loop (I am going to add an INSERT SQL query in here later)
}
else
{
// pause until the button is pressed
}
}
}
catch (SyntaxErrorException ex)
{
MessageBox.Show(ex.Message);
}
finally
{
MessageBox.Show("Done one loop");
}
}
}
}

Sounds like your not ready to learn TPL
So maybe a BackgroundWorker , you can paint it on the form
To make the click cancel the background worker have a look at Cancel backgroundworker
I would some time to learn TPL as its going to create a simpler and more elegant solution.
As for pausing I would refactor the code, you should not keep the reader open waiting on the user.

You do want event-driven response to UI events, always. However, I guess that you don't want to split your logic into a state machine by hand (where each event triggers progress to the next state). Well, you're in luck, the C# compiler has some keywords to build state machines automagically so you don't have to manage the details.
There are actually two different mechanisms for continuation-passing style implemented in C#. The old one, yield return, works great if your UI events are pretty much interchangeable (or you're only interested in one). Works like this:
IEnumerator<int> Coroutine;
// this could be a Form_Load, but don't you need to get the user information before making the database connection?
void BeginQuiz_Click( object sender, EventArgs unused )
{
Coroutine = RunQA();
}
IEnumerator<int> RunQA()
{
// connect to DB
// show first question on UI
return ContinueQA();
}
IEnumerator<int> ContinueQA()
{
// you can use a while loop instead if you really want
for( int question = 0; question < questionCount; ++question )
{
// check answer
if (/* too many wrong answers*/) {
// report failure in DB
yield break;
}
// get next question from DB
// show new question on the UI
// wait for UI action
yield return question;
}
// report score in DB
// update UI with completion certificate
}
void AnswerButton_Click( object sender, EventArgs unused )
{
answer = sender;
Coroutine.MoveNext(); // MAGIC HAPPENS HERE
}
void TimeoutTimer_Tick( object sender, EventArgs unused )
{
answer = TimeoutTimer;
Coroutine.MoveNext();
}
The magic comes from yield return. Every time the function reaches yield return, the compiler saves what you were doing. When the button click event comes and calls MoveNext, the compiler generates code that starts where yield return paused everything, and keeps going from there until the next yield return.
Important note, the code inside ContinueQA doesn't start when RunQA() does return ContinueQA(); It actually starts on the first MoveNext(). So split your code between RunQA() and ContinueQA accordingly.
If you need different pause reasons at different places in your code, then async/await will be more helpful.

A better way to handle this would be the use of a timer. This would allow the form to draw it's controls and handle all input, such as clicking the button.
Adjust the timer interval (ms) to your needs.
Another way of doing this would be, as Mehrzad Chehraz said, to use multi-threading.
On a side note, I would strongly recommend condition checks over the try/catch checks if possible.
Enable/Disable the timer using the button and call the loop when the timer ticks.
Example:
Timer loopTimer = new Timer();
private void Form1_Load(object sender, EventArgs e)
{
loopTimer.Interval = 100;
loopTimer.Tick += loopTimer_Tick;
loopTimer.Enabled = true;
}
void loopTimer_Tick(object sender, EventArgs e)
{
//perform the loop here at the set interval
}
private void button1_Click(object sender, EventArgs e)
{
//pause/play the loop
loopTimer.Enabled = !loopTimer.Enabled;
}

How to safely give my function without making my main form stuck

I have made a WPF application which has a button to move some files attached
to the column cells from one column to another column. The moment when I press
the button it shows a nice animation and moves all files to the next column's cells.
But my real problem is once I give my function color_check(),
my application is getting stuck. I really don't know why. Is there
any help I can get out for this?
Code:
private void button3_Click(object sender, EventArgs e)
{
Hide();
bool done = false;
ThreadPool.QueueUserWorkItem((x) =>
{
using (var splashForm = new Form4())
{
splashForm.Show();
while (!done)
Application.DoEvents();
splashForm.Close();
}
});
move(); //file moving function
//color_check(); if i give this fn, my form stucks and comes to live after 10 - 20 sec
done = true;
MessageBox.Show("TEST FINISHED");
Show();
}
public void color_check() //this is my problem making fn
{
dataGridView1.Refresh();
string strVal = ini.ReadValue("Action", "Doc-Controller");
bool authenticated = true;
if (authenticated == UserInCustomRole(strVal))
{
foreach (DataGridViewRow row in dataGridView1.Rows)
{
// Application.DoEvents();
string fName1 = System.IO.Path.GetFileNameWithoutExtension(row.Cells[3].Value.ToString());
string fName2 = System.IO.Path.GetFileNameWithoutExtension(row.Cells[4].Value.ToString());
if (!string.IsNullOrEmpty(fName1) && !string.IsNullOrEmpty(fName2))
{
var f1 = GetValue(fName1.ToCharArray()[fName1.Length - 2]) * 16 + GetValue(fName1.ToCharArray()[fName1.Length - 1]);
var f2 = GetValue(fName2.ToCharArray()[fName2.Length - 2]) * 16 + GetValue(fName2.ToCharArray()[fName2.Length - 1]);
//if (System.IO.Path.GetFileName(fName1) != System.IO.Path.GetFileName(fName2))
if (f1 > f2)
{
//MessageBox.Show(fName1);
DataGridViewCellStyle style = new DataGridViewCellStyle();
style.BackColor = Color.Yellow;
row.Cells[3].Style = style;
}
else if (f2 > f1)
{
//MessageBox.Show(fName1);
DataGridViewCellStyle style = new DataGridViewCellStyle();
style.BackColor = Color.Yellow;
row.Cells[4].Style = style;
}
if (f1 == f2)
{
DataGridViewCellStyle style = new DataGridViewCellStyle();
style.BackColor = Color.Plum;
row.Cells[4].Style = style;
row.Cells[3].Style = style;
}
}
}
}

The issue is that your code which is invoked on button3_click() is blocking the UI thread. That's why it appears to freeze for a while - the code is executing, and once it's complete the UI thread becomes responsive again.
The way to resolve this is to perform your actions asynchronously on another thread. In .NET 4 and beyond, you can use Tasks and the async/await keywords to help you manage this. If you are working on a version older than .NET 4, then you'll want to take a look at BackgroundWorker or other threading options compatible with your version of .NET.
Note that if you want to modify the GUI in your async method, you may need to use a Dispatcher.Invoke() to do so safely.
Here are some links to help you understand some approaches available to you
C# Blog on Understanding a simple async program
MSDN reference for async/await
Related StackOverflow question on how to use BackgroundWorkers
Related StackOverflow question on how to access the UI thread directly

In a normal UI application, no 2 functions that work on the GUI will run at the same time. This would result in a lot of issues otherwise, which usually would cause the program to crash. For example there could be 2 functions running at the same time that each check if the same list has at least one element and then remove an element - because they run at the same time they first both check if the list has 1 element.
That's why GUI functions all run in the same thread, meaning they run only one at a time. While color_check runs, other functions don't run.
You can launch additional threads and do work on them that is executed in parallel, of you can speed up the color_check function, for example by breaking it up into parts which run at lower priority one at a time, using a dispatcher
Take this:
public void color_check() //this is my problem making fn
{
dataGridView1.Refresh();
string strVal = ini.ReadValue("Action", "Doc-Controller");
bool authenticated = true;
if (authenticated == UserInCustomRole(strVal))
{
foreach (DataGridViewRow row in dataGridView1.Rows)
{
ProcessRow(row);
}
}
}
and change it to this:
public void color_check() //this is my problem making fn
{
dataGridView1.Refresh();
string strVal = ini.ReadValue("Action", "Doc-Controller");
bool authenticated = true;
if (authenticated == UserInCustomRole(strVal))
{
foreach (DataGridViewRow row in dataGridView1.Rows)
{
Dispatcher.BeginInvoke(DispatcherPriority.Background, ()=>{Process(row);});
}
}
}
In this code, Dispatcher.BeginInvoke tells the UI thread that it should run Process(row), as soon as it finds the time. This might result in 200 Process(row) calls that are waiting to be executed. It's still all executed on the UI thread and only one thing at a time. If a mouse click happens after the first hundred have been completed, the GUI thread will first finish number onehunderd and one, and then handle the mouseclick, before picking up the remaining calls to process.
There's a disadvantage to this approach. By allowing other functions to be executed in between different calls to Process(row), you may get surprising results. Especially if these other processes also change the cell styles.

WPF progressbar not showing

I set a WPF ProgressBar's Is indeterminate to True and Visibility to Hidden. In a event handler I am trying to make the ProgressBar visible while a ObservableCollection is being updated (and a ListView whose ItemsSource is the ObservableCollection). I hope DoEvents() from System.Windows.Forms.Application can make it visible but it does not.
I notice SetPBarHelper(() => { ..} ) usually finish much earlier than the ListView shows visual changes.
How do I make the ProgressBar Visible inside event handler codes ?
How to tell if my ListView is still being updated even though the ObserableCollection has finished adding items ?
<ProgressBar x:Name="GeneralProgressBar" Width="300" Height="15" IsIndeterminate="True" Visibility="Hidden"/>
private void SetPBar(bool isVisible)
{
if (isVisible)
GeneralProgressBar.Visibility = System.Windows.Visibility.Visible;
else
GeneralProgressBar.Visibility = System.Windows.Visibility.Hidden;
}
private void SetPBarHelper(Action handler)
{
SetPBar(true); // try to make ProgressBar visible
System.Windows.Forms.Application.DoEvents();
handler(); // use the event handling, which run database query
SetPBar(false); // try to make ProgressBar disappear
}
private void CommandForumImagesBinding_Executed(object sender, ExecutedRoutedEventArgs e)
{
SetPBarHelper(() =>
{
if (e.Parameter == null)
return;
var vm = e.Parameter as ForumViewModel;
if (vm != null)
{
}
});
}
public sealed class ImageGroupCollection : ObservableCollection<ImageGroup>
{
public ImageGroupCollection() : base() { }
public void Update(DateTime start, DateTime end)
{
ClearItems();
var list = MyDatabase.GetRecords(start, end);
if (list != null)
{
foreach (var g in list)
{
Add(g);
}
}
}
}

Your problem is simply because you are blocking the UI thread. You can't do that.
By the time the UI thread is running the message loop again you have set ProgressBar.Visible = false. The ProgressBar is never drawn.
Assuming you are using .net 4.5 You need to rewrite the code as follows.
private async Task SetPBarHelper(Action handler)
{
SetPBar(true); // try to make ProgressBar visible
System.Windows.Forms.Application.DoEvents();
await Task.Run(handler); // use the event handling, which run database query
SetPBar(false); // try to make ProgressBar disappear
}
But overall you need to return control of the UI thread back to the application loop as soon as possible to allow it to redraw the windows, and run the update on a WorkerThread.

Displaying a "User control is loading" message while loading a User Control

I have a Winforms Application with a TabStrip Control. During runtime, UserControls are to be loaded into different tabs dynamically.
I want to present a "User Control xyz is loading" message to the user (setting an existing label to visible and changing its text) before the UserControl is loaded and until the loading is completely finished.
My approaches so far:
Trying to load the User Control in a BackgroundWorker thread. This fails, because I have to access Gui-Controls during the load of the UserControl
Trying to show the message in a BackgroundWorker thread. This obviously fails because the BackgroundWorker thread is not the UI thread ;-)
Show the Message, call DoEvents(), load the UserControl. This leads to different behaviour (flickering, ...) everytime I load a UserControl, and I can not control when and how to set it to invisible again.
To sum it up, I have two questions:
How to ensure the message is visible directly, before loading the User control
How to ensure the message is set to invisible again, just in the moment the UserControl is completely loaded (including all DataBindings, grid formattings, etc.)

what we use is similar to this:
create a new form that has whatever you want to show the user,
implement a static method where you can call this form to be created inside itself, to prevent memory leaks
create a new thread within this form so that form is running in a seperated thread and stays responsive; we use an ajax control that shows a progress bar filling up.
within the method you use to start the thread set its properties to topmost true to ensure it stays on top.
for instance do this in your main form:
loadingForm.ShowLoadingScreen("usercontrollname");
//do something
loadingform.CloseLoadingScreen();
in the loading form class;
public LoadingScreen()
{
InitializeComponent();
}
public static void ShowLoadingScreen(string usercontrollname)
{
// do something with the usercontroll name if desired
if (_LoadingScreenThread == null)
{
_LoadingScreenThread = new Thread(new ThreadStart(DoShowLoadingScreen));
_LoadingScreenThread.IsBackground = true;
_LoadingScreenThread.Start();
}
}
public static void CloseLoadingScreen()
{
if (_ls.InvokeRequired)
{
_ls.Invoke(new MethodInvoker(CloseLoadingScreen));
}
else
{
Application.ExitThread();
_ls.Dispose();
_LoadingScreenThread = null;
}
}
private static void DoShowLoadingScreen()
{
_ls = new LoadingScreen();
_ls.FormBorderStyle = FormBorderStyle.None;
_ls.MinimizeBox = false;
_ls.ControlBox = false;
_ls.MaximizeBox = false;
_ls.TopMost = true;
_ls.StartPosition = FormStartPosition.CenterScreen;
Application.Run(_ls);
}

Try again your second approach:
Trying to show the message in a BackgroundWorker thread. This obviously fails because the BackgroundWorker thread is not the UI thread ;-)
But this time, use the following code in your background thread in order to update your label:
label.Invoke((MethodInvoker) delegate {
label.Text = "User Control xyz is loading";
label.Visible = true;
});
// Load your user control
// ...
label.Invoke((MethodInvoker) delegate {
label.Visible = false;
});
Invoke allows you to update your UI in another thread.

Working from #wterbeek's example, I modified the class for my own purposes:
center it over the loading form
modification of its opacity
sizing it to the parent size
show it as a dialog and block all user interaction
I was required to show a throbber
I received a null error on line:
if (_ls.InvokeRequired)
so I added a _shown condition (if the action completes so fast that the _LoadingScreenThread thread is not even run) to check if the form exists or not.
Also, if the _LoadingScreenThread is not started, Application.Exit will close the main thread.
I thought to post it for it may help someone else. Comments in the code will explain more.
public partial class LoadingScreen : Form {
private static Thread _LoadingScreenThread;
private static LoadingScreen _ls;
//condition required to check if the form has been loaded
private static bool _shown = false;
private static Form _parent;
public LoadingScreen() {
InitializeComponent();
}
//added the parent to the initializer
//CHECKS FOR NULL HAVE NOT BEEN IMPLEMENTED
public static void ShowLoadingScreen(string usercontrollname, Form parent) {
// do something with the usercontroll name if desired
_parent = parent;
if (_LoadingScreenThread == null) {
_LoadingScreenThread = new Thread(new ThreadStart(DoShowLoadingScreen));
_LoadingScreenThread.SetApartmentState(ApartmentState.STA);
_LoadingScreenThread.IsBackground = true;
_LoadingScreenThread.Start();
}
}
public static void CloseLoadingScreen() {
//if the operation is too short, the _ls is not correctly initialized and it throws
//a null error
if (_ls!=null && _ls.InvokeRequired) {
_ls.Invoke(new MethodInvoker(CloseLoadingScreen));
} else {
if (_shown)
{
//if the operation is too short and the thread is not started
//this would close the main thread
_shown = false;
Application.ExitThread();
}
if (_LoadingScreenThread != null)
_LoadingScreenThread.Interrupt();
//this check prevents the appearance of the loader
//or its closing/disposing if shown
//have not found the answer
//if (_ls !=null)
//{
_ls.Close();
_ls.Dispose();
//}
_LoadingScreenThread = null;
}
}
private static void DoShowLoadingScreen() {
_ls = new LoadingScreen();
_ls.FormBorderStyle = FormBorderStyle.None;
_ls.MinimizeBox = false;
_ls.ControlBox = false;
_ls.MaximizeBox = false;
_ls.TopMost = true;
//get the parent size
_ls.Size = _parent.Size;
//get the location of the parent in order to show the form over the
//target form
_ls.Location = _parent.Location;
//in order to use the size and the location specified above
//we need to set the start position to "Manual"
_ls.StartPosition =FormStartPosition.Manual;
//set the opacity
_ls.Opacity = 0.5;
_shown = true;
//Replaced Application.Run with ShowDialog to show as dialog
//Application.Run(_ls);
_ls.ShowDialog();
}
}