I want to create a loop in my windowform application in C++/CLI.
I have the following button:
private: System::Void button17_Click(System::Object^ sender, System::EventArgs^ e) {
this->button17->ForeColor = System::Drawing::Color::Lime;
while (true) {
if (button17->Enabled == true) {
HWND hwnd1;
hwnd1 = FindWindow(NULL, "1");
}
else {
break;
}
} /// End while
}
I created a button with a while() statement. When I press the 'on' button, the loop should execute, and when I press this button again, the loop should end, and the program should stop this while statement.
However, when I press my button, the program does what I want, but my application suspends and can't do anything. What am I doing wrong, and how can make a loop when I press a button, and stop the loop when I press the button again?
C++/CLI is not "just C++". It is for writing code to interface C# or other .Net languages to C++ code. If you want to write "just C++", make a C++ project and use MFC for the GUI.
In any language, the answer is this: A while loop in a button handler will cause the UI thread to be busy with the while loop, and not with such things as redrawing the UI or responding to the subsequent button push. For this, I'd start a background thread at program load, and use a synchronization object to trigger whether the thread is doing work or not.
You are blocking your current thread.
You need to take this loop and put it in a thread. Then launch the thread to run in the background.
while (true) {
if (button17->Enabled == true) {
HWND hwnd1;
hwnd1 = FindWindow(NULL, "1");
}
else {
break;
}
} /// End while
Related
This might be a simple question but I can't figure it out.
I have a form called in my main function:
void Main() {
Mem = new MemoryManager();
Console::WriteLine("Thread Started");
Application::EnableVisualStyles();
Application::SetCompatibleTextRenderingDefault(false);
FinalSolution::ControlPanel form;
Thread^ cLoop = gcnew Thread(gcnew ThreadStart(loop));
cLoop->Start();
Application::Run(%form);
}
All I want to do is, if someone presses a key in general (not just when the program is in focus), it changes the background to a different color.
I have tried a few things but nothing has worked so far. Here is the loop and I have indicated where I want it to happen.
void loop() {
while (true) {
if (GetAsyncKeyState(key)) {
//Here
form.button->BackColor = System::Drawing::Color::ForestGreen;
}
}
}
Of course the issue is that this function doesn't know what form is, but I don't know how to tell it.
Ended up just putting the loop directly in the form header and that solved the problem.
In my application, I am handling a QCloseEvent (when the close button X was pressed):
void MainWindow::closeEvent(QCloseEvent* event)
{
if ( !isAbortedFilestoSave() ) {
this->close();
}
// else abort
}
The if clause is triggereed when no abort was pressed. I would like to implement an else clause where a QCloseEvent is aborted? How?
You must use the ignore() on the event to "abort it" - to let Qt know you don't want the widget to actually close.
The isAccepted() function returns true if the event's receiver has agreed to close the widget; call accept() to agree to close the widget and call ignore() if the receiver of this event does not want the widget to be closed.
Also, no need to call close() yourself - the "X" button does that already, that's why you receive a close event!
So your code should be:
void MainWindow::closeEvent(QCloseEvent* event)
{
// accept close event if are not aborted
event->setAccepted(!isAbortedFilestoSave());
}
I'am very new to threading and quite unclear as to why this is happening in my code, when I click on a button that verifies hyperlinks in my document, I start a new thread that does the verification once it starts I want to disable the ribbon button and enable it again after thread finished but this is not happening and I dont know what is the mistake .Here is what I have tried so far:
public class Alpha :Ribbon1
{
// This method that will be called when the thread is started
public void Beta()
{
foreach() { //do something } after this loop ,enable the button again
button.enable=true //not applying
} }
private void button_Click(object sender, RibbonControlEventArgs e)
{
Alpha oAlpha = new Alpha();
// Create the thread object, passing in the Alpha.Beta method
Thread oThread = new Thread(new ThreadStart(oAlpha.Beta));
// MessageBox.Show("Please wait till the document is checked for invalid links");
// Start the thread
oThread.Start();
button7.Label = "Pls wait";
button7.Enabled = false;
}
Ribbon needs to be rendered again after enable/disable for change to take effect, you can do this by calling IRibbonUI.Invalidate()
I've seen a few references on Stack Overflow about using the Timer Class to do what I want but I'm not convinced it's the right solution to the problem.
Basically, I have a button (in .NET 4.0) that when clicked will go through a few different subroutines and do certain things:
Restart some services
Launch a command line application that finishes automatically
Launch a second command line application that finishes automatically
Launch a third command line application that finishes automatically
The problem I have right now is that the program just goes through each thing and fires it off as quickly as possible - not a problem except that the third command line application must only fire after the first three are completed.
I had a sleep call in the code, except that this froze the UI and I have a status bar on this application that I wanted to have update to let the user know things are occurring.
I was thinking about a Timer object but I'm not sure that would actually cause there to be a pause before doing the next thing.
I'm using a Process.Start method to fire off the command line applications, so it doesn't actually raise an event. Should I just have my subroutine raise an event and then have the third Process.Start method wait for that event to fire before it goes?
This small snippet might help you. Try to get the idea and implement your own code.
try
{
Process myProcess;
myProcess = Process.Start("Notepad.exe");
while (true)
{
if (!myProcess.HasExited)
{
// Discard cached information about the process.
myProcess.Refresh();
// Print working set to console.
Console.WriteLine("Physical Memory Usage: "
+ myProcess.WorkingSet.ToString());
// Wait 2 seconds.
Thread.Sleep(2000);
}
else {
break;
}
}
// Close process by sending a close message to its main window.
myProcess.CloseMainWindow();
// Free resources associated with process.
myProcess.Close();
}
catch(Exception e)
{
Console.WriteLine("The following exception was raised: ");
Console.WriteLine(e.Message);
}
while debugging the java Multithreading program i put breakpoints. after start method is invoking the control is not going to run menthod can you please let me know the debug procedure.
sample code
class Test extends Thread {
public static void main(String[] args) {
try {
Thread t = new Thread(new Test());
t.start();
t.start();
} catch (Exception e) {
System.out.print("e ");
}
}
public void run() {
for(int i = 0; i < 2; i++)
System.out.print(Thread.currentThread().getName() + " ");
}
}
Debugger starts with main thread, since your breakpoint is in main thread.
t.start() spawns a new thread.
But the debugger will continue with the main thread itself.
If you want to debug the newly created thread, then you have to set a breakpoint in run() method also.Then the debugger control goes to the newly created thread, but it is invisible to the user.
If you want to see the control in run() method of newly created thread, then you have to follow the below steps -
Put a breakpoint in run() method along with the main() method.
Start debugging the program till you hit the statement t.start().
After completing t.start(), go to "Debug" view. There you will find 2 threads running.(You can find the "Debug" view in eclipse by going to "Window -> Show View -> Debug").
First one is main thread
Second one is newly created thread (e.g. [Thread-1] )
Click on the second thread to see the control in run method.
After completion of your thread execution, go to the "Debug" view again and click on the main thread to continue with the main thread debugging.
Note: If you continue with the main thread after 3rd step towards the end of the thread, then you will not be able to debug your new thread.