Regarding the usage of xtd::forms::busy_box

[baderouaich]

Hello! I hope you are doing fine!

I have a question regarding xtd::forms::busy_box usage.

It is necessary to call xtd::application::do_events() between xtd::forms::busy_box::show() and xtd::forms::busy_box::hide() in order for the busy_box to be visible, which raises some confusion on where exactly do_events should be called.

for example:

• This one is fine because there are no sub functions and the code is simple:

form1() {
    text("Busy box example");
    
    button1.auto_size(true);
    button1.location({10, 10});
    button1.parent(*this);
    button1.text("Do something...");
    button1.click += [] {
      busy_box::show("Please wait while do something...", "Application busy");
      for (auto count = 0; count < 500; ++count) {
        application::do_events();
        thread::sleep(10);
      }
      busy_box::hide();
    };
  }

• But this one is bit more confusing for me, for example:

form1(){
busy_box::show(*this, "Initializing...", "form1");

  startup_panel_.auto_scroll(true);
  startup_panel_.parent(*this);
  startup_panel_.size(client_size() - drawing::size {0, 100});

application::do_events(); // <-- i must call this here to make busy_box visible
  
  startup_open_recent_projects_list_box_.parent(startup_panel_);
  startup_open_recent_projects_list_box_.location({50, 175});

application::do_events(); // <-- i must call this here to make busy_box visible
  
  some_function();  // <-- should i call application::do_events also from within the function ?

  application::do_events(); // <-- i must call this here to make busy_box visible

  some_function_that_calls_other_init_functions(); // <-- should i call application::do_events() from within all sub-functions ?
  
  busy_box::hide();
}

Is there a better approach to use busy_box correctly ?

Thanks in advance!

[gammasoft71]

I'm fine thanks.

First of all the xtd::application::do_events method processes all Windows messages currently in the message queue.
Read the Remarks and Warningsections for more information about this method.

This is a didactic example, designed to show you how to use the xtd::forms::message_box dialog box.
This example is simple to focused the use of xtd::forms::busy_box.

The following lines simply emulate a time-consuming process:

for (auto count = 0; count < 500; ++count) {
  application::do_events();
  thread::sleep(10);
}

But in real code, you'll never use the for loop with the xtd::threading::thread::sleep and xtd::forms::application::do_event statements.
It's a very bad idea to do complex, time-consuming processing in an event.

Instead, create an xtd::threading::thread or, even better, an xtd::forms::background_worker in which you can call your business classes. Which can take a lot of time without blocking graphic thread events.

See How to create a thread ? wiki for xtd::threading::thread and xtd::forms::background_worker usage.

Examples

The follwing example shows how to use xtd::forms::busy_box with xtd::forms::background_worker :

#include <xtd/forms/application>
#include <xtd/forms/background_worker>
#include <xtd/forms/busy_box>
#include <xtd/forms/button>
#include <xtd/forms/form>
#include <xtd/threading/thread>

using namespace xtd::forms;
using namespace xtd::threading;

class form1 : public form {
public:
  form1() {
    text("Busy box example with background_worker");
    
    backgound_worker1.worker_supports_cancellation(true);
    backgound_worker1.do_work += [] {
      // Call your business class here.
      // the folowing line simulate time consuming process
      thread::sleep(5000);
    };
    
    backgound_worker1.run_worker_completed += [this] {
      busy_box::hide();
      button1.enabled(true);
    };
    
    button1.auto_size(true);
    button1.location({10, 10});
    button1.parent(*this);
    button1.text("Do something...");
    button1.click += [this] {
      button1.enabled(false);
      busy_box::show("Please wait while do something...", "Application busy");
      backgound_worker1.run_worker_async();
    };
    
    form_closed += [this] {
      backgound_worker1.cancel_async();
    };
  }
  
private:
  button button1;
  background_worker backgound_worker1;
};

auto main()->int {
  xtd::forms::application::run(form1 {});
}

The follwing example shows how to use xtd::forms::busy_box with xtd::threading::thread and xtd::forms::control::invoke method :

#include <xtd/forms/application>
#include <xtd/forms/busy_box>
#include <xtd/forms/button>
#include <xtd/forms/form>
#include <xtd/threading/thread>

using namespace xtd::forms;
using namespace xtd::threading;

class form1 : public form {
public:
  form1() {
    text("Busy box example with thread");
        
    button1.auto_size(true);
    button1.location({10, 10});
    button1.parent(*this);
    button1.text("Do something...");
    button1.click += [this] {
      button1.enabled(false);
      busy_box::show("Please wait while do something...", "Application busy");
      thread1 = thread {[this] {
        // Call your business class here.
        // the following line simulates a time-consuming process
        thread::sleep(5000);
        
        invoke([this] {
          busy_box::hide();
          button1.enabled(true);
        });
      }};
      thread1.start();
    };
    
    form_closing += [this](object& sender, form_closing_event_args& e) {
      e.cancel(thread1.is_alive());
    };
  }
  
private:
  button button1;
  thread thread1;
};

auto main()->int {
  xtd::forms::application::run(form1 {});
}

Remarks

This explanation applies to all examples using the xtd::forms::applicaiton::do_events and xtd::threading::thread::sleep methods to simulate a long process.

I hope that's clearer for you.

[baderouaich]

Thank you so much!! it's clear now 👌