Thanks, Alan. It compiles without errors. When run I get this error at
the console:
Threads aren't supported!
// c++ code begin
// -----------------------------------------------------------
#include <gtkmm.h>
#include <iostream>
using namespace std;
class myLabel: public Gtk::Window
{
// blah blah blah
public:
myLabel();
virtual ~myLabel();
protected:
Gtk::Label m_label;
string labeltext;
string newtext;
void myprocess1(void);
};
myLabel::myLabel() :
m_label("Hello World")
{
// myLabel.set_text("hello"); // This line gives errors (*1)
void myprocess1();
set_title("Gtkmm Programming - C++");
add(m_label);
m_label.show();
Glib::Thread::create(sigc::mem_fun(*this, &myLabel::myprocess1), true);
cout << "Window should be displayed" << endl;
}
myLabel::~myLabel()
{
}
void myLabel::myprocess1(void)
{
labeltext = "About to preform a number of processes.\n";
labeltext += "Each process may take up to three hours.\n";
labeltext += "Please carry your daily chores and wait.\n";
cout << labeltext << endl;
m_label.set_text(labeltext);
sleep(10); // Back from a three hour function
newtext = "Back from a three hour function\n";
labeltext += newtext;
m_label.set_text(labeltext);
cout << newtext << endl;
sleep(10); // Back from a three hour function
newtext = "Back from another three hour function\n";
labeltext += newtext;
m_label.set_text(labeltext);
cout << newtext << endl;
}
int main(int argc, char* argv[])
{
if (!Glib::thread_supported())
Glib::thread_init();
else
{
cerr << "Threads aren't supported!" << endl;
exit(1);
}
Gtk::Main kit(argc, argv);
myLabel mylabel;
Gtk::Main::run(mylabel);
return 0;
}
// -----------------------------------------------------------
// c++ code end
-- L. James
--
L. D. James
lja...@apollo3.com
www.apollo3.com/~ljames
On Mon, 2013-08-05 at 08:18 -0700, Alan Mazer wrote:
> Take a look at this. It still doesn't have dispatchers (I'm trying to
> keep it simple). It's possible for this program to crash if you try to
> interact with the window while it's updating. Dispatchers prevent
> that. But this should be otherwise functional, and I didn't want adding
> dispatchers to make understanding the thread concept more difficult.
> Adding dispatchers is just one more step.
>
> All I did here was put your long-running computation into a secondary
> thread, and have that thread update your label.
>
> The problem with your previous approach is that what "run" does is
> display the window and label you've created and then wait for you to
> interact with the window. If you put your computation *before* the
> "run", the window won't be displayed until your computation ends. If you
> put your computation *after" the "run", it won't be executed until you
> close the window.
>
> You can also put your computation *in* the window creation, but this
> means that the program won't be handling any user interactions during
> your computation. If you cover the window with another window, for
> example, and then uncover it again, it will probably be blank until your
> computation is over. Or if you had a button in the window, button
> presses would be ignored until the computation was over.
>
> What you want is for your computation to be going on at the same time as
> "run" is handling user interaction, both of them working together. So
> we create a "thread", which is a separate function that runs
> simultaneously with the "run".
>
> I hope this helps. You probably want to switch from a label to
> something with scroll bars.
>
> -- Alan
>
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