99 lines
3.2 KiB
C++
99 lines
3.2 KiB
C++
// Copyright (c) 2015 Amanieu d'Antras
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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#include <async++.h>
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#include <gtk/gtk.h>
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#include <iostream>
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#include <chrono>
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#include <string>
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// Scheduler implementation
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class gtk_scheduler_impl {
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// Get the task from the void* and execute it in the UI thread
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static gboolean callback(void* p)
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{
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async::task_run_handle::from_void_ptr(p).run();
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return FALSE;
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}
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public:
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// Convert a task to void* and send it to the gtk main loop
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void schedule(async::task_run_handle t)
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{
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g_idle_add(callback, t.to_void_ptr());
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}
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};
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// Scheduler to run a task in the gtk main loop
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gtk_scheduler_impl& gtk_scheduler()
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{
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static gtk_scheduler_impl sched;
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return sched;
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}
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// In order to ensure the UI is always responsive, you can disallow blocking
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// calls in the UI thread. Note that the wait handler isn't called when the
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// result of a task is already available, so you can still call .get() on a
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// completed task. This is completely optional and can be omitted if you don't
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// need it.
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void gtk_wait_handler(async::task_wait_handle)
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{
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std::cerr << "Error: Blocking wait in UI thread" << std::endl;
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std::abort();
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}
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// Thread which increments the label value every ms
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void label_update_thread(GtkLabel *label)
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{
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int counter = 0;
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while (true) {
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// Sleep for 1ms
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std::this_thread::sleep_for(std::chrono::milliseconds(1));
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counter++;
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// Update the label contents in the UI thread
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async::spawn(gtk_scheduler(), [label, counter] {
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gtk_label_set_text(label, std::to_string(counter).c_str());
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});
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}
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}
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int main(int argc, char *argv[])
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{
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// Initialize GTK
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gtk_init(&argc, &argv);
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// Set wait handler on GTK thread to disallow waiting for tasks
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async::set_thread_wait_handler(gtk_wait_handler);
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// Create a window with a label
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GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
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g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
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GtkLabel *label = GTK_LABEL(gtk_label_new("-"));
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gtk_container_add(GTK_CONTAINER(window), GTK_WIDGET(label));
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gtk_widget_show_all(window);
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// Start a secondary thread to update the label
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std::thread(label_update_thread, label).detach();
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// Go to GTK main loop
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gtk_main();
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}
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